Effect of mastectomy on milk fever, energy, and vitamins A, E, and beta-carotene status at parturition

The Efficacy of β-Carotene in Cow Reproduction: A Review

β-carotene supplementation improves the reproductive performance of cattle. However, the research results on this topic have been inconsistent, and no clear conclusion has been reached. In previous reviews of this topic, the functional mechanism of β-carotene in reproduction remained unclear, but subsequent studies have shown that the antioxidant effects of β-carotene protect enzymes involved in ovarian sex steroid hormone production from the effects of oxygen radicals. This role consequently affects normal ovarian follicle dynamics, maintenance of luteal function, and the estrous cycle, and indirectly improves reproductive performance by preventing perinatal diseases and facilitating recovery from these diseases. Several factors must be considered in feeding management to determine whether β-carotene supplementation is effective for improving reproductive performance in cows. The same is true when the animal consumes a large amount of the antioxidant β-carotene due to lactation, aging, or season. Therefore, it is important to consider the balance between the supply and consumption of β-carotene and evaluate whether β-carotene supplementation has an effect on reproductive performance in cows.

Effect of dietary phosphorus deprivation during the dry period on the liver transcriptome of high-yielding periparturient dairy cows

Although dietary phosphorus (P) deprivation extending from the dry period into early lactation impairs health and productivity of cows, restricting dietary P supply during the dry period not only appears to be innocuous but rather effectively mitigates hypocalcemia during the first wk of lactation. To investigate possible negative metabolic effects of P deprivation during the dry period, the present study tested the hypothesis that restricted dietary P supply during the dry period alters the liver transcriptome of dairy cows during the periparturient period. Thirty late-pregnant multiparous Holstein-Friesian dairy cows entering their second, third, or fourth lactation were assigned to either a dry cow ration with low (LP, 0.16% P in DM) or adequate P content (AP, 0.35% in DM) during the last 4 wk of the dry period (n = 15/group). Liver transcriptomics, which was carried out in a subset of 5 second-parity cows of each group (n = 5), and determination of selected hormones and metabolites in blood of all cows, was performed ∼1 wk before calving and on d 3 postpartum. Liver tissue specimens and blood samples were obtained by a micro-invasive biopsy technique from the right tenth intercostal space and puncture of a jugular vein, respectively. One hundred seventy-five hepatic transcripts were expressed differentially between LP versus AP cows in late pregnancy, and 165 transcripts differed between LP versus AP cows in early lactation (fold change >1.3 and <-1.3, P < 0.05). In late pregnancy, the enriched biological processes of the upregulated and the downregulated transcripts were mainly related to immune processes and signal transduction (P < 0.05), respectively. In early lactation, the enriched biological processes of the upregulated and the downregulated transcripts were involved in mineral transport and biotransformation (P < 0.05), respectively. The plasma concentrations of the hormones and acute-phase proteins (progesterone, insulin-like growth factor 1, serum amyloid α, haptoglobin, and 17β-estradiol) determined were not affected by P supply. These results suggest that P deprivation during the dry period moderately affects the liver transcriptome of cows in late pregnancy and early lactation, and causes no effects on important plasma hormones and acute-phase proteins indicating no obvious impairment of health or metabolism of the cows.

Does knowledge of blood calcium concentration at 2 days postpartum affect decisions of calcium supplementation?

Delaying oral Ca supplementation might benefit cows with low blood Ca concentrations at 4 d in milk (DIM), a time when reduced blood total Ca (tCa) is associated with negative health and production outcomes. To implement a targeted approach to manage subclinical hypocalcemia (SCH) at the herd level, it is important to identify which cows benefit from supplemental Ca. Therefore, our objective was to determine if SCH diagnosis at 2 DIM could inform decisions of oral Ca supplementation at 2 and 3 DIM based on milk yield and 4 DIM blood Ca concentration. Data were analyzed from a previously conducted randomized controlled trial on multiparous cows (n = 518) from 4 farms in New York State. Cows were randomly assigned to 1 of 2 treatment groups at calving: (1) control (CON; no Ca supplementation, n = 259) or (2) bolus (BOL; 43 g of oral Ca administered at 2 and 3 DIM postcalving, n = 259). For each parity group (2, 3, 4+), we used generalized linear mixed models to identify serum tCa concentrations at 2 DIM that maximized the difference in milk yield to diagnose SCH. Cows were classified as normocalcemic (NC; parity 2 tCa >1.9 mmol/L, parity 3 tCa >1.87 mmol/L, n = 327; parity ≥4 had no defining threshold) or SCH (parity 2 tCa ≤1.9 mmol/L, parity 3 tCa ≤1.87 mmol/L, n = 58; parity ≥4 had no defining threshold). Parity 2 and 3 cows were further classified into 1 of 4 SCH-treatment groups (SCHTRT) based on 2 DIM SCH status and random treatment allocation: (1) NC-CON, n = 165, (2) SCH-CON, n = 28, (3) NC-BOL, n = 162, or (4) SCH-BOL, n = 30. Generalized linear mixed models were used to analyze the difference in milk yield for the first 10 wk of lactation and tCa at 4 DIM between SCHTRT groups with separate analyses performed for parities 2 and 3. Mean milk yield differed between SCHTRT groups for both parities. For parity 2, SCH-CON and SCH-BOL cows produced more milk than NC-CON and NC-BOL cows with SCH-CON producing 50.9 (95% confidence interval [CI] = 48.4, 53.4) kg/d, SCH-BOL 51.7 (49.1, 54.2) kg/d, NC-CON 47.5 (46.3, 48.7) kg/d, and NC-BOL 47.2 (45.8, 48.5) kg/d of milk. Milk yield was also different between SCHTRT groups for parity 3 with SCH-BOL cows producing more milk than NC-CON and NC-BOL cows. In parity 3, SCH-BOL cows produced 56.3 (95% CI = 53.1, 59.3) kg/d, SCH-CON 51.7 (48.6, 54.7) kg/d, NC-BOL 50.6 (49.0, 52.2) kg/d, and NC-CON 48.7 (46.9, 50.5) kg/d of milk. For both parities, SCH-CON and SCH-BOL cows had lower tCa at 2 DIM than NC-CON and NC-BOL cows. At 4 DIM, tCa concentrations were similar for all SCHTRT groups respective to parity. Our results suggest that although delayed Ca bolus administration does not improve blood Ca concentration when compared with controls, it does support increased milk production in parity 3 cows regardless of Ca status at 2 DIM. Thus, knowledge of blood Ca at 2 DIM should not affect decisions of Ca supplementation in this parity of cows.

Periparturient Mineral Metabolism: Implications to Health and Productivity

Mineral metabolism, in particular Ca, and to a lesser extent phosphorus (P) and magnesium (Mg), is altered with the onset of lactation because of extensive irreversible loss to synthesize colostrum and milk. The transient reduction in the concentration of Ca in blood, particularly when it lasts days, increases the risk of mineral-related disorders such as hypocalcemia and, to a lesser extent, hypophosphatemia. Although the incidence of clinical hypocalcemia can be reduced by prepartum dietary interventions, subclinical hypocalcemia remains prevalent, affecting up to 60% of the dairy cows in the first 3 d postpartum. More importantly, strong associations exist between hypocalcemia and increased susceptibility to other peripartum diseases and impaired reproductive performance. Mechanistic experiments have demonstrated the role of Ca on innate immune response in dairy cows, which presumably predisposes them to other diseases. Hypocalcemia is not related to inadequate Ca intake as prepartum diets marginal to deficient in Ca reduce the risk of the disease. Therefore, the understanding of how Ca homeostasis is regulated, in particular how calciotropic hormones such as parathyroid hormone and 1,25-dihydroxyvitamin D3, affect blood Ca concentrations, gastrointestinal Ca absorption, bone remodeling, and renal excretion of Ca become critical to develop novel strategies to prevent mineral imbalances either by nutritional or pharmacological interventions. A common method to reduce the risk of hypocalcemia is the manipulation of the prepartum dietary cation-anion difference. Feeding acidogenic diets not only improves Ca homeostasis and reduces hypocalcemia, but also reduces the risk of uterine diseases and improves productive performance. Feeding diets that induce a negative Ca balance in the last weeks of gestation also reduce the risk of clinical hypocalcemia, and recent work shows that the incorporation of mineral sequestering agents, presumably by reducing the absorption of P and Ca prepartum, increases blood Ca at calving, although benefits to production and health remain to be shown. Alternative strategies to minimize subclinical hypocalcemia with the use of vitamin D metabolites either fed prepartum or as a pharmacological agent administered immediately after calving have shown promising results in reducing hypocalcemia and altering immune cell function, which might prove efficacious to prevent diseases in early lactation. This review summarizes the current understanding of Ca homeostasis around parturition, the limited knowledge of the exact mechanisms for gastrointestinal Ca absorption in bovine, the implications of hypocalcemia on the health of dairy cows, and discusses the methods to minimize the risk of hypocalcemia and their impacts on productive performance and health in dairy cows.

Effects of timing of oral calcium administration on milk production in high-producing early-lactation Holstein cows

Supplementation of oral Ca via blanket administration of an oral Ca bolus at 0 and 24 h after calving has shown limited success in increasing production and minimizing adverse health events. Recent evidence that reductions in blood Ca at 4 d in milk (DIM) are more closely associated with negative outcomes than hypocalcemia at 0 to 24 h postpartum might explain this lack of Ca bolus efficacy. Therefore, our primary objective was to explore the effect of delayed oral Ca bolus supplementation on milk production, with secondary objectives of exploring the effects on disease incidence and postpartum blood Ca dynamics. We conducted a randomized controlled trial on multiparous Holstein cows (n = 998) from 4 herds in New York. At calving, cows were randomly assigned to 1 of 3 treatment groups: (1) control, no supplemental Ca at or around parturition (CON; n = 343); (2) conventional bolus, an oral Ca bolus containing 43 g of Ca at calving and 24 h later (BOL-C; n = 330); or (3) delayed bolus, an oral Ca bolus containing 43 g of Ca at 48 and 72 h after calving (BOL-D; n = 325). We created generalized linear mixed models to analyze differences in milk yield for the first 10 wk of lactation and serum total Ca (tCa) at 1 and 4 DIM between treatment groups; multivariable Poisson regression models were used to analyze adverse event outcomes (metritis, displaced abomasum, herd removal, or a combination of one or more of the 3) in the first 30 DIM. Milk yield increased by week and was not affected by treatment. However, a treatment by parity group interaction for milk yield showed that BOL-D cows in the third parity produced more milk than third-parity BOL-C or CON cows (BOL-D = 52.0 kg/d, 95% confidence interval [50.6, 53.4] kg/d, BOL-C = 47.9 [46.3, 49.5] kg/d, CON = 49.8 [48.2, 51.2] kg/d). The incidence of adverse health events was similar between treatments (BOL-D = 3.7%, BOL-C = 3.7%, CON = 3.6%). Serum tCa was lower at 1 than 4 DIM, and we detected no difference in tCa between treatment groups. Our findings suggest that delaying oral Ca bolus supplementation has limited influence on blood Ca concentrations but may be beneficial to cohorts of cows as a targeted prophylactic supplement to support milk production.

