Differences between primiparous and multiparous dairy cows in the inter-relationships between metabolic traits, milk yield and body condition score in the periparturient period

Effects of parity and week after calving on the metabolic, redox and immune status of dairy cows

At the onset of lactation in dairy cows, inflammation and oxidative stress may occur and result in a risk of pathologies and lower milk yield. To propose an innovative management strategy for cows during this period, it is essential to better understand these physiological variations. Our objective was to evaluate the metabolic, redox and immune status of 7 primiparous and 8 multiparous Holstein cows during late gestation and the first months of lactation. Blood samples were collected between 3 weeks before calving until 12 weeks postpartum. Milk samples were also collected, but only at the time points after calving. The metabolic (nonesterified fatty acids (NEFA), BHB, glucose, urea, calcium) and redox (reactive oxygen metabolites (ROM), oxidative stress index (OSI), glutathione peroxidase activity, vitamin E) statuses were analyzed in plasma or erythrocytes. The expression of genes related to antioxidant functions was determined in leukocytes collected from milk. For immune status, plasma cytokine levels and the production of reactive oxygen species (ROS) in classical and regulatory neutrophils were measured in 2 whole blood ex vivo challenges. The data were analyzed using a mixed model that included the fixed effects of parity and week and their interaction. Milk yield, plasma NEFA and BHB in wk 2 and 4 after calving were higher in multiparous cows than in primiparous cows, whereas glucose and calcium tended to be lower. Plasma ROM and OSI levels in wk 8 were higher in multiparous than in primiparous cows. Multiparous cows also displayed higher glutathione peroxidase activity in erythrocytes, and antioxidant transcription factor and superoxide dismutase-1 expression levels in milk leukocytes. Moreover, multiparous cows had higher plasma concentrations of vitamin E but lower plasma levels of cytokines CXCL10, CCL2, IL1Rα and IFNγ. Following ex vivo whole blood stimulation with Escherichia coli, lower IL1α and TNFα levels were measured in multiparous than in primiparous cows. Intracellular ROS production by neutrophils was lower in multiparous than in primiparous cows. These results thus indicated marked physiological changes in wk 8 compared with wk 2 and 4 of lactation. These differences in the physiological status of primiparous and multiparous cows offer interesting perspectives for potential dietary strategies to prevent pathologies which take account of parity and week relative to calving.

Intake profile, milk production and energy balance of early lactation spring calving Holstein Friesian and Jersey x Holstein Friesian dairy cows in high utilisation pasture-based systems

Early lactation is a critical period for dairy cows as energy requirements rapidly increase with the onset of lactation, however, early lactation dry matter intakes (DMI) in pasture-based systems are under-measured. The objectives of this study were 1) to measure and profile total DMI (TDMI) and animal performance of dairy cows during early lactation in a pasture-based system 2) to investigate early lactation energy balance in pasture-based systems and 3) to examine production efficiencies including TDMI and milk solids production per 100 kg bodyweight. Eighty spring-calving dairy cows were allocated to a grazing group as they calved over a 2 year period (2021 and 2022). Cows were offered a daily herbage allowance to achieve a post-grazing sward height of 4 cm with silage supplementation when necessary due to inclement weather. Total DMI was measured using the n-alkane technique over a 12 week period from 1st of February to the 23rd of April. Total DMI and daily milk yield were significantly affected by parity with both variables being greatest for third parity animals (17.7 kg DM and 26.3 kg/cow/day, respectively), lowest for first parity (13.2 kg DM and 19.6 kg/cow/day, respectively) and intermediate for second parity animals (16.8 kg DM and 24.1 kg/cow/day, respectively). Peak TDMI was reached on wk 10 for first parity animals (14.6 kg DM), wk 11 for second parity animals (19.3 kg DM) and wk 12 for third parity animals (19.9 kg DM). Parity also had a significant effect on UFL (feed units for milk) feed balance as first parity animals experienced a greater degree of negative energy balance (-3.2 UFL) compared with second and third parity animals (-2.3 UFL). Breed and parity had an effect on production efficiencies during the first 12 weeks of lactation as Jersey x Holstein Friesian cows had greater TDMI/100 kg bodyweight and milk solids/100 kg bodyweight compared with Holstein Friesian cows.

Use of rumination time in health risk assessment of prepartum dairy cows

The objectives of this observational cohort study were to evaluate the associations of rumination time (RT) in the last week of pregnancy with transition cow metabolism, inflammation, health, and subsequent milk production, reproduction, and culling. Pregnant nulliparous (n = 199) and parous (n = 337) cows were enrolled 21 d before the expected calving. RT and physical activity were monitored automatically by sensors from d -21 to 15 relative to calving. Blood samples were collected on d -14, -5, 4, 8, and 12 ± 1 relative to calving. Diagnoses of clinical health problems were performed by researchers from calving to 15 d in milk (DIM). In classification 1, cows were ranked based on average daily RT in the last week of pregnancy and classified into terciles as short RT (SRT), moderate RT (MRT), or long RT (LRT) for association analyses. In classification 2, RT deviation from the parity average was used in a receiver operating characteristic curve to identify the best threshold to predict postpartum clinical disease. Cows were then classified as above the threshold (AT) or below the threshold (BT). Compared with cows with LRT, cows with SRT had greater serum concentrations of NEFA (0.47 vs 0.40 ± 0.01 mmol/L), BHB (0.58 vs 0.52 ± 0.01 mmol/L), and haptoglobin (0.22 vs 0.18 ± 0.008 g/L) throughout the transition period, and reduced concentrations of glucose, cholesterol, albumin, and magnesium in a time-dependent manner. Parous cows with SRT had higher odds of postpartum clinical disease (adjusted odds ratio [AOR]: 3.7; 95% confidence interval [CI]: 2.1-6.4), lower odds of pregnancy by 210 DIM (AOR: 0.34; CI: 0.15-0.75), and lower milk production (46.9 vs 48.6 ± 0.5 kg/d) than parous cows with LRT. Deviation in prepartum RT had good predictive value for clinical disease in parous cows (area under the curve [AUC]: 0.65; CI: 0.60-0.71) but not in nulliparous (AUC: 0.51; CI: 0.42-0.59). Separation of parous cows according to the identified threshold (≤-53 min from the parity average) resulted in differences in serum concentrations of NEFA (AT = 0.31 ± 0.006, BT = 0.38 ± 0.014 mmol/L), BHB (AT = 0.49 ± 0.008, BT = 0.53 ± 0.015 mmol/L), and globulin (AT = 32.3 ± 0.3, BT = 34.8 ± 0.5 g/L) throughout the transition period, as well as in serum cholesterol, urea, magnesium, albumin, and haptoglobin in a time-dependent manner. BT parous cows had higher odds of clinical disease (AOR: 3.7; CI: 2.1-6.4), reduced hazard of pregnancy (AHR: 0.64, CI: 0.47-0.89), greater hazard of culling (AHR: 2.1, CI: 1.2-3.6), and lower milk production (46.3 ± 0.7 vs 48.5 ± 0.3 kg/d). External validation using data from 153 parous cows from a different herd and the established threshold in RT deviation (≤-53 min) resulted in similar predictive value, with the odds of postpartum disease 2.4 times greater in BT than AT (37.5 vs 20.1%). In conclusion, RT in the wk preceding calving was a reasonable predictor of postpartum health and future milk production, reproduction, and culling in parous cows but not in nulliparous cows.

Comparison of three mathematical models to estimate lactation performance in dairy cows

Milk yield dynamics and production performance reflect how dairy cows cope with their environment. To optimize farm management, time-series of individual cow milk yield have been studied in the context of precision livestock farming, and many mathematical models have been proposed to translate raw data into useful information for the stakeholders of the dairy chain. To gain better insights on the topic, this study aimed at comparing 3 recent methods that allow to estimate individual cow potential lactation performance, using daily data recorded by the automatic milking systems of 14 dairy farms (7 Holstein, 7 Italian Simmental) from Belgium, the Netherlands, and Italy. An iterative Wood model (IW), a perturbed lactation model (PLM), and a quantile regression (QR) were compared in terms of estimated total unperturbed (i.e., expected) milk production and estimated total milk loss (relative to unperturbed yield). The IW and PLM can also be used to identify perturbations of the lactation curve and were thus compared in this regard. The outcome of this study may help a given end-user in choosing the most appropriate method according to their specific requirements. If there is a specific interest in the post-peak lactation phase, IW can be the best option. If one wants to accurately describe the perturbations of the lactation curve, PLM can be the most suitable method. If there is need for a fast and easy approach on a very large data set, QR can be the choice. Finally, as an example of application, PLM was used to analyze the effect of cow parity, calving season, and breed on their estimated lactation performance.

Effects of parity, seasonal heat stress, and colostrum collection time postpartum on colostrum quality of Holstein cattle in an arid region

The aim of this study was to determine effects of parity (primiparous vs. multiparous), seasonal heat stress at calving (summer vs. winter), and time postpartum on some parameters associated with colostrum quality in Holstein cows reared in the Sonoran Desert ecosystem. Forty-seven cows (11 primiparous and 36 multiparous) expected to calve during summer, and 46 cows during winter (14 primiparous and 32 multiparous) were randomly selected. Management and feeding before and after parturition were similar for cows in both seasons. After parturition, colostrum from all cows was evaluated for volume, weight, temperature, density, and content of fat, protein, solids non-fat (SNF), and immunoglobulins (IGG). Data were analyzed with a model that included effects of parity status, calving season, and time postpartum, as well as all interactions. Colostrum produced in summer was warmer (P < 0.01) by almost 6 °C than winter colostrum, while colostrum from multiparous was warmer (P = 0.02) by 1.2 °C than that produced by primiparous cows. Colostrum volume and weight were not impacted by parity, calving season or time postpartum. Density, protein, and SNF content in colostrum were higher (P < 0.01) in multiparous vs. primiparous cows, as well as at parturition (0 h postpartum) than at 12 h postpartum (P < 0.01). At calving (0 h), spring colostrum had higher fat content (P < 0.01) and lower (P < 0.01) IGG concentration than that collected in summer, and no difference (P > 0.05) between seasons was observed for these components at 12 h postpartum. Multiparous cows produced colostrum with higher (P < 0.01) IGG concentrations than primiparous cows. In conclusion, only 0-h colostrum and that from multiparous cows was categorized as "Excellent," meanwhile the colostrum produced under summer heat stress was characterized as "Good" with reduced fat content. While the lacteal secretion collected at 12 post-partum still classified as colostrum, substantially lower contents of IGG, protein, fat, and SNF decreased its classification to "Poor" from the classification of "Excellent" at 0 h postpartum.

