Effects of transport age (14 d vs. 28 d of age) on blood total cholesterol, insulin and IGF-1 concentrations of veal calves

The main aim of the current study was to find biomarkers of health in calves transported at different ages. The selected blood parameters were total cholesterol, insulin and IGF-1 and the longitudinal study investigated whether or not these concentrations were different between calves that were transported from the dairy farm to the veal farm at 14 d or 28 d of age. Relationships between these blood variables and health characteristics of veal calves were investigated. In a 34-wk study period, a total of 683 calves originating from 13 Dutch dairy farms were transported at an age of 14 or 28 d to 8 Dutch veal farms. Calves were blood sampled the first wk after birth (mean and SD: 4.4 ± 2.1 d), a day before transport (mean and SD: 25.8 ± 7.3 d) and in wk 2 post-transport (mean and SD: 36.7 ± 12.2 d). In these samples, insulin, IGF-1 and total cholesterol were determined and analyzed with a linear mixed model (LMM). Individual medical treatments were recorded from birth until the day of transport at the dairy farm, and from the moment of arrival at the veal farm until slaughter, and analyzed as a binary response variable (calf treated or not) with a generalized linear mixed model. Fecal (calf with or without loose or liquid manure) and navel (calves with or without swollen and inflamed navel) scores measured during a single visit in wk 2 post-transport were also analyzed as binary response variables, whereas carcass weights at slaughter age were analyzed with a LMM. Cholesterol, insulin and IGF-1 were included as covariates in the previous models to test their relationships with the likelihood of calves being medically treated, fecal and navel scores, and carcass weights. One day before transport 28 d-old calves had higher blood cholesterol (Δ = 0.40 mmol/l) and IGF-1 (Δ = 53.6 ng/ml) concentrations, and evidence of higher insulin (Δ = 12.2 µU/ml) compared with 14 d-old calves. In wk 2 post-transport, 28-d old calves had higher blood IGF-1 (Δ = 21.1 ng/ml), with evidence of higher insulin (Δ = 12.2 µU/ml) concentrations compared with 14-d old calves. Cholesterol concentration measured one day before transport and in wk 2 post-transport had a positive relationship with carcass weight at slaughter (β = 4.8 and 7.7 kg/mmol/l, respectively). Blood cholesterol concentration in wk 2 post-transport was negatively associated with the fecal score measured at the same sampling moment (β = -0.55/mmol/l), with the likelihood of a calf of being treated with antibiotics (β = -0.36/mmol/l) and other medicines (β = -0.45/mmol/l) at the veal farm. Blood IGF-1 concentration in wk 2 post-transport was negatively associated with the likelihood of a calf of being treated with antibiotics and other medicines (both β = -0.01/ng/ml) at the veal farm, and with fecal score recorded in wk 2 post-transport (β = -0.004/ng/ml). When looking at the blood indicators, it appeared that calves transported at 28 d of age were more developed compared with 14 d old calves, thus transport at an older age might be more beneficial for the animals. It can be concluded that both blood cholesterol and IGF-1 concentrations seemed to be valuable biomarkers of health and energy availability in veal calves.

Efficacy of oral administration of specific immunoglobulins in preventing neonatal calf diarrhoea in dairy herds

BACKGROUND

The aim of this study was to evaluate the efficacy of bovine concentrated lactoserum (BCL) containing specific immunoglobulin G against Escherichia coli, rotavirus and coronavirus in preventing neonatal calf diarrhoea (NCD).

METHODS

A total of 489 newborn calves from 35 herds were orally given either BCL or a placebo before the first feeding of colostrum and clinically supervised by the farmers for the first 14 days of life. The diarrhoea score was defined according to the following criteria: 0 = no diarrhoea; 1 = light diarrhoea without medical treatment; 2 = diarrhoea requiring oral treatment (rehydration and/or antibiotic therapy); and 3 = severe diarrhoea requiring parenteral rehydration or resulting in death.

RESULTS

A total of 138 calves suffered from diarrhoea (28%), and 65 (13%) showed signs of diarrhoea requiring treatment. The odds of getting NCD were reduced (odds ratio = 0.326; p < 0.001) in the BCL group. There was a tendency towards a reduction in the duration of NCD in the BCL group (2.25 (±1.7) days vs. 2.88 (±2.7) days in the placebo group) (p = 0.052). Furthermore, no calves died in the BCL group, whereas four calves died in the placebo group.

LIMITATIONS

Because of the design of the study using animals in practice, the mechanisms explaining the clinical findings remain as hypotheses. Diarrhoea scoring performed by farmers has to be analysed and interpreted with caution.

CONCLUSIONS

This study demonstrates that BCL as a single preventive treatment is effective in reducing the incidence of NCD even in a region with good general management of dairy calves and overall good colostrum quality.

Acute phase reaction to lipopolysaccharide-induced mastitis in early lactation dairy cows fed nitrogenic, glucogenic, or lipogenic diets

The availability of certain macronutrients is likely to influence the capacity of the immune system. Therefore, we investigated the acute phase response to intramammary (i.mam.) lipopolysaccharide (LPS) in dairy cows fed a nitrogenic diet (n = 10) high in crude protein, a glucogenic diet (n = 11) high in carbohydrates and glucogenic precursors, or a lipogenic diet (n = 11) high in lipids. Thirty-two dairy cows were fed one of the dietary concentrates directly after calving until the end of trial at 27 ± 3 days in milk (mean ± standard deviation). In wk 3 of lactation, 20 µg of LPS was i.mam. injected in one quarter, and sterile NaCl (0.9%) in the contralateral quarter. Milk samples of the LPS-challenged and control quarter were taken hourly from before (0 h) until 9 h after LPS challenge and analyzed for milk amyloid A (MAA), haptoglobin (HP), and IL-8. In addition, blood samples were taken in the morning, and composite milk samples at morning and evening milkings, from 1 d before until 3 d after LPS challenge, and again on d 9, to determine serum amyloid A (SAA) and HP in blood, and MAA and HP in milk. The mRNA abundance of various immunological and metabolic factors in blood leukocytes was quantified by quantitative reverse-transcription PCR from samples taken at -18, -1, 6, 9, and 23 h relative to LPS application. The dietary concentrates did not affect any of the parameters in blood, milk, and leukocytes. The IL-8 was increased from 2 h, HP from 2 to 3 h, and MAA from 6 h relative to the LPS administration in the milk of the challenged quarter and remained elevated until 9 h. The MAA and HP were also increased at 9 h after LPS challenge in whole-udder composite milk, whereas HP and SAA in blood were increased only after 23 h. All 4 parameters were decreased again on d 9. Similar for all groups, the mRNA abundance of HP and the heat shock protein family A increased after the LPS challenge, whereas the mRNA expression of the tumor necrosis factor α and the leukocyte integrin β 2 subunit (CD18) were decreased at 6 h after LPS challenge. The glucose transporter (GLUT)1 mRNA abundance decreased after LPS, whereas that of the GLUT3 increased, and that of the GLUT4 was not detectable. The mRNA abundance of GAPDH was increased at 9 h after LPS and remained elevated. The acute phase protein response was detected earlier in milk compared with blood indicating mammary production. However, immunological responses to LPS were not affected by the availability of specific macronutrients provided by the different diets.

Hepatic Lipidosis in Ruminants

Hepatic lipidosis (ie, fatty liver) occurs primarily during the first weeks of lactation in dairy cows because of excessive lipolysis overwhelming the concomitant capacity for beta-oxidation and hepatic export of triglycerides. Besides economic losses due to reduced lactational and reproductive performance, close associations with concomitantly occurring infectious and metabolic health disorders, in particular ketosis, exist. Hepatic lipidosis is not only a consequence from the postpartal negative energy balance but also acts as a disease component for further health disorders.

Effects of feeding level, milking frequency, and single injection of cabergoline on blood metabolites, hormones, and minerals around dry-off in dairy cows

This study aimed to investigate the effect of the different dry-off strategies based on reducing feeding level (normal vs. reduced energy density), reducing milking frequency (twice vs. once daily), and administration of a dopamine agonist after last milking (i.e. saline vs. cabergoline injection) on blood metabolites, hormones, and minerals around dry-off. In this experiment, 119 Holstein dairy cows were used in a 2 × 2 × 2 factorial arrangement. In the last week before dry-off, cows were allocated to 1 of the 4 possible dry-off strategies based on feeding level and milking frequency. Within 3 h after last milking, cows were injected with either saline or a D₂ dopamine agonist (cabergoline; Velactis, Ceva Santé Animale, Libourne, France; labeled for use only with abrupt dry-off, e.g., no preceding reduction in feeding level or milking frequency before last milking). After dry-off, all cows were fed the same dry cow diet and data collection continued for a week. Blood samples were collected from the coccygeal vein on d -9, -6, -5, -2, 1, 2, 5, and 7 relative to dry-off. Additionally, blood was sampled at 0, 3, and 6 h relative to injection of either cabergoline or saline, equivalent to d 0.125, 0.250, and 0.375 relative to last milking (dry-off). The reduced feeding level before dry-off caused reduced glucose and insulin concentrations as well as increased free fatty acid concentrations, particularly when reduced feeding level was combined with milking the cows 2× daily. The intramuscular injection of cabergoline caused the expected reduction in circulating prolactin concentrations. In addition, dopamine-agonist cabergoline induced an atypical simultaneous pattern of plasma metabolites (i.e., increased glucose and free fatty acid concentrations), hormones (i.e., reduced insulin and increased cortisol concentrations), and minerals (i.e., reduced calcium concentration), indicating that normal metabolic and mineral homeostatic regulations were hindered after the injection of ergot alkaloid cabergoline. In conclusion, reducing milking frequency seems the best management strategy to reduce milk production at dry-off among those tested in this study.

Effects of different nutrient supply on metabolism and mammary immune response to an LPS challenge in early lactation of dairy cows

Energy and nutrient deficiency in dairy cows in early lactation is considered to contribute to their increased susceptibility to mastitis. We have tested the hypothesis that feeding diets with high contents of either nitrogenic, glucogenic, or lipogenic components in early lactation affects both the endocrine and metabolic status, as well as the mammary immune competence. After calving, cows were fed increasing amounts of concentrate up to 10 kg/d rich in crude protein (nitrogenic, n = 10), glucogenic precursors (glucogenic, n = 11), or lipids (lipogenic, n = 11). In wk 3, one udder quarter was challenged with lipopolysaccharide (LPS) from Escherichia coli. Blood and milk were sampled on the day before LPS challenge (d -1), and on d 0, 1, 2, 3, and 9 after LPS challenge. On the day of LPS challenge additional samples were taken hourly for quarter milk and every 3 h for blood. Urea concentrations were higher in plasma and milk of cows fed the nitrogenic diet. However, plasma concentrations of glucose, cholesterol, triglycerides, β-hydroxybutyrate, nonesterified fatty acids, as well as insulin, glucagon, and insulin-like growth factor-1 were not affected by the different diets. The mammary immune challenge induced a substantial increase of somatic cell count (SCC) in the treated quarter, and a transient decrease of total milk yield and white blood cells similar in all diet groups for one day. The absolute phagocytosis of blood leukocytes was decreased; however, the phagocytosis per cell was increased in glucogenic-fed cows at 6 h after LPS challenge. During mammary inflammation an insulin resistance, shown by increased plasma glucose, insulin, and glucagon, developed similarly in all diet groups. β-hydroxybutyrate and nonesterified fatty acids were decreased at 1 d after LPS challenge in glucogenic-fed cows only. Cholesterol did not change, and triglycerides only decreased significantly in lipogenic-fed cows 6 h after challenge. On d 9 after LPS challenge, SCC and milk yield and metabolic factors were recovered in all groups. In conclusion, the endocrine and metabolic situation, and the immune response to intramammary LPS of dairy cows during early lactation was not substantially influenced by the elevated supply of nitrogenic, glucogenic, or lipogenic components due to the provided feed in this study.