Influence of prepartum dietary cation-anion difference and the magnitude of calcium decline at the onset of lactation on mineral metabolism and physiological responses

The onset of lactation is characterized by substantially altered calcium (Ca) metabolism; recently, emphasis has been placed on understanding the dynamics of blood Ca in the peripartal cow in response to this change. Thus, the aim of our study was to delineate how prepartum dietary cation-anion difference (DCAD) diets and the magnitude of Ca decline at the onset of lactation altered blood Ca dynamics in the periparturient cow. Thirty-two multiparous Holstein cows were blocked by parity, previous 305-d milk yield and expected parturition date, and randomly allocated to either a positive (+120 mEq/kg) or negative (-120 mEq/kg) DCAD diet from 251 d of gestation until parturition (n = 16/diet). Immediately after parturition cows were continuously infused for 24 h with (1) an intravenous solution of 10% dextrose or (2) Ca gluconate (CaGlc) to maintain blood ionized (iCa) concentrations at ∼1.2 mM (normocalcemia) to form 4 treatment groups (n = 8/treatment). Blood was sampled every 6 h from 102 h before parturition until 96 h after parturition and every 30 min during 24 h continuous infusion. Cows fed a negative DCAD diet prepartum exhibited a less pronounced decline in blood iCa approaching parturition with lesser magnitude of decline relative to positive DCAD-fed cows. Cows fed a negative DCAD diet prepartum required lower rates of CaGlc infusion to maintain normocalcemia in the 24 h postpartum relative to positive DCAD-fed cows. Infusion of CaGlc disrupted blood Ca and P dynamics in the immediate 24 h after parturition and in the days following infusion. Collectively, these data demonstrate that prepartum negative DCAD diets facilitate a more transient hypocalcemia and improve blood Ca profiles at the onset of lactation whereas CaGlc infusion disrupts mineral metabolism.

The antidepressant fluoxetine (Prozac®) modulates serotonin signaling to alter maternal peripartum calcium homeostasis

Antidepressant use is two-fold greater in women compared to men; however, most studies have been performed in male subjects. We aimed to understand the impact of selective serotonin reuptake inhibitors (SSRI, most used antidepressants) on calcium homeostasis and steroid metabolism during the peripartum period. Pregnant sheep (n = 10/group) were treated with vehicle or fluoxetine (most common SSRI) during the last month of gestation. Fluoxetine treatment decreased circulating calcium prior to parturition (8.7 ± 0.1 mg/dL vs 8.2 ± 0.1 mg/dL; P = 0.07). In the control group, total calcium decreased after parturition corresponding to the onset of lactogenesis followed by increase in calcium by day 2 postpartum. Interestingly, this normal transient decrease in circulating calcium was absent in fluoxetine-treated ewes. The steroids cortisol and progesterone were not altered by fluoxetine treatment whereas estradiol was decreased after the onset of treatment (12.4 ± 1.3 vs 9.1 ± 1.2 pg/mL, P = 0.05) and prior to parturition (38.1 ± 8.1 vs 22.3 ± 4.2 pg/mL, P = 0.03). Our hypothesis was supported that fluoxetine treatment alters circulating concentrations of calcium in the peripartum period; however, we surprisingly observed a decrease in estradiol concentrations contrary to reports in in vitro studies.

Circulating parathyroid hormone and serotonin in multiparous cows with differing postparturient serum calcium concentrations

Many multiparous dairy cows experience subclinical hypocalcemia (SCH) in the immediate postpartum period as they adapt to the demands of lactation. Furthermore, differing dynamics of SCH in the days following parturition are associated with varied health and production outcomes, with cows experiencing transient SCH producing more milk and facing fewer negative health events than cows with delayed or persistent SCH. Our objectives were to describe differences in mediators of calcium (Ca) homeostasis between cows experiencing differing Ca dynamics postpartum. A prospective cohort of 89 multiparous Holstein cows from 2 herds in New York were classified into 1 of 4 SCH groups based on mean serum total Ca (tCa) at 1 and 4 d in milk (DIM): normocalcemic (NC; [tCa] >1.89 mmol/L at 1 DIM and >2.25 mmol/L at 4 DIM, n = 30); transient SCH (tSCH; [tCa] ≤1.89 mmol/L at 1 DIM and >2.25 mmol/L at 4 DIM, n = 12); delayed SCH (dSCH; [tCa] >1.89 mmol/L at 1 DIM and ≤2.25 mmol/L at 4 DIM, n = 23); and persistent SCH (pSCH; [tCa] ≤1.89 mmol at 1 DIM and ≤2.25 mmol/L at 4 DIM, n = 24). Blood samples were collected at -5, -1, 1 through 5, 7, and 10 DIM and analyzed for tCa, parathyroid hormone (PTH), and serotonin. Repeated measures ANOVA models were used to analyze differences between SCH groups and changes over time for tCa, PTH, and serotonin. During the prepartum period, tCa was greater in the NC, tSCH, and dSCH cows as compared with the pSCH cows and there was marginal evidence for a difference in PTH between SCH groups. Postpartum tCa varied over time between SCH groups. Mean postpartum (95% confidence interval) tCa for respective SCH groups were NC = 2.32 (2.28, 2.35) mmol/L; tSCH = 2.20 (2.14, 2.25) mmol/L; dSCH = 2.17 (2.13, 2.21) mmol/L; and pSCH = 2.03 (1.99, 2.07) mmol/L. Mean concentrations of PTH in the postpartum period were NC = 70.1 (66.2, 74.4) pmol/L; tSCH = 72.1 (66.1, 79.2); dSCH = 75.8 (70.8, 81.5) pmol/L; and pSCH = 77.7 (72.4, 83.9) pmol/L. Serotonin was similar between SCH groups pre- and postpartum and followed a cyclical pattern from 1 to 10 DIM. Our results agreed with our hypothesis that differences in postpartum PTH might exist between cows experiencing different dynamics of SCH in the early lactation period; however, further studies are needed to confirm this difference. If true, this would suggest that Ca homeostasis may be disrupted in cows with dSCH and pSCH. Gaining a better understanding of these modulatory differences may aid in the prevention, management, and treatment of SCH.

Perspective: Transient postparturient hypocalcemia-A lactation-induced phenomenon of high-producing dairy cows

Milk fever is one of the most historically relevant diseases of dairy cows. It is caused by tremendous calcium (Ca) expenditure at the initiation of lactation, so severe that cows can no longer stand and, if left untreated, die. Fortunately, through prepartum nutritional improvements, this version of clinical hypocalcemia is rare in the United States. Nonetheless, the opinion that all versions of postpartum hypocalcemia are detrimental remains pervasive, which is particularly significant given that 50% of cows are subclinically hypocalcemic after calving. This has led to a variety of available management and treatment strategies, ranging from prepartum dietary programs to postpartum Ca gels and boluses, targeted at preventing hypocalcemia in dairy cows. Recent research has determined that postpartum dairy cows can experience different types of subclinical hypocalcemia: transient, persistent, or delayed. We now know cows experiencing transient hypocalcemia as part of the homeorhetic adaptation to lactation are the highest milk producers in modern dairy herds, whereas cows with hypocalcemia several days after calving experience disease and losses in milk production. Therefore, it is wrong to assume all postpartum hypocalcemia is detrimental and that treatment of all cases is considered necessary and beneficial. Research indicates that milk synthesis at the onset of lactation contributes to immediate postpartum hypocalcemia, and that the mammary gland is a critical factor in management of Ca homeostasis. However, cows differ in their ability to manage this phenomenon, and it is possible that immediate postpartum influences such as dry matter intake, inflammation, and immune activation affect appropriate Ca regulation in the days following calving.

Trace Mineral Metabolism: The Maternal-Fetal Bond

Trace minerals are essential nutrients that have many biologic functions, many of which are related to metabolic activities, immune function, and antioxidant capacity. The pregnant dam provides essential nutrients to support fetal development, including trace minerals. Milk is known to be an insufficient source of many trace minerals during the early nursing neonatal period. The fetal liver is capable of concentrating minerals to generate a reserve for use during postnatal life; however, the sufficiency of this reserve is dependent upon maternal mineral status. Appropriate mineral supplementation in the gestational diet is critical to supporting fetal development, maintaining adequate antioxidant capacity to survive the birthing process, and sustain immune function and growth of the newborn animal.

Calcium dynamics and associated temporal patterns of milk constituents in early-lactation multiparous Holsteins

At the onset of lactation, calcium (Ca) homeostasis is challenged. For the transitioning dairy cow, inadequate responses to this challenge may result in subclinical hypocalcemia at some point in the postpartum period. It has been proposed that dynamics of blood Ca and the timing of subclinical hypocalcemia allow cows to be classified into 4 Ca dynamic groups by assessing serum total Ca concentrations (tCa) at 1 and 4 days in milk (DIM). These differing dynamics are associated with different risks of adverse health events and suboptimal production. Our prospective cohort study aimed to characterize the temporal patterns of milk constituents in cows with differing Ca dynamics to investigate the potential of Fourier-transform infrared spectroscopic (FTIR) analysis of milk as a diagnostic tool for identifying cows with unfavorable Ca dynamics. We sampled the blood of 343 multiparous Holsteins on a single dairy in Cayuga County, New York, at 1 and 4 DIM and classified these cows into Ca dynamic groups using threshold concentrations of tCa (1 DIM: tCa <1.98 mmol/L; 4 DIM: tCa <2.22 mmol/L) derived from receiver operating characteristic curve analysis based on epidemiologically relevant health and production outcomes. We also collected proportional milk samples from each of these cows from 3 to 10 DIM for FTIR analysis of milk constituents. Through this analysis we estimated the milk constituent levels of anhydrous lactose (g/100 g of milk and g/milking), true protein (g/100 g of milk and g/milking), fat (g/100 g of milk and g/milking), milk urea nitrogen (mg/100 g of milk), fatty acid (FA) groups including de novo, mixed origin, and preformed FA measured in grams/100 g of milk, by relative percentage, and grams/milking, as well as energy-related metabolites including ketone bodies and milk-predicted blood nonesterified FA. Individual milk constituents were compared among groups at each time point and over the entire sample period using linear regression models. Overall, we found differences among the constituent profiles of Ca dynamic groups at approximately every time point and over the entire sample period. The 2 at-risk groups of cows did not differ from each other at more than one time point for any constituent, however prominent differences existed between the milk of normocalcemic cows and the milk of the other Ca dynamic groups with respect to FA. Over the entire sample period, lactose and protein yield (g/milking) were lower in the milk of at-risk cows than in the milk of the other Ca dynamic groups. In addition, milk yield per milking followed patterns consistent with previous Ca dynamic group research. Though our use of a single farm does limit the general applicability of these findings, our conclusions provide evidence that FTIR may be a useful method for discriminating between cows with different Ca dynamics at time points that may be relevant in the optimization of management or development of clinical intervention strategies.

