Parturition and Hypocalcemia Blunts Calcium Signals in Immune Cells of Dairy Cattle

Metabolic predictors of peri-partum diseases and their association with parity in dairy cows

The predictive values of plasma non-esterified fatty acid (NEFA), beta-hydroxybutyrate (BHB), cholesterol, albumin and calcium to predict risk of peripartum diseases in primiparous (PP) and multiparous (MP) Holstein cows was investigated. Besides it was assessed if the health status interacted with parity on body condition score and metabolic profiles during the transition period. Dairy cows (126 PP and 182 MP) from a commercial dairy free stall herd (loose-housing system) were weekly body condition scored and tail bled for metabolites determination from -3 to +4 weeks relative to calving. Peripartum diseases were diagnosed by a single trained veterinarian, while subclinical diseases (ketosis and hypocalcemia) were diagnosed at the laboratory. Cows were classified as healthy cows, cows with one event, or cows with two clinical events following a prospective observational cohort study, with only healthy cows enrolled at the beginning of the study. The largest incidence was for metritis (26.6%) followed by retained placenta (17.2%) and mastitis (15.2%) with no effect of parity, while subclinical hypocalcemia incidence was greater in MP than PP cows (43% vs 9.5%) respectively. In MP cows albumin concentrations were predictive for metritis at week -2 and for retained placenta at weeks -2 and -1, while cholesterol was predictive for mastitis at week -2, -1 and at calving. The interaction between health status and parity affected all metabolites during the transition period. This study showed a different evolution of metabolic profiles in healthy and sick cows during the transition according to parity, pointing out albumin and cholesterol as diseases predictors before calving.

Differential effects of a single dose of oral calcium based on postpartum plasma calcium concentration in Holstein cows

Our objectives were to determine (1) the effect of a single dose of an oral Ca bolus within 24 h after parturition on plasma Ca concentration, (2) the response of primiparous (PP) and multiparous (MP) cows to this supplementation strategy, and (3) differential responses based on plasma Ca at enrollment. For objective 1, cows from 1 commercial dairy in New York State were enrolled within 19 h after parturition (mean ± standard deviation = 8.3 ± 5.3 h) and randomized within parity group (first, second, and ≥third) to control [CON (n = 25); no placebo] or a single dose bolus treatment [BOL (n = 25); 3 oral Ca boluses supplying 54 to 64 g of Ca]. Plasma Ca was measured repeatedly between 1 and 24 h following treatment. For objectives 2 and 3, cows on 6 commercial farms in New York State were assigned to treatment as for objective 1 (CON, n = 1,973; BOL, n = 1,976). Herd records for health, reproduction, and Dairy Herd Improvement Association test day milk production were collected. Mixed effect multivariable models were developed using repeated measures ANOVA, Poisson regression, or proportional hazard models. Objective 2 analyses considered treatment with periparturient risk factors, whereas objective 3 analyses also considered Ca status. No difference was observed for plasma Ca between 1 and 24 h after treatment. Primiparous cows assigned to BOL calving at >712 d old had decreased risk of one or more health disorders [≤30 d in milk; risk ratio (RR) = 0.65, 95% confidence interval (CI) = 0.51 to 0.84] and those with body condition score >3.5 responded to BOL with increased milk production (CON = 31.7 ± 1.1, BOL = 35.1 ± 1.1 kg/d), as did those with days carried calf >277 (CON = 31.9 ± 1.0, BOL = 34.7 ± 1.0 kg/d). Reduced risk of one or more health disorders was observed in parity ≥3 (RR = 0.85, 95% CI = 0.81 to 0.89) and MP cows with body condition score >3.5 (retained placenta; RR = 0.70, 95% CI = 0.58 to 0.84) or that were lame (displaced abomasum; RR = 0.49, 95% CI = 0.32 to 0.75). Differential responses for PP cows by Ca status were minimal. For MP cows with low plasma Ca, BOL decreased risk of additional Ca treatment (≤1.8 mmol/L; RR = 0.57, 95% CI = 0.40 to 0.80) as well as risk of one or more health disorders (≤2.15 mmol/L; RR = 0.90, 95% CI = 0.85 to 0.95). Supplementation with a single oral dose of Ca could be targeted to periparturient risk groups for improved health. Calcium status did not differentiate responses of PP cows, but MP cows with low Ca at parturition had improved health status when supplemented.

Metabolic and mineral conditions of retained placenta in highly productive dairy cows: pathogenesis, diagnostics and prevention – a review

The time around calving in highly productive dairy cows is a critical period in terms of their metabolism, which is connected with high demands of the foetus as well as with the onset of lactation. Retained placenta in cows may have multifactorial aetiology, but in herds which are free from infectious diseases, the most important reasons are; periparturient metabolic changes and disturbances to the internal balance and stress. During the periparturient period, the most important factor causing immune suppression and hypotony of uterus in cows is metabolic stress due to hormonal and nutritional factors, including metabolic fluctuations, negative energy balance, as well as shortage of proteins, minerals, vitamins and antioxidants. This metabolic stress as a result of an imbalance in the internal metabolic homeostasis activates the hypothalamic-pituitary-adrenocortical axis (HPA) and increases serum corticosterid (cortisol) concentration, especially on the day of calving. Cortisol is a powerful immune suppressive factor that causes depression of leukocyte proliferation and their functions. The periparturient metabolic stress may also stimulate the production of catecholamines, especially adrenalin. Elevated levels of adrenalin activate adrenoreceptors of the myometrium, which in turn cause hypotony or atony of the uterus at calving in cows. Elevated levels of cortisol and adrenalin may significantly inhibit the rejection and expulsion of foetal membranes in cows, resulting in an increased incidence of their retention. These important mechanisms for placental retention in highly productive dairy cows often have primary nutritional metabolic aetiology, but they also occur during secondary metabolic disturbances and metabolic stress during calving. This metabolic and immunological aetiology and pathogenesis of retained placenta usually occur in highly productive periparturient cows on dairy farms in the absence of bovine infectious diseases, which can couse placentitis, stillbirth and the infectious origin of foetal membrane retention. The paper presents the most important metabolic, mineral and immunological disturbances as conditions for retained placenta in dairy cows. It also shows different methods of herd monitoring, important examples of clinical and laboratory diagnostics, and methods of nutritional and veterinary prevention of this health problem in dairy cows.