Combination of milk variables and on-farm data as an improved diagnostic tool for metabolic status evaluation in dairy cattle during the transition period

Milk composition, particularly milk fatty acids, has been extensively studied as an indicator of the metabolic status of dairy cows during early lactation. In addition to milk biomarkers, on-farm sensor data also hold potential in providing insights into the metabolic health status of cows. While numerous studies have explored the collection of a wide range of sensor data from cows, the combination of milk biomarkers and on-farm sensor data remains relatively underexplored. Therefore, this study aims to identify associations between metabolic blood variables, milk variables, and various on-farm sensor data. Second, it seeks to examine the supplementary or substitutive potential of these data sources. Therefore, data from 85 lactations on metabolic status and on-farm data were collected during 3 wk before calving up to 5 wk after calving. Blood samples were taken on d 3, 6, 9, and 21 after calving for determination of β-hydroxybutyrate (BHB), nonesterified fatty acids (NEFA), glucose, insulin-like growth factor-1 (IGF-1), insulin, and fructosamine. Milk samples were taken during the first 3 wk in lactation and analyzed by mid-infrared for fat, protein, lactose, urea, milk fatty acids, and BHB. Walking activity, feed intake, and body condition score (BCS) were monitored throughout the study. Linear mixed effect models were used to study the association between blood variables and (1) milk variables (i.e., milk models); (2) on-farm data (i.e., on-farm models) consisting of activity and dry matter intake analyzed during the dry period ([D]) and lactation ([L]) and BCS only analyzed during the dry period ([D]); and (3) the combination of both. In addition, to assess whether milk variables can clarify unexplained variation from the on-farm model and vice versa, Pearson marginal residuals from the milk and on-farm models were extracted and related to the on-farm and milk variables, respectively. The milk models had higher coefficient of determination (R2) than the on-farm models, except for IGF-1 and fructosamine. The highest marginal R2 values were found for BHB, glucose, and NEFA (0.508, 0.427, and 0.303 vs. 0.468, 0.358, and 0.225 for the milk models and on-farm models, respectively). Combining milk and on-farm data particularly increased R2 values of models assessing blood BHB, glucose, and NEFA concentrations with the fixed effects of the milk and on-farm variables mutually having marginal R2 values of 0.608, 0.566, and 0.327, respectively. Milk C18:1 was confirmed as an important milk variable in all models, but particularly for blood NEFA prediction. On-farm data were considerably more capable of describing the IGF-1 concentration than milk data (marginal R2 of 0.192 vs. 0.086), mainly due to dry matter intake before calving. The BCS [D] was the most important on-farm variable in relation to blood BHB and NEFA and could explain additional variation in blood BHB concentration compared with models solely based on milk variables. This study has shown that on-farm data combined with milk data can provide additional information concerning the metabolic health status of dairy cows. On-farm data are of interest to be further studied in predictive modeling, particularly because early warning predictions using milk data are highly challenging or even missing.

Epidemiological Features of Postpartum Subclinical Ketosis in Dairy Herds in Hokkaido, Japan

This study was carried out as an observational study in order to determine the prevalence of postpartum subclinical ketosis (SCK) in dairy herds in Hokkaido, Japan. From April 2012 to March 2014, blood β-hydroxybutyrate (BHBA) concentration was measured once within 3-88 days in milk (DIM) in 1394 apparently healthy cows from 108 farms to diagnose SCK (≥1.2 mM). In cows within 14 DIM, this was classified as SCK II, and from 15 DIM, this was classified as SCK I. Herds with a combined percentage of SCK I and SCK II of less than 10% were classified as SCK-negative herds, those with percentages of 10-25%, were classified as alert herds, and those with one of 25% or more, we classified as positive herds. The prevalence of SCK in the entire DIM was 17.6%. The prevalence of SCK II (20.2%) tended to occur more frequently than SCK I (16.5%, p = 0.094). The frequency of SCK I was higher at the fourth parity. The number of milking cows in SCK-positive herds was significantly smaller than those of the other two types of herds (p = 0.004). The frequency of SCK-positive herds in tie stalls and with component feeding was higher than for free stall or free barn and with total mixed ration (p = 0.054 and p = 0.002). This study reveals the prevalence of SCK in Hokkaido, Japan, and shows that SCK is associated with parity and the management system.

Parity and nutrient total-tract digestibility in dairy cows during transition period

Cows experience many physiological, nutritional and social changes during transition period. This study aims to evaluate the differences in nutrients total-tract digestibility (nTTD) between primiparous (PP) and multiparous (MP) cows through the transition period. From -23, -5, 0, 7, 14, and 30 days from calving a sample of feed and feces samples were collected from 25 Holstein cows (11 PP and 14 MP) as well as daily rumination time through accelerometers. The results show that average nTTD were different (p ≤ 0.02) for amylase-treated neutral detergent fiber organic matter (aNDFom) and potentially digestible neutral detergent fiber (pdNDF240; 52.5 vs. 54.0 and 78.8 vs. 81.3, respectively in PP vs. MP), while no differences were found regarding pdNDF24 and starch (88.5 vs. 88.6 and 95.1 vs. 96.1, respectively in PP vs. MP). Total-tract starch digestibility (TTstarchD) was different among timepoints (p < 0.01), going from an average of 91.40 up to 97.39% of starch, on times -23 and 14, respectively. Differences in total-tract digestibility of aNDFom among timepoints (p < 0.01) was expected because of differences in diet composition among lactating and non-lactating cows. No differences in daily rumination time (p = 0.92), TTstarchD and total-tract potentially digestible NDF digestibility at 24 h (TTpdNDF24D) were recorded. Our findings show that fiber digestibility during the transition period is higher in MP probably for a different ruminal retention time. These differences should be considered when formulating rations for groups with different parity number.

Invited Review: Increasing Milk Yield and Negative Energy Balance: A Gordian Knot for Dairy Cows?

The continued increase in milk production during the last century has not been accompanied by an adequate dry matter intake (DMI) by cows, which therefore experience a negative energy balance (NEB). NEB is low and of minor importance at low milk yield (MY), such as for the nutrition of one calf, and under these circumstances is considered "natural". MY and low DMI around parturition are correlated and are the reason for the genetic correlation between increasing MY and increasing NEB up to 2000 MJ or more for 2-3 months postpartum in high-genetic-merit dairy cows. The extension and duration of NEB in high-producing cows cannot be judged as "natural" and are compensated by the mobilization of nutrients, particularly of fat. The released non-esterified fatty acids (NEFAs) overwhelm the metabolic capacity of the cow and lead to the ectopic deposition of NEFAs as triglycerides (TGs) in the liver. The subsequent lipidosis and the concomitant hampered liver functions cause subclinical and clinical ketosis, both of which are associated with "production diseases", including oxidative and endoplasmatic stress, inflammation and immunosuppression. These metabolic alterations are regulated by homeorhesis, with the priority of the physiological function of milk production. The prioritization of one function, namely, milk yield, possibly results in restrictions in other physiological (health) functions under conditions of limited resources (NEB). The hormonal framework for this metabolic environment is the high concentration of growth hormone (GH), the low concentration of insulin in connection with GH-dependent insulin resistance and the low concentration of IGF-1, the so-called GH-IGF-1 axis. The fine tuning of the GH-IGF-1 axis is uncoupled because the expression of the growth hormone receptor (GHR-1A) in the liver is reduced with increasing MY. The uncoupled GH-IGF-1 axis is a serious impairment for the GH-dependent stimulation of gluconeogenesis in the liver with continued increased lipolysis in fat tissue. It facilitates the pathogenesis of lipidosis with ketosis and, secondarily, "production diseases". Unfortunately, MY is still increasing at inadequate DMI with increasing NEB and elevated NEFA and beta-hydroxybutyric acid concentrations under conditions of low glucose, thereby adding health risks. The high incidences of diseases and of early culling and mortality in dairy cows are well documented and cause severe economic problems with a waste of resources and a challenge to the environment. Moreover, the growing public concerns about such production conditions in agriculture can no longer be ignored.

Interaction between gestational plane of nutrition and lactation diet composition on lactation performance of Alpine goats of different parities

A study was conducted with 48 multiparous and 31 primiparous Alpine goats to determine the effects of different nutritional planes during gestation and lactation on feed intake, body weight, body condition score and mass index, blood constituent concentrations, and milk yield and composition. Two gestation supplement treatments (GS; Moderate versus High) were imposed for approximately 5.5 months and two lactation diets (LD; Moderate vs. High) within each GS were fed for 16 wk. The Moderate GS (14.2% crude protein; CP) was given at 1.125% body weight (BW; dry matter basis) and the High GS (16.2% CP) was consumed ad libitum, with alfalfa hay available free-choice to all animals. Moderate and High LD contained 16.0 and 16.9% CP and 34.7 and 30.4% neutral detergent fiber, respectively. Body weight (77.5 vs. 72.0 kg) and body condition score (BCS; 3.22 vs. 3.04) at 11 days before kidding were greater (P < 0.05) for High versus Moderate GS, but BW at kidding (62.6 and 64.9 kg; SEM = 1.32) and 3 days later (60.9 and 63.6 kg for Moderate and High GS, respectively; SEM = 1.32) was similar. Litter size (1.9 and 2.4; SEM = 0.59), kid birth weight (3.72 and 3.59 kg; SEM = 0.097), and litter weight (6.55 and 7.13 kg for Moderate and High GS, respectively; SEM = 0.316) were similar between GS diets. However, kid birth weight (3.44 and 3.87 kg; SEM = 0.096) and litter weight (6.23 and 7.46 kg; SEM = 0.364) were greater (P < 0.05) for multiparous versus primiparous goats. Dry matter intake during lactation was greater for Moderate than for High GS (P ≤ 0.051) in kg/day, % BW, and g/kg BW0.75. However, milk fat (3.81, 4.14, 3.85, and 3.77%; SEM = 0.132) and protein concentrations (2.49, 2.50, 2.47, and 2.49%; SEM = 0.047), and raw (2.22, 2.59, 2.39, and 2.45 kg; SEM = 0.173) and energy yields of milk (6.02, 7.42, 6.51, and 6.63 MJ/day for Moderate GS-Moderate LD, Moderate GS-High LD, High GS-Moderate LD, and High GS-High LD, respectively; SEM = 0.453) were not affected by GS, LD, or their interaction. Dry matter intake, milk and its component yields, and heat energy (MJ/day) were higher (P < 0.05) for does than for doelings, but BCS and milk protein and fat concentrations were lower (P < 0.05) for does. Blood nonesterified fatty acid concentration was not affected by any diets, but there was interaction (P < 0.05) between GS and LD for betahydroxybutyric acid concentration. In conclusion, minor to moderate magnitudes of difference in nutritional planes during gestation and lactation had little effect on reproductive and lactation performance, reflecting the considerable capacity of lactating dairy goats for compensatory changes such as feed intake and tissue mobilization and accretion.

Dynamic changes of rumen bacteria and their fermentative ability in high-producing dairy cows during the late perinatal period

Background

High-producing dairy cows face varying degrees of metabolic stress and challenges during the late perinatal period, resulting in ruminal bacteria abundance and their fermentative ability occurring as a series of changes. However, the dynamic changes are still not clear.

Aims/methods

Ten healthy, high-producing Holstein dairy cows with similar body conditions and the same parity were selected, and ruminal fluid from the dairy cows at postpartum 0, 7, 14, and 21 d was collected before morning feeding. 16S rRNA high-throughput sequencing, GC-MS/MS targeted metabolomics, and UPLC-MS/MS untargeted metabolomics were applied in the study to investigate the dynamic changes within 21 d postpartum.