Ruminant Metabolic Diseases: Perturbed Homeorhesis

The 6-week period encompassing parturition, termed the transition period, is recognized as the most fragile period in the life cycle of the ruminant animal. The period accounts for the greatest risk of health events that can adversely affect animal health, lactational performance, and future reproductive success. Critical endocrine and metabolic adaptations take place in allowing the animal to change nutrient priorities from supporting pregnancy to sustaining lactation. A reductionist perspective of underlying pathogenesis provided minimal metabolic disease prevalence improvement. Recent research has recognized metabolic regulatory complexity and role for activated inflammatory response underpinning dysregulation of homeorhesis during transition.

Metabolic Profiling in Ruminant Diagnostics

A herd-based approach and interpretative perspective is necessary in using metabolic profile testing in contrast to individual animal disease diagnostics. Metabolic profile testing requires formulating a question to be answered, followed by the appropriate selection of animals for testing. A range of blood analytes and nutrients can be determined with newer biomarkers being developed. Sample collection and handling and herd-based reference criteria adjusted to time relative to parturition are critical for interpretation. The objective of this article is to review the concepts and practical applications of metabolic profile testing in ruminants.

Effects of different vitamin A supplies on performance and the risk of ketosis in transition cows

This experiment investigated the effects of feeding low and high supplies of vitamin A (VA) during the transition period on plasma metabolites, prevalence of ketosis, and early milk production. In a randomized complete block design, 42 prefresh Holstein cows and 21 heifers were blocked by parity and calving date and assigned to 1 of 3 dietary treatments (n = 21 per treatment unless noted): CON, a transition diet with supplemental VA (75,000 IU/d) to meet the requirement; LVA, a transition diet with no supplemental VA; or HVA, a transition diet receiving supplemental VA (187,500 IU/d) 2.5 times greater than the requirement. Experimental periods were prepartum (-14 d prepartum), postpartum (1 to 30 d in milk), and carryover period (31 to 58 d in milk; common lactating diet with adequate VA was fed). Differences in dry matter intake in the pre- and postpartum periods and milk yield were not detected among treatment. Milk fat, protein, and lactose yields were similar among treatments and not affected by VA. Somatic cell count increased linearly with increasing VA. Body weight and body condition score decreased postpartum, but no VA effect was observed. Plasma retinol concentrations (n = 10 per treatment) decreased at d 2 postpartum and increased as lactation progressed, but the concentrations were unaffected by treatment. Plasma β-carotene (n = 10 per treatment) had a treatment by time interaction and its concentration decreased after parturition and remained low for 2 wk. Plasma fatty acids and β-hydroxybutyrate did not differ among treatments. Milk retinol concentration and yield (n = 10 per treatment) increased as VA supply increased. Segmented neutrophils (%) decreased, and lymphocytes (%) increased in blood with increasing VA supply. In conclusion, providing different supplies of VA did not affect production, mobilization of body fat, and risk of ketosis; however, excessive VA supply may have negatively affected the immune response, in part contributing to increased milk somatic cell counts during early lactation.

Infrared thermography as a tool for the measurement of negative emotions in dairy cows

In commercial dairy cows, the conditions in which they are kept may lead to negative emotional states associated with the development of chronic physiological and behavioural abnormalities that may compromise their health, welfare and productivity. Such states include fear, stress or anxiety. Behavioural rather than physiological tests are more likely to be used to indicate these states but can be limited by their subjectivity, need for specialised infrastructure and training (of the operator and sometimes the animal) and the time-consuming nature of data collection. Popularly used physiological measures such as blood cortisol may be more appropriate for acute rather than chronic assessments but are easily confounded, for example by a response to the act of measurement per se. More sophisticated physiological measures such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) may be impractical due to cost and time and, like blood cortisol, have the confounding associated with the act of measurement. By contrast, infrared thermography of external body surfaces is remote, non-invasive, easily repeated and follows an objective methodology, allowing longitudinal data acquisition for the inference of changes in chronic emotional state over time. The objective of this review was to investigate the potential of infrared thermography to measure cow emotions. In lactating dairy cows, maximum IRT of the eyes and coronary band of the limbs seem to be most representative of thermoregulatory changes, which are repeatable and correlate with behavioural and physiological indicators of emotional state. IRT methodologies have the potential to become a fundamental tool for the objective assessment of welfare state in dairy cows.

Effects of restricted dietary phosphorus supply during the dry period on productivity and metabolism in dairy cows

Phosphorus in bovine nutrition is under ongoing scrutiny because of concerns with excessive amounts of P excreted in manure contributing to environmental pollution. Feeding rations with excessive P content, however, still remains common practice, particularly during the transition period, as limited P supply in late gestation and early lactation is thought to present a risk for health and productivity of high-yielding dairy cows. The objectives of this study were to investigate the effect of restricted P supply during the last 4 wk of pregnancy on Ca and P homeostasis during the transition period in high-yielding dairy cows, and to identify possible effects on metabolism and productivity throughout the following lactation. Thirty late-pregnant multiparous dairy cows were randomly assigned to either a dry cow diet with low (LP) or adequate P (AP) content [0.16 and 0.30% P in dry matter (DM), respectively] to be fed in the 4 wk before calving. After calving all cows received the same ration with adequate P content (0.46% P in DM). Blood, milk, and liver tissue samples were obtained during the dry period and the following lactation, DM intake (DMI), body weight, milk production, and disease occurrence were monitored. Plasma was assayed for the concentrations of P, Ca, Na, and K, metabolic parameters, and liver enzyme activities. Liver tissue was analyzed for mineral, triglyceride, cholesterol, and water contents. Repeated-measures ANOVA was used to identify treatment, time, and treatment × time interaction effects. Cows fed LP had lower plasma P concentrations ([Pi]) than AP cows during restricted P feeding, reaching a nadir of 1.1 mmol/L immediately before calving. After calving, plasma [Pi] of LP cows was at or above the level of AP cows and within the reference range for cattle. Symptoms assumed to be associated with hypophosphatemia were not observed, but plasma Ca was higher from 1 wk before to 1 wk after calving in LP cows, which was associated with a numerically lower incidence of clinical and subclinical hypocalcemia in LP cows. Both treatments had a similar 305-d milk yield (12,112 ± 1,298 kg for LP and 12,229 ± 1,758 kg for AP cows) and similar DMI. Plasma and liver tissue biochemical analysis did not reveal treatment effects on energy, protein, or lipid metabolism. The results reported here indicate that restricted dietary P supply during the dry period positively affected the Ca homeostasis of periparturient dairy cows but did not reveal negative effects on DMI, milk production, or metabolic activity in the following lactation. Restriction of P during the dry period was associated with hypophosphatemia antepartum but neither exacerbated postparturient hypophosphatemia, which is commonly observed in fresh cows, nor was associated with any clinical or subclinical indication of P deficiency in early lactation.

Effect of circadian system disruption on the concentration and daily oscillations of cortisol, progesterone, melatonin, serotonin, growth hormone, and core body temperature in periparturient dairy cattle

Metabolic, circadian, sleep, and reproductive systems are integrated and reciprocally regulated, but the understanding of the mechanism is limited. To study this integrated regulation, the circadian timing system was disrupted by exposing late pregnant nonlactating (dry) cows to chronic shifts in the light-dark phase, and rhythms of body temperature and circulating cortisol (CORT), progesterone (P4), serotonin (5HT), melatonin (MEL), and growth hormone (GH) concentrations were measured. Specifically, across 2 identical studies (1 and 2), at 35 d before expected calving (BEC) multiparous cows were assigned to control (CON; n = 24) and exposed to 16 h light and 8 h dark or phase shift (PS; n = 24) treatments and exposed to 6-h light-dark phase shifts every 3 d until parturition. All cows were exposed to control lighting after calving. Blood samples were collected in the first study at 0600 h on d 35 BEC, d 21 BEC, and 2 d before calving, and d 0, 2, 9, 15, and 22 postpartum (PP). A subset of cows (n = 6/group) in study 1 was blood sampled every 4 h over 48 h beginning on d 23 BEC, 9 BEC, and 5 PP. Body temperature was measured every 30 min (n = 8-16/treatment) for 48 h at 23 BEC and 9 BEC in both studies; and at 14 PP and 60 PP only in study 2. Treatment did not affect levels of CORT, GH, or P4 at 0600 h, but overall level of 5HT was lower and MEL higher in PS cows across days sampled. A 2-component versus single-component cosinor model better described [>coefficient of determination (R²); <Akaike information criterion and <Bayesian information criterion] daily oscillations of all hormones and temperature for both treatments. Circadian rhythm fit (R²) of body temperature and MEL increased from 23 BEC to 9 BEC in CON and was marked by loss of feeding time influence on oscillations in both treatments. Both treatments exhibited circadian rhythms of CORT at 9 BEC, CON cows also exhibited circadian rhythms in P4 at 23 BEC, and 5HT at 9 BEC. Daily oscillations in temperature and hormones, except CORT, were affected by PS treatment in the prepartum and were associated with longer gestation. In the PP, circadian rhythmicity was lost or diminished for all hormones and body temperature in both treatments. Stronger rhythms of body temperature and multiple hormones at 1 wk prepartum may indicate a synchronizing cue to time parturition. Therefore, dairy systems may need to consider management factors that affect circadian clocks in late-gestation cows.