Plasma calcium concentrations are decreased at least 9 hours before parturition in multiparous Holstein-Friesian cattle in a herd fed an acidogenic diet during late gestation

Calcium homeostatic mechanisms are challenged in periparturient multiparous dairy cattle due to the rapid transport of large amounts of calcium into the mammary gland associated with colostrogenesis, resulting in decreased plasma total calcium concentration ([Ca]). An unresolved issue is the timing of the decrease in plasma [Ca] relative to the time of parturition, with the consensus view being that plasma [Ca] does not decrease until after parturition. The objective of this study, therefore, was to characterize the change in plasma [Ca] over time in periparturient dairy cattle. Plasma and mid-stream urine samples were collected daily starting 3 d before calving from 104 periparturient Holstein-Friesian dairy cows in a herd fed an acidogenic total mixed ration during the late dry period. Mixed-models ANOVA and linear and multivariable regression analyses were conducted. Plasma [Ca] decreased in periparturient multiparous cattle (n = 70) but not in primiparous cattle (n = 34). Compared with mean values approximately 72 h before parturition ([Ca] = 2.32 mmol/L), mean plasma [Ca] in multiparous cattle first decreased at 9 h before parturition (2.13 mmol/L) and remained decreased for up to 48 h after parturition, with the lowest mean value (1.87 mmol/L) occurring at 28 h after parturition. Mean 24-h urine Ca excretion was calculated to decrease by 3.5 to 3.8 g in periparturient multiparous cattle. Regression analysis indicated that plasma [Ca] in the 12-h period before and 24-h period after parturition was strongly and negatively associated with age but was also negatively associated with milk production indices. We conclude that plasma [Ca] was decreased at least 9 h before parturition in multiparous dairy cattle fed an acidogenic diet in late gestation, and that calcium homeostasis was disrupted for 2 to 3 d around parturition.

Parâmetros clínicos, hematológicos e bioquímicos de novilhas com hipocalcemia subclínica pré-parto suplementadas com dieta aniônica

RESUMO A hipótese do presente estudo consiste em que uma dieta aniônica prolongada acarretaria uma mobilização mais rápida do cálcio sanguíneo. O objetivo proposto foi avaliar parâmetros clínicos, hematológicos e bioquímicos de novilhas, com hipocalcemia subclínica, submetidas a diferentes períodos de fornecimento de dieta aniônica no pré-parto. Foram utilizadas nove novilhas da raça Holandês induzidas à hipocalcemia subclínica no pré-parto, divididas em três grupos: G0 = sem dieta aniônica antes da indução; G11 = 11 dias de dieta aniônica pré-indução; e G15 = 15 dias de dieta aniônica pré-indução. Foi realizado exame clínico antes e depois da indução, e avaliaram-se cálcio total e ionizado, magnésio e albumina nos dias -2, 0, 1, 2 e 3 (dia 0 = momento da indução) e parâmetros hematológicos nos dias 0, 1, 2 e 3. O G11 apresentou maiores concentrações de cálcio total e ionizado que o G0 e maiores níveis de cálcio total que o G15 (P<0,01). O magnésio teve maiores valores no G15 quando comparado aos outros grupos (P<0,01). O G0 apresentou os maiores valores de monócitos e neutrófilos bastonetes (P<0,01). A dieta aniônica por 11 dias é suficiente para manter a homeostase do cálcio e a resposta leucocitária em novilhas desafiadas a uma diminuição do cálcio sanguíneo.

Short communication: Relationship between methods for measurement of serum electrolytes and the relationship between ionized and total calcium and neutrophil oxidative burst activity in early postpartum dairy cows

The objectives of this study were to (1) compare a test for serum measurement of total Ca (tCa), Mg, and P (VetTest Chemistry Analyzer, IDEXX Laboratories Inc., Westbrook, ME) to reference methods (spectrophotometric assays on a Beckman Coulter 640e automated clinical chemistry analyzer; Beckman Coulter, Brea, CA), (2) determine the relationship between ionized Ca (iCa) and reference method tCa in the immediate postpartum period, and (3) assess the relative value of these blood Ca indices as predictors of neutrophil oxidative burst activity. Samples were collected from multiparous Holstein cows (n = 33) over the first 5 d in milk. A total of 183 samples for objective 1 and 181 samples for objective 2 were available. Neutrophil oxidative burst activity was assessed once between 2 and 5 d in milk (n = 29). Linear regression demonstrated strong relationships between serum tCa, Mg, and P concentrations measured by the VetTest compared with the reference method. Bland Altman analysis indicated that the VetTest values were higher than the reference method by 0.22 mmol/L for tCa, 0.12 mmol/L for Mg, and 0.16 mmol/L for P. Compared with hypocalcemia categorized at ≤2.0 or ≤2.125 mmol/L with the reference method tCa, thresholds for the VetTest measured tCa of ≤2.23 mmol/L (sensitivity = 87%, specificity = 89%) or ≤2.30 mmol/L (sensitivity = 86%, specificity = 96%) could be used. The relationship between whole-blood iCa and reference method serum tCa differed by sampling time point after calving. Compared with identification of hypocalcemia with serum tCa measurements from the reference method (thresholds of ≤2.0 and 2.125 mmol/L), a whole-blood iCa threshold of ≤1.17 mmol/L resulted in the highest combined sensitivities (94 and 82%) and specificities (80 and 94%) at either threshold. Ionized Ca measurements were more consistently related to outcomes of neutrophil oxidative burst activity measured in vitro. The VetTest measurements of serum tCa reliably identified hypocalcemia when thresholds were adjusted to account for the bias of the test. The variation in the relationship between iCa and reference method tCa in the days following parturition suggest that these measures cannot be used interchangeably as indicators of Ca status. The more consistent associations between iCa and in vitro measures of neutrophil function, compared with tCa, indicated that this may be a more sensitive predictor of functional outcomes associated with postpartum Ca status.

Mineral profile of crossbred F 1 Holstein x Gyr dairy cows during the transition period in summer and winter

ABSTRACT The transition period is often a great challenge for dairy cows and mineral imbalances are frequent. With the aim to better understand the mineral profile of F1 Holstein x Gyr dairy cows and their performances under the different conditions of summer and winter, we collected blood samples to measure calcium, magnesium and phosphorus. Samplings were performed during summer and winter, on 15 and 13 pluriparous F1 Holstein x Gyr dairy cows, respectively. Blood sampling started 4 weeks prior to the expected calving date until 30 days postpartum. The mean concentrations of all three minerals had a different pattern during the transition period in each season, representing the interaction time x season. Calcium concentration was lower in winter and more animals suffered from subclinical hypocalcemia (100%) then in summer (38.46%). Magnesium concentration was also lower in winter and 46.67% of animals had hypomagnesemia, contributing for the higher hypocalcemia frequency observed in the same season. A high proportion of animals had hyperphosphatemia what can represent an environmental problem and more attention should be given to it. The high frequency of animals with subclinical hypocalcemia is alarming once that can lead to greater consequences.

Associations between subclinical hypocalcemia and postparturient diseases in dairy cows

Dairy cows suffer blood Ca losses as lactation begins and might be affected by hypocalcemia in its clinical (total serum Ca concentration <1.50 mM) or subclinical form (total serum Ca concentration ≤2.14 mM). Several studies have suggested that hypocalcemia is associated with different health problems of the cow but results from different studies are not consistent. The objective of this study was to assess potential associations between subclinical hypocalcemia (SCHC) and displaced abomasum, intramammary infections, metritis, retained placenta, and ketosis. Also, the associations between SCHC and milk yield and reproductive function were evaluated. After discarding cows (32) with clinical hypocalcemia, a total of 764 cows from 6 different commercial farms were enrolled in this study. Blood samples were collected at 24 to 48 h postcalving and analyzed for total Ca concentration. Odds ratios of the different afflictions potentially associated with SCHC were calculated. Seventy-eight percent of the analyzed cows incurred SCHC. The occurrence of displaced abomasum, ketosis, retained placenta, and metritis was 3.7, 5.5, 3.4, and 4.3 times more likely, respectively, in cows that had SCHC than in cows with normocalcemia. Furthermore, the risk of incurring retained placenta or metritis increased in multiparous cows as serum Ca concentrations decreased compared with that in primiparous cows. Normocalcemic cows, independent of parity, were more likely to show their first estrus sooner after calving than SCHC cows, but no correlation was found between SCHC and other reproductive parameters. Different serum Ca concentration cutoffs were identified for several postpartum afflictions (≤1.93, ≤2.05, ≤2.05, and ≤2.10 mM for ketosis, retained placenta, metritis, and displaced abomasum, respectively). In conclusion, SCHC, defined as serum Ca ≤2.14 mM, is a frequent illness affecting the majority of the dairy cows with important repercussions on health. However, if SCHC were to be used to predict postpartum disease, different serum Ca cutoff points are likely to be needed because best predictive cutoff values varied among postpartum ketosis, displaced abomasum, retained placenta, and metritis.