Results

The results displayed that the structures of ruminal bacteria were significantly altered from 0 to 7 d postpartum (R = 0.486, P = 0.002), reflecting the significantly declining abundances of Euryarchaeota and Chloroflexi phyla and Christensenellaceae, Methanobrevibacter, and Flexilinea genera (P < 0.05) and the obviously ascending abundances of Ruminococcaceae, Moryella, Pseudobutyrivibrio, and Prevotellaceae genera at 7 d postpartum (P < 0.05). The structures of ruminal bacteria also varied significantly from 7 to 14 d postpartum (R = 0.125, P = 0.022), reflecting the reducing abundances of Christensenellaceae, Ruminococcaceae, and Moryella genera (P < 0.05), and the elevating abundances of Sharpea and Olsenella genera at 14 d postpartum (P < 0.05). The metabolic profiles of ruminal SCFAs were obviously varied from 0 to 7 d postpartum, resulting in higher levels of propionic acid, butyric acid, and valeric acid at 7 d postpartum (P < 0.05); the metabolic profiles of other ruminal metabolites were significantly shifted from 0 to 7 d postpartum, with 27 significantly elevated metabolites and 35 apparently reduced metabolites (P < 0.05). The correlation analysis indicated that propionic acid was positively correlated with Prevotellaceae and Ruminococcaceae (P < 0.05), negatively correlated with Methanobrevibacter (P < 0.01); butyric acid was positively associated with Prevotellaceae, Ruminococcaceae, and Pseudobutyrivibrio (P < 0.05), negatively associated with Christensenellaceae (P < 0.01); valeric acid was positively linked with Prevotellaceae and Ruminococcaceae (P < 0.05); pyridoxal was positively correlated with Flexilinea and Methanobrevibacter (P < 0.05) and negatively correlated with Ruminococcaceae (P < 0.01); tyramine was negatively linked with Ruminococcaceae (P < 0.01).

Conclusion

The findings contribute to the decision of nutritional management and prevention of metabolic diseases in high-producing dairy cows during the late perinatal period.

Meager Milk: Lasting Consequences for Adult Daughters of Primiparous Mothers Among Rhesus Macaques (Macaca mulatta)

Among mammals, primipara who initiate reproduction before full maturity can be constrained in their maternal investment, both due to fewer somatic resources and tradeoffs between their own continued development and reproductive effort. Primipara are particularly limited in their capacity to synthesize milk during lactation, the costliest aspect of reproduction for most mammals, especially primates due to long periods of postnatal development. Due to reduced milk transfer, Firstborns may be at elevated risk for long-term consequences of deficits in early life endowment from their primiparous mothers. Here we investigated mass, growth, stature, and lactation performance among N = 273 adult daughters across N = 335 reproductions, who were their own mother's Firstborn or Laterborn progeny, among rhesus macaques (Macaca mulatta) at the California National Primate Research Center. We further explored mass during infancy of the offspring of Firstborn and Laterborn mothers. Firstborns had accelerated growth during infancy, but had slowed growth during juvenility, compared to Laterborns. Although both Firstborns and Laterborns were the same age at reproductive debut, Firstborns had lower body mass, an effect that persisted throughout the reproductive career. Available milk energy, the product of milk energetic density and milk yield, was on average 16% lower for Firstborns compared to Laterborns, a difference that was only partially mediated by their lower mass. Despite differences in their mothers' energy provision through milk, the mass of infants of Firstborn and Laterborn mothers did not differ at peak lactation, suggesting that infants of Firstborns devote a higher proportion of milk energy to growth than infants of Laterborns. To date few studies have explored how early life conditions shape capacities to synthesize milk and milk composition. Our findings contribute new information among primates on how early life maternal endowments are associated with persistent effects long after the period of maternal dependence well into reproductive maturity.

Testing the Induction of Metritis in Healthy Postpartum Primiparous Cows Challenged with a Cocktail of Bacteria

Metritis is a postpartum uterine disease with greater incidence in primiparous than in multiparous cows. In primiparous cows, the impact on production and health is lessened, presumably due to a superior immune response. Here, we tested whether an in vivo model of clinical metritis induction developed for postpartum multiparous Holstein cows would produce similar results in primiparous cows. Thirty-six cows were randomly assigned to one of three groups and received intrauterine infusion within 24 h of parturition. The controls were infused with sterile saline; the low-dose group received a bacterial cocktail containing 103 cfu of Escherichia coli, Trueperella pyogenes, and Fusobacterium necrophorum; and the high-dose group were infused with 106 cfu of the same cocktail. Production, health traits, and the vaginal discharge culture were assessed daily, from enrollment until 14 d in milk. Clinical metritis occurred in 64% of high-dose cows, 33% of the controls, and 42% of low-dose cows, with no significant difference of incidence between groups. However, when accounting by time, high-dose cows had a 2.7 times greater hazard of metritis compared with the controls. The bacterial challenge affected milk production and dry matter intake tended to decrease. In the high-dose group, a greater growth of F. necrophorum in the selective medium was also observed, suggesting an association with metritis. Therefore, this study suggests intrauterine inoculation with 106 cfu of this bacterial cocktail elicits physical and clinical outcomes consistent with clinical metritis.

Evaluation of the Metabolic Relationship between Cows and Calves by Monitoring Calf Health and Cow Automatic Milking System and Metabolic Parameters

With this study, we investigated the relationship between a cow's and calf's metabolic state, and its effect on health status. To achieve this, 20 calves of primiparous and 20 calves of multiparous cows were selected. The calves were monitored for 30 days and scored for signs of disease, as described in McQuirk (2008); according to score, they were divided into healthier calves; the Low calf score group (LCS, 5-8), Medium calf score group (MCS, 9-12) and High calf score group (HCS, 14-17); or calves most prone to disease. Their mothers were monitored for the same period with a Lely Astronaut 3 herd management system (Lely, Maassluis, The Netherlands) for rumination time, milk yield, milk fat, protein, lactose concentrations and milk fat to protein ratio. Both cows and calves were sampled for blood, and concentrations of glucose with β-hydroxybutyrate were registered. The results indicate that primiparous cows had a 16% higher blood glucose concentration (3.03 mmol/L SE = 0.093) compared with multiparous cows (2.61 mmol/L, SE = 0.102) (p < 0.01), but no difference in calf glucose was recorded. Β-hydroxybutyrate levels did not differ significantly between cows and calves by parity group. Rumination time was longest in the HCS group at 550.79 min/d. and was 16% longer compared with the LCS group (461.94 min/d.; p < 0.001) and 8% longer compared with the MCS group (505.56 min/d.; p < 0.001). The MCS group rumination time mean was statistically significantly higher compared with the LCS group by 8% (p < 0.001). Milk yield was also highest in the HCS group (44.8 kg/d.): 19% higher compared with the MCS group (36.31 kg/d., p < 0.001) and 13% higher than the LCS group (38.83 kg/d., p < 0.001). There was also a significant difference between the MCS and LCS groups of 6% (p < 0.001). The HCS group had the highest milk fat concentration (4.47%): it was 4% higher compared with the LCS group (4.28%, p < 0.001) and 5% higher than the MCS group (4.25%, p < 0.001). Milk fat to protein ratio was highest in the HCS group (1.21) and was 7% higher than in the MCS group (1.12, p < 0.001) and 8% higher than in the LCS group (1.11, p < 0.001). The LCS group was determined to have the highest concentration of milk lactose (4.66%). It was 1% higher compared with the MCS group (4.62%, p < 0.001) and 1.07% higher than the HCS group (4.61%, p < 0.001). We can conclude that parity did not affect calf health status and that cows of the HCS group showed symptoms of negative energy balance expressed through higher milk yield, higher milk fat concentration and higher milk fat to protein ratio, with lower milk lactose concentration. Further and more thorough research is needed to evaluate the relationship between pregnant cows and calves.

Effect of Parity, Body Condition Score at Calving, and Milk Yield on the Metabolic Profile of Gyr Cows in the Transition Period

This study aimed to evaluate the effects of parity, body condition score (BCS) at calving, and milk yield on the metabolic profile of Gyr (Zebu) cows. Healthy cows in late pregnancy were grouped according to parity (primiparous, biparous, and multiparous); to BCS scale at calving (high-HBCS and normal-NBCS); and to milk yield (high-HP and moderate-MP production). BCS was assessed, and blood samples were collected on -21, -7, 0, 7, 21, and 42 days relative to parturition. The concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), cholesterol, glucose, total protein (TP), albumin, total calcium (Ca), phosphorus (P), and magnesium (Mg); and activities of aspartate aminotransferase and gamma-glutamyltransferase were measured. Data were analyzed by two-way repeated measures ANOVA. The frequencies of high lipomobilization, subclinical ketosis, subclinical hypocalcemia (SCH), and the occurrence of diseases during early lactation were established. Regardless of grouping, NEFA, BHB, and cholesterol increased during early lactation; glucose showed higher values at calving; TP and albumin were higher at 21 and 42 DIM; and Ca, P, and Mg were lower at calving. Parity had little effect on the metabolic profile, HBCS did not differ from NBCS cows, and HP did not differ from MP cows in most metabolites. High lipomobilization in early lactation and SCH at calving were the most common imbalances but were not related to postpartum diseases. High-yielding Gyr cows have a balanced metabolic profile during the transition period, with few biologically relevant effects of parity, BCS at parturition, or milk yielded.

Influence of the concentrate inclusion level in a grass silage-based diet on hepatic transcriptomic profiles in Holstein-Friesian dairy cows in early lactation

Excessive negative energy balance in early lactation is linked to an increased disease risk but may be mitigated by appropriate nutrition. The liver plays central roles in both metabolism and immunity. Hepatic transcriptomic profiles were compared between 3 dietary groups in each of 40 multiparous and 18 primiparous Holstein-Friesian cows offered isonitrogenous grass silage-based diets with different proportions of concentrates: (1) low concentrate (LC, 30% concentrate + 70% grass silage); (2) medium concentrate (MC, 50% concentrate + 50% grass silage), or (3) high concentrate (HC, 70% concentrate + 30% grass silage). Liver biopsies were taken from all cows at around 14 d in milk for RNA sequencing, and blood metabolites were measured. The sequencing data were analyzed separately for primiparous and multiparous cows using CLC Genomics Workbench V21 (Qiagen Digital Insights), focusing on comparisons between HC and LC groups. More differentially expressed genes (DEG) were seen between the primiparous cows receiving HC versus LC diets than for multiparous cows (597 vs. 497), with only 73 in common, indicating differential dietary responses. Multiparous cows receiving the HC diet had significantly higher circulating glucose and insulin-like growth factor-1 and lower urea than those receiving the LC diet. In response to HC, only the multiparous cows produced more milk. In these animals, bioinformatic analysis indicated expression changes in genes regulating fatty acid metabolism and biosynthesis (e.g., ACACA, ELOVL6, FADS2), increased cholesterol biosynthesis (e.g., CYP7A1, FDPS, HMGCR), downregulation in hepatic AA synthesis (e.g., GPT, GCLC, PSPH, SHMT2), and decreased expression of acute phase proteins (e.g., HP, LBP, SAA2). The primiparous cows on the HC diet also downregulated genes controlling AA metabolism and synthesis (e.g., CTH, GCLC, GOT1, ODC1, SHMT2) but showed higher expression of genes indicative of inflammation (e.g., CCDC80, IL1B, S100A8) and fibrosis (e.g., LOX, LUM, PLOD2). This potentially adverse response to a HC diet in physically immature animals warrants further investigation.