Turnover of Benzoxazinoids during the Aerobic Deterioration of Maize Silage (Zea mays)

While plant-specialized metabolites can affect mammal health, their fate during the aerobic deterioration of crop silage remains poorly understood. In this study, we investigated the metabolization of benzoxazinoids (BXs) in silages of two maize genotypes (W22 wild type and bx1 mutant line) during aerobic deterioration. In W22 plants, concentrations of the aglucone BXs DIMBOA and HMBOA in silage decreased over time upon air exposure, while concentrations of MBOA and BOA increased. Mutant plants had low levels of BXs, which did not significantly vary over time. Aerobic stability was BX-dependent, as pH and counts of yeasts and molds were higher in W22 compared to that in bx1 silage. The nutrient composition was not affected by BXs. These preliminary results may be used to estimate the amounts of BXs provided to farm animals via silage feeding. However, further research is warranted under different harvest and storage conditions.

Endocrine changes during the peripartal period related to colostrogenesis in mammalian species

This review discusses endocrine and functional changes during the transition from late gestation to lactation that are related to the production of colostrum in different mammalian species. Species covered in this article include ungulate species (cattle, sheep, goats, pigs, horses), rodents (rat, mouse), rabbits, and carnivores (cats, dogs), as well as humans. An immediate availability of high quality colostrum for the newborn after birth is crucial in species where a transfer of immunoglobulins (Ig) does not or only partially occur via the placenta during pregnancy. Declining activity of gestagens, in most species progesterone (P4), is crucial at the end of pregnancy to allow for the characteristic endocrine changes to initiate parturition and lactation, but the endocrine regulation of colostrogenesis is negligible. Both, the functional pathways and the timing of gestagen withdrawal differ considerably among mammalian species. In species with a sustaining corpus luteum throughout the entire pregnancy (cattle, goat, pig, cat, dog, rabbit, mouse, and rat), a prostaglandin F2α (PGF2α)-induced luteolysis shortly before parturition is assumed to be the key event to initiate parturition as well as lactogenesis. In species where the gestagen production is taken over by the placenta during the course of gestation (e.g., sheep, horse, and human), the reduction of gestagen activity is more complex, as PGF2α does not affect placental gestagen production. In sheep the steroid hormone synthesis is directed away from P4 towards estradiol-17β (E2) to achieve a low gestagen activity at high E2 concentrations. In humans the uterus becomes insensitive to P4, as parturition occurs despite still high P4 concentrations. However, lactogenesis is not completed as long as P4 concentration is high. Early colostrum and thus Ig intake for immune protection is not needed for the human newborn which allows a delayed onset of copious milk secretion for days until the placenta expulsion causes the P4 drop. Like humans, horses do not need low gestagen concentrations for successful parturition. However, newborn foals need immediate immune protection through Ig intake with colostrum. This requires the start of lactogenesis before parturition which is not fully clarified. The knowledge of the endocrine changes and related pathways to control the key events integrating the processes of colostrogenesis, parturition, and start of lactation are incomplete in many species.

Effect of voluntary waiting period on metabolism of dairy cows during different phases of the lactation

An extended calving interval (CInt) by extending the voluntary waiting period (VWP) could be associated with altered metabolism in dairy cows. The aim of this study was first to evaluate the effects of VWP on metabolism and body condition during the first 305 d after the first calving in the experiment (calving 1), around the end of the VWP, and during pregnancy (280 d before calving 2). Second, the effects of the VWP on metabolism were determined from 2 wk before until 6 wk after calving 2. Third, individual cow characteristics were used to predict milk production and body condition of cows after different VWP. Holstein-Friesian cows (N = 154, 41 primiparous [PP], 113 multiparous [MP]) were blocked for parity, milk production, and lactation persistency, randomly assigned to a VWP of 50, 125, or 200 d (VWP50, VWP125, or VWP200) and followed from calving 1 until 6 wk after calving 2. In the first 6 wk after calving 1 and from 2 wk before until 6 wk after calving 2, weekly plasma samples were analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate, glucose, insulin, and insulin-like growth factor 1 (IGF-1). From wk 7 after calving 1 until 2 wk before calving 2, insulin and IGF-1 were analyzed every 2 wk. Fat- and protein-corrected milk (FPCM) and body weight (BW) gain were measured weekly. Cows were divided in two parity classes based on calving 1 (PP and MP) and remained in these classes after calving 2. During pregnancy, MP cows in VWP200 had greater plasma insulin and IGF-1 concentration and lower FPCM compared with MP cows in VWP125 (insulin: 18.5 vs. 13.9 µU/mL, CI 13.0-19.7, P < 0.01; IGF-1: 198.5 vs. 175.3 ng/mL ± 5.3, P = 0.04; FPCM: 22.6 vs. 30.0 kg/d ± 0.8, P < 0.01) or VWP50 (insulin: 15.8 µU/mL, P < 0.01; IGF-1: 178.2 ng/mL, P < 0.01; FPCM: 26.6 kg/d, P < 0.01) and had a greater daily BW gain compared with cows in VWP50 (3.6 vs. 2.5 kg/d ± 0.2; P < 0.01). After calving 2, MP cows in VWP200 had greater plasma NEFA concentration (0.41 mmol/liter) compared with MP cows in VWP125 (0.30 mmol/liter, P = 0.04) or VWP50 (0.26 mmol/liter, P < 0.01). For PP cows, the VWP did not affect FPCM or body condition during the first lactation in the experiment, or metabolism after calving 2. Independent of the VWP, higher milk production and lower body condition before insemination were associated with higher milk production and lower body condition at the end of the lactation. Variation in these characteristics among cows could call for an individual approach for an extended VWP.

Implications of placentation type on species-specific colostrum properties in mammals

Maternal care is essential to optimally support survival of the offspring. During evolution of mammalian species, different phenotypes have evolved in relation to gestation length, number, size, and maturation stage of the offspring at parturition, as well as colostrum and milk composition. The aim of the present review is to describe relationships between placental function and colostrum and milk composition in different mammalian species. Species covered in this article include humans, rabbits, rodents (rat and mouse), carnivores (cats and dogs), and a variety of ungulate species (cattle, sheep, goats, pigs, and horses). Species-specific aspects are elucidated with a special focus on the transfer of passive immunity. In this regard, the structure and thus the capability of the placenta to transport immunoglobulins from maternal to fetal circulation in utero dictates the necessity of the passive transfer of immunity via colostrum. Consequently, species with exclusive postpartal transfer of immunity such as in all ungulate species have greater immunoglobulin G concentrations in colostrum than species with a prepartal transfer in utero, where especially immunoglobulin A with its local immune function in the gastrointestinal tract is present in colostrum (e.g., rabbit and human). In terms of the nutritional purpose, suckling frequency is an important factor determining the gross composition of colostrum as well as in the mature milk of these species. Milk of nidicolous animals with long intervals in-between suckling events contains more fat than milk of nidifugous animals with constant access to their mother. However, the importance of colostrum and milk consumption for newborn animals and human babies goes beyond nutrition and the transfer of immunity. Numerous bioactive components such as growth factors, hormones, and oligosaccharides are enriched in colostrum and transition milk, which support the development of the intestinal tract and local immune system.

282 Metabolic and Endocrine Changes in Dairy Cows fed Different Diets at dry-off

Concentrate withdrawal and feed restriction reduce milk production to facilitate dry-off. We investigated the impact of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in either crude protein (nitrogenic, n=14), glucogenic precursors (glucogenic, n=14), or lipids (lipogenic, n=15). On d 3 before dry-off, total feed allowance was restricted to 50 % in one-half of the animals of each dietary group whereas feed allowance remained unchanged in the other animals. Statistical analysis (SAS, version 9.4) was carried out using a mixed model with dietary group, time, and diet×time interaction as fixed effects (Significance assumed at P&lt; 0.05). Feed restriction immediately resulted in a negative energy balance (NEB) and decreased milk production (P&lt; 0.05). Concomitantly, concentrations of non-esterified fatty acids (NEFA) increased, whereas insulin, insulin-like growth factor-1 (IGF-1), and glucagon decreased (P&lt; 0.05). After dry-off, energy balance turned positive and plasma NEFA decreased again. Plasma glucose, insulin, and IGF-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were greater in non-restricted compared with restricted animals after dry-off (P&lt; 0.05). Milk and plasma urea concentrations were increased in cows fed the nitrogenic concentrate (P&lt; 0.05). Overall, metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood.

Effect of Type of Cow-Calf Contact on Health, Blood Parameters, and Performance of Dairy Cows and Calves

Prolonged cow-calf contact (CCC) could potentially improve dairy calf welfare. However, it is currently unknown how different types of CCC affect animals' biological functions. We evaluated health and performance parameters of dairy calves and their dams, where calves: (i) had no contact with their dam (NC), in which the calf was removed from the dam directly after birth (n = 10); (ii) were allowed to have partial contact (PC) with their dam, in which the calf was housed in a calf pen adjacent to the cow area allowing physical contact on the initiative of the dam but no suckling (n = 18); (iii) were allowed to have full contact (FC) with their dam, including suckling, in which calves were housed together with their dams in a free-stall barn (n = 20). Throughout the first 7 weeks postpartum, data were collected on the health status, fecal microbiota, hematological profile, immune and hormonal parameters, and growth rates of calves, and on the health status, metabolic responses, and performance of dams. Overall, FC calves had more health issues (P = 0.02) and a tendency for higher antibiotic usage (P = 0.07) than NC calves. Additionally, FC calves showed elevated levels of erythrocytes, hematocrit, hemoglobin, and leukocytes on day 49 compared to NC calves (P < 0.001). Calf fecal microbiota changed over time, and we found preliminary evidence that fecal microbiota is affected by the type of CCC, as reflected by differences in relative abundances of taxa including Lactobacillus in FC calves compared to NC and PC calves except on days 7 and 66. The FC calves had a greater average daily gain in body weight than NC and PC calves (P = 0.002). Cow health was not affected by the type of CCC, although in the first 7 weeks of lactation FC cows had a lower machine-gained milk yield accompanied by a lower fat percentage than NC and PC cows (P < 0.001). These results indicate that full contact posed a challenge for calf health, presumably because the housing conditions of FC calves in this experimental context were suboptimal. Secondly, ad libitum suckling leads to higher weight gains and negatively affected milk fat content besides machine-gained yields. More research into strategies to improve cow-calf housing and management in CCC systems is warranted.

Effect of different dietary regimens at dry-off on performance, metabolism, and immune system in dairy cows

Concentrate withdrawal and feed restriction are commonly used to reduce milk production and to facilitate dry-off, but may impair immune function in dairy cows. We investigated the effect of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses, as well as on leukocyte function before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in crude protein (nitrogenic, n = 14), glucogenic precursors (glucogenic, n = 14), or lipids (lipogenic, n = 15). On d 3 before dry-off, total feed allowance was restricted to 50% in half of the animals of each dietary group, whereas feed allowance remained unchanged in the other animals. Performance parameters (milk yield, milk composition, and dry matter intake) were recorded, and daily blood and milk samples were taken and analyzed for various metabolic and endocrine parameters. Additionally, activity and mRNA abundance of several genes in leukocytes were measured at selected time points before and after feed restriction and dry-off, respectively. Feed restriction immediately resulted in a negative energy balance and decreased milk production. Concomitantly, concentrations of nonesterified fatty acids increased, whereas insulin, insulin-like growth factor-1, and glucagon decreased. After dry-off, energy balance turned positive and plasma nonesterified fatty acids decreased. Plasma glucose, insulin, and insulin-like growth factor-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were higher in nonrestricted compared with restricted animals after dry-off. The experimental concentrate types marginally affected the investigated metabolic and endocrine factors, with the exception of elevated milk and plasma urea concentrations in cows fed the nitrogenic concentrate. Chemotactic and phagocytic activity of leukocytes were not affected by diets, feed restriction, or dry-off. Likewise, blood leukocyte mRNA abundance encoding for tumor necrosis factor α (TNF), heat shock protein family A (HSP70), and the glucose transporters (GLUT) 1 and 3 remained unchanged throughout the study period. Overall, the short-term negative energy balance induced by feed restriction was temporarily accompanied by metabolic adaptations, but did not alter the studied factors related to the immune system. Metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood.