Effects of rumen-protected methionine and choline supplementation on vaginal discharge and uterine cytology of Holstein cows

Methionine is one of the most limiting amino acids in dairy diets and low feed intake around the time of calving could lead to decreased synthesis of phosphatidylcholine. An alternative pathway for phosphatidylcholine is to have choline as a precursor. The objective of this study was to determine the effects of feeding rumen-protected methionine and choline pre – and postpartum on reproduction of Holstein cows. Seventy-two Holstein cows were randomly assigned to four treatments from 21 days before calving to 30 days in milk (DIM): supplementation with rumen-protected methionine (MET; n = 20, received 0.08% of the dry matter (DM) of the diet/d as methionine, Smartamine M® to a Lys:Met = 2.9:1), rumen-protected choline (CHO; n = 17, received 60 g/d choline, Reassure), both rumen protected methionine and choline (MIX; n = 19, received 0.08% of the DM of the diet/d as methionine to a Lys:Met = 2.9:1 and 60 g/d choline), or no supplementation to serve as control (CON; n = 16, fed total mixed ration with a Lys:Met = 3.5:1). Cows were evaluated at 4, 7, 10, 13, 15, 17, and 30 d after calving for the presence of secretion using the Metricheck® device. On 15, 30, and 72 d after calving, the uterine endometrium of all cows was sampled using a cytological brush and streaked onto slides for analysis of the presence of polymorphonuclear neutrophils (PMN). We hypothesized that cows supplemented with methionine would have lower metricheck smell scores and lower rates of PMN than non-supplemented cows. On d 30, a treatment difference was detected using the metricheck score and smell (P < 0.04), with treatment MIX (score = 0.38) having a lower score than CHO (score = 2.11). Supplementing cows with rumen-protected methionine may have a beneficial effect on cows’ uterine health.

Prepartal Energy Intake Alters Blood Polymorphonuclear Leukocyte Transcriptome During the Peripartal Period in Holstein Cows

In the dairy industry, cow health and farmer profits depend on the balance between diet (ie, nutrient composition, daily intake) and metabolism. This is especially true during the transition period, where dramatic physiological changes foster vulnerability to immunosuppression, negative energy balance, and clinical and subclinical disorders. Using an Agilent microarray platform, this study examined changes in the transcriptome of bovine polymorphonuclear leukocytes (PMNLs) due to prepartal dietary intake. Holstein cows were fed a high-straw, control-energy diet (CON; NE_L = 1.34 Mcal/kg) or overfed a moderate-energy diet (OVE; NE_L = 1.62 Mcal/kg) during the dry period. Blood for PMNL isolation and metabolite analysis was collected at −14 and +7 days relative to parturition. At an analysis of variance false discovery rate <0.05, energy intake (OVE vs CON) influenced 1806 genes. Dynamic Impact Approach bioinformatics analysis classified treatment effects on Kyoto Encyclopedia of Genes and Genomes pathways, including activated oxidative phosphorylation and biosynthesis of unsaturated fatty acids and inhibited RNA polymerase, proteasome, and toll-like receptor signaling pathway. This analysis indicates that processes critical for energy metabolism and cellular and immune function were affected with mixed results. However, overall interpretation of the transcriptome data agreed in part with literature documenting a potentially detrimental, chronic activation of PMNL in response to overfeeding. The widespread, transcriptome-level changes captured here confirm the importance of dietary energy adjustments around calving on the immune system.

Judicious use of prophylactic antimicrobials to reduce abdominal surgical site infections in periparturient cows: part 1 - a risk factor review

Surgical site infections (SSI) are an uncommon, but significant, consequence of surgical interventions. There are very few studies investigating SSI risk in veterinary medicine, and even fewer in cattle, despite the fact that major surgeries are commonly conducted on livestock. Furthermore, the suboptimal conditions under which such surgeries are frequently performed on livestock could be considered an important risk factor for the development of SSIs. With increasing public concern over the contribution of veterinary-prescribed antimicrobials to the emergence of antimicrobial-resistant bacteria in people, there is widespread scrutiny and criticism of antimicrobial use in livestock production medicine systems. While the causal link between antimicrobial resistance in livestock and people is heavily debated, it is clear that the prevalence of antimicrobial resistance, in any population, is closely correlated with the antimicrobial 'consumption' within that population. As the veterinary profession explores ways of addressing the emergence and selection of antimicrobial-resistant bacteria in food-producing animals, there is a need for veterinarians and producers to carefully consider all areas of antimicrobial use, and employ an evidence-based approach in designing appropriate clinical protocols. This paper aims to review current knowledge regarding the risk factors related to abdominal SSI in periparturient cows, and to encourage practitioners to judiciously evaluate both their standard operating procedures and their use of antimicrobials in these situations. In a second paper, to be published in a subsequent issue of Veterinary Record, these principles will be used to provide specific evidence-based recommendations for antimicrobial use in bovine abdominal surgery.

A study of the incidence of milk fever in Jersey and Holstein cows at a dairy farm in Beatrice, Zimbabwe

A 3-year prospective study investigated the incidence of milk fever in Jersey and Holstein cows at a commercial dairy farm in Beatrice, Zimbabwe. The overall incidence of milk fever at the farm was 7.98%. Incidence of milk fever in Jerseys (14.78%) was significantly higher (p < 0.05) than that in Holsteins (4.82%). Incidence of milk fever in Jerseys beyond their fourth parity (24.85%) was significantly higher (p < 0.05) than that in Jerseys in their second (5.90%), third (6.49%) and fourth (8.73%) parities. Incidence of milk fever in Holsteins beyond their fourth parity (8.29%) was significantly higher (p < 0.05) than that in Holsteins in their second (1.43%), third (1.82%) and fourth (2.91%) parities. No significant difference existed in milk fever incidences between the second, third and fourth parities in either Jersey or Holstein cows. Incidence of milk fever in Jersey cows producing over 6114 litres per 305-day lactation (27.07%) was significantly higher than that in Jerseys producing less than 6114 litres of milk per 305-day lactation (p < 0.05). Incidence of milk fever in Holsteins producing more than 9149 litres per 305-day lactation (10.49%) was significantly higher than that in Holsteins producing less than 9149 litres of milk per 305-day lactation (p < 0.05). No significant difference existed between incidences of milk fever between the first, second and third quartile producers (p > 0.05) in either Jersey or Holstein cows. This study confirms that the risk of developing milk fever is higher in Jerseys and also increases with increasing parity and higher levels of milk production in both breeds, thus advocating for special considerations when dairy cows fit these criteria.