Hepatic Global Transcriptomic Profiles of Holstein Cows According to Parity Reveal Age-Related Changes in Early Lactation

Cows can live for over 20 years, but their productive lifespan averages only around 3 years after first calving. Liver dysfunction can reduce lifespan by increasing the risk of metabolic and infectious disease. This study investigated the changes in hepatic global transcriptomic profiles in early lactation Holstein cows in different lactations. Cows from five herds were grouped as primiparous (lactation number 1, PP, 534.7 ± 6.9 kg, n = 41), or multiparous with lactation numbers 2-3 (MP2-3, 634.5 ± 7.5 kg, n = 87) or 4-7 (MP4-7, 686.6 ± 11.4 kg, n = 40). Liver biopsies were collected at around 14 days after calving for RNA sequencing. Blood metabolites and milk yields were measured, and energy balance was calculated. There were extensive differences in hepatic gene expression between MP and PP cows, with 568 differentially expressed genes (DEGs) between MP2-3 and PP cows, and 719 DEGs between MP4-7 and PP cows, with downregulated DEGs predominating in MP cows. The differences between the two age groups of MP cows were moderate (82 DEGs). The gene expression differences suggested that MP cows had reduced immune functions compared with the PP cows. MP cows had increased gluconeogenesis but also evidence of impaired liver functionality. The MP cows had dysregulated protein synthesis and glycerophospholipid metabolism, and impaired genome and RNA stability and nutrient transport (22 differentially expressed solute carrier transporters). The genes associated with cell cycle arrest, apoptosis, and the production of antimicrobial peptides were upregulated. More surprisingly, evidence of hepatic inflammation leading to fibrosis was present in the primiparous cows as they started their first lactation. This study has therefore shown that the ageing process in the livers of dairy cows is accelerated by successive lactations and increasing milk yields. This was associated with evidence of metabolic and immune disorders together with hepatic dysfunction. These problems are likely to increase involuntary culling, thus reducing the average longevity in dairy herds.

Plasma metabolomics reveals major changes in carbohydrate, lipid, and protein metabolism of abruptly weaned beef calves

¹H NMR-based metabolomics was used to study the effect of abrupt weaning on the blood metabolome of beef calves. Twenty Angus calves (258 ± 5 kg BW; 5 to 6 months old) were randomly assigned to a non-weaned (NW) group that remained grazing with their dam or a weaned (W) group that underwent abrupt separation from their dam to a separate paddock on d 0 of the study. Body weight, behaviour, and blood samples for cortisol and metabolomics were measured at d 0, 1, 2, 7, and 14 of the study. On d 1 and 2, W calves spent less time grazing and ruminating, and more time vocalising and walking, had a greater concentration of cortisol, NEFA, 3-hydroxybutyrate, betaine, creatine, and phenylalanine, and lesser abundance of tyrosine (P < 0.05) compared to NW calves. Compared to NW calves at d 14, W calves had greater (P < 0.01) relative abundance of acetate, glucose, allantoin, creatinine, creatine, creatine phosphate, glutamate, 3-hydroxybutyrate, 3-hydroxyisobutyrate, and seven AA (alanine, glutamate, leucine, lysine, phenylalanine, threonine and valine) but lesser (P < 0.05) relative abundance of low density and very low-density lipids, and unsaturated lipids. Both PCA and OPLS-DA showed no clustering or discrimination between groups at d 0 and increasing divergence to d 14. Blood metabolomics is a useful tool to quantify the acute effects of stress in calves during the first 2 days after abrupt weaning, and longer-term changes in carbohydrate, lipid and protein metabolism due to nutritional changes from cessation of milk intake and greater reliance on forage intake.

Stayability in Simmental cattle as affected by muscularity and body condition score between calvings

The present study aimed to investigate the association between stayability (STAY) traits, muscularity, and body condition score (BCS) in the Italian Simmental dual-purpose cows. Data were collected from 2,656 cows linearly scored in their first lactation from 2002 to 2020 and reared in 324 herds. The binary trait STAY, which is the ability of a cow to stay in the herd, was obtained for each cow-lactation available up to parity 5 (from STAY1-2 to STAY4-5). Analysis of STAY was carried out using logistic regression, considering the fixed effect of energy corrected milk, conception rate, somatic cell score, and muscularity or BCS predicted at different time points. The herd of linear classification and residual error were the random effects. Primiparous cows with a medium BCS and muscularity in early lactation presented a more favorable STAY across life compared to thinner ones (P &lt; 0.05). In fact, cows with an intermediate BCS/muscularity were more likely to stay in the herd after the third lactation (STAY3-4), compared to those presenting a lower BCS/muscularity (P &lt; 0.01). However, cows whose muscularity was high were generally less likely to start the third lactation compared to the others. A potential explanation for this could be the willing to market cows with good conformation for meat purpose. Simmental is in fact a dual-purpose breed known for the good carcass yield and meat quality. This study demonstrates how muscularity and BCS available early in life can be associated with the ability of Simmental cows to stay in the herd.

Metabolic and physiological adaptations to first and second lactation in Holstein dairy cows

Huge differences exist between cow yields and body sizes during their first and second lactations. The transition period is the most critical and investigated phase of the lactation cycle. We compared metabolic and endocrine responses between cows at different parities during the transition period and early lactation. Eight Holstein dairy cows were monitored at their first and second calving during which they were reared under the same conditions. Milk yield, dry matter intake (DMI), and body weight (BW) were regularly measured, and energy balance, efficiency, and lactation curves were calculated. Blood samples were collected on scheduled days from -21 d relative to calving (DRC) to 120 DRC for the assessment of metabolic and hormonal profiles (biomarkers of metabolism, mineral status, inflammation, and liver function). Large variations in the period in question for almost all variables investigated were observed. Compared with their first lactation, cows during their second lactation had higher DMI (+15%) and BW (+13%), their milk yield was greater (+26%), lactation peak was higher and earlier (36.6 kg/d at 48.8 DRC vs. 45.0 kg/d at 62.9 DRC), but persistency was reduced. Milk fat, protein, and lactose contents were higher during the first lactation and coagulation properties were better (higher titratable acidity, faster and firmer curd formation). Postpartum negative energy balance was more severe the during the second lactation (1.4-fold at 7 DRC) and plasma glucose was lower. Circulating insulin and insulin-like growth factor-1 were lower in second-calving cows during the transition period. At the same time, markers of body reserve mobilization (β-hydroxybutyrate and urea) increased. Moreover, albumin, cholesterol, and γ-glutamyl transferase were higher during second lactation, whereas bilirubin and alkaline phosphatase were lower. The inflammatory response after calving was not different, as suggested by the similar haptoglobin concentrations and only transient differences in ceruloplasmin. Blood growth hormone did not differ during the transition period but was lower during the second lactation at 90 DRC, whereas circulating glucagon was higher. These results agree with the differences in milk yield and confirmed the hypothesis of a different metabolic and hormonal status between the first and second lactation partly related to different degrees of maturity.

Metabolic and physiological adaptations to first and second lactation in Holstein dairy cows: Postprandial patterns

Dairy cows during their first and second lactation have different milk yield, body development, feed intake, and metabolic and endocrine statuses. However, large diurnal variations can also exist in terms of biomarkers and hormones related to feeding behavior and energy metabolism. Thus, we investigated the diurnal patterns of the main metabolic plasma analytes and hormones in the same cows during their first and second lactations in different stages of the lactation cycle. Eight Holstein dairy cows were monitored during their first and second lactation, during which they were reared under the same conditions. Blood samples were collected before the morning feeding (0 h) and after 1, 2, 3, 4.5, 6, 9, and 12 h on scheduled days between -21 d relative to calving (DRC) and 120 DRC for the assessment of some metabolic biomarkers and hormones. Data were analyzed using the GLIMMIX procedure of SAS (SAS Institute Inc.). Regardless of parity and stage of lactation, glucose, urea, β-hydroxybutyrate, and insulin peaked a few hours after the morning feeding, whereas nonesterified fatty acids decreased. The insulin peak was attenuated during the first month of lactation, whereas postpartum growth hormone spiked on average 1 h after the first meal in cows during their first lactation. This peak occurred earlier than during the second lactation. Most of the differences in diurnal trends between lactations were observed in the postpartum period (and in some cases even in early lactation). Glucose and insulin were higher during the first lactation throughout the day, and the differences increased 9 h after feeding. Conversely, nonesterified fatty acids and β-hydroxybutyrate showed the opposite trend, and their plasma concentrations at 9 and 12 h after feeding differed between lactations. These results confirmed the differences observed between the first 2 lactations in prefeeding metabolic marker concentrations. Furthermore, plasma concentrations of investigated analytes showed high variability during the day, and thus we advise caution when interpreting metabolic biomarker data in dairy cows, especially during the periods close to calving.

Effect of parity on non-esterified fatty acid, oxidant/antioxidant status, and zinc and copper levels around periparturient period in Beetal goats of Himalayan Region

The study was conducted to evaluate the effect of parity and physiological status on non-esterified fatty acid (NEFA), oxidative stress, and zinc and copper levels among the Beetal breed of goat. Thirty dual-purpose Beetal goats reared under the semi-intensive system were selected and based on parity were divided into three groups with 10 animals each viz. Early parity (EP; ≤2 parity), mid parity (MP; 3-6 parity), and late parity (LP; ≥7 parity). Blood samples were collected 3 weeks and 1 week pre-kidding followed by 1, 2, 4, and 8 weeks post-kidding for the estimation of NEFA, oxidant (malondialdehyde [MDA], antioxidant (superoxide dismutase [SOD], catalase [CAT], glutathione [GSH], glutathione peroxidase [GSH-Px], and glutathione S-transferase [GST]), and zinc and copper levels. Significant (p < 0.01) increase was observed in NEFA and MDA levels as the goats approached kidding and continued till 2 weeks post-kidding in MP and LP and 1 week post-kidding in EP goats. Significant decrease in SOD (p < 0.05), CAT (p < 0.05), GSH-Px (p < 0.01), GSH (p < 0.01), and GST (p < 0.05) activities were observed as goats approached kidding and continued to decrease up to 2 weeks post-kidding. Zinc and copper levels showed a significant decline from 3 weeks pre-kidding to 2 weeks post-kidding in MP and LP and 1 week post-kidding in EP goats. A significant effect of parity was observed on MDA (p < 0.05), GSH (p < 0.05), and GSH-Px (p < 0.05) activities only; however, parity × sampling time interaction was observed in all the parameters. Findings highlight a different metabolic, trace mineral (zinc and copper), and oxidative response around the periparturient period in Beetal goats, with the EP goats, responding first to increased metabolic and oxidative stress and also first to recover from oxidant/antioxidant imbalance.

