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

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

Association of precalving serum NEFA concentrations with postpartum diseases and reproductive performance in multiparous Holstein cows: Cut-off values

BACKGROUND

High concentrations of NEFA relative to a defined reference or 'cut-point' values before calving can predict the risk of specific or collective periparturient disease events.

OBJECTIVES

A field-based cohort study was conducted to evaluate the value and critical points of serum nonesterified fatty acids (NEFA) at the precalving time to predict the occurrence of postpartum diseases and reproductive performance in dairy cows.

METHODS

Blood samples were taken from 521 high-yielding dairy cows at 1 week (±3 days) before calving and NEFA levels were measured. Health and reproduction information of each cow includes dystocia, retained placenta, milk fever, metritis, mastitis, pregnancy in the first insemination and pregnancy in the first two inseminations, and culling in the first 60 days of lactation and milk production.

RESULTS

Our results show that there are significant relationships between precalving NEFA with the probability of pregnancy at the first and the first two inseminations after calving. The cows that had NEFA concentrations less than 0.5 mmol/L at the last week of pregnancy were 3.51 and 3.15 times more likely to be pregnant at first insemination and the first two inseminations, respectively. Also, our results showed that there are significant relationships between precalving NEFA concentration and the likelihood of dystocia and milk fever. The probability of dystocia and milk fever occurrence were 2.56 and 1.91 times greater in those cows that had NEFA concentrations more than 0.3 mmol/L, respectively.

CONCLUSIONS

The present results indicated that Increasing NEFA during the prepartum period could adversely affect the reproductive efficiency of dairy cows.

Evaluating the inclusion of alfalfa hay in diets fed to multigravid Holstein cows in their transition to early lactation

The objectives of this study were to determine the dry matter intake (DMI), urine pH, Ca concentration in blood, Ca output in urine, and frequency of hypocalcemia in pregnant and nonlactating dairy cows consuming diets containing different hays and acidogenic products during the prepartum period. Eighty pregnant and nonlactating Holstein cows approaching their second or greater calving were fed 1 of 4 experimental diets according to a 2 × 2 factorial arrangement of treatments during the prepartum period (21 d before calving). Diets included either grass hay (GH) or alfalfa hay (AH) and calcium chloride (CL) or polyhalite (PO) as the acidogenic products. All diets had a dietary cation-anion difference (DCAD) below -190 mEq/kg of dry matter (DM). Grass hay contained 75 g/kg crude protein, 749 g/kg neutral detergent fiber, 3.6 g/kg Ca, 0.9 g/kg Na, 18.8 g/kg K, 3.8 g/kg Cl, 1.5 g/kg S, and a cation-anion difference equal to 290 mEq/kg of DM. Alfalfa hay contained 196 g/kg crude protein, 456 g/kg neutral detergent fiber, 15.2 g/kg Ca, 1.6 g/kg Na, 25 g/kg K, 7.7 g/kg Cl, 3.2 g/kg S, and a cation-anion difference equal to 292 mEq/kg of DM. Cows consuming GH tended to consume more DM than cows consuming AH (11.6 vs. 10.8 kg/d) but DMI did not differ between acidogenic products. Urine pH decreased below 6.5 for all diets, although cows consuming the GHPO diet had the highest urine pH. The concentration of Ca in plasma decreased substantially around calving but neither hay type nor acidogenic product affected it. Urinary Ca output was lowest for cows consuming the GHPO diet. No associations existed between dietary treatments and the frequencies of normocalcemia and hypocalcemia. Under the conditions of this study, in which alfalfa and grass hays had similar cation-anion differences, we concluded that the inclusion of alfalfa hay in prepartum diets does not necessarily increase the frequency of hypocalcemia. The cation-anion difference of the alfalfa hay, more than the concentration of potassium alone, may be a key determinant of whether alfalfa hay fits in a prepartum feeding program for prepartum dairy cows. Further research should explore this relationship.

Considerations in the Diagnosis and Treatment of Early Lactation Calcium Disturbances

This article reviews the history of clinical hypocalcemia and the evolving definition of subclinical hypocalcemia, targeting a concept for consideration that not all hypocalcemia is negative. With a goal of presenting bovine practitioners information to assist with individual animal hypocalcemia diagnosis and treatment as well as herd-level monitoring and prevention, we present current methods of direct calcium measurement, therapeutic interventions for clinical hypocalcemia, and postpartum calcium supplementation options and their efficacy. We encourage veterinarians to understand calcium dynamics in the immediate postpartum period and evaluate how individual cow therapy and herd prevention protocols can assist with supporting calcium regulation.

Plasma ionized calcium and magnesium concentrations and prevalence of subclinical hypocalcemia and hypomagnesemia in postpartum grazing Holstein cows from southern Chile

The objective was to determine the plasma concentrations of ionized Ca (iCa) and Mg (iMg) and to establish the prevalence of subclinical hypocalcemia (SCHC) and hypomagnesemia (SCHM) in dairy cows at calving (within 6 hours of parturition) and at 7 days postpartum (pp) in Chilean grazing herds with spring parturitions. Plasma iCa and iMg were assessed using a clinical analyzer. A total of 113 and 175 cows in 18 herds selected at random were sampled at calving and at 7 days pp, respectively. From these 18 herds, 11 herds provided reliable records of lactation number and 8 cows per herd were scored for body condition and sampled at calving and then at 7 days pp. Ionized Ca concentrations for the 18 herds were 0.99 ± 0.16 mmol/L (calving) and 1.01 ± 0.13 mmol/L [7 d pp (P > 0.05)]. Ionized Mg concentrations were 0.58 ± 0.12 mmol/L and 0.51 ± 0.09 mmol/L (P ≤ 0.05). For the 11 herds, iCa concentrations at calving were 1.06 mmol/L (lactation 1), 1.02 mmol/L (lactation 2) and 0.89 mmol/L (lactation ≥ 3), while iMg concentrations were 0.63 mmol/L, 0.60 mmol/L, and 0.61 mmol/L, respectively. Herd prevalence for SCHC (iCa < 1.0 mmol/L) at calving was 64.8%. Prevalence by parity was 40%, 54.5% and 86.7% for lactations 1, 2 and ≥ 3, respectively. Herd prevalence of SCHC on day 7 pp was 30.1%. For SCHM (iMg < 0.52 mmol/L) prevalence was 21.6% and 48.9% at calving and at 7 days pp, respectively.