Effect of oral calcium administration on the cure and reproductive performance of Holstein cows diagnosed with puerperal metritis

Our objective was to evaluate the effect of oral calcium administration on clinical cure, survival, subsequent presentation of peripartal health disorders, and reproductive performance of Holstein cows diagnosed with puerperal metritis (PM) under certified organic management. A second objective was to evaluate the metabolic status at calving and at the time of PM diagnosis (d 0) in affected and matched healthy cows. Cows diagnosed with PM (n = 200) were assigned randomly to receive 1 of 2 treatments: (1) control received 3.75 mL of Optimum UterFlush [Van Beek Natural Science, Orange City, IA, containing yucca extract, cinnamaldehyde, thymol, and a proprietary blend of carvacrol (4-isopropyl-2-methylphenol, at 0.47 g/mL)] diluted in 117 mL of distilled water by intrauterine infusion, administered every other day for a total of 3 treatments (n = 100); (2) calcium-supplemented (CA) received the same intrauterine treatment plus 6 oral capsules providing calcium ('O' Cal-D Cap, Bio-Vet Inc., Barneveld, WI; 7.5-9.0 g of Ca/capsule) once per day, for 3 consecutive days after diagnosis of PM. All cows received hypertonic saline solution (500 mL of 7.2% solution i.v. once), dextrose (500 mL of 50% solution i.v. once), and oral aspirin (5 boluses/d for 3 d). Outcome variables included fever, presence of fetid vaginal discharge, and uterine score at d 6 and 14 after diagnosis, survival at 30 and 100 d in milk, reproductive performance, and incidence of other health disorders after PM. A group of 200 control healthy cows (CH) was matched with PM cows at d 0, and calcium and fatty acid serum concentrations were determined at calving and at the day of diagnosis of PM (d 0). Calcium status was also assessed in PM cows at d 1, 2, 3, and 6 after diagnosis. Treatment effects were tested by logistic regression, repeated measures analysis, and ANOVA. Average calcium serum concentrations at d 0 were lower in PM cows (1.57 mmol/L) compared with CH cows (2.10 mmol/L). In PM cows, calcium concentrations at d 1, 2, 3, and 6 after diagnosis were significantly higher in the CA group. Fatty acid serum concentrations at calving and at d 0 were higher in PM cows compared with CH cows (0.48 vs. 0.37 mmol/L and 0.49 vs. 0.35 mmol/L, for calving and d 0). No effect was observed for calcium administration on health and survival outcomes. However, the proportion of cows inseminated by 150 d in milk was greater for CA compared with control cows (66 vs. 55%). In conclusion, supplementing oral calcium at the time of diagnosing PM had no effect on health. High fatty acid concentrations at calving were significant risk factors for occurrence of PM. Furthermore, cows affected with PM had lower calcium and higher fatty acid concentrations than CH cows at d 0.

Effect of serum calcium status at calving on survival, health, and performance of postpartum Holstein cows and calves under certified organic management

The study objective was to assess the effect of hypocalcemia (HYPO; ≤2.0 mmol/L) of the dam at calving on survival, health, and performance of lactating dairy cows and their calves under certified organic management. Prepartum dairy cows (primiparous, n = 445; multiparous, n = 328) from 1 dairy herd were monitored (prepartum pen) for imminent signs of parturition (appearance of amniotic sac outside the vulva) until birth. All calves were subject to the same newborn care, colostrum management, and failure of passive transfer assessment (serum total protein ≤5.5 mg/dL). Serum total calcium of cows was determined in samples taken within 2 h after calving. To define HYPO cows after calving, a cut-point of total serum Ca concentration with optimal sensitivity and specificity to predict metritis or calf diarrhea was established by using the receiver operator characteristic. The effect of HYPO on survival (died or culled within 60 DIM), health status, and pregnancy per artificial insemination (PAI) for first services of lactating cows were analyzed using the GLIMMIX procedure of SAS. Additionally, the effect of HYPO at calving on days in milk (DIM) at first service (DIMFS), milk yield (kg), milk components (percent fat and protein), and somatic cell count were analyzed for the first 3 Dairy Herd Improvement Association (DHIA) tests using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). The effect of parity (primiparous and multiparous), body condition score at calving, and manure hygiene score at calving were also included in the statistical models. The effect of HYPO at calving on calf survival, serum total protein, and diarrhea within 10 d of age were assessed using GLIMMIX procedure of SAS. The overall prevalence of HYPO was 14.6% (2.7% for primiparous and 30.8% for multiparous cows). Cows experiencing HYPO at calving had greater proportion of metritis (25.1 vs. 14.7%) and culling within 60 DIM (15.9 vs. 6.8%) compared with non-HYPO cows, respectively. For the first 3 DHIA tests, milk yield and components did not differ between HYPO and non-HYPO cows. The DIMFS as well as proportion of cows with dystocia, births of twins, mastitis, and PAI at first service were not different between HYPO and non-HYPO cows. The proportion of stillbirth, weaned calves, and serum total protein did not differ between calves born from HYPO or non-HYPO cows. However, calves born from HYPO cows had greater incidence of diarrhea (49%) than calves born (33.3%) from non-HYPO cows. Findings from the present study showed that HYPO at calving had significant health implications for both dams and calves under certified organic management.

Association between subclinical hypocalcemia in the first 3 days of lactation and reproductive performance of dairy cows

The objective of this study was to determine the effects of subclinical hypocalcemia on reproductive performance in dairy cows. In a prospective cohort study, 97 cows on 2 dairy farms with automatic milking systems were monitored for subclinical hypocalcemia. Animals were enrolled 7 ± 3 days prior to estimated calving date and three parity groups were defined based on the lactation that the animals were going to start: lactation = 1, lactation = 2, and lactation ≥3. Serum calcium concentration (Ca) was measured in all animals in the first 3 DIM and subclinical hypocalcemia (SCH) was defined as Ca ≤ 8.6 mg/dL; animals that presented a low Ca level during all 3 days were classified as chronic SCH (cSCH). Return to cyclicity during the voluntary waiting period was analyzed based on weekly progesterone concentrations measured in serum. Information on reproductive outcomes (i.e., number of breedings, pregnancy status, days open, etc.), were collected from on-farm software after all study cows had completed their study period. Chronic SCH was present in all parity groups with higher incidence in multiparous animals (20% of parity = 1, 32% of parity = 2; and 46% of parity ≥ 3 animals). The cSCH animals took longer to show active ovaries when compared to eucalcemic and SCH animals. In a multivariable Cox's Proportional Hazard model animals with normal Ca were 1.8 times more likely to return to cyclicity by the end of the voluntary waiting period when compared to cSCH animals. Animals with cSCH also had 0.27 odds of being pregnant at first service compared to eucalcemic cows when analyzed by multivariable logistic regression. Subclinical hypocalcemia had a negative effect on return of ovarian function during the voluntary waiting period and decreased the odds of pregnancy at first service. Those cows with cSCH had an even more pronounced impaired reproductive function than those with one subclinical measurement.