Relationship between microclimate and cow behavior and milk yield under low-temperature and high-humidity conditions

This study aimed to evaluate the relationship between temperature (T), relative humidity (RH), and temperature and humidity index (THI), milk yield (MY), rumination time (RT), and activity (AT) of dairy cows in different parities under low temperature and high humidity (LTHH). In this study, the number of samples each day was determined by all healthy cows in the barn with parity and days in milk (DIM) within 5 and 305, respectively. The box plot method was used for screening and removing outliers of dairy cow indicators after classification according to parity and DIM. To remove the effect of DIM on MY, a bivariate regression model was used to standardize the MY in milk yield index (MYI). The best bivariate regression model based on the lowest Akaike information criterion was used to analyze the relationship between behavioral parameters, MYI, and microclimate indicators for each parity. In the barn with the microclimate at a low temperature above 0°C, high RH was negatively correlated with MYI in primiparous and multiparous cows but positively correlated with AT in primiparous and multiparous cows and RT in multiparous cows (p &lt; 0.05), so RH was a significant factor related to MYI, RT, and AT of cows. The 2-day lagged daily average T and THI were correlated with MYI in primiparous cows (p &lt; 0.05). The inflection point value of 71.9 between AT and RH in the multiparity as the upper limit of RH was beneficial for improving comfort and MY in all parity dairy cows. Compared with MYI and RT, AT had a higher R2 with a microclimate indicator, so it could be used as a better indicator for assessing the LTHH. Comparing the R2 of multiparous cows to T (R2 = 0.0807) and THI (R2 = 0.1247), primiparous cows had higher R2 in MYI to T (R2 = 0.2833) and THI (R2 = 0.3008). Therefore, primiparous cows were more susceptible to T and THI. The inflection point values for MYI to T and THI were greater in primiparous cows than in multiparous cows, indicating that primiparous cows had a smaller tolerance range to T and THI than multiparous cows. Thus, parity should be considered when studying the relationship between MY, T, and THI under LTHH.

Associations of automated body condition scores at dry-off and through early lactation with milk yield of Holstein cows

The objective of this study was to analyze the associations of body condition score (BCS) and BCS change (∆BCS) during the dry period and the first 100 d of lactation with daily milk yield. Examining the involvement of health status in the associations between BCS and milk yield was a secondary objective of this research. Data included 12,042 lactations in 7,626 Holstein cows calving between April 2019 and January 2022 in a commercial dairy operation located in Colorado, USA. BCSs were generated daily by an automated BCS camera system located at the exit of the milking parlor. The assessment points selected for this study were dry-off (BCSdry), calving (BCS1), 7 DIM (BCS7), 14 DIM (BCS14), 21 DIM (BCS21), and nadir (nBCS; defined as the lowest daily BCS from calving to 100 DIM). Subsequently, these BCS were categorized considering quartiles (Q1 = 25% lowest BCS; Q4 = 25% greatest BCS), separately for primiparous and multiparous cows. Changes in BCS were calculated from dry-off to calving (multiparous); and from calving to 7 DIM, 14 DIM, 21 DIM, and nadir and assigned into quartile categories considering Q1 as the 25% of cows with the greatest decrease of BCS. Lactations were classified based on the number of health events before nadir as healthy, affected by one event, or having multiple events. Data were examined in primiparous and multiparous cows separately using ANOVA. The least square means for daily milk at 60 DIM and 305 DIM were calculated by category of BCS and ∆BCS at multiple time points and time periods. Subsequently, lactation curves were created by BCS and ∆BCS categories and by health status. Multivariable models included calving season and BCS1 as covariables. The largest differences in milk yield among categories of BCS and ∆BCS were identified for BCS originated at nadir and for the ∆BCS between calving and nadir. The differences in average daily milk yield between cows in the lowest and the greatest nBCS category (Q1 vs. Q4) were 3.3 kg/d (60 DIM) and 3.4 kg/d (305 DIM) for primiparous cows and 2.4 kg/d (60 DIM) and 2.1 kg/d (305 DIM) for multiparous cows. During the period from calving to nadir, primiparous cows in Q1 (greatest decrease of BCS) produced 4.3 kg/d (60 DIM) and 3.8 kg/d (305 DIM) more than cows in Q4. For multiparous cows, the differences were 3.0 kg/d (60 DIM) and 1.9 kg/d (305 DIM) in favor of Q1 cows. Overall, the associations between BCS and ∆BCS categories and milk yield were not consistent across time and they depended on the parity category. Nonetheless, as the assessment of BCS and ∆BCS approached the nadir, the association between greater milk yield and lower BCS or greater reduction in BCS became more evident.

Lactation from the inside out: Maternal homeorhetic gastrointestinal adaptations regulating energy and nutrient flow into milk production

Lactation invokes homeorhetic processes to ramp up and supply milk synthesis components to fulfil nutritional, immunological and microbiological requirements of developing offspring, overseen by complex neuroendocrine networks. The maternal gut meets these intense metabolic demands, supported by hyperphagia and rapid adjustments to process larger food quantities. Enteroplasticity describes an inherent ability of the gastrointestinal tract to harness metabolic and structural adaptations that increase nutrient absorption. Most shifts in response to increased demands are transitory and by secreting milk, the continuous energetic drain out of the maternal body avoids development of pathological metabolic diseases. Lactation has various positive benefits for long-term maternal health but many females do not lactate for long post pregnancy and younger women are increasingly pre-disposed to excessive body mass and/or metabolic complications prior to reproducing. Inadvertently invoking intestinal adaptations to harvest and store excess nutrients has negative health implications with increased risks for both mother and offspring.

Proportion of Concentrate in the Diet of Early Lactation Dairy Cows Has Contrasting Effects on Circulating Leukocyte Global Transcriptomic Profiles, Health and Fertility According to Parity

The functionality of circulating leukocytes in dairy cows is suppressed after calving, with negative energy balance as a risk factor. Leukocyte transcriptomic profiles were compared separately in 44 multiparous (MP) and 18 primiparous (PP) Holstein-Friesian cows receiving diets differing in concentrate proportion to test whether immune dysfunction could be mitigated by appropriate nutrition. After calving, cows were offered either (1) low concentrate (LC); (2) medium concentrate (MC) or (3) high concentrate (HC) diets with proportions of concentrate to grass silage of 30%:70%, 50%:50% and 70%:30%, respectively. Cow phenotype data collected included circulating metabolites, milk yield and health and fertility records. RNA sequencing of circulating leukocytes at 14 days in milk was performed. The HC diet improved energy balance in both age groups. There were more differentially expressed genes in PP than MP cows (460 vs. 173, HC vs. LC comparison) with few overlaps. The MP cows on the LC diet showed upregulation of the complement and coagulation cascade and innate immune defence mechanisms against pathogens and had a trend of more cases of mastitis and poorer fertility. In contrast, the PP cows on the HC diet showed greater immune responses based on both gene expression and phenotypic data and longer interval of calving to conception. The leukocytes of MP and PP cows therefore responded differentially to the diets between age, nutrient supply and immunity affecting their health and subsequent fertility.

A Mathematical Model of Estradiol Production from Ultrasound Data for Bovine Ovarian Follicles

In this paper, we present a new way to assess the concentration of estradiol (E2) and Insulin Growth Factor-1 (IGF) based on the results from ultrasound scans combined with mathematical models. The IGF1 model is based on the progesterone (P4) concentration, which can be estimated with models calculating P4 level based on the size/volume of corpus luteum (CL) measured during ultrasound scans. At this moment little is known about the underlying reasons for double ovulation and silent heat occurrences. Both of these are linked to the level of IGF1: double ovulations are linked to higher IGF1 levels and and silent heat is linked to lower E2 to P4 ratio. These models can help to improve understanding of the related concentrations of E2 and IGF1. Currently, it is known that diet and genetic factors have an impact on ovulation rates and silent heat. In this study, we also examine the decline of the production of E2 in vivo by atretic follicles throughout the process of atresia. This is the first recorded quantitative description of this decline.

The Influence of Energy Balance, Lipolysis and Ketogenesis on Metabolic Adaptation in Cows Milked Twice and Three Times Daily

Increasing milk production requires increasing milking frequency (MF) from two times daily (2X) to three (3X) or more. High milk production leads to negative energy balance (NEB) and homeorhesis, characterized by lipolysis, ketogenesis, and endocrinological changes. The relationship among energy balance (EB), lipolysis, and ketogenesis with endocrine and metabolic parameters in blood of cows milked 2X and 3X daily was studied. Holstein Friesian cows milked 2X (n = 45) and 3X (n = 45) were analyzed, with approximately 50% of cows in each group in positive EB (PEB) and 50% in NEB. After determining EB, blood samples were collected from all cows and blood serum was analyzed for non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), glucose (GLU), cholesterol (CHOL), triglycerides (TGC), total bilirubin (TBIL), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), calcium (Ca), inorganic phosphate (P), total protein (TPROT), albumin (ALB), urea, insulin (INS), T3, T4, and cortisol (CORT), and the RQUICKIBHB index of insulin resistance was calculated. Cows milked 3X in NEB represent a special cluster that partially overlaps with cows milked 2X in NEB and has no contact points with cows in PEB. Cows milked 3X had higher levels of NEFA, BHB, AST, GGT, TBIL, and CORT and lower levels of GLU, Ca, INS, and T4. Cows milked 3X in NEB had higher levels of NEFA, BHB, AST, GGT, TBIL, and CORT and lower levels of GLU, CHOL, TGC, TPROT, P, INS, RQUICKIBHB, and T3 compared with cows milked 2X in NEB and cows in PEB. In cows milked 3X, lipolysis and ketogenesis were much more prominent, and EB levels were lower, implying a pronounced shift in homeorhesis. Metabolic and endocrinology parameters were determined mainly by the values of EB, NEFA, and BHB in cows milked 3X in NEB compared with other categories of cows. The results confirm the peculiarity of metabolic adaptation in cows with increased MF, characterized not only by differences in the concentration of metabolites but also in their interactions.