Temporal profiles describing markers of inflammation and metabolism during the transition period of pasture-based, seasonal-calving dairy cows

The physiology of the dairy cow while transitioning from pregnancy to lactation is complex, with multifactorial processes studied extensively for the role they play in manifestation of disease along with associated economic losses and compromised animal welfare. Manuscripts outlining associations among nutrition, production, physiology, and genetics variables and transition cow disorders are common in literature, with blood analytes that are central to energy metabolism (e.g., nonesterified fatty acids; NEFA, β-hydroxybutyrate; BHB) often reported. Immunity and inflammation have increasingly been explored in the pathogenesis and persistence of disorders, with cytokines and acute phase proteins well documented. However, most of these studies have involved cows fed total mixed rations, which may not always reflect profiles of blood analytes and other physiological indicators of transition cow health in grazing cows consuming fresh pasture. Considering the comparatively lesser characterization of these analytes and markers in pasture-based, seasonal-calving dairy cows, we compiled a database consisting of 2,610 cow lactations that span 20 yr of transition cow research in New Zealand. Using this database, analyte profiles from approximately 28 d precalving to 35 d postcalving were identified in dairy cows with a range of genetics, milk production potentials, and pasture-based farm management systems. These profiles characterize changes in energy reserves and metabolism (NEFA, BHB, glucose, insulin, growth hormone, insulin-like growth factor-1, leptin, body condition score, body weight), liver function (globulin, aspartate aminotransferase, glutamate dehydrogenase, gamma-glutamyl transpeptidase, bilirubin, cholesterol, liver triacylglycerides), protein metabolism (albumin, total protein, albumin:globulin ratio, creatinine, urea, creatine kinase), mineral balance (calcium, magnesium, phosphate, potassium, sodium, chloride, bicarbonate), inflammation (IL-1β, IL-6, haptoglobin, reactive oxygen species, total antioxidant capacity), and uterine health (polymorphonuclear cells, macrophage cells, vaginal discharge score). Temporal changes are generally consistent with previously characterized homeorhetic changes experienced by the dairy cow during the transition from pregnancy to lactation in both pastoral and housed systems. Some of the profiles had not previously been presented for pastoral systems, or in some cases, presented for either system. Our results indicate that moderate-yielding dairy cows undergo similar homeorhetic changes to high-yielding housed cows; however, differences in diet composition result in greater BHB concentrations than expected, based on their milk production and NEFA concentrations. In addition, most cows were able to transition to a state of higher energy requirement following calving, albeit with an increased metabolic challenge in the liver, and only a small percentage of cows were classified with severe hepatic lipidosis or severe hyperketonemia. Increases in metabolic function of the liver were accompanied by changes in indicators of the immune system and changes in mineral balance that, combined, probably reflect the innate response to the transition from gestation to lactation.

Major Nutritional Metabolic Alterations Influencing the Reproductive System of Postpartum Dairy Cows

Early successful conception of postpartum dairy cows is crucial in determining the optimum reproductive efficiency and profitability in modern dairy farming. Due to the inherent high production potential of modern dairy cows, the extra stress burden of peri-parturient events, and associated endocrine and metabolic changes causes negative energy balance (NEBAL) in postpartum cows. The occurrence of NEBAL is associated with excessive fat mobilization in the form of non-esterified fatty acids (NEFAs). The phenomenon of NEFA mobilization furthers with occurrence of ketosis and fatty liver in postpartum dairy cows. High NEFAs and ketones are negatively associated with health and reproductive processes. An additional burden of hypocalcemia, ruminal acidosis, and high protein metabolism in postpartum cows presents further consequences for health and reproductive performance of postpartum dairy cows. This review intends to comprehend these major nutritional metabolic alterations, their mechanisms of influence on the reproduction process, and relevant mitigation strategies.

Effect of Negative Energy Balance on Plasma Metabolites, Minerals, Hormones, Cytokines and Ovarian Follicular Growth Rate in Holstein Dairy Cows

Introduction

The aim of this study was to evaluate the effect of negative energy balance (NEB) on the final growth of the dominant ovarian follicle in Holstein cows.

Material and Methods

Cows at 14 to 21 d postpartum from an intensive dairy farm were randomly selected and allocated into a positive energy balance group (PEB, with β-hydroxybutyric acid (BHBA) level < 1.2 mmol/L, n = 15) and an NEB group (BHBA > 1.2 mmol/L, n = 15). Plasma samples were collected at 21, 50 and 55 d postpartum to assess the concentrations of energy metabolites, minerals, hormones and cytokines. Ovaries were examined by transrectal ultrasound on days 50 and 55 (120 hours later) to evaluate the diameter of the largest follicle.

Results

Compared with PEB cows, there were a more severe body condition loss and a lower milk yield in NEB cows (P < 0.05) and these had greater concentrations of plasma BHBA, non-esterified fatty acids, triglycerides, urea nitrogen, growth hormone, interleukin 6, and fibroblast growth factor 21 and lesser concentrations of plasma glucose, total cholesterol, insulin, insulin-like growth factor 1, insulin-like growth factor binding protein 3, leptin, brain-derived neurotrophic factor and angiopoietin-like protein 8 on d 21 (P < 0.05), while plasma minerals were not affected by energy status (P > 0.05). These changes persisted until the end of the study period (50–55 days postpartum) resulting in a lower follicular growth rate for cows in the NEB than the PEB group.

Conclusion

These observations indicate that follicular growth rate is associated with measurable changes in energy metabolite, hormone and cytokine concentrations caused by early postpartum NEB.

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.

Prepartum factors associated with postpartum diseases in pasture-based dairy cows

This cross-sectional observational study aimed to identify prepartum management, environmental, and animal factors associated with clinical -lameness, metritis, mastitis- and subclinical -calcium imbalance, magnesium imbalance- diseases in pasture-based dairy cows. A total of 565 cows from 25 commercial dairy farms in southern Chile were enrolled over four months. Data on prepartum management and environmental conditions were obtained through a survey and inspections of prepartum paddocks. Cows were evaluated two times. In the first evaluation, between 30 to 3 days before calving, cows were assessed for lameness, body condition score, and blood samples were collected to measure nonesterified fatty acid (NEFA), calcium (Ca), and magnesium (Mg). In the second evaluation, between 3 to 21 DIM, cows were assessed for metritis, lameness, and blood samples were collected and analyzed for total Ca and Mg concentration. Cows were considered as having Ca imbalance if Ca < 2.0 mmol/L, and Mg imbalance if Mg < 0.65 mmol/L. Postpartum clinical mastitis was diagnosed based on the foremilk's daily condition and udder assessed by the milker at each milking during the postpartum transition period. Multivariable logistic regression models, controlling for the farm as a random effect, were built to identify prepartum factors for each postpartum disease. The odds of postpartum lameness were higher for cows that were lame during the prepartum period, had elevated prepartum NEFA concentrations, had greater parity, and for cows that were kept in paddocks with no grass cover. The odds of metritis were higher in cows with lower parity, with increased prepartum NEFA, in cows that had dystocia, and farms with predominantly Holstein breed, and that did not have calving records. The odds of clinical mastitis were higher for cows lame during the prepartum period. The odds of Ca imbalance were higher in cows with a long dry period, dystocic calving, and in farms without prepartum anionic salts supplementation. The odds of Mg imbalance were higher in cows with lower prepartum Mg concentrations, higher prepartum Ca concentration, and higher parity. Our findings indicate that farmers could benefit from refining these areas to improve their cows' health and welfare.