Increased serum serotonin improves parturient calcium homeostasis in dairy cows

Hypocalcemia in dairy cows is caused by the sudden increase in calcium demand by the mammary gland for milk production at the onset of lactation. Serotonin (5-HT) is a key factor for calcium homeostasis, modulating calcium concentration in blood. Therefore, it is hypothesized that administration of 5-hydroxy-l-tryptophan (5-HTP), a 5-HT precursor, can increase 5-HT concentrations in blood and, in turn, induce an increase in blood calcium concentration. In this study, 20 Holstein dairy cows were randomly assigned to 2 experimental groups. Both groups received a daily i.v. infusion of 1 L of either 0.9% NaCl (C group; n = 10) or 0.9% NaCl containing 1 mg of 5-HTP/kg of BW (5-HTP group, n = 10). Infusions started d 10 before the estimated parturition and ceased the day of parturition, resulting in at least 4 d of infusion (8.37 ± 0.74 d of infusion). Until parturition, blood samples were collected every morning before the infusions, after parturition samples were taken daily until d 7, and a final sample was collected on d 30. Milk yield was recorded during this period. No differences between groups were observed for blood glucose, magnesium, and β-hydroxybutyrate. Cows receiving the 5-HTP infusion showed an increase in fatty acid concentrations from d -3 to -1 before parturition. Serum 5-HT concentrations were increased at d -4 related to parturition until d 5 postpartum in the 5-HTP group compared with the C group. In addition, cows from the 5-HTP group had increased 5-HT concentrations in colostrum, but not in mature milk, on d 7 postpartum. Serum calcium concentrations decreased in both groups around parturition; however, calcium remained higher in the 5-HTP group than in controls, with a significant difference between groups on d 1 (1.62 ± 0.08 vs. 1.93 ± 0.09 mmol/L in control and 5-HTP groups, respectively) and d 2 (1.83 ± 0.06 vs. 2.07 ± 0.07 mmol/L in control and 5-HTP groups, respectively). Additionally, colostrum yield (first milking) was lower in the 5-HTP group compared with the C group, but without consequences on colostrum IgG concentrations. Milk yield did not differ between groups during the rest of the experiment. The study data were consistent with the concept that infusion of 5-HTP to dairy cows increases blood 5-HT concentrations, which in turn is a significant regulatory component in the chain of effectors that affect calcium status around parturition, hence the occurrence of clinical or subclinical hypocalcemia.

A weekly postpartum PGF2α protocol enhances uterine health in dairy cows

Postpartum uterine health in dairy cows is crucial for the maintenance of good reproductive performance. In order to improve uterine health and reduce puerperal intrauterine infection, 608 Holstein cows received a weekly PGF_2α protocol (3 i.m. injections of PGF_2α at 7, 14 and 21 d postpartum). For comparison, 593 cows in the control group received injections of sterile saline at the same time. Uterine score at 14 d postpartum, the prevalence of endometritis at 21-27 d postpartum, and subsequent reproduction performance was evaluated. Cows in the treated group exhibited higher tonicity (P<0.05) of the uterus, with less prevalence of endometritis (10.4%, 63/608 vs. 34.6%, 205/593; P<0.001), and required shorter time to the first AI postpartum (67.5±3.4 d vs. 84.4±3.7 d, P<0.05) and to pregnancy (114.5±5.4 d vs. 131.4±5.8 d, P<0.05). In conclusion, the present study demonstrated that uterine health in Holstein cows can be promoted while puerperal infection can be suppressed by this weekly postpartum PGF_2α protocol.

Differentially expressed serum proteins associated with calcium regulation and hypocalcemia in dairy cows

Objective

Hypocalcemia is an important metabolic disease of dairy cows during the transition period, although the effect of hypocalcemia on biological function in dairy cows remains unknown.

Methods

In this study, proteomic, mass spectrum, bioinformatics and western blotting were employed to identify differentially expressed proteins related to serum Ca concentration. Serum samples from dairy cows were collected at three time points: 3rd days before calving (day −3), the day of calving (day 0), and 3rd days after calving (day +3). According to the Ca concentration on day 0, a total of 27 dairy cows were assigned to one of three groups (clinical, subclinical, and healthy). Samples collected on day −3 were used for discovery of differentially expressed proteins, which were separated and identified via proteomic analysis and mass spectrometry. Bioinformatics analysis was performed to determine the function of the identified proteins (gene ontology and pathway analysis). The differentially expressed proteins were verified by western blot analysis.

Results

There were 57 differential spots separated and eight different proteins were identified. Vitamin D-binding protein precursor (group-specific component, GC), alpha-2-macroglobulin (A2M) protein, and apolipoprotein A-IV were related to hypocalcemia by bioinformatics analysis. Due to its specific expression (up-regulated in clinical hypocalcemia and down-regulated in subclinical hypocalcemia), A2M was selected for validation. The results were consistent with those of proteomic analysis.

Conclusion

A2M was as an early detection index for distinguishing clinical and subclinical hypocalcemia. The possible pathogenesis of clinical hypocalcemia caused by GC and apolipoprotein A-IV was speculated. The down-regulated expression of GC was a probable cause of the decrease in calcium concentration.

The association of plasma glucose, BHBA, and NEFA with postpartum uterine diseases, fertility, and milk production of Holstein dairy cows

The objective of this study was to investigate the association between the metabolic indicators such as nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and glucose during the transition period and the development of uterine diseases. In total, 181 Holstein dairy cows were enrolled in the study. Plasma glucose, NEFA, and BHBA concentrations were measured at -50, -6, 3, 7, and 14 days relative to parturition. All cows enrolled in the study were evaluated for retained placenta (RP), metritis, and endometritis. Metritis and RP were diagnosed and treated by trained farm personnel. Clinical endometritis was evaluated by a veterinarian at 35 days in milk using a Metricheck device. We found plasma glucose concentration to be associated with the occurrence of metritis and clinical endometritis. Moreover, cows with an increased calving-to-conception interval (>150 days) presented higher plasma glucose concentrations than cows that became pregnant within the first 150 days, whereas BHBA and NEFA were not associated with the occurrence of any uterine disorder. Receiver operating characteristic (ROC) curves were used in an attempt to determine the cow-level critical thresholds for the occurrence of metritis, and endometritis. In addition, pairwise comparisons of area under the curve (AUC) of ROC curves for the critical thresholds for glucose, BHBA, and NEFA predicting the same uterine disease were performed. Glucose at 3 days in milk was the best predictor for metritis and endometritis diagnosis, with AUC values of 0.66 and 0.67, respectively. Multivariable logistic regressions were performed and showed that cows with higher levels of glucose at Day 3 were at 6.6 times higher odds of being diagnosed with metritis, and 3.5 times higher odds of developing clinical endometritis, compared with cows with lower glucose levels. Finally, a simple linear regression analysis demonstrated a negative correlation between daily milk yield in the first and second weeks of lactation and plasma glucose concentrations measured at Days 7 and 14, respectively. Concentrations of NEFA and BHBA were not found to be associated with milk production.