First-milking colostrum mineral concentrations and yields: Comparison to second milking and associations with serum mineral concentrations, parity, and yield in multiparous Jersey cows

This observational study described first-milking colostrum mineral concentrations and total yields, and evaluated its associations with cow serum mineral concentrations, parity, and first postpartum milking yield in 100 multiparous Jersey cows from a single herd fed a negative dietary cation-anion difference diet prepartum. Additionally, first- and second-milking colostrum mineral concentrations and total yields were compared in a subset of 65 cows. Serum minerals (Ca, P, Mg, Na, K, Zn, Fe, Cu) were assessed before first milking. Cows were milked at 9 h and 4 min ± 3 h and 32 min and at 21 h and 11 min ± 3 h and 43 min postpartum (± standard deviation); yields were recorded and samples collected for mineral concentrations assessment (Ca, P, Mg, Na, K, Zn, Fe, Cu). Linear regression was used to evaluate the associations between first-milking colostrum mineral concentrations and total yields and cows' serum mineral concentrations, parity, first-milking colostrum yield, and calving-to-milking interval. The most abundant minerals in first-milking colostrum were (least squares mean ± standard error of the mean) Ca (55.71 ± 13.52 mmol/L; 8.75 ± 5.74 g) and P (41.91 ± 13.01 mmol/L; 5.26 ± 3.72 g), followed by Na (39.65 ± 13.23 mmol/L; 3.08 ± 1.77 g), K (36.47 ± 7.57 mmol/L; 5.79 ± 4.20 g), Mg (13.43 ± 3.09 mmol/L; 1.25 ± 0.78 g), Zn (272.12 ± 113.34 μmol/L; 71.98 ± 55.34 mg), Fe (12.51 ± 3.79 μmol/L; 2.56 ± 1.55 mg), and Cu (3.34 ± 1.22 μmol/L; 0.77 ± 0.56 mg). Higher concentrations of Ca, Mg, Na, Zn, Fe, and Cu, and total yields of Mg, Zn, Fe, and Cu were observed at first- compared with second-milking colostrum. Serum and first-milking colostrum Cu concentrations were positively associated, but no significant associations were observed between other minerals' serum and first-milking colostrum concentrations or total yields. Parity was associated with first-milking colostrum Ca, P, K, and Fe concentrations and yields; younger multiparous cows had higher concentrations and total yields of these minerals. Linear (Fe), quadratic (P, Na, and K), and cubic (Mg, Zn, and Cu) associations were observed between first-milking colostrum mineral concentrations and yield. In all cases, mineral total yields were linearly associated with first-milking colostrum yield. In conclusion, variation in first-milking colostrum mineral concentrations and total yields across cows could be partially explained by cow parity and colostrum yield. Further research including primiparous and cows under different management settings is needed to expand the knowledge and understanding of colostrum mineral concentrations and total yields in dairy cows.

A Randomized Clinical Trial Evaluating the Effect of an Oral Calcium Bolus Supplementation Strategy in Postpartum Jersey Cows on Mastitis, Culling, Milk Production, and Reproductive Performance

Simple Summary

The time around parturition is a challenging period in the lactation cycle of high-yielding dairy cows as it is characterized by several endocrine, metabolic, and physiological changes. Among those challenges, calcium demands are rapidly increased to support colostrogenesis and lactogenesis during a time of reduced dry matter intake; invariably, some cows may suffer from clinical and subclinical hypocalcemia. Oral calcium supplementation is a common preventative strategy adopted in the postpartum of high-yielding dairy cows to minimize the negative impact of suboptimal blood calcium concentration during this period. Despite a great number of studies evaluating the effects of oral calcium supplementation in postpartum Holstein cows, very limited information is available for the Jersey breed. This study aimed to evaluate the effect of an oral Ca supplementation strategy in the first 24 h after parturition on health and production outcomes in multiparous Jersey cows. Overall, treatment did not improve milk production or reproductive performance compared to control cows. Additionally, treatment had no effect on early lactation culling. A tendency for a minor impact on the odds of mastitis was evident though it depended on the parity of the cows.

Abstract

The objectives of this study were to evaluate the effects of a postpartum oral calcium supplementation strategy in multiparous Jersey cows on (1) the odds of clinical mastitis in the first 60 days in milk (DIM); (2) the odds of culling up to 60 DIM; (3) the risk of pregnancy in the first 150 DIM; (4) milk production in the first 15 weeks of lactation. A randomized clinical trial was performed in a dairy herd located in west Texas, United States. A total of 809 cows were used in the final analyses. Overall, postpartum oral calcium supplementation did not influence milk production, reproductive performance, or culling. Among second parity cows, oral calcium supplementation tended to decrease the odds of clinical mastitis in the first 60 DIM compared to controls; however, no differences were observed for cows in parities three and greater. To date, data evaluating the effect of postpartum oral calcium supplementation in multiparous Jersey cows are limited. In our study, oral calcium supplementation tended to reduce clinical mastitis in second parity cows. No positive benefits based on the reduction of culling, and improvement of milk production and reproductive performance were evident for the herd included in this study.

Effects of Postpartum Supplemental Oral Ca for Dairy Cows Fed Prepartum Dietary Acidogenic Salts

Simple Summary

Low blood calcium after calving is problematic in dairy cows, particularly for older cows and for Jerseys vs. Holsteins. Feeding acidogenic salts before calving and oral Ca supplementation post-calving help mitigate this. We evaluated: (1) a novel approach to delivering acidogenic salts prepartum applicable to small dairies and (2) the combined effects of prepartum acidogenic salts and postpartum oral Ca supplementation for both Holsteins and Jerseys of varying parity. We found this novel approach to providing acidogenic salts to be effective. We also found preliminary evidence that shortening the time of application of this technology may enhance its beneficial effects. Responses to prepartum acidogenic salts and postpartum oral calcium supplementation were very different for second vs. greater than second parity cows. Finally, we found an increased risk of low blood calcium, particularly in older Jersey cows, when either prepartum urinary calcium excretion was low or colostrum production was high.

Abstract

Postpartum hypocalcemia is a problem in dairy cows. Both the Jersey vs. Holstein breed and increasing parity are known risk factors. Our objectives were: (1) to evaluate a simple approach to provide dietary acidogenic salts suitable for application on small dairies and (2) to evaluate the combined effects of degree of acidification and oral Ca supplementation along with breed and parity group on periparturient Ca status of Holstein and Jersey cows. Cows were moved weekly from the far-off dry pen at 260 days pregnant to the close-up pen, where all cows received the acidogenic diets. The diet was offered as a total mixed ration and CaCl₂, and our source of acidogenic salts was top-dressed in liquid form and mixed in by hand. Thirty-six cows were blocked by parity group (parity = 2 vs. parity ≥ 3) and breed (Holstein vs. Jersey) and assigned to one of two treatments (no intervention or postpartum oral Ca bolus supplementation) in an alternating fashion, based on expected date of parturition. Urinary acidification appeared complete within 3–4 days. Increased urinary Ca excretion was >93% of maximum from 7–21 days before falling to <5% of maximum by 28 days. Serum Ca concentrations 12–24 h postpartum were lower for Jerseys vs. Holsteins and for parity ≥ 3 vs. parity = 2 cows. Serum Ca over 6–48 h postpartum decreased and increased, respectively, with oral Ca supplementation for parity = 2 and parity ≥ 3 cows. Decreased prepartum urinary Ca excretion and increased colostrum yield appear to be independent risk factors of hypocalcemia for parity ≥ 3 Jerseys.

Physiological adaptations in early-lactation cows result in differential responses to calcium perturbation relative to nonlactating, nonpregnant cows

The peripartal cow experiences a rapid change in calcium metabolism at the onset of lactation. Research has focused on understanding how mammary-derived factors, such as serotonin (5HT) and parathyroid hormone like hormone (PTHLH), aid in coordinating these calcemic adaptations to lactation. Therefore, the aim of our study was to determine how induced subclinical hypocalcemia influences physiological responses, specifically the 5HT-PTHLH-Ca axis, in lactating and nonlactating dairy cows to elucidate the potential contribution of the mammary gland. Twelve nonlactating, nonpregnant (NL) multiparous Holstein cows and 12 early-lactation (EL) multiparous Holstein cows received either (1) a continuous 24-h intravenous solution of 0.9% NaCl or (2) 5% ethylene glycol tetraacetic acid (EGTA) solution in 0.9% NaCl (n = 6 EL, n = 6 NL per treatment) with the aim of maintaining blood ionized calcium (iCa) less than 1.0 mM. Mammary gland biopsies were taken immediately after and 48 h after termination of infusion. Blood was sampled hourly during infusion and 4, 8, 12, 24, 48, and 72 h after termination of infusion. Infusion of EGTA successfully decreased blood iCa concentrations. However, EL EGTA-infused cows required increased rates of EGTA infusion to maintain iCa below 1.0 mM. Circulating and mammary serotonin concentrations were increased in EL relative to NL cows, with no difference as a result of EGTA infusion. Mammary PTHLH expression was increased in EL cows, with highest expression observed in EL EGTA-infused cows. Collectively, these data demonstrate the robust adaptations EL cows have to maintain Ca homeostasis and the supporting roles 5HT and PTHLH may play.

Effects of restricted dietary phosphorus supply to dry cows on periparturient calcium status

Restricted dietary P supply to transition dairy cows has recently been reported to beneficially affect the Ca balance of periparturient cows. The objective of the present study was to determine whether this effect on the Ca balance can be reproduced when limiting the P-restricted feeding to the last 4 wk of gestation. A total of 30 dairy cows in late pregnancy were randomly assigned to a dry cow diet with either low or adequate P content (0.16 and 0.30% P in DM, respectively) to be fed in the 4 wk before expected calving. After calving, all cows received the same lactating cow ration with adequate P content (0.46% P in DM). Blood was collected daily from 4 d antepartum until calving, at calving (d 0), 6 and 12 h after calving (d +0.25 and d +0.5, respectively) and on days +1, +2, +3, +4 and +7 relative to calving. Blood gas analyses were conducted to determine the concentration of ionized Ca in whole blood ([Ca²⁺]), and plasma was assayed for concentrations of inorganic phosphorus ([Pi]), total calcium, parathyroid hormone ([PTH]), 1,25-dihydroxyvitamin D ([1,25-(OH)₂D₃]), and CrossLaps ([CTX]), a biomarker for bone resorption (Immunodiagnostic Systems GmbH). Repeated-measures ANOVA was conducted to study treatment, time, and lactation number effects. The mean [Ca²⁺] in P-deprived cows remained above the threshold of 1.10 mmol/L throughout the study, and values were higher compared with cows on adequate P supply between d 0 and d +2 and on d +4. The [Ca²⁺] differed between treatments at the sampling times d 0, d +0.25, d +0.5, d +2, and d +4. Plasma [PTH] and [1,25-(OH)₂D₃] did not differ between treatments, but P-deprived cows had greater [CTX] than cows with adequate P supply at d +1, d +2, and d +7. These results indicate that restricted dietary P supply to during the last 4 wk of the dry period improves the Ca homeostasis of these cows in the first days of lactation, an effect that seems to be primarily driven by increased bone tissue mobilization.