Changes in the Relationship between Ionized and Total Calcium in Clinically Healthy Dairy Cows in the Period around Calving

Simple Summary

Hypocalcemia is a widespread problem in dairy cows in the first days after calving, which increases the risk for secondary diseases. In practice, the measurement of total blood serum or plasma calcium is widely used to diagnose hypocalcemia. The present study demonstrates a high discrepancy between total and ionized calcium specifically around calving, suggesting that only ionized calcium provides an accurate indication of the animal’s calcium status during that period. We developed an optimized model for prediction of ionized calcium from total calcium, non-esterified fatty acids, beta-hydroxybutyric acid, cholesterol, and phosphorous. However, the precision of that model is still unsatisfactory.

Abstract

We aimed to establish a model for prediction of iCa from tCa, using multivariable regressions with diverse blood constituents. Blood was taken from 14 cows at days −2, 0, 2, 4, 7, and 14 relative to parturition. Cows were clinically healthy, and no hypocalcaemia prophylaxis and treatment were applied. Total calcium and further parameters were determined from frozen serum. Ionized calcium, blood gases, and electrolytes were determined from heparin-stabilized blood samples. Linear regression between iCa and tCa was estimated. Precision improved only slightly using a multivariable model. Best precision was achieved when estimating the iCa:tCa ratio from other blood constituents. To identify the reason behind the poorly predictive value of tCa for iCa, the relative changes of iCa and tCa around calving were calibrated to the respective values of day −2 (=100%) for each cow. An increase in the iCa:tCa ratio was observed from 0.43 at day −2 to 0.48 at day 0, followed by a gradual decrease towards 0.43 at day 7. We conclude that routine measurement of iCa should be implemented in the diagnosis of hypocalcaemia. An optimized estimate of iCa from tCa with non-esterified fatty acids (NEFA), beta-hydroxybutyric acid, cholesterol, and phosphorous as co-predictors is still poorly satisfying.

Determination of Blood Glucose, Total Protein, Certain Minerals, and Triiodothyronine during Late Pregnancy and Postpartum Periods in Crossbred Dairy Cows

The late pregnancy (3^rd trimester) and the postpartum period (PPP) (calving date or day zero to day 45) are very critical periods for the fertility and production in dairy cows. This study was designed to investigate blood glucose, total protein (TP), calcium (Ca), phosphorus (P), magnesium (Mg), iron (Fe), and triiodothyronine (T3) during late pregnancy and the PPP. Twenty-seven apparently healthy multiparous crossbred dairy cows (Friesian × Kenana) were included in this study. The cows were randomly allocated into three groups: group A (n = 10), cows with late pregnancy, group B (n = 7), cows in the PPP, and group C (n = 10), nonpregnant cows as control. One-way ANOVA was used to analyze the data. The results of this study showed that blood glucose was higher in late pregnancy and the PPP than in nonpregnant cows. The TP was significantly lower in late pregnant cows than during the PPP and in nonpregnant cows. Ca, P, and Mg were not significantly different between periods. Serum Fe and T3 were significantly lower during the PPP than that in late pregnant and nonpregnant cows. The results can provide indications of the nutritional status of dairy cows and a diagnostic tool to avoid the metabolic disorders that may occur during late pregnancy and the PPP.

Association of blood calcium concentration in the first 3 days after parturition and energy balance metabolites at day 3 in milk with disease and production outcomes in multiparous Jersey cows

Research exploring specific associations of markers of negative energy balance and Ca in postpartum Jersey cows with lactation performance is lacking. Our objectives were to evaluate the associations of total Ca concentration (tCa) measured at 1 through 3 d in milk (DIM) and free fatty acids (FFA), β-hydroxybutyrate (BHB), and glucose measured at 3 DIM with (1) the risk of multiparous Jersey cows being diagnosed with early-lactation diseases and culling, (2) milk production in the first 9 wk of lactation, and (3) the risk of pregnancy in the first 150 DIM. A cohort study was performed in 1 dairy herd in Texas. Multivariable Poisson regression models were built to evaluate the association of the analytes of interest with the risks of early-lactation diseases and culling in the first 60 DIM (i.e., binary outcomes). Linear mixed models were used to evaluate the association of the analytes of interest with milk production within the first 9 wk of lactation, and a Cox proportional hazard model was built to assess the risk of pregnancy within 150 DIM. A total of 380 cows were used in the final analyses. Total Ca measured at 1 through 3 DIM was not associated with the risk of metritis. Cows with increased FFA and BHB had an increased risk of being diagnosed with metritis and clinical mastitis, respectively. Increased concentrations of glucose and FFA and decreased tCa at 3 DIM were associated with an increased risk of culling. Reduced tCa concentrations at 1 DIM (≤1.84 mmol/L) and 2 DIM (≤2.04 mmol/L) were associated with increased milk production across the first 9 wk of lactation compared with tCa concentrations above those thresholds. Total Ca was not associated with milk production when assessed at 3 DIM, whereas increased FFA (≥0.37 mmol/L) and decreased glucose (≤2.96 mmol/L) at 3 DIM were associated with increased milk production. None of the metabolites measured were associated with the risk of pregnancy in the first 150 DIM. Our results demonstrate that tCa concentration assessed in the first 3 DIM show temporary associations with milk production and culling in multiparous Jersey cows. Although increased concentration of FFA assessed at 3 DIM was associated with greater milk yield, it was a detrimental factor for the risk of metritis. This study attempted to better elucidate the relationship of tCa, FFA, BHB, and glucose assessed in early postpartum with health and performance of Jersey cows. Based on this study, assessments performed at 3 DIM using tCa concentration ≤1.99 mmol/L for increased risk of early-lactation culling and FFA ≥0.43 mmol/L for increased risk of metritis could be used as starting points. More studies evaluating the dynamics of energy balance markers and tCa in postpartum Jersey cows using a greater number of herds are needed to better inform dairy consultants on critical levels for exacerbated postpartum negative energy balance and subclinical hypocalcemia for the Jersey breed.

Dissolution Rates of Calcium Boluses and Their Effects on Serum Calcium in Dairy Cattle

Purpose

Calcium supplement boluses vary greatly in content and bioavailability.

Methods

In vivo dissolution and bioavailability studies were conducted to compare commercial calcium supplement boluses with various contents of calcium chloride and calcium carbonate. The products studied included: Bolus 1 (high calcium chloride, no calcium carbonate), Bolus 2 (medium calcium chloride, medium calcium carbonate), and Bolus 3 (low calcium chloride, high calcium carbonate). A bolus was placed in a pre-weighed coarse mesh net for 30, 60, 90, 120, 180, and 240 minutes to measure dissolution rates in the rumen of fistulated animals. To measure calcium uptake, 27 Holstein cows (second and third lactation) were randomly allocated to one of three oral calcium protocols: Treatment 1 (two high calcium chloride boluses at time 0); Treatment 2 (one high calcium chloride bolus at time 0 with a second bolus 12 hours later); or Treatment 3 (two high calcium carbonate boluses at time 0). Treatments were initiated within 12 hours following calving and this was considered time 0.