Limiting factors for milk production in dairy cows: perspectives from physiology and nutrition

Milk production in dairy cows increases worldwide since many decades. With rising milk yields, however, potential limiting factors are increasingly discussed. Particularly, the availability of glucose and amino acids is crucial to maintain milk production as well as animal health. Limitations arise from feed sources, the rumen and digestive tract, tissue mobilization, intermediary metabolism and transport, and the uptake of circulating nutrients by the lactating mammary gland. The limiting character can change depending on the stage of lactation. Although physiological boundaries are prevalent throughout the gestation-lactation cycle, limitations are aggravated during the early lactation period when high milk production is accompanied by low feed intake and high mobilization of body reserves. The knowledge about physiological constraints may help to improve animal health and make milk production more sustainably. The scope of this review is to address contemporary factors related to production limits in dairy cows from a physiological perspective. Besides acknowledged physiological constraints, selected environmental and management-related factors affecting animal performance and physiology will be discussed. Potential solutions and strategies to overcome or to alleviate these constraints can only be presented briefly. Instead, they are thought to address existing shortcomings and to identify possibilities for optimization. Despite a scientific-based view on physiological limits, we should keep in mind that only healthy animals could use their genetic capacity and produce high amounts of milk.

247 Metabolic Adaptation to Short-term of Dietary Nutrient Imbalances in Mid Lactation Dairy Cows

This study investigated the short-term metabolic and endocrine responses to different levels of concentrate formulated to particularly provide one major macronutrient source. Based on parity number, lactational stage, milk yield and BW, 9 mid lactating cows (211 ± 19 d in milk) were grouped into 3 blocks of 3 animals each. Concentrate supplements (aminogenic: rich in crude protein and nitrogen sources; glucogenic: high content of carbohydrates and glucogenic precursors; lipogenic: high lipid content) were fed in a factorial arrangement at 3 increasing levels for 3 d each. Milk yield, BW and feed intake were recorded daily. Blood and milk were sampled every 3 d at the end of each concentrate level. Statistical analysis was carried out using a mixed model with concentrate supplement and level as fixed, and block and animal as random factors. Milk fat, protein, lactose and urea contents were determined. In blood, concentrations of various metabolites, endocrine factors and enzyme activities (e.g. glucose, non-esterified fatty acids (NEFA), β-hydroxybutyrate, urea, cholesterol, triglycerides, insulin, glucagon, ASAT, GGT, GLDH) were measured. Milk yield, milk composition and BW were not affected by diets and concentrate levels. Feed intake increased in cows receiving the aminogenic and lipogenic diet. Milk und plasma urea concentrations were clearly elevated in the aminogenic and to a lesser extent in the lipogenic treatment compared to the glycogenic diet (P &lt; 0.05). Glucose concentrations in plasma were not affected by treatments, whereas insulin and glucagon increased only in the aminogenic treatment with concomitantly reduced NEFA concentrations (P &lt; 0.05). Activities of ASAT, GGT and GLDH as well as the total antioxidant capacity were not affected by diets (P &gt;0.05). To conclude, immediate metabolic and endocrine responses occurred due to the short-term dietary changes. Particularly a surplus of nitrogen supply affected metabolic responses and stimulated insulin and glucagon secretion.

PSXII-18 Immunoglobulin G content and composition of colostrum in different cattle breeds

Immunoglobulins (Ig) are essential bioactive components in colostrum that enable passive immunization of newborn calves. Compared to mature milk, concentrations of fat and protein are greater in colostrum, and represent a vital source of energy and nutrients. Colostral IgG was shown to vary between individual dairy cows, but comparative data on different breeds and performance levels are scarce. The objective of the present field study was to investigate the contents of total IgG, fat, protein, and lactose in colostrum in different Swiss and German dairy and dual-purpose breeds. We collected colostrum samples of 458 cows of 13 different breeds (dairy breeds: Brown Swiss, Swiss and German Holstein Friesian, and New Zealand Holstein; dual-purpose breeds: German Fleckvieh, Holstein Friesian × Montbéliarde, Montbéliarde, Murnau-Werdenfels, Original Braunvieh, Pinzgauer, Rhetic Gray, and Simmental; beef type crossbred Charolais × Holstein Friesian). Colostrum samples were obtained between 5 and 900 min after calving and analyzed for total IgG, fat protein, and lactose contents. Statistical analysis was carried out using a GLM model with breed, parity number, and time of colostrum collection as fixed effects. Immunoglobulin G concentrations varied between 12.7 and 204.0 mg/mL. No effect of breeding purpose (i.e., dairy or dual-purpose), nor of previous lactation yield on IgG content was observed. However, milking of cows for the first time later than 12 h after parturition resulted in lower colostrum IgG concentrations compared to colostrum harvest within 9 h after calving (P &lt; 0.05). Multiparous cows had a higher colostral IgG concentration than primiparous cows (P &lt; 0.0001). Overall, concentrations of IgG and other constituents in colostrum varied widely in the different cattle breeds. High-yielding dairy cows did not have poorer colostrum quality compared to lower yielding animals or beef and dual-purpose breeds, which suggests an individually different transfer of circulating IgG into colostrum.

Plant chemistry and food web health

Plants are systemically relevant to our planet not only by constituting a major part of its biomass, but also because they produce a vast diversity of bioactive phytochemicals. These compounds often modulate interactions between plants and the environment, and can have substantial effects on plant consumers and their health. By taking a food web perspective, we highlight the role of bioactive phytochemicals in linking soils, plants, animals and humans and discuss their contributions to systems health. The analysis of connections among food web components revealed an underexplored potential of phytochemicals to optimize food web health and productivity.

Pathogen dependent effects of high amounts of oxytocin on the bloodmilk barrier integrity during mastitis in dairy cows

INTRODUCTION

The reduction of antibiotic use in food producing animals becomes increasingly important. Therefore, suitable alternatives for mastitis treatment in dairy cows have to be considered. Oxytocin (OT) induces milk ejection and hence supports milk removal from infected mammary quarters. Beyond udder emptying, the injection of very high dosages of OT causes increased somatic cell counts (SCC) in milk and enables the transfer of immunoglobulins (Ig) from blood into milk through a reduced blood-milk barrier integrity. The aim of the present study was to investigate pathogen-specific changes of SCC, the blood derived milk components lactate dehydrogenase (LDH), serum albumin (SA), and IgG in milk of cows suffering from mastitis caused by different pathogens treated with two intravenous injections of high dosages of OT (100 IU). Milk samples from 184 dairy cows from different farms were collected on day 1 (day of clinical examination and mastitis diagnosis) and on days 2, 3, 14, and 28. Bacteriological examination (day 1) identified involved pathogens. Cows were randomly assigned to treatment (OT injections on days 1 and 2) or control group (no OT). Independently of the assigned experimental group, cows received the common therapy protocol of the veterinary practice after sample collection if the general condition was affected. Milk SCC, LDH, SA, and IgG changed specifically depending on involved pathogens. Highest values of all three parameters were measured in mastitis caused by Streptococcus uberis. Changes were less pronounced with other Streptococci spp., Staphylococci spp. or Corynebacterium bovis. Oxytocin treatment did not affect any of the studied parameters independent of the involved pathogen. Only in quarters infected with Staphylococci other than Staphylococcus aureus a decreased SCC and increased IgG concentrations in quarters, where no pathogens were detected, were observed. Thus, high dosage OT administration is obviously not suitable as a stand-alone mastitis treatment in dairy cows.

Plasma cholesterol levels and short-term adaptations of metabolism and milk production during feed restriction in early lactating dairy cows on pasture

Low plasma total cholesterol (TC) concentrations are characteristic during the negative energy balance in early lactating dairy cows. The objective was to investigate short-term effects of different TC concentrations during an aggravated energy deficiency through a 1-week concentrate withdrawal on adaptations of metabolism and milk production. Multiparous Holstein cows (n = 15) were investigated during 3 week beginning at 24 ± 7 DIM (mean ± SD). Cows were kept on pasture and received additional concentrate in experimental week 1 and 3, while in week 2, concentrate was withdrawn. Blood was sampled once and milk twice daily. Based on their average TC concentration during week 1 (prior to concentrate withdrawal), cows were retrospectively assigned into a high (H-Chol; n = 8, TC ≥ 3.36 mmol/L) and a low TC groups (L-Chol; n = 7, TC < 3.36 mmol/L). Concentrations of phospholipids and lipoproteins were higher in H-Chol compared to L-Chol throughout the study (p < 0.05). During concentrate withdrawal, milk yield, glucose and insulin concentrations decreased similarly in both groups, while milk fat, milk acetone and plasma BHB were higher in H-Chol compared to L-Chol (p < 0.05). Compared to initial values, plasma NEFA, TAG and VLDL increased in both groups within 2 days after concentrate withdrawal (p < 0.05). Concentrations of NEFA during week 2 were greater in L-Chol compared to H-Chol (p < 0.05). Despite reintroduction of concentrate, milk yield in H-Chol remained lower for two more days compared to week 1 (p < .05), whereas milk yield recovered immediately in L-Chol. Activity of aspartate aminotransferase was higher in H-Chol compared to L-Chol in week 2 (p < 0.05). Greater plasma TC concentrations were associated with a reduced increase of NEFA. Further research is warranted if TC concentrations are related to adipose tissue mobilization and fatty acid turnover.

Expressive suppression and cognitive reappraisal in veterans with PTSD: Results from the mind your heart study

OBJECTIVE

This study examined whether expressive suppression (ES), a maladaptive regulation strategy, was more strongly associated with PTSD diagnosis and symptom clusters in veterans than cognitive reappraisal (CR), an adaptive regulation strategy.

METHOD

In a cohort study, 746 participants recruited from VHA facilities completed Clinician Administered PTSD Scale-IV, Emotion Regulation Questionnaire, and Patient Health Questionnaire. Participants were categorized into groups: Current, Remitted/Lifetime, and Never PTSD.

RESULTS

One-way ANOVA revealed significant differences between Current PTSD and both Remitted and Never PTSD for ES, but not CR. The Remitted and Never PTSD groups did not vary significantly from each other and were collapsed into one group for regressions. Adjusting for sex, race, employment, and comorbid depression, binary logistic regression showed ES, but not CR, was associated with increased likelihood of Current PTSD (p < .001, OR: 1.43). ES was also significantly associated with increased odds of meeting criteria for all symptom clusters (ps < 0.001). CR was not significantly associated with meeting criteria for Current PTSD or any symptom cluster.

LIMITATIONS

Cross-sectional design and use of self-report limit causality inferences that can be drawn.

CONCLUSIONS

ES is associated with increased odds of Current PTSD diagnosis and symptom clusters. Veterans in the Remitted and Never PTSD groups did not differ significantly. Greater suppression of emotional expression is more strongly linked with PTSD criteria in veterans than decreased cognitive reappraisal.