Effects of postpartum milking strategy on plasma mineral concentrations and colostrum, transition milk, and milk yield and composition in multiparous dairy cows

The effects of postpartum milking strategy on plasma mineral concentrations, blood β-hydroxybutyrate (BHB) concentration, and colostrum, transition milk, and first monthly test milk yield and composition were evaluated in 90 multiparous Jersey and Jersey × Holstein crossbreed cows from a commercial farm. Before first postpartum milking, cows were randomly assigned to the following milking strategies, implemented during the first 2 d postpartum: twice-a-day milking (M2, standard industry practice, milking every 12 h; n = 22), once-a-day milking (M1, milking every 24 h; n = 24), restricted milking (MR, 3-L milking every 12 h; n = 21), and delayed milking (MD, no milking for the first 24 h, and milking every 12 h afterward; n = 23). Blood samples for total plasma Ca, P, and Mg determination were collected from enrollment every 4 h up to 48 h, and at 3 d in milk. Blood BHB concentration was determined at 3 and 11 d in milk. Colostrum and transition milk yields were recorded, and samples were collected at each study milking for IgG and somatic cell count (SCC) determinations. Information for first monthly test milk yield and composition was obtained from the Dairy Herd Improvement Association. Statistical analyses were conducted using generalized multiple linear and Poisson regressions with Dunnett adjustment and M2 as reference group for mean comparisons. Overall, plasma Ca concentration within 48 h after enrollment was higher for MD (2.17 mmol/L), tended to be higher for MR (2.15 mmol/L), and was similar for M1 (2.09 mmol/L) compared with M2 cows (2.06 mmol/L). No statistically significant differences compared with M2 cows were observed for plasma P and Mg concentrations. Colostrum and transition milk and total Ca harvested within 48 h after enrollment were lower for M1, MR, and MD compared with M2 cows. The MD strategy prevented harvesting colostrum with >50 g of IgG/L. No statistically significant effects were detected on plasma mineral concentrations at 3 DIM, blood BHB concentration, colostrum and transition milk SCC within 48 h after enrollment, or milk yield, energy-corrected milk yield, and SCC at first monthly test. Our results suggest that postpartum plasma Ca concentration may be influenced by postpartum milking strategy, without interfering with future milk yield and udder health. Further studies should evaluate whether the proposed milking strategies in early postpartum affect production, reproduction, or health.

Graduate Student Literature Review: Serotonin and calcium metabolism: A story unfolding

The peripartum period is characterized by dynamic shifts in metabolic, mineral, and immune metabolism as the dairy cow adapts to the demands of lactation. Emphasis over the past decade has been placed on understanding the biology of the large shift in calcium metabolism in particular. Moreover, research has also focused on exploring the role of serotonin during the transition period and lactation and further unraveling its relationship with calcium. This review aimed to demonstrate the integration of calcium physiology during the peripartal period and throughout lactation. More specifically, we sought to discuss the knowledge gained in recent years on calcium metabolism, mammary calcium transport, serotonin metabolism, and the serotonin-calcium axis. Herein we also discuss the challenges and limitations of current research and where that leaves the present understanding of the serotonin-calcium axis as we seek to move forward and continue exploring this interesting relationship.

Association of low serum calcium concentration after calving with productive and reproductive performance in multiparous Jersey cows

Consequences of postpartum low blood calcium (Ca) concentration are still under study and literature describing this condition in Jersey cows is scarce. A prospective cohort study was conducted to evaluate the association of low serum Ca concentration shortly after calving with milk and energy-corrected milk yields, somatic cell count linear score, and pregnancy to first service and within 150 d in milk in multiparous Jersey cows from 2 commercial herds. Blood samples for serum Ca determination were collected on average at 3 h 10 min postpartum from 352 multiparous Jersey cows. Productive data up to the 10th monthly test were obtained from the Dairy Herd Improvement Association and reproductive data were obtained from herd records. Multiple linear, log-binomial, and Cox's proportional hazards regressions were used to evaluate the association of low serum Ca concentration with productive and reproductive outcomes. Serum Ca concentration ≤2.18 mmol/L was associated with 1.43 and 1.85 kg/d more milk and energy-corrected milk. However, lower serum Ca concentrations were associated with a 0.28-unit-higher somatic cell count linear score per monthly test (Ca ≤2.00 mmol/L), and decreased pregnancy risk at first service (risk ratio = 0.64; Ca ≤1.94 mmol/L) and hazard of pregnancy within 150 d in milk (hazard ratio = 0.40; Ca ≤1.90 mmol/L). The present study is based on a convenience sample of multiparous Jersey cows from 2 commercial herds; further research including more herds and additional blood Ca determinations is needed to describe postpartum blood Ca dynamics and its association with productive and reproductive outcomes for the Jersey breed.

Serum Vitamin D Is Associated with Antioxidant Potential in Peri-Parturient Cows

Dairy cows experience increased oxidative stress during periods of transition such as at the cessation of lactation and around the periparturient period, thus increasing disease risk. Despite routine supplementation of transition cow diets with certain vitamins in an attempt to mitigate oxidative stress, there is no currently available data directly linking vitamin supplementation with antioxidant potential (AOP) in transition cows. The objective of this study was to determine the association between serum vitamins and biomarkers of oxidative stress in healthy cows. Blood samples were collected from 240 cows at dry off (DO), close up (CU), and 2-10 days post-calving (DIM2-10). Blood samples were analyzed for vitamins (A, D, E), β-carotene, reactive oxygen species (ROS), and AOP. Spearman correlations and mixed linear regression models were used to assess associations between vitamins and measures of oxidant status. Vitamin D concentrations were positively associated with AOP at the CU and DIM2-10. Based on the positive association with AOP, additional in-vitro studies were conducted that showed vitamin D mitigated barrier integrity loss in endothelial cells during oxidative stress. These results indicate for the first time that vitamin D may have a role in promoting antioxidant potential in transition dairy cows.

Effects of dietary phosphorus concentration during the transition period on plasma calcium concentrations, feed intake, and milk production in dairy cows

Our aim was to evaluate the effects of a low or high dietary phosphorus (P) concentration during the dry period, followed by either a high or low dietary P concentration during the first 8 wk of lactation, on plasma Ca concentrations, feed intake, and lactational performance of dairy cattle. Sixty pregnant multiparous Holstein Friesian dairy cows were assigned to a randomized block design with repeated measurements and dietary treatments arranged in a 2 × 2 factorial fashion. The experimental diets contained 3.6 (Dry-HP) or 2.2 (Dry-LP) g of P/kg of dry matter (DM) during the dry period, and 3.8 (Lac-HP) or 2.9 (Lac-LP) g of P/kg of DM during 56 d after calving period. In dry cows, plasma Ca concentrations were 3.3% greater when cows were fed 2.2 instead of 3.6 g of P/kg of DM. The proportion of cows being hypocalcemic (plasma Ca concentrations <2 mM) in the first week after calving was lowest with the low-P diets both during the dry period and lactation. Plasma Ca concentrations in wk 1 to 8 after calving were affected by dietary P level in the dry period and in the lactation period, but no interaction between both was present. Feeding Dry-LP instead of Dry-HP diets resulted in 4.1% greater plasma Ca values, and feeding Lac-LP instead of Lac-HP diets resulted in 4.0% greater plasma Ca values. After calving, plasma inorganic phosphate (Pi) concentrations were affected by a 3-way interaction between sampling day after calving, and dietary P levels during the dry period and lactation. From d 1 to d 7 postpartum, cows fed Lac-HP had increased plasma Pi concentrations, and the rate appeared to be greater in cows fed Dry-LP versus Dry-HP. In contrast, plasma Pi concentrations decreased from d 1 to d 7 postpartum in cows fed Lac-LP, and this decrease was at a higher rate for cows fed Dry-HP versus Dry-LP. After d 7, plasma Pi concentrations remained rather constant at 1.5 to 1.6 mM when cows received Lac-HP, whereas with Lac-LP plasma Pi concentrations reached stable levels (i.e., 1.3-1.4 mM) at d 28 after calving. Milk production, DM intake, and milk concentrations of P, Ca, fat, protein, and lactose were not affected by any interaction nor the levels of dietary P. It is concluded that the feeding of diets containing 2.2 g of P/kg of DM during the last 6 wk of the dry period and 2.9 g of P/kg of DM during early lactation increased plasma Ca levels when compared with greater dietary P levels. These low-P diets may be instrumental in preventing hypocalcemia in periparturient cows and do not compromise DM intake and milk production. Current results suggest that P requirements in dairy cows during dry period and early lactation can be fine-tuned toward lower values than recommended by both the National Research Council and the Dutch Central Bureau for Livestock Feeding. Caution however is warranted to extrapolate current findings to entire lactations because long-term effects of feeding low-P diets containing 2.9 of g/kg of DM on production and health needs further investigation.

Effects of calcium supplementation, incomplete milking, and vitamin D3 injection on serum total calcium concentration during the first 24 hours after parturition in dairy cows fed an anionic diet during late gestation

OBJECTIVE

To evaluate various strategies for prevention of subclinical hypocalcemia (SH) during the first 24 hours after parturition in dairy cows.

ANIMALS

165 multiparous German Holstein cows from 1 herd.

PROCEDURES

All cows were fed a ration with a moderate dietary cation-anion difference (approx 0 mEq/100 g of dry matter; anionic diet) for the last 2 to 3 weeks of gestation. In the first part of a 2-part study, cows were randomly assigned to 1 of 4 treatment groups (no calcium supplementation [n = 30], oral administration of a calcium bolus alone [34] or in combination with IV administration of 500 mL of a calcium solution [34] or incomplete milking during the first 24 hours after parturition [34]). In part 2, cows in their fifth or greater parity were randomly assigned to receive vitamin D₃ (20,000 U/kg, IM; n = 15) 7 days before the predicted calving date or a control group (18). A calcium bolus was orally administered within 30 minutes after parturition to all cows of part 2. Serum total calcium (Ca_t) concentration was measured immediately after parturition and every 2 hours thereafter for 24 hours and compared among treatment groups. Subclinical hypocalcemia was defined as a Ca_t concentration < 2.00 mmol/L.