Results

Bolus 1 was the quickest to dissolve (<90 minutes), followed by Bolus 2 (<240 minutes). The high calcium carbonate bolus (Bolus 3) remained after 240 minutes in vivo with a minimum of 75% of the original bolus weight still intact. Cows with severe hypocalcemia (<1.8 mmol/L) responded with a higher serum calcium increase than cows with milder hypocalcemia (>1.8 mmol/L, <2.12 mmol/L). The high calcium carbonate bolus group (Treatment 3) did not show a rapid increase in serum calcium as compared to the high calcium chloride groups (Treatments 1 and 2). The animals receiving Treatment 1 had a greater and more persistent serum calcium response than animals receiving Treatment 2.

Conclusion

The study outcome suggests that calcium chloride/calcium sulfate boluses are more effective at generating a serum calcium response than boluses containing high amounts of calcium carbonate and that two boluses administered rapidly after calving may be more effective than the traditional treatment of giving 2 boluses 12 hours apart.

Association between serum calcium dynamics around parturition and common postpartum diseases in dairy cows

The objective of this study was to compare periparturient serum Ca dynamics (CaDyn) in cows with and without diseases in early lactation. The study enrolled 1,949 cows from a commercial dairy farm in northern Germany. Blood samples were drawn 7 d before expected calving date and on d 0, 1, 3, and 7 after calving and analyzed for serum Ca concentration. Cows were monitored for clinical hypocalcemia (CH), ketosis, left displaced abomasum (LDA), retained placenta, acute puerperal metritis (APM), mastitis, and pneumonia. To evaluate the association between CaDyn and diseases during the transition period, repeated measures ANOVA with first-order autoregressive covariance were performed. Serum CaDyn of healthy cows (i.e., without any of the aforementioned diseases) was compared with CaDyn of cows with one of the aforementioned diseases (CH, ketosis, APM, mastitis, LDA, and pneumonia), and cows with multiple diseases (CH+, ketosis+, APM+, mastitis+, LDA+, and pneumonia+). Separate models were built for primiparous and multiparous cows. For primiparous cows, we evaluated the association between CaDyn and ketosis (healthy cows vs. cows with ketosis vs. cows with ketosis+) and CaDyn and APM (healthy cows vs. cows with APM vs. cows with APM+). The same models were built for multiparous cows. Three additional models were built for multiparous cows to evaluate the association between CaDyn and CH (healthy cows vs. cows with CH vs. cows with CH+), mastitis (healthy cows vs. cows with mastitis vs. cows with mastitis+), or LDA (healthy cows vs. cows with LDA vs. cows with LDA+). In primiparous cows, serum Ca concentrations of cows with ketosis, APM, and APM+ were significantly reduced on d 3 and 7 after calving, compared with healthy cows. Serum Ca concentrations of primiparous cows with ketosis+ were reduced on d 3, but not on d 7 after calving. Multiparous cows with CH had significantly reduced serum Ca concentrations on d 0, 1, and 3 compared with healthy cows. On d 3 and 7, serum Ca concentration of CH+ cows was significantly reduced compared with healthy multiparous cows. Multiparous cows with ketosis and ketosis+ had significantly reduced serum Ca concentrations on d 1 and 3 compared with healthy cows. Cows with APM+ had significantly increased serum Ca concentrations on d 0 and reduced serum Ca concentrations on d 3, compared with healthy cows. Whereas multiparous cows with mastitis had a reduced serum Ca concentration on d 1, mastitis+ cows had a reduced serum Ca concentration on d 1 and 3, compared with healthy multiparous cows. Overall, multiparous cows with LDA+ had reduced serum Ca concentrations. Especially a delayed onset of hypocalcemia (d 3 and 7) was indicative for the development of disease in primiparous cows. In multiparous cows, reduced serum Ca concentrations on d 1 and 3 were associated with occurrence of diseases. Future studies should evaluate whether reduced serum Ca concentrations are a cause or concomitant circumstance of diseases in early lactation.

Cluster analysis to evaluate disease risk in periparturient dairy cattle

Predicting periparturient disease risk is of immense value to the dairy industry. Periparturient diseases are interrelated with each other; however, predicting the onset risk of these diseases has predominantly been based on a single blood parameter for a single disease. This study examined a new diagnostic method to predict the risk of periparturient diseases. We conducted cluster analysis of multiple blood constituents from 20 Holstein cattle at 1 week post-partum, and the cattle were divided into two groups, A or B. We then compared the periparturient and early-lactation blood constituents of these groups. Group B had significantly higher 3-hydroxybutyric acid concentrations and were suspected to have subclinical ketosis. Group B also had significantly lower calcium concentrations, with a tendency for subclinical hypocalcemia. We also performed discriminant analysis using blood parameters at 1 week post-partum, which grouped the population into the same two groups as the cluster analysis based on three variables: inorganic phosphorus, calcium, and either phospholipids or total cholesterol. We further showed that these discriminant functions could be used to predict the risk of periparturient disease even before parturition. Our results indicate that cluster analysis with multiple blood constituents is useful for predicting periparturient disease risks.

Effects of postpartum oral calcium supplementation on milk yield, milk composition, and reproduction in multiparous Jersey and Jersey × Holstein crossbreed cows

The objective of the present study was to evaluate the effects of postpartum oral calcium supplementation on milk yield, energy-corrected milk yield, milk fat concentration, milk protein concentration, and somatic cell count linear score across the first 3 monthly tests postpartum, peak milk yield, risk of pregnancy at first service, and hazard of pregnancy by 150 d in milk on 1,129 multiparous Jersey and Jersey × Holstein crossbreed cows from 2 commercial dairies. After calving, cows were systematically assigned to control (no oral calcium supplementation; n = 567) or oral calcium supplementation at 0 and 1 d in milk (oral Ca; 50 to 60 g of calcium as boluses; n = 562). Monthly test milk yield, composition, and somatic cell count information was obtained from the Dairy Herd Improvement Association. Herd records were used for reproductive data. Statistical analysis was conducted using generalized multiple linear, Poisson, and Cox's hazard regressions. Treatment effects were evaluated considering cow-level information available at parturition (parity, breed, previous lactation milk yield, previous lactation length, dry period length, gestation length, body condition, and locomotion score at calving, calving ease, and calf sex). In addition, for a subset of cows serum calcium concentration before treatment administration was evaluated (n = 756). Overall, oral calcium supplementation did not affect the evaluated productive and reproductive variables. However, effects conditional to previous lactation length and calving locomotion score were observed. Milk yield and energy-corrected milk yield across the first 3 monthly tests were 1.8 kg/d higher for supplemented cows with a previous lactation length within the fourth quartile, compared with control cows on the same quartile. Energy-corrected milk yield tended to be 1.1 kg/d lower for supplemented cows with a previous lactation length within the first quartile, compared with control counterparts. Peak milk yield tended to be 1.6 kg higher for supplemented cows with a calving locomotion score ≥2, compared with control cows with the same locomotion score. Treatment effects were not conditional to serum calcium concentration before treatment administration. Our results suggest that postpartum oral calcium supplementation effects are conditional to cow-level factors such as previous lactation length and calving locomotion score in multiparous Jersey and Jersey × Holstein crossbreed cows.