Study on the rumen fermentation, growth performance and carcass characteristics according to the supplementation of lupin flake in Hanwoo steers

This study was conducted to determine the rumen fermentation dynamics of lupin flakes and elucidate the effects of lupin flake supplementation on the growth performance, blood metabolites, and carcass characteristics of Hanwoo steers. In vitro and in situ trials of lupin grains and lupin flakes were conducted using three Hanwoo cows with rumen fistulas. The feeding trial included 40 early-fattening Hanwoo steers randomly divided into four groups: control, T1, T2, and T3. Their formula feed contained 0%, 3%, 6%, and 9% lupin flakes, respectively. In vitro rumen pH and ammonia concentrations were lower in the lupin flake group than in the lupin grain group after 6 and 24 h of incubation, respectively (p < 0.05). Concentrations of propionate, butyrate, and total volatile fatty acids were higher in the lupin flake group than in the lupin grain group after 12 h of incubation (p < 0.05), as was the crude protein disappearance rate at 9 and 12 h of rumen fermentation (p < 0.05). Supplementation with lupin flakes did not affect the average daily gain. Compared to that in the control group, dry matter intake was lower in the lupin flake-supplemented groups (p < 0.05); the feed conversion ratio was lower in T2 and T3 (p < 0.05); and plasma total protein concentration in 29-month-old steers was lower in T1 and T3 (p < 0.05). Plasma triglyceride concentration was lower in the lupin flake-supplemented groups than in the control group (p < 0.05). The incidence rate of yield grade A was higher in T1 and T2 than in the control group; the incidence rate of meat quality 1⁺ grade or higher was highest in T2. The carcass auction price was higher in T2 than in the other groups. Overall, compared to whole lupin grains, lupin flakes seem to more substantially affect rumen ammonia concentrations and crude protein disappearance rate. Additionally, we suggest that supplementation with 6% lupin flake formula feed exerts positive effects on the feed conversion ratio, yield grade, and quality grade of Hanwoo steers.

Effect of Plant Bioactive Compounds Supplemented in Transition Dairy Cows on the Metabolic and Inflammatory Status

(1) Background: This study evaluated the effects of a plant bioactive (Phyto Ax’Cell, Phytosynthese, Mozac, France) on the inflammatory status and health of dairy cows during calving. (2) Methods: 46 Holstein crossbred cows were randomized into a control group (CON, n = 23) and the Phyto Ax’Cell group (PAC, n = 23). PAC received Phyto Ax’Cell at 25 g/cow/day, from 15 days prepartum to 7 days postpartum. Blood analyses were performed weekly from D-7 to D14 to evaluate the energy metabolism and inflammatory status; rectal temperature was measured daily within 14 days from calving day (D0). (3) Results: PAC showed lower serum haptoglobin at D7 (0.55 vs. 0.79 mg/mL; p < 0.05) and D14 (0.44 vs. 0.66 mg/mL; p < 0.05). CON had a higher number of circulating white blood cells and granulocytes on D7 (p < 0.05). Fewer cows from PAC showed hyperthermia (≥39 °C) during the first 2 weeks postpartum (−7%, p < 0.05). Energy metabolism, which was represented by the NEFA/cholesterol ratio, improved (0.21 vs. 0.36 at D0, p < 0.1; 0.19 and 0.15 vs. 0.36 and 0.32, respectively, at D+7 and D+14, p < 0.05) under the plant bioactive supplementation. (4) Conclusions: The results suggest that the anti-inflammatory plant bioactive compound with Brazilian green propolis administered during calving had a beneficial effect on the energy and inflammatory status of dairy cows.

Herd level economic comparison between the shape of the lactation curve and 305 d milk production

Herd milk production performance is generally evaluated using the herd's average 305-day milk production (HM305). Economic comparisons between herds are also often made using HM305. Comparing herds is thus based on summarized milk production, and not on the form of the lactation curves of the cows within the herd. Cow lactation curve characteristics can be aggregated on a calendar year basis to herd lactation curve characteristics (HLCC) (herd magnitude, herd time to peak yield and herd persistency). Thus far, no literature has evaluated whether the shape of the lactation curve (described by HLCC) is better able to explain the economic variation of herds than summarized milk production such as HM305 does. This study aims to determine whether HM305 or HLCC is better able to explain the variation in economic performance between herds. To do so, we evaluated 8 years of Dutch longitudinal data on milk production and the financial accounts of 1,664 herds. Cow lactation curve characteristics were calculated through lactation curve modeling and aggregated to HLCC on a calendar year basis for two parity groups (primiparous cows and multiparous cows). Using income over feed cost per cow (IOFC-cow) or per 100 kg milk (IOFC-milk) as the dependent variable separately, we developed four linear mixed models. Two models were used to analyse the association between herd economic performance and HLCC; the other two models were used to analyse the association between herd economic performance and HM305. A Cox test and J test were used to compare two non-nested models to investigate whether HM305 or HLCC better explain IOFC. The average IOFC-cow was €2,305 (SD = 408) per year, while the average IOFC-milk was €32.1 (SD = 4.6). Results showed that HLCC and HM305 explain the same amount of variance of IOFC-cow or IOFC-milk. IOFC-cow was associated with HM305 and HLCC (except herd time to peak yield for primiparous cows). Herd magnitude was most strongly associated with IOFC-cow, followed by herd persistency and herd time to peak yield of multiparous cows. IOFC-milk was not associated with HM305 or HLCC (except for a weak negative association with herd persistency for primiparous cows). IOFC-cow and IOFC-milk were driven most by time effects. In conclusion, HLCC and HM305 explain the same amount of variance in IOFC-cow or IOFC-milk. HLCC is more computationally expensive, while HM305 is more readily available.

Evaluation of Heat Stress Effects in Different Geographical Areas on Milk and Rumen Characteristics in Holstein Dairy Cows Using Robot Milking and Rumen Sensors: A Survey in South Korea

This survey investigated, using robotic milking and rumen sensors, the effects of an adjusted temperature−humidity index (THI) in different geographical areas on milk yield, fat and protein, rumen temperature, and activity in lactating Holstein cows. We additionally explored the effect of parity on milk and rumen temperature and activity under different THI levels during the summer. From January to September 2020, four farms (276 dairy cows) were subjected to the use of robot milking machines, and two farms (162 dairy cows) to the use of rumen sensors. For the temperature and humidity data, the THI was calculated on the basis of the data from the Korea Meteorological Administration (KMA). The data were analyzed using the GLM procedure of SAS. Milk yield and milk protein decreased (p < 0.05), and milk fat increased (p < 0.05) at all farms during the summer, from July to August, when the temperature and humidity were high (THI = 72−79). Milk yields were the highest in the fifth, sixth, seventh, and eighth parities, and the lowest in the fourth (p < 0.05). Milk fat concentration was the highest in the fourth parity and the lowest in the first parity (p < 0.05). In the first parity, the highest levels of milk protein and lactose were seen (5.24% and 4.90%, respectively). However, milk protein concentration was the lowest in the third parity, and the lactose concentration was the lowest in the fifth, sixth, seventh, and eighth parities. According to the rumen sensor, the rumen temperature of the dairy cows at the two farms also continued to increase (p < 0.05) from July to August, and then decreased (p < 0.05) in September. However, the activity in the rumen was increased (p < 0.05) from July to September. In the second parity, the highest rumen temperature (39.02 °C) was observed, while the lowest value (38.28 °C) was observed in the third parity. The highest value of rumen activity (12.26 mg) was observed in the second parity and the lowest value (11.31 mg) in the fourth parity. These data, taken together, confirm that a high THI during summer conditions negatively affects milk yield, milk protein content, and rumen temperature and activity in lactating Holstein cows. It is also demonstrated that various parities affect milk characteristics and the rumen environment in the summer season.

Effects of replacing inorganic salts of trace minerals with organic trace minerals in pre- and postpartum diets on feeding behavior, rumen fermentation, and performance of dairy cows

Our objectives were to evaluate the effects of complete replacement of supplementary inorganic salts of trace minerals (STM) by organic trace minerals (OTM) in both pre- and postpartum diets on feeding behavior, ruminal fermentation, rumination activity, energy metabolism, and lactation performance in dairy cows. Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 d before their expected calving date. Both groups received the same diet, except for the source of trace minerals (TM). The STM group was supplemented with Co, Cu, Mn, and Zn sulfates and Na selenite, whereas the OTM group was supplemented with Co, Cu, Mn, and Zn proteinates and selenized yeast. Treatments continued until 156 days in milk and pre- and postpartum diets were formulated to meet 100% of recommended levels of each TM in both treatments, taking into consideration both basal and supplemental levels. Automatic feed bins were used to assign treatments to individual cows and to measure feed intake and feeding behavior. Rumination activity was monitored by sensors attached to a collar from wk -3 to 3 relative to calving. Blood metabolites were evaluated on d -21, -10, -3, 0, 3, 7, 10, 14, 23, and 65 relative to calving. Ruminal fluid samples were collected using an ororuminal sampling device on d -21, 23, and 65 relative to calving, for measurement of ruminal pH and concentration of volatile fatty acids. Cows were milked twice a day and milk components were measured monthly. Cows supplemented with OTM tended to have longer daily feeding time (188 vs. 197 min/d), and greater dry matter intake (DMI; 12.9 vs. 13.3 kg), and had a more positive energy balance (3.6 vs. 4.2 Mcal/d) and shorter rumination time per kg of dry matter (DM; 40.1 vs. 37.5 min/kg of DM) than cows supplemented with STM during the prepartum period. In the postpartum period, OTM increased DMI in multiparous cows (24.1 vs. 24.7 kg/d) but not in primiparous cows (19.1 vs. 18.7 kg/d). The difference in DMI of multiparous cows was more evident in the first 5 wk of lactation, when it averaged 1 kg/d. Milk yield was not affected by treatment in multiparous cows (44.1 vs. 44.2 kg/d); however, primiparous cows supplemented with OTM had lesser yields than primiparous cows supplemented with STM (31.9 vs. 29.8 kg/d). Cows supplemented with OTM had a greater percentage of protein in milk (3.11 vs. 3.17%), reduced concentration of nonesterified fatty acids in serum (0.45 vs. 0.40 mmol/L), and rumination activity (30.1 vs. 27.8 min/kg of DM) than cows supplemented with STM. At the end of the transition period, cows supplemented with OTM had reduced molar proportion of acetate, reduced pH, and tended to have a greater concentration of total volatile fatty acids in ruminal fluid. In conclusion, complete replacement of STM by OTM caused modest changes in rumen fermentation, feeding behavior, energy metabolism, and performance of dairy cows, improving postpartum DMI in multiparous cows and reducing circulating levels of nonesterified fatty acids. The pre-absorptive effects of TM source and the parity specific responses on performance warrant further research.

Characterization and mitigation option of greenhouse gas emissions from lactating Holstein dairy cows in East China

BACKGROUND

This study investigated greenhouse gas (GHG) emission characteristics of lactating Holstein dairy cows in East China and provided a basis for formulating GHG emission reduction measures. GreenFeed system was used to measure the amount of methane (CH₄) and carbon dioxide (CO₂) emitted by the cows through respiration. Data from a commercial cow farm were used to observe the effects of parity, body weight, milk yield, and milk component yield on CH₄ and CO₂ emissions.