RESULTS

In part 1, the mean ± SD Ca_t concentration during the 24 hours after parturition for the IV-treated group (2.28 ± 0.42 mmol/L) was greater than that for the other 3 groups, each of which had a mean Ca_t concentration < 2.00 mmol/L. In part 2, the mean Ca_t concentration for the vitamin D₃-treated cows was greater than that for control cows and remained above 2.00 mmol/L for the duration of the observation period.

CONCLUSIONS AND CLINICAL RELEVANCE

Intramuscular administration of vitamin D₃ or IV administration of a calcium solution in combination with oral administration of a calcium bolus might alleviate SH during the first 24 hours after parturition in dairy cows fed an anionic diet during late gestation.

Low dietary protein increases vitamin A absorption and deposition into milk in periparturient rats

Our objective was to study the effect of differing dietary crude protein and vitamin A on retinoid metabolism in a periparturient rat model. Sixty female rats, approximately 21 d before parturition, were fed rations containing either low protein (13%; LP) or high protein (22%; HP) crude protein and either low vitamin A (3 IU/g; LA) or high vitamin A (5 IU/g; HA), yielding treatments HPHA, HPLA, LPHA, and LPLA. Samples were collected at d -14, d +3, and +10 relative to parturition and analyzed for all-trans retinoid acid (RA), 13-Cis RA, and retinol. At d -14, serum all-trans RA concentrations decreased compared to baseline. At both d +3 and d +10, serum retinol increased and liver 13-Cis RA decreased. In the small intestine, 13-cis RA was higher in HPHA than HPLA pre-partum (0.93±0.12 vs. 0.40±0.12 ng/ml, P=0.04). Post-partum, 13-cis RA was lower in high vitamin HPHA and LPHA groups (0.35±0.06 and 0.38±0.06 ng/ml) than in low vitamin A HPLA and LPLA treatments (0.50±0.06 and 1.32±0.06 ng/ml, P<0.01). In rats fed LA diets, TNF-alpha expression tended to be lower in HPLA than LPLA groups on day +3 (0.69±0.34 vs 1.00±0.52, P=0.08), but not day +10 (0.56±0.25 vs. 1.00±0.49 Fold Change, P>0.10). Retinoids accumulated during pregnancy and were mobilized during lactation. The sequestration of retinoids was increased when dietary protein content was low. Further studies are needed to investigate how retinoid metabolism could be manipulated to improve vitamin A delivery to milk.

The Physiological Roles of Vitamin E and Hypovitaminosis E in the Transition Period of High-Yielding Dairy Cows

Simple Summary

In high-yield cows, most production diseases occur during transition periods. Alpha-tocopherol, the most biologically active form of vitamin E, declines in blood and reaches the lowest levels (hypovitaminosis E) around calving. Hypovitaminosis E is associated with the incidence of peripartum diseases. Therefore, many studies which have been published for more than 30 years have investigated the effects of α-tocopherol supplementation. This α-tocopherol deficiency was thought to be caused by complex factors. However, until recently, the physiological factors or pathways underlying hypovitaminosis E in the transition period have been poorly understood. In the last 10 years, the α-tocopherol-related genes expression, which regulate the metabolism, transportation, and tissue distribution of α-tocopherol in humans and rodents, has been reported in ruminant tissues. In this paper, we discuss at least six physiological phenomena that occur during the transition period and may be candidate factors predisposing to a decreased blood α-tocopherol level and hypovitaminosis E with changes in α-tocopherol-related genes expression.

Abstract

Levels of alpha-tocopherol (α-Toc) decline gradually in blood throughout prepartum, reaching lowest levels (hypovitaminosis E) around calving. Despite numerous reports about the disease risk in hypovitaminosis E and the effect of α-Toc supplementation on the health of transition dairy cows, its risk and supplemental effects are controversial. Here, we present some novel data about the disease risk of hypovitaminosis E and the effects of α-Toc supplementation in transition dairy cows. These data strongly demonstrate that hypovitaminosis E is a risk factor for the occurrence of peripartum disease. Furthermore, a study on the effectiveness of using serum vitamin levels as biomarkers to predict disease in dairy cows was reported, and a rapid field test for measuring vitamin levels was developed. By contrast, evidence for how hypovitaminosis E occurred during the transition period was scarce until the 2010s. Pioneering studies conducted with humans and rodents have identified and characterised some α-Toc-related proteins, molecular players involved in α-Toc regulation followed by a study in ruminants from the 2010s. Based on recent literature, the six physiological factors: (1) the decline in α-Toc intake from the close-up period; (2) changes in the digestive and absorptive functions of α-Toc; (3) the decline in plasma high-density lipoprotein as an α-Toc carrier; (4) increasing oxidative stress and consumption of α-Toc; (5) decreasing hepatic α-Toc transfer to circulation; and (6) increasing mammary α-Toc transfer from blood to colostrum, may be involved in α-Toc deficiency during the transition period. However, the mechanisms and pathways are poorly understood, and further studies are needed to understand the physiological role of α-Toc-related molecules in cattle. Understanding the molecular mechanisms underlying hypovitaminosis E will contribute to the prevention of peripartum disease and high performance in dairy cows.

Graduate Student Literature Review: What do we know about the effects of clinical and subclinical hypocalcemia on health and performance of dairy cows?

This narrative literature review summarizes findings regarding the associations of clinical and subclinical hypocalcemia with postpartum health, reproduction, and milk production. To better understand the effects of hypocalcemia, we reviewed clinical and subclinical presentations of the condition and the dynamics of blood Ca concentration in the early postpartum period. We summarize and discuss the associations between hypocalcemia and performance of dairy cows. Up to 50% of dairy cows suffer from at least one disease event in the transition period. The important roles of calcium in muscle contraction and immune function make it a key component of metabolism, inflammation, and defense against infection. Although the effect of clinical hypocalcemia (milk fever) on health and performance is clear, the definition of subclinical hypocalcemia (SCH) and its consequences for health and performance are still ambiguous. Differences in study designs, sampling protocols, Ca concentration thresholds, and sample sizes that may be underpowered for health and reproduction outcomes lead to inconsistent conclusions on the effects of SCH. On current evidence, classification of SCH should be based on at least 2 measurements of blood calcium, using cutpoints supported with relevant data, which may vary depending on the outcome of interest. Arbitrary or poorly supported interpretative thresholds for blood Ca concentrations should be abandoned. Transient SCH appears to be associated with greater milk yield, whereas SCH that is present several days after calving is associated with lesser production and greater disease risk. However, when blood calcium is measured days after calving, primary effects of calcium metabolism may be confounded by feed intake, inflammation, or disease, which might either contribute to or be a consequence of hypocalcemia. Additional research is needed to refine sampling schemes to classify SCH, and to better inform the goals and means of prevention of SCH.

Effects of injectable calcitriol on mineral metabolism and postpartum health and performance in dairy cows

Objectives were to determine the effects of an injectable formulation of calcitriol on Ca concentration, risk of clinical diseases, and performance in dairy cows. Cows were blocked by lactation number (1 vs. >1) and calving sequence and, within block, assigned randomly within 6 h of calving to receive subcutaneously vehicle only (CON, n = 450) or 200 (CAL200, n = 450) or 300 μg of 1α,25-dihydroxyvitamin D₃ (CAL300, n = 450). Cows were fed the same acidogenic diet prepartum. Blood was sampled before treatment administration and again during the first 11 d postpartum and analyzed for concentrations of ionized Ca (iCa), total Ca (tCa), Mg (tMg), and P (tP), β-hydroxybutyrate, carboxylated osteocalcin (cOC), and undercarboxylated osteocalcin (uOC). Cows were evaluated for diseases in the first 60 d postpartum. Reproduction and survival were monitored for the first 300 d postpartum. Calcitriol increased concentration of blood iCa (CON = 1.12 vs. CAL200 = 1.23 vs. CAL300 = 1.27 mM), plasma tCa (CON = 2.29 vs. CAL200 = 2.44 vs. CAL300 = 2.46 mM), and plasma tP (CON = 1.72 vs. CAL200 = 2.21 vs. CAL300 = 2.28 mM), and differences were observed during the first 5 d postpartum for iCa and tCa, and the first 7 d postpartum for tP. Concentrations of tMg were lower in calcitriol-treated cows than in CON cows (CON = 0.81 vs. CAL200 = 0.78 vs. CAL300 = 0.75 mM), and differences were observed during the first 5 d postpartum. Calcitriol increased plasma concentrations of cOC (CON = 14.5 vs. CAL200 = 23.0 vs. CAL300 = 19.8 ng/mL) and uOC (CON = 1.6 vs. CAL200 = 3.4 vs. CAL300 = 2.6 ng/mL). Prevalence of subclinical hypocalcemia was less in calcitriol-treated cows (CON = 19.0 vs. CAL200 = 4.7 vs. CAL300 = 9.3%); however, benefits on health were only observed in overconditioned cows (n = 270/1,350). Calcitriol reduced incidence of retained placenta (CON = 14.3 vs. CAL200 = 5.1 vs. CAL300 = 5.9%), puerperal metritis (CON = 12.7 vs. CAL200 = 6.1 vs. CAL300 = 2.5%), and morbidity (CON = 72.1 vs. CAL200 = 57.4 vs. CAL300 = 56.9%) in cows with BCS greater than 3.50, but no benefit on health was observed in cows with BCS equal to or less than 3.50 at parturition. Milk yield did not differ among treatments. Pregnancy at first AI did not differ, but pregnancy rate after the first AI was slower for calcitriol-treated cows because of reduced insemination rate and pregnancy per AI. We found that CAL200 reduced death but increased culling in cows without calving problems. Collectively, results indicate that treatment with calcitriol at parturition was effective in improving concentrations of iCa, tCa, and tP, which reduced the risk of hypocalcemia. Pregnancy rate was reduced by calcitriol treatment, and benefits on health performance were limited to overconditioned cows. Thus, treatment of all cows is not supported, and proper identification of cohorts of cows that benefit from postpartum interventions that increase blood calcitriol or calcium is needed.