Associations between lying behavior and activity and hypocalcemia in grazing dairy cows during the transition period

Hypocalcemia is a common metabolic disorder of transition dairy cows that is considered a gateway disease, increasing the risk of other health disorders and reducing cow performance. Clinical milk fever is associated with long periods of recumbency, and it is plausible that cows experiencing non-paretic hypocalcemia may spend more time lying; hence, lying behavior and activity measures may be useful in identifying at-risk cows. The objective of this study was to describe associations among blood calcium (Ca) status at calving and lying behavior and activity measures during the transition period in grazing dairy cows. Blood was sampled on the day of calving (d 0), and d 1, 2, 3, and 4 postcalving, and analyzed for total plasma Ca concentration. Twenty-four multiparous Holstein-Friesian and Holstein-Friesian × Jersey grazing dairy cows were classified, retrospectively, as clinically hypocalcemic (CLIN; blood Ca ≤ 1.4 mmol/L at 1 or more consecutive samplings within 48 h postcalving, but without parturient paresis). These cows were pair-matched (using milk production potential from their estimated breeding value for milk protein, mean body weight at wk -5 and -6 precalving, and, where possible, parity) with 24 cows classified as subclinically hypocalcemic (SUB; blood Ca > 1.4 and < 2.0 mmol/L at 2 consecutive samplings within 48 h postcalving), and 24 cows classified as normocalcemic (NORM; blood Ca ≥ 2.0 mmol/L at 3 consecutive samplings within 72 h postcalving). Lying behavior and activity were monitored using triaxial accelerometers from -21 to +35 d relative to calving. Data were summarized to calculate daily lying time (h/d), daily number of lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). On d 0, the CLIN group were less active and spent approximately 2.6 h longer lying than the SUB and NORM groups, particularly between 0200 and 1400 h. On d 0, the NORM group had fewer LB (16.3/d) than the SUB and CLIN groups (18.2 and 19.2/d, respectively). These differences in behavior were no longer detected 2 d postcalving, and no further differences were observed. The day before calving, the CLIN group spent 1.4 h longer lying down than did the SUB and NORM groups. Further, the relative change in steps from a precalving baseline period (d -14 to -7) until d 0 was positively, linearly associated with blood Ca concentration within 24 h postcalving. Future work should consider daily and temporal changes in behavior in individual cows to determine the potential for these measures to allow early detection of hypocalcemia.

Technical note: Effect of delayed analysis of cooled lithium-heparinized whole blood on the stability of ionized calcium, ionized magnesium, sodium, potassium, chloride, glucose, and lactate in samples from dairy cows

The objectives of this study were to describe the stability of bovine whole-blood electrolytes, glucose, and lactate in samples collected in lithium heparin tubes and stored in thermoconductive modules immersed in ice water. A total of 99 Jersey cows (40 first-parity, 18 second-parity, and 41 third-parity or greater cows) from a commercial dairy farm in West Texas were enrolled between June and July 2018. Blood was collected from the jugular vein using a 60-mL polypropylene syringe and equally distributed into 5 spray-dried evacuated lithium heparin tubes. Baseline samples were analyzed within 90 s of collection using a benchtop blood gas analyzer. The remaining 4 tubes were stored in a thermoconductive, passive-temperature-regulating module inside a cooler with ice water. At 30 min and 2, 4, and 8 h post-collection, samples were removed from the temperature-regulating module, gently inverted for 10 s, and analyzed. Repeated-measures models were built to evaluate the effect of time on the stability of ionized Ca (iCa), ionized Mg (iMg), Na, K, Cl, glucose, and lactate. Most of the analytes investigated remained stable up to 8 h under ice water storage conditions before analysis, including iCa, iMg, Cl, glucose, and lactate. However, Na and K were significantly affected by delayed analysis: Na remained stable up to 4 h post-collection, but K was not stable starting at 2 h post-collection. The results of this study are useful in helping future researchers and consultants to recognize acceptable time delays between whole blood collection and processing or analysis for electrolytes, glucose, and lactate.

Impacts of subclinical hypocalcemia on physiological, metabolic, and productive responses of Holstein × Gir dairy cows

This study compared physiological and productive parameters in ¾ Holstein × ¼ Gir dairy cows diagnosed or not with subclinical hypocalcemia (SCH) during early lactation. Nonlactating, multiparous cows (n = 32) were enrolled in this experiment 21 d prior to expected date of calving. Cows were maintained in a single pen with ad libitum access to corn silage before calving and received a limit-fed prepartum concentrate. Cow body weight (BW) and body condition score (BCS) were recorded weekly, and blood samples were collected on days −21, −14, −9, −6, and −3 relative to expected calving. After calving (day 0), cows were managed in a single pen with ad libitum access to a total mixed ration, and were milked twice daily. Cow BW and BCS were recorded upon calving and then weekly. Milk production was recorded daily and milk samples collected weekly until 30 d in milk (DIM). Blood was collected during the first 5 DIM, and at 6, 9, 16, 23, and 30 DIM. Cows were classified with SCH when mean total serum Ca during the first 5 DIM was ≤2.125 mmol/L. Cows diagnosed with SCH (n = 11) had less (P ≤ 0.04) mean BCS (2.85 vs. 3.07; SEM = 0.07) and less concentrations of serum insulin (0.396 vs. 0.738 ppmol/L; SEM = 0.115) and insulin-like growth factor I (35.9 vs. 57.9 ng/mL; SEM = 4.2), and these outcomes were noted since 21 d prior to expected calving. Cows diagnosed with SCH had greater (P < 0.01) serum concentrations of cortisol at calving (30.2 vs. 22.4 ng/mL; SEM = 2.0), serum haptoglobin at 3 and 6 DIM (0.453 vs. 0.280 mg/mL on day 3 and 0.352 vs. 0.142 mg/mL on day 6; SEM = 0.046), and tended (P = 0.09) to have greater mean concentrations of nonesterified fatty acids from calving to 30 DIM (0.368 vs. 0.304 μEq/L; SEM = 0.026). No differences were detected (P ≥ 0.41) for cow BW and milk production. Cows diagnosed with SCH had less (P = 0.05) mean concentrations of milk total solids (13.2 vs. 13.8 %; SEM = 0.21), tended to have less (P ≤ 0.10) mean concentrations of milk fat (4.34 vs. 4.81 %; SEM = 0.20), protein (3.31 vs. 3.45 %; SEM = 0.05), and lactose (4.45 vs. 4.55 %; SEM = 0.04), and had greater (P = 0.02) milk somatic cell count during the initial 14 DIM (504 vs. 140 cells/μL; SEM = 90). Collectively, Holstein × Gir cows diagnosed with SCH upon calving had altered periparturient physiological parameters denoting reduced energy nutritional, increased milk somatic cell count, and less concentration of milk components during early lactation compared with normocalcemic cows.