Genetic parameters of subclinical macromineral disorders and major clinical diseases in postparturient Holstein cows

The main objective of this study was to assess the genetic parameters of subclinical disorders associated with subclinical hypocalcemia, hypophosphatemia, subclinical hypomagnesemia, hypokalemia, and hyperphosphatemia, as well as major clinical diseases after calving in Holstein cows. The secondary objective was to estimate the associated genetic and phenotypic correlations among these subclinical and clinical conditions after calving in Holstein cows. The study was conducted in 9dairy herds located in Northern Greece. None of the herds used any kind of preventive measures for milk fever (MF). A total of 1,021 Holstein cows with pedigree information were examined from November 2010 until November 2012. The distribution across parities was 466 (parity 1), 242 (parity 2), 165 (parity 3), and 148 (parity 4 and above) cows. All cows were subjected to a detailed clinical examination and blood was sampled on d 1, 2, 4, and 8 after calving. Serum concentrations of Ca, P, Mg, and K were measured in all samples, whereas β-hydroxybutyrate (BHB) was measured only for d 8. The final data set included 4,064 clinical and 16,848 biochemical records (4,020 Ca, 4,019 P, 4,020Mg, 3,792K, and 997 BHB). Data of 1,988 observations of body condition score at d 1 and 8 were also available. All health traits were analyzed with a univariate random regression model. The genetic analysis for macromineral-related disorders included 986 cows with no obvious signs of MF (35 cows with MF were excluded). Analysis for other health traits included all 1,021 cows. A similar single record model was used for the analysis of BHB. Genetic correlations among traits were estimated with a series of bivariate analyses. Statistically significant daily heritabilities of subclinical hypocalcemia (0.13-0.25), hypophosphatemia (0.18-0.33), subclinical hypomagnesemia (0.11-0.38), and hyperphosphatemia (0.14-0.22) were low to moderate, whereas that of hypokalemia was low (0.08-0.10). The heritability of body condition score was 0.20±0.10. Statistically significant daily heritabilities of clinical diseases were those of MF (0.07-0.11), left displaced abomasum (0.19-0.31), and mastitis (0.15-0.41). Results suggest that these health disorders are heritable traits and could be minimized with proper genetic selection. Statistically significant phenotypic correlations were estimated for the first time between macromineral concentrations and almost all transition cow metabolic and infectious health disorders.

Periparturient immunosuppression and strategies to improve dairy cow health during the periparturient period

Common health problems observed during peripartum include milk fever, mastitis, fatty liver disease, ketosis, dystocia, retained placenta, metritis, hypomagnesaemia and abomasal displacements. The increased incidence of health problems observed during the periparturient period can be partly attributed to suboptimal immune responses. Factors contributing to decreased periparturient immunity include the act of parturition itself, impaired leukocytic activity, effects of colostrogenesis and lactogenesis, and associated hypocalcemia and negative energy balance. Nutritional and other management strategies represent a relevant short-term strategy aimed at improving the health and welfare of the transitioning cow. Additionally, it is important to consider improving the health of dairy herds through the genetic selection of animals with enhanced robustness by identifying those with superior disease resistance or resilience in the face of infection. As a consequence these animals are better able to cope with the production and environmental stresses. These may provide long-term selection strategies for improving the health and welfare of the transitioning cow particularly when combined with sound management practices, allowing dairy cattle to reach their full genetic potential.

Serotonin and calcium homeostasis during the transition period

The transition from pregnancy to lactation puts significant, sudden demands on maternal energy and calcium reserves. Although most mammals are able to effectively manage these metabolic adaptations, the lactating dairy cow is acutely susceptible to transition-related disorders because of the high amounts of milk being produced. Hypocalcemia is a common metabolic disorder that occurs at the onset of lactation. Hypocalcemia is also known to result in poor animal welfare conditions. In addition, cows that develop hypocalcemia are more susceptible to a host of other negative health outcomes. Different feeding tactics, including manipulating the dietary cation-anion difference and administering low-calcium diets, are commonly used preventative strategies. Despite these interventions, the incidence of hypocalcemia in the subclinical form is still as high as 25% to 30% in the United States dairy cow population, with a 5% to 10% incidence of clinical hypocalcemia. In addition, although there are various effective treatments in place, they are administered only after the cow has become noticeably ill, at which point there is already significant metabolic damage. This emphasizes the need for developing alternative prevention strategies, with the monoamine serotonin implicated as a potential therapeutic target. Our research in rodents has shown that serotonin is critical for the induction of mammary parathyroid hormone-related protein, which is necessary for the mobilization of bone tissue and subsequent restoration of maternal calcium stores during lactation. We have shown that circulating serotonin concentrations are positively correlated with serum total calcium on the first day of lactation in dairy cattle. Administration of serotonin's immediate precursor through feeding, injection, or infusion to various mammalian species has been shown to increase circulating serotonin concentrations, with positive effects on other components of maternal metabolism. Most recently, preliminary data suggest that manipulation of the serotonergic axis precalving may positively affect postcalving calcium dynamics. Combined, our research suggests a potential mechanism by which serotonin acts on the mammary gland to maintain circulating maternal calcium concentrations. Further research into serotonin's potential as a therapeutic target could contribute significantly as a preventive strategy against hypocalcemia in early lactation dairy cows.

Elevation of circulating serotonin improves calcium dynamics in the peripartum dairy cow

Hypocalcemia is a metabolic disorder that affects dairy cows during the transition from pregnancy to lactation. Twelve multiparous Holstein cows and twelve multiparous Jersey cows were intravenously infused daily for approximately 7 days prepartum with either saline or 1.0mg/kg bodyweight of the immediate precursor to serotonin synthesis, 5hydroxy-l-tryptophan (5-HTP). On infusion days, blood was collected before, after, and at 2, 4, and 8h postinfusion. Blood and urine were collected daily before the infusion period, for 14 days postpartum and on day 30 postpartum. Milk was collected daily during the postpartum period. Feed intake and milk yield were unaffected by 5-HTP infusion postpartum. Cows infused with 5-HTP had elevated circulating serotonin concentrations prepartum. Infusion with 5-HTP induced a transient hypocalcemia in Jersey cows prepartum, but not in any other treatment. Holstein cows infused with saline had the highest milk calcium on the day of and day after parturition. Postpartum, circulating total calcium tended to be elevated, and urine deoxypyridinoline (DPD) concentrations were elevated in Holstein cows infused with 5-HTP. Overall, Jerseys had higher urine DPD concentrations postpartum when compared with Holsteins. Taken together, these data warrant further investigation of the potential therapeutic benefit of 5-HTP administration prepartum for prevention of hypocalcemia. Further research should focus on delineation of mechanisms associated with 5-HTP infusion that control calcium homeostasis during the peripartum period in Holstein and Jersey cows.