Serum retinol, β-carotene, and α-tocopherol as biomarkers for disease risk and milk production in periparturient dairy cows

The effectiveness of using serum vitamin concentrations as biomarkers to predict diseases in dairy cows during the periparturient period is not well known. The objective of this study was to evaluate the association between serum β-carotene, retinol, and α-tocopherol concentrations and periparturient cow diseases in commercial dairies. We measured serum concentrations of these vitamin-active compounds at dry-off and during close-up (approximately 3 wk before calving) and early lactation (approximately 7 d post-calving), and we examined their association with clinical diseases in the first 30 d in milk. Diseases were diagnosed by trained personnel and recorded using database software. Blood samples were taken from 353 cows from 5 different farms over a 3-yr period. Blood samples were analyzed for β-carotene, retinol, α-tocopherol, and cholesterol. We built separate mixed logistic regression models for each disease outcome: hyperketonuria, lameness, mastitis, uterine diseases (retained placenta or metritis), and an aggregate outcome. For the aggregate outcome, a cow was considered positive if she had one or more of the following: hyperketonuria, lameness, mastitis, uterine disease, pneumonia, milk fever, or displaced abomasum. Concentrations of all 3 fat-soluble vitamins decreased significantly in early lactation relative to the 2 prepartum sampling times. Serum retinol concentrations at close-up and early lactation were negatively associated with odds of developing postpartum hyperketonuria. At early lactation, cows with uterine disease had lower serum retinol concentrations than cows without uterine disease. Similarly, lower serum retinol concentrations were associated with greater odds of having any one disease in the aggregate outcome. First-test 305-d mature-equivalent milk yield was positively correlated with increased serum α-tocopherol and negatively correlated with β-carotene concentrations. This study demonstrates the potential for serum β-carotene, retinol, and α-tocopherol to serve as biomarkers for disease risk.

Short communication: The effect of ruminal administration of 5-hydroxy-l-tryptophan on circulating serotonin concentrations

The monoamine serotonin has been shown to regulate peripartal calcium homeostasis in multiparous cows and be a possible mitigation tool for hypocalcemia. Increasing circulating serotonin concentrations via prepartum intravenous (IV) administration of the serotonin precursor 5-hydroxy-L-tryptophan (5-HTP) increases postpartum calcium concentrations. However, the ability of 5-HTP to be used orally or ruminally to alter circulating serotonin concentrations has not been established. Hence, our objective was to determine if ruminal administration of 5-HTP altered circulating serotonin concentrations. Four ruminally cannulated, nonlactating, nonpregnant multiparous Holstein dairy cows were randomly assigned to 1 of 4 treatments in a 4 × 4 replicated Latin square with 4-d periods separated by a 7-d washout. On d 1 and 2 of each period, cows were dosed with 1 of 4 experimental treatments as follows: (1) 0 mg/kg of body weight (BW) of 5-HTP, (2) 1 mg/kg of BW of intraruminal 5-HTP, (3) 2 mg/kg of BW of intraruminal 5-HTP, or (4) 1 mg/kg of BW of IV 5-HTP. Infusions were administered over a 1-h period, and all groups not receiving 5-HTP IV were infused with an equal volume of IV saline to that of IV 1 mg/kg of BW of 5-HTP treatment. Continuous serial blood samples were collected beginning after d 2 of treatment administration. Whole blood serotonin concentrations were higher in cows dosed with 2 mg/kg of BW of intraruminal 5-HTP immediately after dosing when compared with cows dosed with 0 mg/kg of BW of 5-HTP on d 2, but were similar on d 3 and 4 of the experimental period. Cows receiving IV 5-HTP had the highest circulating serotonin concentrations relative to all other treatments. These findings demonstrated that 2 intraruminal dosings of 5-HTP at 2 mg/kg of BW resulted in elevated circulating serotonin concentrations relative to the control immediately after dosing. This supports the potential for 5-HTP to be used orally to manipulate circulating serotonin concentrations.

Metabolic Stress in the Transition Period of Dairy Cows: Focusing on the Prepartum Period

All modern, high-yielding dairy cows experience a certain degree of reduced insulin sensitivity, negative energy balance, and systemic inflammation during the transition period. Maladaptation to these changes may result in excessive fat mobilization, dysregulation of inflammation, immunosuppression, and, ultimately, metabolic or infectious disease in the postpartum period. Up to half of the clinical diseases in the lifespan of high-yielding dairy cows occur within 3 weeks of calving. Thus, the vast majority of prospective studies on transition dairy cows are focused on the postpartum period. However, predisposition to clinical disease and key (patho)physiological events such as a spontaneous reduction in feed intake, insulin resistance, fat mobilization, and systemic inflammation already occur in the prepartum period. This review focuses on metabolic, adaptive events occurring from drying off until calving in high-yielding cows and discusses determinants that may trigger (mal)adaptation to these events in the late prepartum period.

Evaluation of oxidant/antioxidant status, metabolic profile and milk production in cows with metritis

Background

The aim of the study was to evaluate oxidant/antioxidant status in 21 Holstein dairy cows with metritis compared to 8 healthy controls. Blood samples were taken during the first 21 days postpartum. Malondialdehyde (MDA), a marker of oxidative stress, total antioxidant status (TAS) and antioxidant parameters such as glutathione peroxidase (GPx), selenium (Se), vitamins A and E and beta-carotene were determined from all cows. The differences in beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), calcium, bilirubin concentrations and aspartate aminotransferase (AST) activity were also monitored, as were milk production and milk composition. Metritis was defined by an unpleasant discharge of varying color (milky-grey/brown/sanguineous) and consistency (muco-purulent/purulent/watery) and by the presence of increased temperature (> 38.5 °C) in cows within 21 days postpartum. Rectal examination revealed increased uterine size, thickened uterine wall and increased uterine tone. The affected cows had significantly reduced daily milk production. Additionally, hematological parameters and haptoglobin concentration were also measured in metritic cows.

Results

Higher MDA concentration (P <  0.001) was recorded in cows with metritis, while vitamin A and vitamin E concentrations were lower (P <  0.01) compared to healthy cows. Higher BHB (P <  0.05), NEFA (P <  0.05), AST (P <  0.05) and bilirubin (P <  0.001) concentrations was recorded in cows with metritis as compared to the control group. Significant differences in beta-carotene concentration, GPx activity, and Se, TAS and Ca concentrations in cows with metritis compared to control group were not observed in the present study (P >  0.05). Milk production was decreased in the cows with metritis (P <  0.001) and alterations in milk composition were also observed in metritic cows as compared to healthy cows.

Conclusions

The results of the study showed that cows with metritis in early postpartum are exposed to a higher degree of oxidative stress and that the incidence of metritis can negatively affect milk production in dairy cows.

The effect of prepartum negative dietary cation-anion difference and serum calcium concentration on blood neutrophil function in the transition period of healthy dairy cows

Our objectives were to assess the effects of a diet with a negative dietary cation-anion difference (DCAD) before calving on phagocytosis (Pc) and oxidative burst (OB) function of circulating neutrophils, and to determine the associations of serum ionized (iCa) and total calcium (tCa) concentrations with Pc and OB in transition dairy cows. We hypothesized that multiparous cows fed a negative DCAD diet prepartum would have greater iCa and tCa, and thus improved Pc and OB. From 3 wk before expected parturition until calving, 38 healthy multiparous cows from 3 farms were assigned to negative DCAD treatment (TRT; -100 mEq/kg of diet dry matter; n = 21) or a control (CON; 95 mEq/kg of dry matter; n = 17) diet. Each farm was on one treatment or the other at a time, but all farms contributed cows to both groups. Urine pH was measured weekly and in TRT was 6.1 ± 0.8 with 80% of 50 samples <7 and 74% ≤ 6.5. Phagocytosis, OB, iCa, and tCa were measured at d -7, 1, and 4 relative to calving. Median fluorescence intensity for Pc (MFIP) and OB (MFIOB), and the shift of percentage of cells active for Pc (PPc) and OB (POB) were measured in isolated, stimulated neutrophils via flow cytometry. Outcomes were assessed with mixed linear regression models accounting for repeated measures. There were no differences between treatments in the 4 neutrophil function outcomes. Although MFIOB varied over time, there were no interactions of treatment with time for any outcome. Serum ionized and tCa did not differ between TRT and CON. The least squares means ± standard deviation for iCa were: d -7, 1.23 ± 0.12 vs. 1.21 ± 0.12; d 1, 1.07 ± 0.12 vs. 1.02 ± 0.12; d 4, 1.16 ± 0.12 vs. 1.17 ± 0.12 mmol/L for TRT and CON, respectively; and for tCa: d -7 2.39 ± 0.25 vs 2.44 ± 0.31; d 1, 2.01 ± 0.25 vs 1.97 ± 0.31; d 4, 2.33 ± 0.25 vs 2.32 ± 0.31 mmol/L, respectively. The proportion of blood samples with tCa <2.15mmol/L at d -7, 1 and 4 was 5, 76, and 13%, respectively, with no differences between TRT and CON. Correlations of iCa or tCa with each of the 4 polymorphonuclear leukocyte (PMN) function outcomes were weak (r < |0.3|). We did not observe the hypothesized differences in aspects of innate immunity in clinically healthy multiparous cows fed a negative DCAD. We underline that cows that experienced clinical disease were excluded from this study, which is important for interpretation of the results.

Effect of two postpartum intramuscular treatments with β-carotene (Carofertin®) on the blood concentration of β-carotene and on the reproductive performance parameters of dairy cows

The aim of the study was to determine whether two postpartum intramuscular treatments with 200 mg of beta-(β-)carotene (Carofertin; Alvetra u. Werfft, Vienna, Austria) in a 14-day interval increases β-carotene concentrations in blood, particularly around the time of the first artificial insemination (AI), and to test the effect of the treatment on fertility parameters, luteal size, and progesterone blood levels of dairy cows. A total of 297 Holstein dairy cows were enrolled in the study. Between 28 and 34 days postpartum (dpp) β-carotene concentrations were measured in blood samples using an on-site test (iCheck carotene; BioAnalyt, Teltow, Germany). Cows with a β-carotene concentration <3.5 mg/L, indicating a deficiency of β-carotene, were allocated either to the β-carotene treatment group BCT (n = 123) or to the control group CON (n = 121). Cows with concentrations ≥3.5 mg/L were assigned to an optimally supplied reference group (REF; n = 53). Cows in the BCT group received 200 mg of β-carotene intramuscularly at 28-34 dpp and at 42-48 dpp. Further blood samples were collected at 35-41 dpp, 42-48 dpp, 49-55 dpp, and in the week after the first AI and their β-carotene concentrations were analyzed. Between day 10 and 14 after the first AI, the blood progesterone concentration was measured and the size of the corpus luteum (CL) was determined by ultrasound. Blood β-carotene concentrations increased in the BCT cows in the week after the treatment with a peak at 49-55 dpp and were significantly higher than in the CON group at each time point after the first treatment. Logistic regression models, however, revealed that the treatment with β-carotene had no effect on first service conception rate, days to first service, time to pregnancy, or percentage of pregnant cows within 150 dpp. Furthermore, there was no effect on progesterone concentration or the size of the CL between the groups. In conclusion, two treatments with Carofertin postpartum increased β-carotene blood concentrations but had no effect on the fertility parameters in this study.