Subclinical hypomagnesemia: Prevalence and causes in dairy cows in the semiarid region of the state of Paraíba, Brazil

ABSTRACT In dairy farming, cows display important metabolic changes during the transition period, particularly high-production cows, which need nutrients in greater quantity to meet the required demand. The aim of this study was to determine the prevalence of subclinical hypomagnesemia in pre- and post-partum dairy cows inserted in milk-production systems in the Sousa microregion and the district of São João do Rio do Peixe, both in the State of Paraíba, Brazil. As such, visits were made every two weeks to 34 rural properties, where the team collected 357 blood samples by venepuncture, 106 from pre-partum lactating cows and 251 from lactating cows in the post-partum period. It was found that the properties supplied three types of mineral supplement: a single supplement of NaCl, a supplement of NaCl + mineral base, and a commercial supplement. The cows receiving the commercial mineral supplement had the highest prevalence (10.53%) of the disorder, even showing a significant difference (P < .05) between the other types of supplement. In relation to reproductive period, it was found that the post-partum cows had a higher prevalence of subclinical hypomagnesemia (9.96%) than did the pre-partem cows (8.49%); there was, however, no significant difference (P > .05) between the two. Studies such as this are fundamental for alerting rural and technical producers to the occurrence of subclinical hypomagnesemia in the region, in addition to the damage caused by metabolic disorders.

Symposium review: The impact of management and facilities on cow culling rates

This symposium review examines the association between comfort and cow longevity, with a particular emphasis on optimizing resting behavior in confinement-housed systems. Housed dairy cattle demonstrate a variety of negative behavioral and physiological effects when lying time is restricted, with cows prioritizing the recovery of rest over feeding when both are deprived. There is, however, wide individual-cow variation in daily lying times, influenced by an array of cow-, housing-, and management-related factors. Cow-related factors include individual preference, parity, stage of lactation cycle, milk yield, ill health, and lameness. Lying time tends to increase with age and days in milk and during periods of ill health, whereas milk yield is negatively correlated with lying time. The effect of lameness is complicated by severity and by interactions with bedding type, which modifies the cows' ability to rise and lie down. Generally, lame cows suffer prolonged lying bouts of greater variability in length and take fewer bouts per day. Often this results in an overall increase in lying time. Thus, higher standards of cow comfort and improved cow health are not always reflected by longer lying times. Housing and management factors that influence resting behavior include the design of the resting area, access to the resting space, and the thermal microenvironment of the lying area. Provision of dry, deep loose bedding, stocking cows to allow each animal access to a resting space, allowing sufficient time to access the resting area, and providing heat abatement to reduce heat load optimize resting behavior. Because lameness and poor body condition are commonly found in culled dairy cattle, the link between cow comfort and culling is likely mediated through lameness onset and management. Optimal comfort helps prevent the onset of lameness and facilitates recovery once cows become lame, which limits the effect of lameness on feeding behavior and reduces the risk for other health-related disorders, poor reproductive performance, and early herd removal. Cow comfort cannot be assessed by measuring the duration of lying time alone. Rather, comfort is reflected by the optimization of resting behavior, providing facilities and management to allow cows to lie down when they choose to do so for as long as they need to.

Association of transient, persistent, or delayed subclinical hypocalcemia with early lactation disease, removal, and milk yield in Holstein cows

Our objectives were to evaluate the association of subclinical hypocalcemia (SCH) dynamics with the risk of early lactation disease, removal, and milk production. We conducted a prospective observational cohort study in 407 Holstein cows in 2 dairy herds in New York. Cows were stratified by parity group (144 primiparous, 263 multiparous) and classified into 1 of 4 groups based on postpartum plasma Ca concentrations previously associated with improved milk production or increased risk of disease: normocalcemic (NC; primiparous [Ca] >2.15 mmol/L at 1 and 2 d in milk, n = 67; multiparous [Ca] >1.77 at 1 d in milk and 2.20 mmol/L at 4 d in milk, n = 109); transient SCH (tSCH; primiparous [Ca] ≤2.15 at 1 d in milk and >2.15 mmol/L at 2 d in milk, n = 25; multiparous [Ca] ≤1.77 at 1 d in milk and >2.20 mmol/L at 4 d in milk, n = 50); persistent SCH (pSCH; primiparous [Ca] ≤2.15 mmol/L at 1 and 2 d in milk, n = 33; multiparous [Ca] ≤1.77 at 1 d in milk and ≤2.20 mmol/L at 4 d in milk, n = 34); or delayed SCH (dSCH; primiparous [Ca] >2.15 at 1 d in milk and ≤2.15 mmol/L at 2 d in milk, n = 19; multiparous [Ca] >1.77 at 1 d in milk and ≤2.20 mmol/L at 4 d in milk, n = 70). Evaluated outcomes were development of an adverse event [hyperketonemia (blood β-hydroxybutyrate concentration ≥1.2 mmol/L at 3, 5, 7, or 10 d in milk), metritis, displaced abomasum, or herd removal in the first 60 d in milk] and average milk yield per day across the first 10 wk of lactation. Multivariable Poisson regression was used to analyze the adverse event outcome and generalized linear mixed models for milk yield analysis. Primiparous cows with tSCH were no more likely to have an adverse event than NC cows [risk ratio = 1.3; 95% confidence interval (CI) = 0.5 to 3.2], whereas multiparous cows tended to have a higher risk for an adverse event than NC cows (risk ratio = 1.4; 95% CI = 0.9 to 2.1). However, pSCH cows were 4.1 (95% CI = 2.1 to 7.9, primiparous) and 1.8 (95% CI = 1.2 to 2.7, multiparous) times more likely, and dSCH cows 3.2 (95% CI = 1.5 to 7.0, primiparous) and 1.9 (95% CI = 1.3 to 2.6, multiparous) times more likely, to have an adverse event than NC cows. Primiparous and multiparous cows with tSCH made more milk per day than NC, pSCH, or dSCH cows across the first 10 wk of lactation. Primiparous cows averaged 28.5 ± 0.7, 31.9 ± 1.1, 29.7 ± 0.9, and 28.7 ± 1.2 kg/d, and multiparous cows averaged 44.6 ± 0.7, 49.1 ± 1.1, 46.4 ± 1.3, and 41.4 ± 0.9 kg/d for NC, tSCH, pSCH, and dSCH cows, respectively. Our results suggest that cows with tSCH adapt well to early lactation, develop fewer disease or removal events than pSCH or dSCH cows, and make more milk than NC, pSCH, or dSCH cows. Cows with pSCH or dSCH, regardless of parity group, are at an increased risk for early lactation disease or removal events.