Evaluation of ear skin temperature as a cow-side test to predict postpartum calcium status in dairy cows

Subclinical hypocalcemia is considered a gateway disease that increases susceptibility to other metabolic and infectious diseases in transition dairy cows. In the absence of a cow-side test, however, it is difficult to identify hypocalcemic cows. The objective of this study was to evaluate ear skin temperature as a diagnostic predictor of serum calcium concentration. We conducted a cross-sectional study on 7 commercial dairy farms, involving 251 cows 0 to 48h after calving. Skin temperature of the ears (STEar) was scored manually by palpating both ears. An infrared thermometer was used to measure ear temperature, skin temperature on the coxal tuber (STCox), and ambient temperature. Rectal temperature was measured using a digital thermometer. A blood sample was drawn to determine serum calcium concentration. Hypocalcemia was defined as serum calcium below 2.0mmol/L, irrespective of clinical symptoms. Serum calcium concentration <2.0mmol/L in connection with clinical symptoms was defined as clinical milk fever; serum calcium concentration <2.0mmol/L without clinical symptoms was defined as subclinical hypocalcemia. Multivariate analysis using the GENLINMIXED procedure and receiver operating characteristic analysis were performed to evaluate whether serum calcium concentration could be predicted using ear temperature and other temperature estimates. The prevalence of hypocalcemia was 3.3, 27.3, 32.8, and 69.6% for cows in first, second, third, and fourth or greater lactation, respectively. None of the cows in first and second lactation had clinical milk fever. The prevalence of clinical milk fever was 6.0 and 20.3% for cows in their third and fourth or greater lactation, respectively. A decrease in ear temperature of 0.39°C [95% confidence interval (CI): 0.25-0.54] was associated with a decrease of 0.1mmol/L in serum calcium concentration. Ambient temperature, however, was a major confounder for ear temperature. With an increase in ambient temperature of 1°C, STEar rose by 0.78°C (95% CI: 0.67-0.90). Hypothermia was more pronounced in clinical milk fever (median 21.8°C; interquartile range 14.7-27.0°C) compared with subclinical hypocalcemia (median 27.6°C, interquartile range 22.1-30.8°C). All temperature estimates had only accurate test characteristics based on their area under the curve for prediction of subclinical hypocalcemia (area under the curve for STEar, STCox, and rectal temperature were 0.641, 0.668, and 0.606, respectively) when cows with clinical milk fever were excluded. Although ear temperature has been associated with serum calcium concentration, ear temperature cannot be recommended for diagnosis of subclinical hypocalcemia.

Periparturient stress and immune suppression as a potential cause of retained placenta in highly productive dairy cows: examples of prevention

The immune system during the periparturient period is impaired. At this time the most important factor causing immune-suppression in highly productive cows is metabolic stress resulting from hormonal and metabolic fluctuations, a negative energy balance, shortage of proteins, minerals and vitamins which are required to meet the demands of the fetus as well as the onset of lactation. This stress can activate the hypothalamic-pituitary-adrenocortical axis (HPA), which results in increase plasma corticosteroids. As a result, the cortisol concentration during the periparturient period increases by several folds particularly on the day of calving. Cortisol is a powerful immune-suppressive agent. During stress, this hormone causes depression of the leukocyte proliferation and their functions. Decreased phagocytosis of neutrophils, decreased cytotoxic ability of lymphocytes, as well as depressed activity of their cytokines, make it impossible for the normal, efficient maternal immune recognition and rejection of fetal membranes (as a foreign, allogeneic tissue expressed fetal antigens—MHC class I proteins by trophoblast cells) and finally results in their retention in cows. The metabolic periparturient stress also activates production of catecholamines, especially adrenalin. Adrenalin activates adrenoreceptors of the myometrium and then causes hypotony or atony of the uterus. Thus, cortisol and adrenalin inhibit rejection and expulsion of fetal membranes and cause their retention. These mechanisms of retained placenta (RP) often have a metabolic etiology and occur in herds, where important infectious diseases causing placentitis are absent or prevented. The aim of this article is to show the fundamental mechanisms occurring during periparturient stress and the accompanied immune-suppression in cows, as well as their consequences in relation to RP. The paper also gives examples of the symptomatic prevention of RP in cows caused by metabolic and immune suppressive factors. The prevention of RP was carried out using drugs which inhibit the activity of cortisol or adrenalin in dairy cows during calving.

Seasonal variation in vitamin D status of beef cattle reared in the central United States

The objective was to retrospectively measure seasonal sunlight-associated variation in serum concentrations of 25-hydroxyvitamin D (25OHD) in beef cattle. The concentration of 25OHD was measured in crossbred animals born from March to May in 2011 and 2012. Vitamin D status 2 to 3 mo after birth (period 1) was only available for 2012 calves and was measured in June 2012. Period 1 animals had serum 25OHD concentrations of 26.3 ± 1.5 ng/mL. The 25OHD concentrations for late summer (period 2) were 46.6 ± 1.4 and 51.0 ± 1.5 ng/mL for 2011 and 2012, respectively. Serum concentration of 25OHD in early fall (period 3) were 63.8 ± 1.4 and 55.2 ± 1.5 ng/mL for calves in 2011 and 2012, respectively. Values observed for both late summer and early fall indicated vitamin D sufficiency (P < 0.001) compared with period 1. With diminishing exposure to ultraviolet B and consuming ∼800 IU or 1800 IU (2011 and 2012, respectively) of supplemental vitamin D, the calves' midwinter (period 4) 25OHD concentrations fell to 15.2 ± 1.6 and 16.7 ± 1.5 ng/mL for 2011 and 2012, respectively, after 4 to 5 mo on a finishing diet (P < 0.0001). This is considered vitamin D insufficiency in most species. Results indicate that calves are marginally sufficient to insufficient for vitamin D based on serum 25OHD concentrations soon after birth and during winter. Some individual animals would be classified vitamin D deficient. In the absence of sufficient UVB exposure, the dietary vitamin D requirements for rapidly growing beef cattle may need to be increased.

Prepartum and postpartum nutritional management to optimize fertility in high-yielding dairy cows in confined TMR systems

The 6 to 8-week period centered on parturition, known as the transition or periparturient period, is critical to welfare and profitability of individual cows. Fertility of high-producing cows is compromised by difficult transitions. Deficiencies in either nutritional or non-nutritional management increase risk for periparturient metabolic disorders and infectious diseases, which decrease subsequent fertility. A primary factor impeding fertility is the extent of negative energy balance (NEB) early postpartum, which may inhibit timing of first ovulation, return to cyclicity, and oocyte quality. In particular, pronounced NEB during the first 10 days to 2 weeks (the time of greatest occurrence of health problems) is critical for later reproductive efficiency. Avoiding over-conditioning and preventing cows from over-consuming energy relative to their requirements in late gestation result in higher dry matter intake (DMI) and less NEB after calving. A pooled statistical analysis of previous studies in our group showed that days to pregnancy are decreased (by 10 days) by controlling energy intake to near requirements of cows before calving compared with allowing cows to over-consume energy. To control energy intake, total mixed rations (TMR) must be well balanced for metabolizable protein, minerals and vitamins yet limit total DM consumed, and cows must uniformly consume the TMR without sorting. Dietary management to maintain blood calcium and rumen health around and after calving also are important. Opportunities may exist to further improve energy status in fresh cows. Recent research to manipulate the glucogenic to lipogenic balance and the essential fatty acid content of tissues are intriguing. High-producing cows that adapt successfully to lactation can have high reproductive efficiency, and nutritional management of the transition period both pre- and post-calving must facilitate that adaptation.