Effect of maternal supplementation with essential fatty acids and conjugated linoleic acid on metabolic and endocrine development in neonatal calves

We tested the hypothesis that the maternal supply of essential fatty acids (EFA), especially α-linolenic acid, and conjugated linoleic acid (CLA), affects glucose metabolism, the endocrine regulation of energy metabolism and growth, and the intestinal development of neonatal calves. We studied calves from dams that received an abomasal infusion of 76 g/d coconut oil (CTRL; n = 9), 78 g/d linseed oil and 4 g/d safflower oil (EFA; n = 9), 38 g/d Lutalin (BASF SE) containing 27% cis-9,trans-11 and trans-10,cis-12 CLA (CLA; n = 9), or a combination of EFA and CLA (EFA+CLA; n = 11) during the last 63 d of gestation and early lactation. Calves received colostrum and transition milk from their own dam for the first 5 d of life. Insulin-like growth factor (IGF)-I, leptin, and adiponectin concentrations were measured in milk. Blood samples were taken before first colostrum intake, 24 h after birth, and from d 3 to 5 of life before morning feeding to measure metabolic and endocrine traits in plasma. On d 3 of life, energy expenditure was evaluated by a bolus injection of NaH¹³CO₃ and determination of CO₂ appearance rate. On d 4, additional blood samples were taken to evaluate glucose first-pass uptake and ¹³CO₂ enrichment after [¹³C₆]-glucose feeding and intravenous [6,6-²H₂]-glucose bolus injection, as well as postprandial changes in glucose, nonesterified fatty acids (NEFA), insulin, and glucagon. On d 5, calves were killed 2 h after feeding and samples of small intestinal mucosa were taken for histomorphometric measurements. The concentrations of IGF-I, adiponectin, and leptin in milk decreased during early lactation in all groups, and the concentrations of leptin in first colostrum was higher in EFA than in CTRL cows. Plasma glucose concentration before first colostrum intake was higher in EFA calves than in non-EFA calves and was lower in CLA calves than in non-CLA calves. Plasma IGF-I concentration was higher on d 1 before colostrum intake in EFA calves than in EFA+CLA calves and indicated an overall CLA effect, with lower plasma IGF-I in CLA than in non-CLA calves. Postprandial NEFA concentration was lowest in EFA and CLA calves. The postprandial rise in plasma insulin was higher in EFA than in non-EFA calves. Plasma adiponectin concentration increased from d 1 to d 2 in all groups and was higher on d 3 in CLA than in non-CLA calves. Plasma leptin concentration was higher on d 4 and 5 in EFA than in non-EFA calves. Maternal fatty acid treatment did not affect energy expenditure and first-pass glucose uptake, but glucose uptake on d 4 was faster in EFA than in non-EFA calves. Crypt depth was lower, and the ratio of villus height to crypt depth was higher in the ilea of CLA than non-CLA calves. Elevated plasma glucose and IGF-I in EFA calves immediately after birth may indicate an improved energetic status in calves when dams are supplemented with EFA. Maternal EFA and CLA supplementation influenced postprandial metabolic changes and affected factors related to the neonatal insulin response.

Glucose metabolism and the somatotropic axis in dairy cows after abomasal infusion of essential fatty acids together with conjugated linoleic acid during late gestation and early lactation

Sufficient glucose availability is crucial for exploiting the genetic potential of milk production during early lactation, and endocrine changes are mainly related to repartitioning of nutrient supplies toward the mammary gland. Long-chain fatty acids, such as essential fatty acids (EFA) and conjugated linoleic acid (CLA), have the potential to improve negative energy balance and modify endocrine changes. In the present study, the hypothesis that combined CLA and EFA treatment supports glucose metabolism around the time of calving and stimulates insulin action and the somatotropic axis in cows in an additive manner was tested. Rumen-cannulated German Holstein cows (n = 40) were investigated from wk 9 antepartum (AP) until wk 9 postpartum (PP). The cows were abomasally supplemented with coconut oil (CTRL, 76 g/d); 78 g/d of linseed and 4 g/d of safflower oil (EFA); Lutalin (CLA, isomers cis-9,trans-11 and trans-10,cis-12 CLA, each 10 g/d); or the combination of EFA+CLA. Blood samples were collected several times AP and PP to determine the concentrations of plasma metabolites and hormones related to glucose metabolism and the somatotropic axis. Liver tissue samples were collected several days AP and PP to measure glycogen concentration and the mRNA abundance of genes related to gluconeogenesis and the somatotropic axis. On d 28 AP and 21 PP, endogenous glucose production (eGP) and glucose oxidation (GOx) were measured via tracer technique. The concentration of plasma glucose was higher in CLA than in non-CLA-treated cows, and the plasma β-hydroxybutyrate concentration was higher in EFA than in non-EFA cows on d 21 PP. The eGP increased from AP to PP with elevated eGP in EFA and decreased eGP in CLA-treated cows; GOx was lower in CLA than in CTRL on d 21 PP. The plasma insulin concentration decreased after calving in all groups and was higher in CLA than in non-CLA cows at several time points. Plasma glucagon and cortisol concentrations on d 21 PP were lower in CLA than non-CLA groups. The glucagon/insulin and glucose/insulin ratios were higher in CTRL than in CLA group during the transition period. Plasma IGF-I concentration was lower in EFA than non-EFA cows on d 42 AP and was higher during the dry period and early lactation in CLA than in non-CLA cows. The IGF binding protein (IGFBP)-3/-2 ratio in blood plasma was higher in CLA than in non-CLA cows. Hepatic glycogen concentration on d 28 PP was higher, but the mRNA abundance of PC and IGFBP2 was lower in CLA than non-CLA cows on d 1 PP. The EFA treatment decreased the mRNA abundance of IGFBP3 AP and PCK1, PCK2, G6PC, PCCA, HMGCS2, IGFBP2, and INSR at several time points PP. Results indicated elevated concentrations of plasma glucose and insulin along with the stimulation of the somatotropic axis in cows treated with CLA, whereas EFA treatment stimulated eGP but not mRNA abundance related to eGP PP. The systemic effects of the combined EFA+CLA treatment were very similar to those of CLA treatment, but the effects on hepatic gene expression partially corresponded to those of EFA treatment.

Postpartal resumption of ovarian activity in dairy cows: Implications for herbage-based feeding systems in Switzerland

INTRODUCTION

Milk production in Switzerland is mainly based on herbage feeding with little input of concentrates. The present study investigated the effects of a solely herbage-based diet with (C) and without concentrate (nC) supplementation on luteal activity, milk production and metabolic status in 23 multiparous Holstein dairy cows with early or delayed resumption of ovarian cyclicity post partum (pp). Cows were retrospectively assigned either to a group with early (until d 25 pp, EOV) or delayed resumption of ovarian activity (> d 30 pp, DOV), resulting in four subgroups depending on concentrate feeding: DOV-C, DOV-nC, EOV-C, EOV-nC. Milk progesterone (P4) concentration was measured every 3 d, and different metabolites were analyzed in weekly blood samples. Resumption of ovarian activity was detected between d 19 and 25 pp in EOV, and between d 30 and 60 pp in DOV. In DOV-C, resumption of cyclicity tended to start earlier (38.3 ± 1.7 d pp) compared to DOV-nC (45.2 ± 6.3 d pp; P = 0.10). Independent of grouping, the ovarian activity occurred later in cows with greater plasma β-hydroxybutyrate (BHB) concentrations (P  1 ng/mL did not differ between groups (P > 0.05), but milk P4 peaks during the experiment were higher in EOV compared to DOV (P .

Free and bound cortisol, corticosterone, and metabolic adaptations during the early inflammatory response to an intramammary lipopolysaccharide challenge in dairy cows

Glucocorticoids, particularly cortisol and corticosterone, are key homeostatic regulators during metabolic and endocrine adaptations including inflammatory responses. Besides the established response of total cortisol (TC) concentrations during inflammatory processes in dairy cows, we investigated changes of corticosterone, free cortisol (FC), and serum albumin as the main protein of unspecific cortisol binding, in response to an intramammary lipopolysaccharide (LPS) challenge. Furthermore, we evaluated relationships of glucocorticoid responses with concomitant alterations of metabolites and their endocrine regulators, insulin and glucagon. Blood samples of 10 multiparous Holstein dairy cows (26.8 ± 3.4 d in milk, previous lactation yield: 7,601 ± 938 kg; mean ± SD) were obtained every 30 min up to 5 h after the LPS instillation, and rectal temperature and heart rate were measured in parallel. Corticosterone was measured by enzyme immunoassay, TC by radioimmunoassay, and the proportion of FC by ultrafiltration. A mixed model was used to evaluate differences within the investigated parameters among selected time points (0, 3.5, and 5 h relative to the intramammary LPS administration). Rectal temperature increased up to 41.6 ± 0.1°C at 5 h after the LPS application. Concentrations of TC and corticosterone increased until 3.5 h, and the proportion of FC relative to TC more than doubled until 3.5 h after LPS administration. Serum albumin concentration was reduced at 5 h compared with initial values, whereas concentrations of insulin, glucagon, and glucose were increased after 5 h compared with 0 h. In conclusion, the stimulation of the immune system by the intramammary LPS administration is accompanied by distinct metabolic and endocrine changes. Corticosterone and TC concentrations react similarly in response to the LPS challenge and earlier compared with metabolic adaptations. The increased need of active cortisol is covered by both increased secretion and a higher percentage of FC.

Colostrum composition and immunoglobulin G content in dairy and dual-purpose cattle breeds

Immunoglobulins (Ig) are essential components in the colostrum of bovine species that enable passive immunization of newborn calves. Concentrations of fat and protein are greater in colostrum compared with mature milk and represent a vital source of energy and nutrients. Colostral IgG was shown to vary between individual dairy cows, but comparative data on different breeds and performance levels are scarce. The objective of the present field study was to investigate the contents of total IgG, fat, protein, and lactose in colostrum in different Swiss and German dairy and dual-purpose breeds. We collected colostrum samples of 458 cows of 13 different breeds (dairy breeds: Brown Swiss, Swiss and German Holstein Friesian, and New Zealand Holstein; dual-purpose breeds: German Fleckvieh, Holstein Friesian × Montbéliarde, Montbéliarde, Murnau-Werdenfels, Original Braunvieh, Pinzgauer, Rhetic Gray, and Simmental; and beef-type crossbred: Charolais × Holstein Friesian). Colostrum samples were obtained between 5 and 900 min after calving and analyzed for total IgG, fat protein, and lactose contents. Immunoglobulin G concentrations varied between 12.7 and 204.0 mg/mL. No effect of breeding purpose (i.e., dairy or dual-purpose) nor of previous lactation yield on IgG content was observed. However, milking of cows for the first time later than 12 h after parturition resulted in lower colostrum IgG concentrations compared with colostrum harvest within 9 h after calving (P < 0.05). Multiparous cows had a higher colostral IgG concentration than primiparous cows (P < 0.0001). Overall, concentrations of IgG and other constituents in colostrum varied widely in the different cattle breeds. High-yielding dairy cows did not have poorer colostrum quality compared with lower-yielding animals or beef and dual-purpose breeds, which suggests an individually different transfer of circulating IgG into colostrum.