Cow-level factors associated with subclinical hypocalcemia at calving in multiparous Jersey cows

The objective of our study was to identify cow-level factors associated with subclinical hypocalcemia at calving (SCH) in multiparous Jersey cows. A total of 598 Jersey and 218 Jersey × Holstein crossbreed cows from 2 commercial dairy herds were enrolled in a retrospective cohort study. Blood samples to determine total Ca concentration were collected from the coccygeal vessels at 3 h 19 min (±2 h 33 min) after calving. We used 2 serum Ca concentration thresholds to define SCH: <2.00 mmol/L (SCH-2.00) and <2.12 mmol/L (SCH-2.12). We evaluated the association of cow-level factors with SCH with multivariable Poisson regression models. Variables evaluated for association with SCH were herd; parity (2, 3, and ≥4); breed; previous lactation length and 305-d mature-equivalent milk yield; previous lactation first test milk yield and last test somatic cell count; lengths of calving interval, gestation, dry, and close-up periods; body condition and locomotion scores at calving; calving ease; and calf sex for singletons. We categorized continuous variables into quartiles (≤25th percentile, interquartile range and ≥75th percentile). The prevalence of SCH among Jersey cows was 40 (SCH-2.00) and 64% (SCH-2.12). Jersey cows of higher parity had greater risk of SCH-2.00 and SCH-2.12. The risk of SCH-2.12 was higher after birthing male calves. We also found a tendency for previous lactation length and previous lactation 305-d mature-equivalent milk yield effect to affect risk of SCH-2.12. The risk of SCH-2.12 was lower for cows that had a previous lactation length shorter than the 25th percentile compared with cows that had a previous lactation length within the interquartile range. The risk of SCH-2.12 was higher for cows that had a previous lactation 305-d mature-equivalent milk yield below the 25th percentile compared with cows that had a previous lactation 305-d mature-equivalent milk yield above the 75th percentile. Also, Jersey × Holstein crossbreed was associated with increased risk of SCH-2.00. In the multivariable analysis, we observed no association between SCH and previous lactation first test milk yield; last test somatic cell count; lengths of calving interval, gestation, dry, and close-up periods; body condition and locomotion scores at calving; and calving ease. Our study identified parity, breed, calf sex, previous lactation length, and previous lactation 305-d mature-equivalent milk yield as cow-level factors associated with SCH in multiparous Jersey cows.

Effect of induced hypocalcemia in nonlactating, nonpregnant Holstein cows fed negative DCAD with low, medium, or high concentrations of calcium

The main objective of this study was to determine how feeding different dietary calcium (Ca) concentrations in combination with a negative dietary cation-anion difference (DCAD) would affect the cow's response to induced hypocalcemia. We conducted an experiment with multiparous, nonlactating, nonpregnant Holstein cows fed a negative DCAD (average -18.2 across all diets) for 21 d with low (LC; 0.45% Ca; n = 5), medium (MC; 1.13% Ca; n = 6), or high (HC; 2.02% Ca; n = 6) concentrations of dietary Ca. Urine and blood samples were collected and urine pH measured daily during the 21-d feeding period prior to hypocalcemia challenge. Cows were then subjected to a controlled induction of hypocalcemia to determine how dietary Ca intake affected the response to a hypocalcemia challenge. On days 22, 23, and 24, hypocalcemia was induced with an intravenous infusion of 5% EGTA in 2 different cows from each treatment daily. During infusion, blood samples were collected every 15 min until 60% of prechallenge ionized calcium (iCa) concentrations were achieved. Samples were collected postinfusion at 0, 2.5, 5, 10, 15, 30, and every 30 min thereafter until 90% of prechallenge iCa was reached. Blood pH, hematocrit, and serum total Ca (tCa), sodium (Na), potassium (K), phosphorous (P), magnesium (Mg), and serotonin did not differ (P > 0.05) among treatments during the feeding period. Blood iCa (P = 0.04) and glucose (P = 0.03) were significantly elevated in HC compared with LC and MC cows during the feeding period. Urine pH was less than 6.0 in all cows, but was lowest in LC (P = 0.02) compared with MC and HC cows during the feeding period. Urine Ca, P, Mg, and deoxypyridinoline did not differ among treatments (P > 0.05). Cows fed HC maintained higher concentrations of iCa (P = 0.03) during the challenge period than MC (P = 0.04), and LC (P = 0.004), and required a longer time to reach 60% of whole blood iCa, and required more EGTA to reach 60% iCa than MC or LC cows (P = 0.01). Serum tCa decreased in all cows during infusion (P < 0.0001) but did not differ among treatments. Serotonin concentrations were elevated in MC cows compared with HC and LC cows during EGTA infusion (P = 0.05), suggesting an interdependent relationship between iCa and serotonin. Cows fed HC had a slower rate of decrease in iCa, but not tCa, when induced with hypocalcemia, indicating potential metabolic benefits of feeding higher dietary Ca in combination with a negative DCAD.

Associations of subclinical hypocalcemia with fertility in a herd of grazing dairy cows