RESULTS

Mean herd responses throughout the study were as follows: 111 cows completed all experimental processes, while 42 cows were rejected because they were sick or had not visited the GreenFeed system 20 times. On average, lactating days of cows was 138 ± 19.04 d, metabolic weight was 136.5 ± 9.5 kg, parity was 2.8 ± 1.0, dry matter intake (DMI) was 23.1 ± 2.6 kg/d, and milk yield was 38.1 ± 6.9 kg/d. The GreenFeed system revealed that CH₄ production (expressed in CO₂ equivalent, CO₂-eq) was found to be 8304 g/d, [Formula: see text]/DMI was 359 g/kg, [Formula: see text]/energy-corrected milk (ECM) was 229.5 g/kg, total CO₂ production (CH₄ production plus CO₂ production) was 19,201 g/d, total CO₂/DMI was 831 g/kg, and total CO₂/ECM was 531 g/kg. The parity and metabolic weight of cows had no significant effect on total CO₂ emissions (P > 0.05). Cows with high milk yield, milk fat yield, milk protein yield, and total milk solids yield produced more total CO₂ (P < 0.05), but their total CO₂ production per kg of ECM was low (P < 0.05). The total CO₂/ECM of the medium and high milk yield groups was 17% and 27% lower than that of the low milk yield group, respectively.

CONCLUSIONS

The parity and body condition had no effect on total CO₂ emissions, while the total CO₂/ECM was negatively correlated with milk yield, milk fat yield, milk protein yield, and total milk solids yield in lactating Holstein dairy cows. Measurement of total CO₂ emissions of dairy cows in the Chinese production system will help establish regional or national GHG inventories and develop mitigation approaches to dairy production regimes.

Effects of wildfire smoke exposure on innate immunity, metabolism, and milk production in lactating dairy cows

Wildfires are particularly prevalent in the Western United States, home to more than 2 million dairy cows that produce more than 25% of the nation's milk. Wildfires emit fine particulate matter (PM_2.5) in smoke, which is a known air toxin and is thought to contribute to morbidity in humans by inducing inflammation. The physiological responses of dairy cows to wildfire PM_2.5 are unknown. Herein we assessed the immune, metabolic, and production responses of lactating Holstein cows to wildfire PM_2.5 inhalation. Cows (primiparous, n = 7; multiparous, n = 6) were monitored across the wildfire season from July to September 2020. Cows were housed in freestall pens and thus were exposed to ambient air quality. Air temperature, relative humidity, and PM_2.5 were obtained from a monitoring station 5.7 km from the farm. Animals were considered to be exposed to wildfire PM_2.5 if daily average PM_2.5 exceeded 35 µg/m³ and wildfire and wind trajectory mapping showed that the PM_2.5 derived from active wildfires. Based on these conditions, cows were exposed to wildfire PM_2.5 for 7 consecutive days in mid-September. Milk yield was recorded daily and milk components analysis conducted before, during, and after exposure. Blood was taken from the jugular vein before, during, and after exposure and assayed for hematology, blood chemistry, and blood metabolites. Statistical analysis was conducted using mixed models including PM_2.5, temperature-humidity index (THI), parity (primiparous or multiparous), and their interactions as fixed effects and cow as a random effect. Separate models included lags up to 7 d to identify delayed and persistent effects from wildfire PM_2.5 exposure. Exposure to elevated PM_2.5 from wildfire smoke resulted in lower milk yield during exposure and for 7 d after last exposure and higher blood CO₂ concentration, which persisted for 1 d following exposure. We observed a positive PM_2.5 by THI interaction for eosinophil and basophil count and a negative PM_2.5 by THI interaction for red blood cell count and hemoglobin concentration after a 3-d lag. Neutrophil count was also lower with a combination of higher THI and PM_2.5. We found no discernable effect of PM_2.5 on haptoglobin concentration. Effects of PM_2.5 and THI on metabolism were contingent on day of exposure. On lag d 0, blood urea nitrogen (BUN) was reduced with higher combined THI and PM_2.5, but on subsequent lag days, THI and PM_2.5 had a positive interaction on BUN. Conversely, THI and PM_2.5 had a positive interacting effect on nonesterified fatty acids (NEFA) on lag d 0 but subsequently caused a reduction in circulating NEFA concentration. Our results suggest that exposure to high wildfire-derived PM_2.5, alone or in concert with elevated THI, alters systemic metabolism, milk production, and the innate immune system.

Effects of Parity and Stage of Lactation on Trend and Variability of Metabolic Markers in Dairy Cows

Simple Summary

The rise in milk yield per cow, herd size, and the percentage of primiparous cows in dairy herds increasingly requires optimized health management in order to ensure the health of the cows. The transition period (three weeks before to three weeks after calving) has a key role in health problems, because dairy cows undergo tremendous metabolic changes. Metabolic monitoring provides an in-depth insight into how the cows cope with these challenges. A remarkable variability in the metabolic parameters reflects the adaptation of dairy cows during the transition from pregnancy to lactation. In addition, primiparous cows undergo physical adaptations because of growth, first gestation, the maturation of the mammary glands, the onset of lactation, and fighting for social dominance. Previous studies have rarely considered these specific demands due to the influences of parity and the lactation stage. Thus, the objective of our study was to describe the variation in metabolic parameters due to parity and the stage of lactation based on a huge number of primiparous and multiparous cows, observed at all stages of lactation, in a retrospective analysis of laboratory data. The remarkable impact of both parity and lactation was elucidated for most parameters. This should be taken into account for a correct interpretation of the laboratory diagnostics in the framework of metabolic monitoring.

Abstract

Metabolic monitoring is a tool that is helpful with the increasing requirements regarding feeding and health management in dairy herds. This study aimed at describing the trend and variability of different biochemical parameters in blood and urine in relation to the stages of lactation and parity, in a retrospective analysis of laboratory data from clinically healthy German Holstein cows. The results were derived from metabolic monitoring in Thuringia (Germany), during 2009–2019. A total of 361,584 measured values, of 13 different metabolic variables, were assigned to parity (primiparous and multiparous) and stage of lactation (10 classes from −30 to 300 days in milk). The Kruskal–Wallis test was applied for the evaluation of differences regarding parity or the stage of lactation. Non-esterified fatty acids, beta hydroxybutyrate, and the activity of aspartate aminotransferase in serum were clearly affected by parity and lactation. Serum concentrations of cholesterol, bilirubin, and phosphorus, as well as the serum activity of glutamate dehydrogenase, were affected by the stage of lactation, while parity impacted urea concentration. The serum activity of creatine kinase, serum concentrations of calcium, and urine concentrations of net acid base excretion, potassium, and sodium were not affected by parity or lactation. In conclusion, specific reference limits, with respect to parity and the stage of lactation, are necessary.

Qualitative and Quantitative Changes in Total Lipid Concentration and Lipid Fractions in Liver Tissue of Periparturient German Holstein Dairy Cows of Two Age Groups

Fatty liver syndrome (FLS) is a common disease in high-producing dairy cows. Studies in humans suggest that the different hepatic lipid fractions play a role in this context. In dairy cows, little is known about the composition of fat stored in the liver, its periparturient dynamics, and the effect of cows' age. Therefore, our goal was to generate primary data in healthy cows to serve as reference values for future studies. Eight healthy German Holstein cows (2nd lactation, n = 3; ≥3rd lactation, n = 5) were examined 14 d antepartum and 7, 28, and 42 d postpartum. The examinations included clinical assessment, liver biopsy, blood sampling, and recording of milk yield. Total lipids (TL) in liver tissue were measured gravimetrically. The TL were separated into lipid fractions (triacylglycerol, TAG; phospholipids, PL; non-esterified fatty acids, NEFA; and cholesterol esters) using thin-layer chromatography, followed by gas chromatography for fatty acid determination. Concentrations of NEFA, ß-hydroxybutyrate, and cholesterol were analyzed in blood. Concentrations of TL, TAG, NEFA, and cholesterol esters in liver tissue and NEFA in blood increased in the periparturient period. The older cows had higher hepatic TL, TAG, and PL concentrations, higher relative hepatic concentrations of TAG in TL, higher NEFA concentrations in blood, a greater decrease in body condition, and higher milk yields between d 9 and 40 than the younger cows. We proposed that due to higher milk yield, older cows mobilized and deposited more fat in the liver, and the increase in hepatic TAG concentration was longer-lasting than in younger cows. Higher levels of structural lipids (PL) in older cows could be explained by higher demand for storage of TAG and cholesterol esters in lipid droplets or for the export of TAG via very-low-density lipoproteins. Results show that hepatic fat storage is a reversible process and does not necessarily cause clinical disease. Nevertheless, older cows have a more sustained and greater increase in hepatic TAG concentration, which may explain their increased risk of FLS. The results are limited in their extrapolation due to the small sample size and thereby possible selection bias but present a valuable basis for future studies.

Using publicly available weather station data to investigate the effects of heat stress on milk production traits in Canadian Holstein cattle

Heat stress imposes a challenge to the dairy industry, even in northern latitudes. In this study, publicly available weather station data was combined with test-day records for milk, fat, and protein yields to identify the temperature-humidity index (THI) thresholds at which heat load starts affecting milk production traits in Canadian Holstein cows. Production loss per THI unit above the threshold for each trait was estimated. Test-day records from 2010-2019 from 166,749 cows raised in Ontario and from 221,214 cows raised in Quebec were analyzed. Annual economic losses due to heat stress were estimated from the average losses of fat and protein yields based on the annual average of 156 days with THI exceeding the calculated thresholds. Average thresholds for the daily maximum (THI_max) and daily average (THI_avg) THI estimated across lactations in both provinces were THI_max (THI_avg) 68 (64), 57 (50), and 60 (58) for milk, fat, and protein yield, respectively, indicating that milk components are more sensitive to heat stress. An economic loss of about $34.5 million per year was estimated. Our findings contribute to an initial investigation into the impact of heat stress on the Canadian dairy industry and provides a basis for genetic studies on heat tolerance.

Sensor based time budgets in commercial Dutch dairy herds vary over lactation cycles and within 24 hours

Cows from 8 commercial Dutch dairy farms were equipped with 2 sensors to study their complete time budgets of eating, rumination, lying, standing and walking times as derived from a neck and a leg sensor. Daily sensor data of 1074 cows with 3201 lactations was used from 1 month prepartum until 10 months postpartum. Farms provided data over a 5 year period. The final models (lactational time budget and 24h time budget) showed significant effects of parity, farm and calving season. When primiparous cows were introduced in the lactational herd, they showed a decrease in lying time of 215 min (95% CI: 187–242) and an increase in standing time of 159 min (95% CI: 138–179), walking time of 23 min (95% CI: 20–26) and rumination time of 69 min (95% CI: 57–82). Eating time in primiparous cows increased from 1 month prepartum until 9 months in lactation with 88 min (95% CI: 76–101) and then remained stable until the end of lactation. Parity 2 and parity 3+ cows decreased in eating time by 30 min (95% CI: 20–40) and 26 min (95% CI: 18–33), respectively, from 1 month before to 1 month after calving. Until month 6, eating time increased 11 min (95% CI: 1–22) for parity 2, and 24 min (95% CI: 16–32) for parity 3+. From 1 month before calving to 1 month after calving, they showed an increase in ruminating of 17 min (95% CI: 6–28) and 28 min (95% CI: 21–35), an increase in standing time of 117 min (95% CI: 100–135) and 133 min (95% CI: 121–146), while lying time decreased with 113 min (95% CI: 91–136) and 130 min (95% CI: 114–146), for parity 2 and 3+, respectively. After month 1 in milk to the end of lactation, lying time increased 67 min (95% CI: 49–85) for parity 2, and 77 min (95% CI: 53–100) for parity 3+. Lactational time budget patterns are comparable between all 8 farms, but cows on conventional milking system (CMS) farms with pasture access appear to show higher standing and walking time, and spent less time lying compared to cows on automatic milking system (AMS) farms without pasture access. Every behavioral parameter presented a 24h pattern. Cows eat, stand and walk during the day and lie down and ruminate during the night. Daily patterns in time budgets on all farms are comparable except for walking time. During the day, cows on CMS farms with pasture access spent more time walking than cows on AMS farms without pasture access. The average 24h pattern between parities is comparable, but primiparous cows spent more time walking during daytime compared to older cows. These results indicate a specific behavioral pattern per parameter from the last month prepartum until 10 months postpartum with different patterns between parities but comparable patterns across farms. Furthermore, cows appear to have a circadian rhythm with varying time budgets in the transition period and during lactation.