Short communication: Comparative estimation of colostrum quality by Brix refractometry in bovine, caprine, and ovine colostrum

Newborn ungulates depend on the timely supply of colostrum containing sufficient immunoglobulins to obtain passive immunity against disease. Brix refractometry enables a rapid on-farm estimation of colostrum quality and has been intensively studied in bovines. However, the suitability of Brix refractometers for assessing colostrum quality in goats and ewes has been scarcely evaluated. The present study compared bovine, caprine, and ovine colostrum quality estimation using an optical Brix refractometer. In addition, between-species variations in the relationships between Brix values and colostrum constituents (IgG, fat, protein, and lactose) and the accuracy of Brix refractometry at different cutoff values were evaluated by a receiver operating characteristic curve analysis. We measured the Brix value and contents of IgG, fat, protein, and lactose in 324 colostrum samples (108 cows, 116 does, and 100 ewes). Thresholds for classification of good colostrum quality (as determined by ELISA) were set at 50 mg IgG/mL in cows and 20 mg/mL in does and ewes. Bovine colostrum showed the greatest IgG concentrations compared with caprine and ovine colostrum. Fat and protein content was higher in sheep colostrum compared with the other species, whereas the highest lactose concentrations were detected in goat colostrum. Brix values ranged from 11.4 to 34.6% (22.1 ± 4.2%; mean ± standard deviation), 15.4 to 40.0% (28.5 ± 6.8%), and 8.8 to 39.8% (21.6 ± 5.3%) in bovine, ovine, and caprine colostrum, respectively. In all 3 species, Brix was highly correlated with IgG and protein concentrations (cows, r = 0.83 and 0.98; goats, r = 0.83 and 0.89; sheep, r = 0.75 and 0.87). Optimal cutoff points for greatest accuracy of Brix measurements were 19.3% Brix in cows [with 87.1% sensitivity (Se) and 100% specificity (Sp)], 20.7% Brix in does (with 53.5% Se and 100% Sp), and 26.5% Brix in ewes (with 75% Se and 91.3% Sp). In conclusion, Brix refractometry is an acceptable tool for on-farm estimations of colostrum quality in does and ewes despite distinct between-species variations in colostrum composition.

Reappraisal of Interpersonal Criticism in Social Anxiety Disorder: A Brain Network Hierarchy Perspective

Emotion regulation is thought to involve communication between and within large-scale brain networks that underlie emotion reactivity and cognitive control. Aberrant network interaction might therefore be a key neural feature of mental disorders that involve emotion dysregulation. Here we tested whether connectivity hierarchies within and between emotion reactivity and cognitive reappraisal networks distinguishes social anxiety disorder (SAD) patients (n = 70) from healthy controls (HC) (n = 25). To investigate network organization, we implemented a graph-theory method called Dependency Network Analysis. Participants underwent fMRI while watching or reappraising video clips involving interpersonal verbal criticism. During reappraisal, the reappraisal network exerted less influence on the reactivity network in SAD participants. Specifically, the influence of the right inferior frontal gyrus on both reappraisal and reactivity networks was significantly reduced in SAD compared with HC, and correlated negatively with negative emotion ratings among SAD participants. Surprisingly, the amygdala exhibited reduced influence on the reappraisal network in SAD relative to HC. Yet, during the watch condition, the left amygdala's influence on the reactivity network increased with greater social anxiety symptoms among SAD participants. These findings refine our understanding of network organization that contributes to efficient reappraisal or to disturbances in applying this strategy in SAD.

Milk urea nitrogen concentration is higher in Brown Swiss than in Holstein dairy cows despite identical feeding

Milk urea nitrogen (MUN) content is closely related to blood urea nitrogen (BUN) concentration and reflects the balance of dietary crude protein and energy supply for ruminal microbial metabolism. The present study investigated whether the higher MUN content in Brown Swiss (BSW) compared with Holstein (HOL) cows is related to milk production and feeding conditions. Therefore, we evaluated test-day records of three consecutive official milk recordings from 86 BSW and 200 HOL cows kept on the same farm under identical feeding and management conditions. In addition, the relationships between BUN and MUN assessed either by an enzymatic method or by mid-infrared spectroscopy were analysed. For the second objective, milk and blood samples (1,112 samples each) were collected in parallel from day 5 until day 150 of lactation from 141 dairy cows housed at different farms. Concentrations of MUN determined either enzymatically (MUN_ENZ ) or by Fourier transform infrared spectroscopy (FTIR; MUN_IR ) were regressed on the BUN concentrations of the concomitantly obtained blood samples. Both MUN_IR and MUN_ENZ were well correlated with BUN (r = .93 and .89 respectively). Concentration of MUN was higher in BSW compared with HOL independently of lactational stage or parity number (p < .0001). Protein and fat content were higher in BSW than in HOL (p < .05). Primiparous cows had lower milk yield and ECM (p < .001 for BSW, p < .0001 for HOL) than multiparous in both breeds. Multiparous BSW had a similar milk production than primiparous HOL (p = .13). In conclusion, BSW cows have higher MUN than HOL when kept under identical feeding and management conditions. The higher MUN in BSW compared with HOL cows is not related to milk production and therefore rather genetically determined.

0256 Can a Single Night’s Sleep Architecture Predict Next-Day Affect and Affect Regulation?

Introduction

Disrupted sleep has been shown to alter next-day affective functioning by decreasing positive mood, increase negative reactivity, and impairing people’s ability to regulate their affect. However, few studies have examined how particular aspects of sleep timing and architecture influence typical daytime affect. Based on clinical and laboratory research on reactivity to emotional stimuli, we hypothesized a particularly important role for REM sleep in next-day affective functioning.

Methods

We analyzed a subset of N = 64 from a larger study of healthy adult community members who had complete data from a single night of ambulatory polysomnography (PSG) at home as well as morning and evening diaries. We tested whether PSG-derived total sleep time, sleep efficiency, REM percentage, REM latency, and SWS latency predicted self-reported negative mood and use of affect regulation the following morning and day using linear regression models.

Results

Surprisingly, there were no significant associations (p &gt; 0.05) between any of the five PSG sleep architecture measures with self-reported negative morning mood, daytime mood, or daytime affective regulation.

Conclusion

This finding indicates that objective sleep measures from a single night of at home PSG in a healthy adult population are not necessarily predictive of an individual’s subsequent emotional well-being on the following day.

Support

National Science Foundation Graduate Fellowship

Metabolic status is associated with the recovery of milk somatic cell count and milk secretion after lipopolysaccharide-induced mastitis in dairy cows

Infections of the mammary gland in dairy cows are commonly accompanied by reduced milk production and feed intake and poor milk quality. The metabolic status of early-lactating cows is known to affect immune response to pathogens and imposed immune challenges. We investigated the extent to which metabolic status before an intramammary lipopolysaccharide (LPS) challenge (LPS-CH) is associated with immune response, milk production, and feed intake and the recovery thereof. In 15 Holstein cows, weekly blood sampling and daily recording of dry matter intake, milk yield, milk composition, and body weight (to calculate energy balance) was started immediately after parturition. In wk 4 after parturition, cows underwent an intramammary LPS-CH (50 μg of LPS into 1 quarter). Blood and milk samples were taken in parallel at 30- and 60-min intervals, respectively, until 10 h after the LPS application. Plasma concentrations of glucose, nonesterified fatty acids, β-hydroxybutyrate (BHB), cortisol, and insulin were analyzed. In milk, serum albumin, IgG concentration, somatic cell count (SCC), and lactate dehydrogenase (LDH) activity were determined. Dry matter intake and milk yield were recorded for an additional 6 d. Milk of the LPS-treated quarter was sampled at every milking for 8 d after the challenge. Based on plasma glucose concentrations in wk 1 to 4 after parturition before the LPS-CH, cows were retrospectively grouped into a high-glucose group (HG; 3.34-3.93 mmol/L, n = 7) and a low-glucose group (LG; 2.87-3.31 mmol/L, n = 8). Data were evaluated using mixed models with time, group, and time × group interaction as fixed effects and cow as repeated subject. Glucose was lower and BHB was higher in LG compared with HG before LPS-CH, whereas dry matter intake, energy balance, and SCC did not differ. During LPS-CH, SCC and LDH increased similarly in HG and LG, body temperature increased less in HG, and BHB and nonesterified fatty acids were higher in LG compared with HG. Dry matter intake declined in both groups during the day of the LPS-CH but recovered to prechallenge values faster in HG. Milk yield recovered within 2 d after the LPS-CH with no differences in morning milkings, whereas evening milk yield increased faster in HG. During 8 d after LPS-CH, SCC, LDH, IgG, and serum albumin in milk were lower in HG compared with LG. In conclusion, the level of circulating glucose and BHB concentrations in cows was associated with metabolic responses during an LPS-CH as well as the recovery of udder health and performance thereafter.

Effects of colostrum instead of formula feeding for the first 2 days postnatum on whole-body energy metabolism and its endocrine control in neonatal calves

Colostrum provides high amounts of nutritive and non-nutritive substrates, which are essential for calf nutrition and passive immunization. Colostral growth factors and hormones have beneficial effects on postnatal maturation and may affect substrate utilization and energy expenditure in neonatal calves. We tested the hypothesis that energy metabolism and its endocrine regulation differ during the first 10 d of life in calves fed either colostrum or a milk-based formula with a similar nutrient composition to colostrum, but largely depleted of bioactive substances, for the first 2 d postnatum. Male Holstein calves (n = 18) were fed either pooled colostrum (COL; n = 9) or a milk-based formula (FOR; n = 9) for the first 2 d of life. From d 3 on, all calves received same milk replacer. On d 2 and 7 of life, calves were placed in a respiration chamber for indirect calorimetric measurements to calculate heat production, fat (FOX) and carbohydrate oxidation (COX), as well as respiratory quotient. Blood was sampled on d 1 before first colostrum intake and on d 2, 3, 7, 8, 9, and 10 before morning feeding, to measure plasma concentrations of immunoglobulins, metabolites, and hormones. Additional postprandial blood samples were taken on d 1 and 9 at 30, 60, 120, 240, and 420 min after milk feeding. Liver samples were collected on d 10 of life to determine gene expression related to energy metabolism. Formula-fed calves showed lower plasma concentrations of total protein, immunoglobulins, haptoglobin, leptin, adiponectin, and insulin-like growth factor (IGF) binding protein (IGFBP)-4 during the whole study but temporarily higher plasma concentrations of urea, insulin, glucagon, triglyceride, and cholesterol on the first day after feeding, compared with concentrations in COL. The temporary increase in glucagon, triglyceride, and cholesterol on d 1 reversed on d 2 or 3, showing higher concentrations in COL than in FOR calves. In FOR, IGF-I, IGFBP-2, and IGFBP-3 were lower on d 3 than in COL. Interestingly, FOR calves had higher heat production during respiratory measurements on d 2 and higher body temperature on d 2, 3, and 5 than those of COL. The hepatic mRNA abundance of cytosolic phosphoenolpyruvate carboxykinase was higher in FOR than in COL. Our results indicate that first milk feeding after birth influenced whole-body energy expenditure but not FOX and COX in neonatal calves, and the absorption of colostral leptin and adiponectin might affect insulin sensitivity on d 1 of life.

Body condition and insulin resistance interactions with periparturient gene expression in adipose tissue and lipid metabolism in dairy cows

Adipose tissue plays an important role in a cow's ability to adapt to the metabolic demands of lactation, because of its central involvement in energy metabolism and immunity. High adiposity and adipose tissue resistance to insulin are associated with excessive lipid mobilization. We hypothesized that the response to a glucose challenge differs between cows of different body condition 21 d before and after calving and that the responses are explainable by gene expression in subcutaneous adipose tissue (SAT). In addition, we aimed to investigate insulin resistance with gene expression in SAT and lipid mobilization around parturition. Multiparous Holstein cows were grouped according to body conditions score (BCS) 4 wk before calving, as follows: BCS ≤ 3.0 = thin (T, n = 14); BCS 3.25 to 3.5 = optimal (O, n = 14); BCS ≥ 3.75 = over-conditioned (OC, n = 14). We collected SAT on d -21 and d 21 relative to calving. A reverse-transcriptase quantitative (RT-q)PCR was used to measure gene expression related to lipid metabolism. One hour after the collection of adipose tissue, an intravenous glucose tolerance test was carried out, with administration of 0.15 g of glucose per kg of body weight (with a 40% glucose solution). Once weekly from the first week before calving to the third week after calving, a blood sample was taken. The transition to lactation was associated with intensified release of energy stored in adipose tissue, a decrease in the lipogenic genes lipoprotein lipase (LPL) and diacylglycerol O-acyltransferase 2 (DGAT2), and an increase in the lipolytic gene hormone-sensitive lipase (LIPE). On d -21, compared with T cows, OC cows had lower mRNA abundance of LPL and DGAT2, and the latency of fatty acid response after glucose infusion was also longer (8.5 vs. 23.3 min) in OC cows. Cows with higher insulin area under the curve on d -21 had concurrently lower LPL and DGAT2 gene expression and greater concentration of fatty acids on d -7, d 7, and d 14. In conclusion, high adiposity prepartum lowers the whole-body lipid metabolism response to insulin and causes reduced expression of lipogenic genes in SAT 3 weeks before calving. In addition, more pronounced insulin release after glucose infusion on d -21 is related to higher lipid mobilization around calving, indicating an insulin-resistant state, and is associated with lower expression of lipogenic genes in SAT.