The main objective was to assess the associations of subclinical hypocalcemia (SCH), diagnosed at parturition (SCH-0) and 7 d in milk (SCH-7), with fertility in a herd of grazing dairy cows. Additional objectives were to characterize Ca concentration on 0 and 7 d in milk (DIM), assessing the risk factors for SCH-0 and SCH-7 and also the relationship with health status (metritis, endometritis, subclinical ketosis, and culling). A prospective observational study was carried out in a dairy farm in Argentina. Holstein cows (n = 126) were body condition scored (BCS, 1-5) on -21 ± 3, 0, 7 ± 3, and 28 ± 7 DIM and blood was collected on 0 and 7 ± 3 DIM to determine Ca and β-hydroxybutyrate concentrations. Calcium concentrations <2.0 and <2.14 mmol/L were used to define SCH-0 and SCH-7, respectively. The associations of SCH with (1) the odds for pregnancy to first service (P1AI) and pregnancy by 100 DIM (P100) were evaluated by logistic models, (2) the services per pregnancy was evaluated by a Poisson regression model, and (3) the hazards of insemination and pregnancy were evaluated with proportional hazards regression models whereas median days from calving to first insemination and to pregnancy were estimated by Kaplan-Meier method. Additionally, Ca concentration was assessed by linear regression models, and the associations of SCH-0 and SCH-7 with the odds for metritis, endometritis, subclinical ketosis, and culling were evaluated by logistic models. Calcium concentrations were similar at 0 and 7 DIM (2.40 vs. 2.41 mmol/L, respectively); they were higher in cows calving in fall than in summer (2.58 vs. 2.24 mmol/L), and they also were higher in primiparous than in multiparous cows (2.53 vs. 2.28 mmol/L, respectively). The proportion of cows having SCH-0 and SCH-7 was 27.3 and 39.3%, respectively. Fall-calving cows had lower odds for SCH-0 [odds ratio (OR) = 0.31, 95% confidence interval (CI) = 0.12-0.86] than summer-calving cows, multiparous cows had higher odds for SCH-0 (OR = 3.96, 95% CI = 1.09-14.39) than primiparous cows, and cows with prepartum BCS ≥3.00 had higher odds for SCH-0 (OR = 4.03, 95% CI = 1.17-13.89) than in cows with BCS <3.00. Conversely, parity and prepartum BCS were not important predictors for SCH-7. Surprisingly, SCH-0 was not a risk factor for SCH-7. Cows with SCH-0 had lower odds for P1AI (OR = 0.26, 95% CI = 0.07-0.99) than normocalcemic cows, given that P1AI was 14 versus 38%, respectively. The hazard of first service was not associated with SCH-0 (hazard ratio = 1.03, 95% CI = 0.63-1.70) but cows with SCH-0 had lower hazard of pregnancy (hazard ratio = 0.39, 95% CI = 0.16-0.98) and took 32 d longer to get pregnant (105 vs. 73) than normocalcemic cows. Conversely, SCH-7 was not associated with fertility. Finally, SCH-0 and SCH-7 were associated with the odds for subclinical ketosis and metritis, respectively. In conclusion, SCH-0 but not SCH-7 is associated with reduced fertility in a herd of grazing dairy cows, but both were associated with health status.

Descriptive study for culling and mortality in five high-producing Spanish dairy cattle farms (2006-2016)

Background

High turnover rate in dairy farms due to culling and mortality is associated with poor animal welfare, an increase in production costs and lower economic benefits for the dairy farm. Understanding cow elimination better would help to formulate specific prevention measures and improve the efficiency of milk production in dairy farms. Culling and mortality data from five standard high-producing dairy farms in Spain were analysed over a period of 11 years (2006–2016). Data were collected by the same veterinary team and using the same software system.

Results

Significant between-herd differences in eliminated cows were observed for type of elimination (slaughter or death on the farm), age at elimination, cause of elimination, number of lactations and production parameters, such as total days in milk, life milk yield, litres per day of productive life and litres per day of life. Culling and mortality were higher during the hot season and for cows of second and third parities. Between-herd differences were observed. Reproductive disorders (30.2%) were the most frequent reason for elimination, with low production (23.4%) being the second most frequent reason. Accidents on the farm (7.7%) were a more frequent cause of elimination than metabolic diseases (7.2%), locomotor disorders (2.4%) and obstetrics (2.4%).

Conclusions

Veterinary teams or farmers’ associations can use culling and mortality information for benchmarking cow farms if data collection and analysis is standardised for comparability. The analysis of culling and mortality information should help farmers to improve efficiency.

Electronic supplementary material

The online version of this article (10.1186/s13028-018-0399-z) contains supplementary material, which is available to authorized users.

Effect of blood ionised calcium concentration at calving on fertility outcomes in dairy cattle

Clinical and subclinical hypocalcaemia are common in dairy cows, yet evidence in the literature assessing their impact on fertility is inconsistent. The aim of this prospective cohort study was to examine associations between blood ionised calcium concentration at calving and fertility outcomes in dairy cattle. Blood samples were taken from 137 Holstein cows from four commercial dairy herds within 24 hours of calving and analysed for blood ionised calcium using an Epocal Point of Care Analyser (Epocal, Ottawa, Canada). Data collected from routine veterinary fertility examinations and herd records were used to investigate the association of ionised calcium with the outcomes: time to first service, time to conception and endometritis. There were significant negative associations between blood ionised calcium concentration and time to first service (HR 1.33, P=0.001) and blood ionised calcium concentration and time to conception (HR 1.16, P=0.04). There was no significant association between blood ionised calcium concentration and endometritis. The results of this study imply that management policies that minimise the reduction in blood ionised calcium concentration in the periparturient dairy cow are likely to improve reproductive outcomes and should be considered as part of the multifactorial approach to optimising dairy cow fertility.

Proteomics and metabolomics characterizing the pathophysiology of adaptive reactions to the metabolic challenges during the transition from late pregnancy to early lactation in dairy cows

The transition from late pregnancy to early lactation is a critical period in a dairy cow's life due to the rapidly increasing drain of nutrients from the maternal organism towards the foetus and into colostrum and milk. In order to cope with the challenges of parturition and lactation, comprehensive adaptive reactions comprising the endocrine and the immune system need to be accomplished. There is high variation in this coping ability and both metabolic and infectious diseases, summarized as "production diseases", such as hypocalcaemia (milk fever), fatty liver syndrome, laminitis and ketosis, may occur and impact welfare, productive lifespan and economic outcomes. Proteomics and metabolomics have emerged as valuable techniques to characterize proteins and metabolite assets from tissue and biological fluids, such as milk, blood and urine. In this review we provide an overview on metabolic status and physiological changes during the transition period and the related production diseases in dairy cows, and summarize the state of art on proteomics and metabolomics of biological fluids and tissues involved in metabolic stress during the peripartum period. We also provide a current and prospective view of the application of the recent achievements generated by omics for biomarker discovery and their potential in diagnosis.

BIOLOGICAL SIGNIFICANCE

For high-yielding dairy cows there are several "occupational diseases" that occur mainly during the metabolic challenges related to the transition from pregnancy to lactation. Such diseases and their sequelae form a major concern for dairy production, and often lead to early culling of animals. Beside the economical perspective, metabolic stress may severely influence animal welfare. There is a multitude of studies about the metabolic backgrounds of such so called production diseases like ketosis, fatty liver, or hypocalcaemia, although the investigations aiming to assess the complexity of the pathophysiological reactions are largely focused on gene expression, i.e. transcriptomics. For extending the knowledge towards the proteome and the metabolome, the respective technologies are of increasing importance and can provide an overall view of how dairy cows react to metabolic stress, which is needed for an in-depth understanding of the molecular mechanisms of the related diseases. We herein review the current findings from studies applying proteomics and metabolomics to transition-related diseases, including fatty liver, ketosis, endometritis, hypocalcaemia and laminitis. For each disease, a brief overview of the up to date knowledge about its pathogenesis is provided, followed by an insight into the most recent achievements on the proteome and metabolome of tissues and biological fluids, such as blood serum and urine, highlighting potential biomarkers. We believe that this review would help readers to be become more familiar with the recent progresses of molecular background of transition-related diseases thus encouraging research in this field.