Modulation of immune function in the bovine uterus peripartum

There is a high risk of clinical or subclinical reproductive tract disease in the postpartum period in dairy cows. An integrated process of adaptive events should occur synchronously, including a robust but well-regulated immune response in the uterus. Failure of this process may result in reproductive tract inflammatory disease. Up to half of postpartum dairy cows are affected by metritis, purulent vaginal discharge (PVD), or subclinical endometritis. After parturition there is damage to the birth canal, the superficial layer of the endometrium is naturally wounded, and essentially all dairy cows have bacterial contamination in the uterus. Neutrophils are the most abundant type of inflammatory cell and the main line of defence against infection in the uterus. A prompt influx of neutrophils is associated with uterine health. Avoidance of clinical disease (metritis and PVD) depends in large part on how effective the immune response is at limiting the burden and effects of bacterial pathogens, while the occurrence of subclinical endometritis is more a function of avoiding excessive or persistent inflammation. Glucose supply, hypocalcemia, lipid mobilization from body fat, ketosis, and the flux of pro-inflammatory cytokines influence immune response and change rapidly and variably among individual cows. Effective but well-regulated inflammatory response will be favoured by best management practices for transition cows, but specific interventions to modulate immune response to prevent uterine disease remain developmental.

Evaluation of Oxidative Stress in Dairy Cows with Left Displacement of Abomasum

Simple Summary

The present study evaluated oxidative and antioxidant status in dairy cows with Left Displacement of the Abomasum (LDA), an economically important postpartum disease in cattle. The oxidant capacity of plasma measured with a test fo reactive oxygen metabolites, the d-ROMs test, was significantly higher and the plasma biological antioxidant potential (BAP), measured with the BAP test was lower in the LDA group compared with the control group. Oxidative status was assessed using an arbitrary index obtained from the ratio between d-ROMs and BAP and the results showed that cows with LDA experience an imbalance between oxidants and antioxidants.

Abstract

Left Displacement of the Abomasum (LDA) is a condition that occurs in high-producing postpartum dairy cows and it causes economic losses. Studies performed in the last decade indicate that adult dairy cows experience oxidative stress. Increasing interest in the role of oxidative status in ruminant medicine has emphasized the need to develop reliable methods to assess it. A few studies have evaluated the relationship between LDA and oxidative status, mostly through the determination of single parameters of oxidation and the determination of antioxidant status separately, with contrasting results. The aim of this study was to assess the oxidative status by the measurement of Reactive Oxygen Metabolites with d-ROMs and Biological Antioxidant Potential BAP and the calculation of the Oxidative Status index in 74 multiparous dairy cows with LDA. Each case was matched with a control herdmate. The amount of free oxygen radicals in plasma samples was determined using the d-ROMs test, the concentration of antioxidants was measured using the BAP test and the Oxidative Status index was also calculated. The concentration of d-ROMs was significantly higher in the study group compared to the control group (179 ± 37.7 U CARR and 158 ± 23.0 U CARR, respectively), while the concentration of BAP was significantly lower in the study group than in the control group (2156 ± 98.1 µmol/L vs. 2558 ± 108.5 µmol/L). The Oxidative Status index value was significantly higher in cows with LDA than in healthy cows (8.3 ± 1.51 vs. 6.2 ± 0.76). The results of this study indicated that an inbalance between oxidants and antioxidants occurred in cattle with LDA.

Technical note: Rapid field test for the quantification of vitamin E, β-carotene, and vitamin A in whole blood and plasma of dairy cattle

Fast and easy tests for quantifying fat-soluble vitamins such as vitamin E and vitamin A, as well as β-carotene, in whole blood without a need to preprocess blood samples could facilitate assessment of the vitamin status of dairy cattle. The objective of this study was to validate a field-portable fluorometer/spectrophotometer assay for the rapid quantification of these vitamins in whole blood and plasma of dairy cows and calves. We measured the concentrations of vitamin E and β-carotene in whole blood and plasma from 28 dairy cows and 11 calves using the iCheck test (BioAnalyt GmbH, Teltow, Germany) and compared the results with the current analytical standard (HPLC) in 2 independent laboratories, one at the University of Potsdam (Germany) and at one at DSM Nutritional Products Ltd. (Kaiseraugst, Switzerland). For vitamin A, the HPLC measurements were done only in the laboratory in Germany. The whole-blood concentrations of vitamin E as determined by iCheck (blood-hematocrit-corrected) ranged from 1.82 to 4.99 mg/L in dairy cows and 0.34 to 3.40 mg/L in calves. These findings were moderately correlated (R² = 0.66) with the values assessed by HPLC in dairy cattle (cows + calves). When calves were excluded, the correlation was higher (R² = 0.961). The β-carotene and vitamin A values obtained by the reference method HPLC were highly correlated with the iCheck methods in whole blood (R² = 0.99 and 0.88, respectively). In plasma, we observed strong correlations between the concentrations assessed by iCheck and those of HPLC for vitamin E (R² = 0.97), β-carotene (R² = 0.98), and vitamin A (R² = 0.92) in dairy cattle (cows + calves). For vitamin E, β-carotene, and vitamin A, we compared the relationship between the differences obtained by the iCheck assay and the HPLC measurements, as well as the magnitude of measurements, using Bland-Altman plots to test for systematic bias. For all 3 vitamins, the differences values were not outside the 95% acceptability limits; we found no systematic error between the 2 methods for all 3 analytes.

A 100-Year Review: From ascorbic acid to zinc-Mineral and vitamin nutrition of dairy cows

Mineral and vitamin nutrition of dairy cows was studied before the first volume of the Journal of Dairy Science was published and is still actively researched today. The initial studies on mineral nutrition of dairy cows were simple balance experiments (although the methods available at the time for measuring minerals were anything but simple). Output of Ca and P in feces, urine, and milk was subtracted from intake of Ca and P, and if values were negative it was often assumed that cows were lacking in the particular mineral. As analytical methods improved, more minerals were found to be required by dairy cows, and blood and tissue concentrations became primary response variables. Those measures often were poorly related to cow health, leading to the use of disease prevalence and immune function as a measure of mineral adequacy. As data were generated, mineral requirements became more accurate and included more sources of variation. In addition to milk yield and body weight inputs, bioavailability coefficients of minerals from different sources are used to formulate diets that can meet the needs of the cow without excessive excretion of minerals in manure, which negatively affects the environment. Milk, or more accurately the lack of milk in human diets, was central to the discovery of vitamins, but research into vitamin nutrition of cows developed slowly. For many decades bioassays were the only available method for measuring vitamin concentrations, which greatly limited research. The history of vitamin nutrition mirrors that of mineral nutrition. Among the first experiments conducted on vitamin nutrition of cows were those examining the factors affecting vitamin concentrations of milk. This was followed by determining the amount of vitamins needed to prevent deficiency diseases, which evolved into research to determine the amount of vitamins required to promote overall good health. The majority of research was conducted on vitamins A, D, and E because these vitamins have a dietary requirement, and clinical and marginal deficiencies became common as diets for cows changed from pasture and full exposure to the sun to stored forage and limited sun exposure. As researchers learned new functions of fat-soluble vitamins, requirements generally increased over time. Diets generally contain substantial amounts of B vitamins, and rumen bacteria can synthesize large quantities of many B vitamins; hence, research on water-soluble vitamins lagged behind. We now know that supplementation of specific water-soluble vitamins can enhance cow health and increase milk production in certain situations. Additional research is needed to define specific requirements for many water-soluble vitamins. Both mineral and vitamin research is hampered by the lack of sensitive biomarkers of status, but advanced molecular techniques may provide measures that respond to altered supply of minerals and vitamins and that are related to health or productive responses of the cow. The overall importance of proper mineral and vitamin nutrition is known, but as we discover new and more diverse functions, better supplementation strategies should lead to even better cow health and higher production.

Changes in the expression of α-tocopherol-related genes in liver and mammary gland biopsy specimens of peripartum dairy cows

Blood α-tocopherol (α-Toc) concentrations decline gradually throughout the prepartum period, reaching the nadir after calving in dairy cows. The 6 α-Toc-related molecules [α-Toc transfer protein (TTPA); afamin; scavenger receptor class B, Type I; ATP-binding cassette transporter A1; tocopherol-associated protein (SEC14L2); and cytochrome P450 family 4, subfamily F, polypeptide 2 (CYP4F2)] are expressed in liver and other peripheral tissues. These molecules could regulate α-Toc transport, blood concentrations, and metabolism of α-Toc. Therefore, the aim of this study was to evaluate the changes in the expression of α-Toc-related genes in liver and mammary gland tissues of dairy cows around calving, which have remained elusive until now. In experiment (Exp.) 1, 28 multiparous Holstein cows were used (from -5 to 6 wk relative to parturition) to monitor the changes in dietary α-Toc intake, blood concentrations of α-Toc, and lipoproteins; in Exp. 2, 7 peripartum Holstein cows were used (from -4 to 4 wk relative to parturition) for liver tissue biopsy; and in Exp. 3, 10 peripartum Holstein cows were used (from -8 to 6 wk relative to parturition) to carry out the mammary gland tissue biopsy and milk sampling. In Exp. 1, the serum α-Toc concentrations declined gradually with decreasing amount of α-Toc intake and plasma high-density lipoprotein concentrations toward calving time. However, in the early lactation period after calving, serum α-Toc concentrations remained at a lower concentration despite the recovery of α-Toc intake and plasma high-density lipoprotein concentrations. In Exp. 2, just after calving, the TTPA, SEC14L2, afamin, and albumin mRNA expression levels in the liver were temporarily downregulated, and the hepatic mRNA levels of endoplasmic reticulum stress-induced unfolded protein response markers and acute-phase response marker increased at calving. In Exp. 3, the concentrations of α-Toc in colostrum were greater than those in precolostrum (samples were collected at wk -1 relative to parturition) and mature milk. The expression of TTPA, SEC14L2, and CYP4F2 mRNA in bovine mammary gland tissue was detected. However, TTPA and SEC14L2 mRNA expressions showed the opposite trends: the expression levels of TTPA mRNA peaked whereas SEC14L2 mRNA reached a nadir at calving. These results indicate that the expression of α-Toc-related genes involved in specific α-Toc transfer and metabolism in the liver and mammary gland are altered during calving. Moreover, these changes might be associated with the maintenance of lower serum α-Toc concentrations after calving.