Pattern of milk yield and immunoglobulin concentration and factors associated with colostrum quality at the quarter level in dairy cows after parturition

First colostrum yield and constituents as well as milk yield during established lactation vary considerably among mammary quarters in dairy cows. However, data on the development of milk yield, IgG concentration, and their distribution per quarter within cows during the first milkings after calving are scarce. We analyzed milk production and IgG concentration at the individual quarter level in 29 multiparous Holstein cows during the first 5 milkings after calving. Cow- and calf-related factors (time interval between calving and first milking, parity number, previous lactation yield, gestation length, dry period length, sex, and birth weight of the calf) potentially affecting first colostrum quality and quantity were assessed. Milking of first colostrum was carried out between 30 and 180 min after parturition. Further milkings were performed twice daily. Quarter milk yield varied between 0.1 and 5.5 kg at the first milking and between 1.4 and 5.1 kg at the fifth milking relative to parturition. Quarter IgG concentration ranged between 18.8 and 106.0 mg/mL at the first milking and between 0.8 and 46.1 mg/mL at the fifth milking. Distribution of milk yield and IgG concentration among quarters was not entirely repeatable during the first 5 successive milkings after parturition; that is, the ranking of quarters changed (intraclass correlation coefficients for quarter milk yield and IgG concentration: 0.64 and 0.79, respectively). The average hourly milk production increased in all quarters, ranging from 0.02 to 0.26 kg/h between the first 2 milkings up to 0.11 to 0.45 kg/h between the fourth and fifth milkings. First colostrum yield was not affected by any of the evaluated cow- and calf-related factors. Quarter colostrum IgG concentration was higher in cows with a higher previous lactation yield, whereas a lower colostrum IgG content was observed in cows with a longer gestation period and consequently heavier calves. In conclusion, milk yield and IgG concentration of individual quarters varied considerably, and their distribution among quarters within cows was moderately repeatable in consecutive milkings and changed partially over time. The decline of IgG concentration was independent of the concomitant increase in milk secretion, with changes occurring at different rates in individual quarters. Our results confirm the independence of the single mammary quarters at the onset of lactation despite an identical exposure to endocrine stimuli.

The APOB loss-of-function mutation of Holstein dairy cattle does not cause a deficiency of cholesterol but decreases the capacity for cholesterol transport in circulation

The loss-of-function mutation of the apolipoprotein (APO) B gene (APOB) in Holstein cattle accounts for increased losses in calves that are homozygous for this mutation. Heterozygous carriers of the APOB mutation are clinically healthy but show decreased concentrations of plasma cholesterol and lipoproteins. So far, the metabolic effects of the mutation have only been investigated in heterozygous calves, bulls, and nonlactating females. In high-yielding dairy cows, a marked decrease in cholesterol concentration in plasma during early lactation is part of the usual metabolic changes. Given the essential role of cholesterol in fatty acid and lipid metabolism, a specific effect of the APOB mutation on metabolism and performance in dairy cows is expected. Therefore, the aim of the present study was to investigate the effects of different APOB genotypes on metabolic parameters, hepatic metabolism, and lactation and reproductive performance. Twenty pairs of full siblings with similar age, performance, and calving were investigated. Both animals of each pair were kept on the same farm and consisted of a heterozygous carrier (CDC) and a noncarrier (CDF) of the APOB mutation associated with cholesterol deficiency. Blood samples were taken in early (25.5 ± 4.7 d in milk) and mid lactation (158.2 ± 11.1 d in milk; mean ± SD), and analyzed for nonesterified fatty acids, β-hydroxybutyrate, glucose, insulin-like growth factor-1, aspartate aminotransferase and gamma-glutamyltransferase activity, total cholesterol, free cholesterol, triacylglycerols, high density lipoprotein-cholesterol, and phospholipids. The evaluation of milk production, milk gross composition, and lactation persistency was based on official Dairy Herd Improvement Association recordings. Cholesterol and lipoprotein concentrations were lower in CDC cows than in CDF cows in early and mid lactation. Metabolic parameters, triacylglycerol concentration in plasma, and lactation and reproductive performance did not differ between CDC cows and CDF cows. The low cholesterol concentrations associated with the APOB mutation in heterozygous carriers are not because of a primary deficiency of cholesterol at a cellular level, as the term "cholesterol deficiency" suggests, but rather a consequence of reduced capacity for its transport in circulation. Overall, the data of the present study suggest that, despite the presence of the APOB mutation, cholesterol is not limiting for animals' metabolic adaptation and performance in heterozygous Holstein cows.

Immunoglobulin G content and colostrum composition of different goat and sheep breeds in Switzerland and Germany

Colostrum represents the sole source to acquire humoral immunity and is an important energy source for newborn lambs and goat kids. However, colostrum composition (i.e., the contents of IgG, fat, protein, and lactose) is affected by various factors such as parity and litter size and, potentially, by breed. In the present study, we examined the colostrum composition of different goat and sheep breeds raised for milk and meat production in Switzerland and Germany. Ten goat breeds (Anglo-Nubian, Appenzell, Boer, Bunte Deutsche Edelziege, Chamois-colored, Grisons Striped, Peacock, Saanen, Toggenburg, and Valais Blackneck) and 10 sheep breeds (Brown-Headed Meat, East Friesian Milk, German Blackheaded Mutton, Gray Horned Heath, Lacaune Dairy, Merino Land, Swiss Black-Brown Mountain, Swiss Charollais, Swiss White Alpine, and Valais Blacknose) were involved in this study. First colostrum samples were obtained from ewes (n = 100) and goats (n = 116) between 10 and 390 min after parturition and analyzed for total IgG, fat, protein, and lactose contents. Colostral IgG concentrations varied between 4.8 and 75.0 mg/mL in goats, and between 6.2 and 65.4 mg/mL in ewes, and the time interval between milking and parturition did not affect colostral IgG concentrations. In goats, the highest IgG concentrations were found in Boer (meat-type; 61.0 ± 10.3 mg/mL; mean ± SD) and the lowest concentrations were observed in Bunte Deutsche Edelziege (milk-type; 26.5 ± 12.5 mg/mL). In sheep, East Friesian Milk and Lacaune Dairy showed the lowest colostral IgG concentrations (17.9 ± 7.3 and 20.2 ± 8.0 mg/mL, respectively), and the highest values were observed in the Merino Land breed (44.2 ± 15.7 mg/mL). The lowest fat and protein concentrations and concomitantly highest lactose concentrations were observed in colostrum of East Friesian Milk and Lacaune Dairy sheep. Parity number did not affect colostrum composition in sheep or goats. In contrast, colostral fat content was higher in ewes bearing twins and triplets than in those carrying singletons. Increasing litter size tended to be associated with higher protein and lower lactose concentrations in ovine (i.e., singletons vs. twins vs. triplets) and caprine colostrum (i.e., singletons vs. twins), whereas colostral IgG concentrations were not affected by litter size. In conclusion, IgG and concentrations of other colostrum constituents showed a wide range in goats and ewes and were mainly affected by the type of breed.

Invited review: Metabolic challenges and adaptation during different functional stages of the mammary gland in dairy cows: Perspectives for sustainable milk production

Milk production of dairy cows has increased markedly during recent decades and continues to increase further. The evolutionarily conserved direction of nutrients to the mammary gland immediately after calving provided the basis for successful selective breeding toward higher performance. Considerable variation in adaptive responses toward energy and nutrient shortages exists; however, this variation in adaptability recently gained interest for identifying more metabolically robust dairy cows. Metabolic challenges during periods of high milk production considerably affect the immune system, reproductive performance, and product quality as well as animal welfare. Moreover, growing consumer concerns need to be taken into consideration because the public perception of industrialized dairy cow farming, the high dependency on feed sources suitable for human nutrition, and the apparently abundant use of antibiotics may affect the sales of dairy products. Breeding for high yield continues, but the metabolic challenges increasingly come close to the adaptational limits of meeting the mammary gland's requirements. The aim of the present review is to elucidate metabolic challenges and adaptational limitations at different functional stages of the mammary gland in dairy cows. From the challenges and adaptational limitations, we derive perspectives for sustainable milk production. Based on previous research, we highlight the importance of metabolic plasticity in adaptation mechanisms at different functional stages of the mammary gland. Metabolic adaptation and plasticity change among developing, nonlactating, remodeling, and lactational stages of the mammary gland. A higher metabolic plasticity in early-lactating dairy cows could be indicative of resilience, and a high performance level without an extraordinary occurrence of health disorders can be achieved.

Milk yield loss in response to feed restriction is associated with mammary epithelial cell exfoliation in dairy cows

In dairy cows, feed restriction is known to decrease milk yield by reducing the number of mammary epithelial cells (MEC) in the udder through a shift in the MEC proliferation-apoptosis balance, by reducing the metabolic activity of MEC, or both. The exfoliation of MEC from the mammary epithelium into milk is another process that may participate in regulating the number of MEC during feed restriction. The aim of the present study was to clarify the mechanisms that underlie the milk yield loss induced by feed restriction. Nineteen Holstein dairy cows producing 40.0 ± 0.7 kg/d at 77 ± 5 d in milk were divided into a control group (n = 9) and a feed-restricted group (n = 10). Ad libitum dry matter intake (DMI) was recorded during a pre-experimental period of 2 wk. For 29 d (period 1), cows were fed either 100 (control) or 80% (feed-restricted) of their ad libitum DMI measured during the pre-experimental period. Then, all cows were fed ad libitum for 35 d (period 2). Milk production and DMI were recorded daily. Blood and milk samples were collected once during the pre-experimental period; on d 5, 9, and 27 of period 1; and on d 5, 9, and 30 of period 2. Mammary epithelial cells were purified from milk using an immunomagnetic method to determine the rate of MEC exfoliation. Mammary tissue samples were collected by biopsy at the end of each period to analyze the rates of cell proliferation and apoptosis and the expression of genes involved in synthesizing constituents of milk. Feed restriction decreased milk yield by 3 kg/d but had no effect on rates of proliferation and apoptosis in the mammary tissue or on the expression of genes involved in milk synthesis. The daily MEC exfoliation rate was 65% greater in feed-restricted cows than in control cows. These effects in feed-restricted cows were associated with reduced insulin-like growth factor-1 and cortisol plasma concentrations. When all cows returned to ad libitum feeding, no significant difference on milk yield or MEC exfoliation rate was observed between feed-restricted and control cows, but refeeding increased prolactin release during milking. These results show that the exfoliation process may play a role in regulating the number of MEC in the udders of dairy cows during feed restriction without any carryover effect on their milk production.