Effect of two formulations of recombinant bovine somatotropin on milk production and body condition of cattle under intensive management in Peru

The effect of recombinant somatotropin (rbST) application in cattle has been demonstrated in temperate climate but very limited studies are available in tropical regions. The objective of this study was to compare the effect of the application of two different formulations of rbST on the milk yield and body condition of dairy cattle in a commercial herd under intensive production in Peru. We evaluated the application of 500 mg of active rbST in a zinc sesame oil (ZSO-rbST; n = 44) or vitamin E lecithin (VEL-rbST; n = 45) vehicle while control cows (n = 42) did not receive any application. The application of rbST was performed by every 14 days for 12 cycles, for a total of 168 days. The application of rbST increased the milk production of primiparous and multiparous cows by 3 and 3.2 kg/day for the VEL-rbST formulation respectively when compared with control cows (p < 0.01) and no difference in milk production was observed between the ZSO-rbST formulation and the control group (p > 0.05). However, no significant difference on milk production was observed between the rbST formulations evaluated. The effect of rbST per injection cycle indicated differences in milk production and economic return for the 12 cycles between rbST and control in primiparous group, while in multiparous, no differences were found between ZSO-rbST and control (p > 0.05), but differences were observed between VEL-rbST and control in 41% of the cycles (p < 0.05). No differences in body condition were found between the two rbST formulations and the control group during the evaluation. In conclusion, the application of rbST promoted higher milk production of cattle which had a positive impact on the economic income of the farmer.

Effect of physiological status and parity on metabolic and trace element profile of crossbred Rambouillet sheep of Himalayan region

The study was designed to evaluate the effect of physiological status and parity on metabolic profile in crossbred Rambouillet ewes of the Himalayan region. The study was conducted on 20 ewes divided into two groups, primiparous (PP) and multiparous (MP), with 10 ewes in each group. Blood samples were collected on 4- and 1-week pre-lambing and 1- and 4-week post-lambing to measure metabolic parameters and minerals. The glucose (p < 0.01), total plasma protein (TPP) (p < 0.05), albumin (p < 0.05), blood urea nitrogen (BUN) (p < 0.05), cholesterol (p < 0.05), triglyceride (p < 0.01), high-density lipoprotein cholesterol (HDL-C) (p < 0.05), calcium (Ca) (p < 0.01), phosphorus (Pi) (p < 0.05), magnesium (Mg) (p < 0.01), copper (Cu) (p < 0.05), and zinc (Zn) (p < 0.01) levels revealed significant change along the time with the concentration decreasing from 3-week pre-lambing to immediate post-lambing; thereafter, levels increased steadily. Significant increase (p < 0.01) was observed in non-esterified fatty acid (NEFA), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), iron (Fe) (p < 0.05), and bilirubin (p < 0.05) concentrations along the sampling time. No group difference was observed in any of the parameters; however, parity and time interaction was observed in glucose, NEFA, GGT, Ca, and Pi. While NEFA levels were significantly high in pre-lambing in PP ewes compared to MP ewes, the post-lambing levels were significantly high in MP ewes. Pre-lambing levels of GGT were at par between the two groups; however, post-lambing levels were significantly high in MP ewes. Glucose, Ca, and Pi were low during pre-lambing in PP ewes and post-lambing in MP ewes. The result showed that ewes show a significant change in metabolic profile and trace minerals during late gestation and immediate postpartum; however, these changes were more pronounced during late gestation in primiparous and post-lambing in multiparous.

Application of PGF2α at the moment of fixed-time artificial insemination in crossbred beef cows

Although studies have shown positive effects of gonadotropin releasing hormone (GnRH) or prostaglandin F_2α (PGF_2α) at the moment of fixed-time artificial insemination (FTAI) in the conception rate (CR) of cattle, its effects on treatments based on progesterone (P4) and estradiol benzoate (EB) is still not conclusive. The objective of this study was (1) to evaluate the effect of a PGF_2α analogue at FTAI in the CR of crossbred beef cows submitted to a 11d FTAI protocol based on P4 and EB; and (2) to describe the CR between PGF_2α-treated and control cows in different body condition scores (BCS) and parity categories. Crossbred (½ Nellore and ½ Angus) beef cows were submitted to a synchronization protocol and randomly assigned into 2 groups: Control (n = 163), at FTAI cows received 2 mL of saline solution as a placebo, and PGF_2α (n = 163), at FTAI cows were treated with PGF_2α analogue (10 mg of dinoprost tromethamine). Pregnancy diagnosis was performed 33d post-FTAI. Binary logistic regression model was used to analyze the effect of PGF_2α treatment on CR. There was no difference in CR between PGF_2α and control groups (P > 0.05; odds ratio (OR) = 0.92; confidence interval (CI) = 0.59-1.4). A greater CR was found in heifers (P = 0.0006, OR = 2.65, CI = 1.61 - 4.38) and multiparous (P = 0.0006, OR = 2.12, CI = 1.04 - 4.3) when compared to primiparous cows. Cows with low BCS (4; 9-point scale) showed lower CR when compared with moderate BCS (5-6; 9-point scale) (P < 0.05; OR = 0.10; CI = 0.06 - 0.18). There was no numerical difference on CR between PGF_2α-treated and control cows in different BCS and parity categories. The results suggested that the CR in this study was not influenced by 10 mg PGF_2α analogue at FTAI.

Determining Immunoglobulin Content of Bovine Colostrum and Factors Affecting the Outcome: A Review

The immunoglobulin concentration in bovine colostrum should be measured to ensure feeding with sufficient immunoglobulins (≥50 mg immunoglobulin G mL-1). Adequate feeding prevents diseases, promotes development, and has a positive influence on the adult animal. Indirect and direct measurement methods are available for this purpose. Direct measurement methods cannot be easily used in practice; therefore, farmers use indirect methods such as a colostrometer and a refractometer. Many factors influence the immunoglobulin concentration of colostrum; some of them have already been intensively researched. In particular, lactation and temporal aspects play an essential role. Newer aspects such as dry period, seasonal influences, and genetics are gaining importance, but their impact on immunoglobulin content has not been sufficiently investigated. Developments are still needed, especially in data management. This review analyzes the outcome of different studies on the indirect and direct measurement methods and discusses different factors influencing the immunoglobulin concentration of bovine colostrum.

Evaluation of Non-linear Models to Predict Potential Milk Yield of Beef Cows According to Parity Order Under Grazing

This study aimed to evaluate the effect of parity order on milk yield (MY) and composition over time of grazing beef cows and to evaluate non-linear models to describe the lactation curve. Thirty-six pregnant Nellore cows (12 nulliparous, 2 years; 12 primiparous, 3 years; and 12 multiparous, 4-6 years) were included in the study. With calving day assigned as day 0, milking was performed using a milking machine to estimate MY on days 7, 14, 21, 42, 63, 91, 119, 154, and 203. Dummy variable analyses were applied to estimate its effects on MY, composition (kg and percentage), afternoon/morning, and afternoon/total proportions. Since multiparous cows had higher MY than nulliparous and primiparous cows, two different groups were used for lactation curve analysis: Mult (multiparous) and Null/Prim (nulliparous and primiparous). The MY estimated by the last edition of BR-Corte (Nutrient Requirements of Zebu and Crossbred Cattle) equation was compared with the observed values from this study. Five nonlinear models proposed by Wood (WD), Jenkins & Ferrell (JF), Wilmink (WK), Henriques (HR) and Cobby & Le Du (CL) were evaluated. Models were validated using an independent dataset of multiparous and primiparous cows. The estimates for parameters a, b, and c of the CL equation were compared between groups, and the BR-Corte equation used the model identity methodology. Nulliparous and primiparous cows displayed similar MY (P > 0.05); however, multiparous cows had an average MY that is 0.70 kg/day greater than that of nulliparous and primiparous cows (P < 0.05). Milk protein and total solids were higher for multiparous cows (P < 0.05). Effect of days in milking was found for milk fat, protein, and total solids (P < 0.05). The yield of all milk components was higher for multiparous cows than for nulliparous and primiparous cows. The afternoon/morning and afternoon/total proportions of milk production were not affected by parities and days in milking (P > 0.05), with an average of 0.76 and 0.42, respectively. The BR-Corte equation did not correctly estimate the MY (P < 0.05). The equations of WD, WK, and CL had the best estimate of MY for both Mult and Null/Prim datasets. The equations had a very similar Akaike's information criterion with correction and mean square error of prediction.

Effects of genotype, parity, season and their interactions on milk yield in crossbred dairy cattle

The crossbred dairy cattle (CDC) have been gaining popularity in the tropical countries for their increased milk yield within a short period of time because of heterogenic additive gene action. Hence, we aimed to investigate whether genotype, parity, season and their interactions had any effect on average daily milk yield (ADMY) of the CDC in a dairy farm at Chattogram district, Bangladesh, for a period of 3 years from January 2016 to December 2019. Total 16,425 retrospective lactation records of 150 multiparous Sahiwal × Friesian₁ (Sahiwal = 50%, HF = 50%), Local × Friesian₁ (Local = 50%, HF = 50%) and Local × Friesian₂ (Local = 25%, HF = 75%) CDC from the first to the third parities (50 for each parity) were collected from the farm records. The generalized linear model and principal component analysis identified substantial impacts of genotype, parity, season and their interactions on ADMY of the CDC. The herd level least squared ADMY was 11.22 ± 0.04 kg/days on a 305-days typical lactation period. The Sahiwal × Friesian₁ CDC produced 7.2% and 5.5% more milk than the Local × Friesian₁ and Local × Friesian₂ respectively. The CDC produced maximum milk in the second parity, which was 7.8% and 0.34% more than the first and third parities. Similarly, the highest ADMY was recorded in the spring, which was 10.8%, 7.3% and 6.6% more than the fall, summer and winter respectively. It was concluded that the Sahiwal × Friesian₁ crossbred produced maximum milk in the spring season at the second parity while other determinants remained constant. The changing patterns of milk yield in different genotype, parity and seasons provided scientific evidence for improving feeding strategy to optimize herd level milk yield of CDC in the commercial dairy farms under tropical perspective.