Short communication: Circulating serotonin is related to the metabolic status and lactational performance at the onset of lactation in dairy cows

Serotonin (5-hydroxytryptamine, 5-HT) affects many physiological functions because it is involved in glucose and lipid metabolism, calcium homeostasis, and regulation of lactation in dairy cows. This study aimed to examine physiological differences in serum 5-HT concentrations (high vs. low) and their association with metabolic status and milk production at the onset of lactation. Twelve multiparous Holstein dairy cows were milked within 4 h of calving, and blood and milk samples were collected at the first 6 subsequent milkings after parturition and at the evening milkings on d 5, 8, 10, and 14. Cows were retrospectively divided into 2 groups (6 cows/group): low serum 5-HT (LSS) and high serum 5-HT (HSS) according to their calculated areas under the curve (AUC) for serum 5-HT for the entire experimental period (cut-off: 46,000 ng/mL × 324 h). Concentrations of 5-HT, free fatty acids (FFA), β-hydroxybutyrate (BHB), glucose, calcium, and IGF-1 were measured in blood. Milk was analyzed for fat, protein, lactose, and 5-HT concentrations. Milk yield was recorded at each milking and energy-corrected milk yield was calculated. Serum 5-HT concentrations were higher in HSS than in LSS [AUC (ng/mL × 324 h): 57,830 ± 4,810 vs. 25,005 ± 5,930]. The amount of energy-corrected milk was lower in HSS than in LSS. The HSS group produced less colostrum and had decreased milk yield, specifically during the first 6 milkings. Concentrations of FFA, BHB, and glucose in plasma did not differ between groups. Concentrations of IGF-1 in serum were elevated in HSS compared with LSS throughout the experiment. Total circulating calcium concentrations in serum tended to be higher in HSS than in LSS. Milk fat and protein yields were decreased in HSS compared with LSS. Milk 5-HT decreased overall during the experimental period, with LSS maintaining higher 5-HT concentrations than HSS until d 14 of lactation. In conclusion, cows with high serum 5-HT concentrations showed a reduced metabolic load at the onset of lactation, concomitantly lower milk yield, and a reduced energy output via milk.

Prevalence of subclinical ketosis and production diseases in dairy cows in Central and South America, Africa, Asia, Australia, New Zealand, and Eastern Europe

Subclinical ketosis (SCK) and periparturient diseases considerably account for economic and welfare losses in dairy cows. The majority of scientific reports investigating the prevalence of SCK and production diseases are based on empirical studies conducted in Western Europe and North America. The present study surveyed the prevalence of SCK and production-related clinical diseases in early lactating cows in various countries across the world other than those in North America and Western Europe. Twelve countries of South and Central America (Argentina, Brazil, Chile, Colombia, Mexico), Africa (South Africa), Asia (Thailand, China), Eastern Europe (Russia, Ukraine), Australia, and New Zealand were assessed, and data from a total of 8,902 cows kept at 541 commercial dairy farms were obtained. A minimum of five cows per farm were blood sampled and examined once after parturition up to day 21 of lactation. Blood concentration of β-hydroxybutyrate was measured (threshold for SCK: 1.2 mmol/L), and the presence of production-related diseases such as milk fever, retained placenta, mastitis, metritis, displaced abomasum, lameness, and clinical ketosis was recorded. More than 95% of all cows were examined in their second week of lactation. Across all investigated countries, the SCK prevalence was 24.1%, ranging from 8.3% up to 40.1%. The prevalence of production-related diseases detected during the first 21 d of lactation was relatively low (<5%). Calculated odds ratios did not indicate an elevated risk for production diseases in cows with SCK. Despite differences in production systems across countries and variation between individual farms within a region, the present study data on SCK prevalence align with observations in Western European and North American dairy herds. At the very early stage of sampling and clinical examination for detection of SCK, it cannot be excluded that certain production diseases such as displaced abomasum, lameness, and mastitis have developed later.

Effects of concentrate supplementation in early lactation on nutrient efficiency, ruminal fermentation and reticular pH of zero-grazing dairy cows with differing milk production potentials

In Switzerland, fresh herbage is a favoured feed for dairy cows due to its high quality and availability and low production costs. However, transition and early lactation are periods characterized by an increased nutrient demand that may not be covered by herbage alone. To compare the effects of concentrate supplementation in early lactation on nutrient efficiency and ruminal fermentation, 24 multiparous Holstein cows were assigned to two performance groups according to their previous lactation milk yield: high- (8,959 ± 984 kg) and low- (6,204 ± 1,000 kg) potential cows. Within this group, cows were allocated to two treatment groups receiving either herbage ad libitum (n = 11) or herbage supplemented with concentrate (n = 13). The experiment started for each cow 2 weeks before the predicted calving date (LW-2) and lasted until lactation week (LW) 8. Milk yield and dry matter intake (DMI) were recorded daily. The reticular pH was measured continuously using a telemetric pH bolus. Milk components and ruminal fermentation traits were analysed in LW-2, LW2, LW4, LW6 and LW8. Supplemented cows (p < 0.001) and high-potential cows (p = 0.015) produced more milk than unsupplemented cows and low-potential cows, respectively. Milk acetone was affected by supplementation (p < 0.001) and milk potential (p = 0.002) and was especially high in unsupplemented, high-potential cows until LW6. Supplementation caused a decrease in herbage DMI (p < 0.001) but resulted in an increased total DMI (p < 0.001), whereas milk potential had no effect on DMI. Associated with an increasing DMI (p < 0.001), ruminal volatile fatty acid concentration (p = 0.024) increased and reticular pH (p < 0.001) decreased from LW2 until LW6. Apart from that, effects on ruminal fermentation and reticular pH were minor. In conclusion, even though apparent nutrient efficiency was high, high-potential cows without supplementation seem to struggle more with reduced nutrient availability than other cows; therefore, they appear to be more prone to metabolic stress and consequently to production diseases.

Free and bound cortisol in plasma and saliva during ACTH challenge in dairy cows and horses

Cortisol levels reflect hypothalamic-pituitary-adrenocortical (HPA) axis activity. While most plasma cortisol is supposed to be bound to the soluble corticosteroid-binding globulin (CBG), only free cortisol (FC) actively regulates metabolic and immunological processes. We aimed to establish a multispecies suitable method to assess FC in cows and horses which in combination with total cortisol (TC) allows interpreting proportional changes of cortisol in saliva as well as in blood in response to a standardized HPA axis activation via ACTH. We further investigated if the ratios of cortisol fractions as obtained at basal levels in healthy horses (herbivorous and monogastric) and dairy cows (herbivorous and ruminant) change during HPA axis activation, and to which extent saliva cortisol (SC) is representative for alterations in plasma FC and adrenal cortex reactivity. However, it was not the objective of the present study to directly compare the two species. Dosages of ACTH applied in cows and horses were based on published data. Synthetic ACTH was intravenously administered to eight dairy cows (0.16 µg/kg BW) and five horses (1 µg/kg BW). Blood and saliva were collected every 30 min for 3 h from a jugular vein catheter, and analyzed for TC and SC, the ratio of free cortisol (rFC), and the concentration of FC (cFC) in plasma. During the entire sampling period of the ACTH test, plasma TC was paralleled by blood cFC, rFC, and SC in both cows and horses. All cortisol fractions increased within 30 min of ACTH administration compared to basal values (0 min, P < 0.05). Peak TC concentration reached 63.2 ± 9.6 ng/mL and 73.2 ± 11.8 ng/mL in bovine and equine plasma, respectively. Peak values of rFC averaged 17.9 ± 4.5% in cows and 19.2 ± 7.8% in horses. The ratio of SC to cFC in horses remained similar during the ACTH challenge suggesting that SC is recruited from plasma FC. However, SC increased less compared to plasma TC and FC during HPA axis activation in cows. In conclusion, the short-term activation of the HPA axis caused not only an elevation of TC, but also a similar increase of rFC in both species. SC closely reflected changes of FC in horses, but less accurately in cows. The concomitant evaluation of changes among cortisol fractions might give further indications on adaptation mechanisms in glucocorticoid regulation as well as differentiate cortisol-related health disorders.

Physiological and behavioural responses of grazing dairy cows to an acute metabolic challenge

Due to seasonal changes in the quality and quantity of herbage, the nutrient supply to grazing dairy cows is not always sufficient, which may increase their metabolic load. To investigate the temporal pattern of behavioural changes in relation to concomitant metabolic alterations, we subjected 15 multiparous early lactating Holstein dairy cows (24 (SD 7.4) days in milk) to a short-term metabolic challenge, which we provoked by abruptly withdrawing concentrate for 1 week. Cows grazed full-time and were supplemented with concentrate in experimental week (EW) 1 and EW 3, whereas concentrate was withdrawn in EW 2. We analysed milk and blood samples to characterise the metabolic changes and found that the total yield of milk and protein decreased (p < 0.05) and fat yield, fat-to-protein ratio and acetone content increased (p < 0.05) from EW 1 to EW 2. Plasma glucose and insulin concentrations were lower (p < 0.05), and concentrations of nonesterified fatty acids and beta-hydroxybutyrate were higher (p < 0.05) in EW 2 compared with EW 1. Apart from ingestive and rumination behaviour and activity, we also monitored the use of an automated brush on pasture. While time spent eating and ruminating increased (p < 0.05) in EW 2 compared with EW 1, time spent idling decreased (p < 0.05). Concomitantly, while time standing and moving increased (p < 0.05) from EW 1 to EW 2, walking time decreased (p < 0.05). The daily proportion of cows using the automated brush decreased (p < 0.05) in EW 2 compared with EW 1, as did the duration of brushing per day. In conclusion, grazing cows experiencing a metabolic challenge try to compensate for the nutrient deficiency by increasing eating time, a behavioural element important for short-term survival. Due to the strong impact of weather conditions, we cannot currently recommend observation of outdoor brushing activity to address short-term alterations in the metabolic state of grazing cows.

Disturbed bovine mitochondrial lipid metabolism: a review

In mammals, excess energy is stored primarily as triglycerides, which are mobilized when energy demands arise and cannot be covered by feed intake. This review mainly focuses on the role of long chain fatty acids in disturbed energy metabolism of the bovine species. Long chain fatty acids regulate energy metabolism as ligands of peroxisome proliferator-activated receptors. Carnitine acts as a carrier of fatty acyl groups as long-chain acyl-CoA derivatives do not penetrate the mitochondrial inner membrane. There are two different types of disorders in lipid metabolism which can occur in cattle, namely the hypoglycaemic-hypoinsulinaemic and the hyperglycaemic-hyperinsulinaemic type with the latter not always associated with ketosis. There is general agreement that fatty acid β-oxidation capability is limited in the liver of (ketotic) cows. In accord, supplemental L-carnitine decreased liver lipid accumulation in periparturient Holstein cows. Of note, around parturition concurrent oxidation of fatty acids in skeletal muscle is highly activated. Also peroxisomal β-oxidation in liver of dairy cows may be part of the hepatic adaptations to a negative energy balance (NEB) to break down fatty acids. An elevated blood concentration of nonesterified fatty acids is one of the indicators of NEB in cattle among others like increased β-hydroxy butyrate concentration, and decreased concentrations of glucose, insulin, and insulin-like growth factor-I. Assuming that liver carnitine concentrations might limit hepatic fatty acid oxidation capacity in dairy cows, further study of the role of acyl-CoA dehydrogenases and/or riboflavin in bovine ketosis is warranted.

Adipose tissue insulin receptor and glucose transporter 4 expression, and blood glucose and insulin responses during glucose tolerance tests in transition Holstein cows with different body condition

Glucose uptake in tissues is mediated by insulin receptor (INSR) and glucose transporter 4 (GLUT4). The aim of this study was to examine the effect of body condition during the dry period on adipose tissue mRNA and protein expression of INSR and GLUT4, and on the dynamics of glucose and insulin following the i.v. glucose tolerance test in Holstein cows 21 d before (d -21) and after (d 21) calving. Cows were grouped as body condition score (BCS) ≤3.0 (thin, T; n = 14), BCS = 3.25 to 3.5 (optimal, O; n = 14), and BCS ≥3.75 (overconditioned, OC; n = 14). Blood was analyzed for glucose, insulin, fatty acids, and β-hydroxybutyrate concentrations. Adipose tissue was analyzed for INSR and GLUT4 mRNA and protein concentrations. During the glucose tolerance test 0.15 g/kg of body weight glucose was infused; blood was collected at -5, 5, 10, 20, 30, 40, 50, and 60 min, and analyzed for glucose and insulin. On d -21 the area under the curve (AUC) of glucose was smallest in group T (1,512 ± 33.9 mg/dL × min) and largest in group OC (1,783 ± 33.9 mg/dL × min), and different between all groups. Basal insulin on d -21 was lowest in group T (13.9 ± 2.32 µU/mL), which was different from group OC (24.9 ± 2.32 µU/mL. On d -21 the smallest AUC 5-60 of insulin in group T (5,308 ± 1,214 µU/mL × min) differed from the largest AUC in group OC (10,867 ± 1,215 µU/mL × min). Time to reach basal concentration of insulin in group OC (113 ± 14.1 min) was longer compared with group T (45 ± 14.1). The INSR mRNA abundance on d 21 was higher compared with d -21 in groups T (d -21: 3.3 ± 0.44; d 21: 5.9 ± 0.44) and O (d -21: 3.7 ± 0.45; d 21: 4.7 ± 0.45). The extent of INSR protein expression on d -21 was highest in group T (7.3 ± 0.74 ng/mL), differing from group O (4.6 ± 0.73 ng/mL), which had the lowest expression. The amount of GLUT4 protein on d -21 was lowest in group OC (1.2 ± 0.14 ng/mL), different from group O (1.8 ± 0.14 ng/mL), which had the highest amount, and from group T (1.5 ± 0.14 ng/mL). From d -21 to 21, a decrease occurred in the GLUT4 protein levels in both groups T (d -21: 1.5 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL) and O (d -21: 1.8 ± 0.14 ng/mL; d 21: 0.8 ± 0.14 ng/mL). These results demonstrate that in obese cows adipose tissue insulin resistance develops prepartum and is related to reduced GLUT4 protein synthesis. Regarding glucose metabolism, body condition did not affect adipose tissue insulin resistance postpartum.

Consequences of dietary energy source and energy level on energy balance, lactogenic hormones, and lactation curve characteristics of cows after a short or omitted dry period

Omitting the dry period (DP) generally reduces milk production in the subsequent lactation. The aim of this study was to evaluate the effect of dietary energy source-glucogenic (G) or lipogenic (L)-and energy level-standard (std) or low-on milk production; energy balance (EB); lactogenic hormones insulin, insulin-like growth factor 1 (IGF-1), and growth hormone (GH); and lactation curve characteristics between wk 1 and 44 postpartum in cows after a 0-d or 30-d DP. Cows (n = 110) were assigned randomly to 3 transition treatments: a 30-d DP with a standard energy level required for expected milk yield [30-d DP(std)], a 0-d DP with the same energy level as cows with a 30-d DP [0-d DP(std)], and a 0-d DP with a low energy level [0-d DP(low)]. In wk 1 to 7, cows were fed the same basal ration but the level of concentrate increased to 6.7 kg/d for cows fed the low energy level and to 8.5 kg/d for cows fed the standard energy level in wk 4. From wk 8 postpartum onward, cows received a G ration (mainly consisting of corn silage and grass silage) or an L ration (mainly consisting of grass silage and sugar beet pulp) with the same energy level contrast (low or std) as in early lactation. Cows fed the G ration had greater milk, lactose, and protein yields, lower milk fat percentage, greater dry matter and energy intakes, and greater plasma IGF-1 concentration compared with cows fed the L ration. Dietary energy source did not affect EB or lactation curve characteristics. In cows with a 0-d DP, the reduced energy level decreased energy intake, EB, and weekly body weight gain, but did not affect milk production or lactation curve characteristics. A 30-d DP resulted in a greater total predicted lactation yield, initial milk yield after calving, peak milk yield, energy intake, energy output in milk, days to conception [only when compared with 0-d DP(low)], plasma GH concentration [only when compared with 0-d DP(std)], and decreased weekly body weight gain compared with a 0-d DP. A 30-d DP decreased both the increasing and the declining slope parameters of the lactation curve and the relative rate of decline in milk yield (indicating greater lactation persistency) compared with a 0-d DP, and decreased plasma insulin and IGF-1 concentration, and EB. In conclusion, feeding a G ration after wk 7 in milk improved energy intake and milk production, but did not affect EB compared with an L ration. For cows without a DP, a reduced dietary energy level did not affect milk production and lactation curve characteristics, but did decrease EB and weekly body weight gain. A 30-d DP increased milk yield and lactation persistency, but decreased milk fat and protein content, EB, and plasma insulin and IGF-1, compared with a 0-d DP.

Rapid Communication: Cholesterol deficiency-associated APOB mutation impacts lipid metabolism in Holstein calves and breeding bulls

During the last months, the number of reports on Holstein calves suffering from incurable idiopathic diarrhea dramatically increased. Affected calves showed severe hypocholesterolemia and mostly died within days up to a few months after birth. This new autosomal monogenic recessive inherited fat metabolism disorder, termed cholesterol deficiency (CD), is caused by a loss of function mutation of the bovine gene. The objective of the present study was to investigate specific components of lipid metabolism in 6 homozygous for the mutation (CDS) and 6 normal Holstein calves with different genotypes. Independent of sex, CDS had significantly lower plasma concentrations of total cholesterol (TC), free cholesterol (FC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C), triacylglycerides (TAG), and phospholipids (PL) compared with homozygous wild-type calves ( < 0.05). Furthermore, we studied the effect of the genotype on cholesterol metabolism in adult Holstein breeding bulls of Swissgenetics. Among a total of 254 adult males, the homozygous mutant genotype was absent, 36 bulls were heterozygous carriers (CDC), and 218 bulls were homozygous wild-type (CDF). In CDC bulls, plasma concentrations of TC, FC, HDL-C, LDL-C, VLDL-C, TAG, and PL were lower compared with CDF bulls ( < 0.05). The ratios of FC:cholesteryl esters (CE) and FC:TC were higher in CDC bulls compared with CDF bulls, whereas the ratio of CE:TC was lower in CDC bulls compared with CDF bulls ( < 0.01). In conclusion, the CD-associated mutation was shown to affect lipid metabolism in affected Holstein calves and adult breeding bulls. Besides cholesterol, the concentrations of PL, TAG, and lipoproteins also were distinctly reduced in homozygous and heterozygous carriers of the mutation. Beyond malabsorption of dietary lipids, deleterious effects of apolipoprotein B deficiency on hepatic lipid metabolism, steroid biosynthesis, and cell membrane function can be expected, which may result in unspecific symptoms of reduced fertility, growth, and health.

The effect of dry period length and postpartum level of concentrate on milk production, energy balance, and plasma metabolites of dairy cows across the dry period and in early lactation

Shortening or omitting the dry period (DP) improves energy balance (EB) in early lactation because of a reduction in milk yield. Lower milk yield results in lower energy demands and requires less energy intake. The aim of this study was to evaluate the effects of DP length and concentrate level postpartum on milk yield, feed intake, EB, and plasma metabolites between wk -4 and 7 relative to calving of cows of second parity or higher. Holstein-Friesian dairy cows (n = 123) were assigned randomly to 1 of 2 DP lengths: 0-d DP (n = 81) or 30-d DP (n = 42). Prepartum, cows with a 0-d DP received a lactation ration based on grass silage and corn silage (6.4 MJ of net energy for lactation/kg of dry matter). Cows with a 30-d DP received a dry cow ration based on grass silage, corn silage, and straw (5.4 MJ of net energy for lactation/kg of dry matter). Postpartum, all cows received the same basal lactation ration as provided to lactating cows prepartum. Cows with a 0-d DP were fed a low level of concentrate up to 6.7 kg/d based on the requirement for their expected milk yield (0-d DP-L; n = 40) or the standard level of concentrate up to 8.5 kg/d (0-d DP-S; n = 41), which was equal to the concentrate level for cows with a 30-d DP (30-d DP-S; n = 42) based on requirements for their expected milk yield. Prepartum dry matter intake, concentrate intake, basal ration intake, energy intake, plasma β-hydroxybutyrate (BHB), and insulin concentrations were greater and plasma free fatty acids (FFA) and glucose concentrations were lower, but EB was not different in cows with a 0-d DP compared with cows with a 30-d DP. During wk 1 to 3 postpartum, milk fat yield and plasma BHB concentration were lower and dry matter intake and concentrate intake were greater in cows with a 0-d DP compared with cows with a 30-d DP. During wk 4 to 7 postpartum, fat- and protein-corrected milk (FPCM), lactose content, and lactose and fat yield were lower in 0-d DP-L or 0-d DP-S cows compared with 30-d DP-S cows. Basal ration intake, EB, body weight, plasma glucose, and insulin and insulin-like growth factor-1 concentrations were greater and plasma FFA and BHB concentrations were lower in 0-d DP-L and 0-d DP-S cows compared with 30-d DP-S cows. Concentrate and energy intake were lower in 0-d DP-L cows than in 0-d DP-S or 30-d DP-S cows. Milk yield and concentrations of plasma metabolites did not differ in wk 4 to 7, although EB was lower in wk 6 and 7 postpartum in 0-d DP-L cows than in 0-d DP-S cows. In conclusion, a 0-d DP reduced milk yield and improved EB and metabolic status of cows in early lactation compared with a 30-d DP. Reducing the postpartum level of concentrate of cows with a 0-d DP did not affect fat- and protein-corrected milk yield or plasma FFA and BHB concentrations in early lactation but did reduce EB in wk 6 and 7 postpartum.

Quarter vs. composite colostrum composition assessed by Brix refractometry, specific gravity and visual color appearance in primiparous and multiparous dairy cows

The control of colostrum quality is essential for successful calf rearing. Instruments for on-farm colostrum quality determination are mostly utilized for testing composite colostrum samples, but do not take potential variation between quarters into account. In cases of low composite colostrum quality, feeding of better quality colostrum from individual quarters might be beneficial. The objective of the present study was to identify relationships between colostrum color, colostrum quality and composition. Besides laboratory methods, a colostrometer and a Brix refractometer were used to assess colostrum quality at quarter levels. Quarter and composite colostrum samples from 17 primiparous and 11 multiparous Holstein cows were analyzed for total IgG, fat, protein and lactose content; color was measured by a spectrophotometer. In the present study, an IgG concentration below 50 g/L as determined by ELISA was found in 14.3% of the analyzed quarter samples. Concentration and mass of IgG in composite colostrum samples were greater in multiparous compared with primiparous cows. Specific gravity (SG) of colostrum of individual and composite samples was lower in primiparous compared with multiparous cows. Milk fat content was greater in quarter and composite colostrum samples of primiparous compared with multiparous dairy cows. No clear relationships between IgG content and SG, Brix, and the color space coordinates L*, a*, and b* were detected. Interestingly, results indicate that despite a similar range of the variables investigated, correlations between those parameters can differ at quarter compared to composite level. Not only for SG and Brix determination, but also for the color space coordinates measured, correlation coefficients with IgG concentration of the respective samples were greater at a composite compared with the individual quarter level. In conclusion, accuracy and limitations of on-farm instruments estimating colostrum quality apply to both quarter colostrum samples and composite evaluations. Identification of quarters with superior colostrum quality would possibly be a way to improve the immunization of newborn calves. However, the potential on-farm methods validated in the present study to estimate quarter colostrum quality are not sufficiently sensitive to distinguish between quarters. This is due to the variation of gross colostrum composition between individual quarters of a cow.