Perfil mineral de vacas mestiças Girolanda no período de transição em sistema semi-intensivo em duas estações do ano

Neste estudo foi avaliado o perfil metabólico de vacas leiteiras no período de transição durante o verão e o inverno. Foram utilizados 31 animais pluríparos mestiços girolando em cada estação, totalizando 62 vacas. No verão permaneciam em pasto com suplementação de silagem de milho e concentrado. No inverno, a exigência nutricional era suprida apenas com silagem de milho e concentrado. Foram feitas um total de 11 coletas de sangue de cada animal segundo o seguinte protocolo: quatro coletas pré-parto espaçadas semanalmente, no dia do parto e com 2, 5, 10, 15, 21 e 30 dias pós-parto. Foram avaliadas as concentrações de cálcio, fósforo e magnésio. Todos os analitos variaram em função do estatus fisiológico. As concentrações médias de cálcio e magnésio foram maiores no verão do que no inverno. Em ambas as estações, as menores concentrações médias de cálcio ocorreram próximas ao parto, sendo que 75% dos animais no inverno e 35,48% dos animais no verão estavam hipocalcêmicos. Apenas no décimo dia as concentrações de cálcio voltaram aos níveis do pré-parto, demonstrando que esse tempo é necessário para a adaptação da nova condição de lactante. As concentrações de magnésio foram menores no pós-parto do que no pré-parto nas duas estações, demonstrando a necessidade desse mineral para a produção de leite. As concentrações médias de magnésio permaneceram sempre dentro dos valores de referência, porém 19% dos animais aos dois dias pós-parto no inverno e 7% dos animais aos 10 dias pós-parto no verão tinham concentrações inferiores a esses limites. As concentrações de fósforo sofreram grande variação ao longo do peri-parto, porém sempre em níveis elevados, sendo que 49,8% dos animais no inverno e 37,3% no verão tinham níveis de fósforo acima dos valores de referência

Changes of Serum Calcium Concentration, Frequency of Ruminal Contraction and Feed Intake Soon after Parturition of Dairy Cows Fed Difructose Anhydride III

Requirements to control the large decrease in serum calcium (Ca) due to parturition and to increase the feed intake soon after parturition have been well accepted in dairy cows. This study was aimed to investigate the feed intake affected by serum Ca concentration with difructose anhydride (DFA) III supplement in dairy cows soon after parturition. Fourteen transition Holstein cows were divided into DFA and control (CONT) groups within 1 to 5 parity variations in each group. Measurement schedule for an individual cow was from 14 d before parturition to 7 d following parturition. The cows in DFA group were supplied 0.2 kg/head/d of DFA III feed containing 40 g of pure DFA III while the cows in CONT group received no DFA III. Other feeding procedures were the same for all cows in both groups. At parturition (d 0), serum Ca concentration sharply declined in both groups (p<0.05). Time interval for recovery from decreased serum Ca to its normal range (>9.0 mg/dL) tended to be faster in DFA group (12 h) than in the CONT group (48 h), but the differences were not significant. Active ruminal contraction was observed in DFA group at following parturition of d 1 (p<0.05), d 3 (p<0.05), and d 5 (p<0.01). Dry matter (DM) intake did not differ between the groups. However, positive correlations were observed between serum Ca concentration and ruminal contraction (p<0.001), and between ruminal contraction and DM intake (p<0.001) during following parturition. According to multiple regression analysis (R(2) = 0.824, p<0.001), the DM intake was positively affected by serum Ca concentration and ruminal contraction. These results suggest that feed intake soon after parturition in dairy cows can be increased by improvement of serum Ca concentration and active ruminal contraction, but DFA III supplementation in this study did not improve the lower serum Ca concentration due to parturition.

The Mammary Gland in Mucosal and Regional Immunity

The mammary gland (MG) lacks a mucosa but is part of the mucosal immune system because of its role in passive mucosal immunity. The MG is not an inductive site for mucosal immunity. Rather, synthesis of immunoglobulin (Ig)A by plasma cells stimulated at distal inductive sites dominate in the milk of rodents, humans, and swine whereas IgG1 derived from serum predominates in ruminants. Despite the considerable biodiversity in the role of the MG, IgG passively transfers the maternal systemic immunological experience whereas IgA transfers the mucosal immunological experience. Although passive antibodies are protective, they and other lacteal constituents can be immunoregulatory. Immune protection of the MG largely depends on the innate immune system; the monocytes–macrophages group together with intraepithelial lymphocytes is dominant in the healthy gland. An increase in somatic cells (neutrophils) and various interleukins signal infection (mastitis) and a local immune response in the MG. The major role of the MG to mucosal immunity is the passive immunity supplied to the suckling neonate.

Effect of supranutritional organic selenium supplementation on postpartum blood micronutrients, antioxidants, metabolites, and inflammation biomarkers in selenium-replete dairy cows

Dairy cows have increased nutritional requirements for antioxidants postpartum. Supranutritional organic Se supplementation may be beneficial because selenoproteins are involved in regulating oxidative stress and inflammation. Our objective was to determine whether feeding Se-yeast above requirements to Se-replete dairy cows during late gestation affects blood micronutrients, antioxidants, metabolites, and inflammation biomarkers postpartum. During the last 8-weeks before calving, dairy cows at a commercial farm were fed either 0 (control) or 105 mg Se-yeast once weekly (supranutritional Se-yeast), in addition to Na selenite at 0.3 mg Se/kg dry matter in their rations. Concentrations of whole-blood (WB) Se and serum Se, erythrocyte glutathione (GSH), and serum albumin, cholesterol, α-tocopherol, haptoglobin, serum amyloid A (SAA), calcium, magnesium, phosphorus, non-esterified fatty acids, and β-hydroxybutyrate were measured directly after calving, at 48 h, and 14 days of lactation in 10 cows of each group. Supranutritional Se-yeast supplementation affected indicators of antioxidant status and inflammation. Cows fed a supranutritional Se-yeast supplement during the last 8-weeks of gestation had higher Se concentrations in WB (overall 52 % higher) and serum (overall 36 % higher) at all-time points, had higher SAA concentrations at 48 h (98 % higher), had higher erythrocyte GSH (38 % higher) and serum albumin concentrations (6.6 % higher) at 14 days, and had lower serum cholesterol concentrations and higher α-tocopherol/cholesterol ratios at calving and at 48 h compared with control cows. In conclusion, feeding Se-replete cows during late gestation a supranutritional Se-yeast supplement improves antioxidant status and immune responses after calving without negatively impacting other micronutrients and energy status.

Blood calcium dynamics after prophylactic treatment of subclinical hypocalcemia with oral or intravenous calcium

Total serum Ca dynamics and urine pH levels were evaluated after prophylactic treatment of subclinical hypocalcemia after parturition in 33 multiparous Jersey × Holstein crossbreed cows. Cows were blocked according to their calcemic status at the time of treatment [normocalcemic (8.0-9.9 mg/dL; n = 15) or hypocalcemic (5.0-7.9 mg/dL; n = 18)] and randomly assigned to 1 of 3 treatments: control [no Ca supplementation (n = 11)]; intravenous Ca [Ca-IV (n = 11), 500 mL of 23% calcium gluconate (10.7 g of Ca and 17.5 g of boric acid as a solubilizing agent; Durvet, Blue Springs, MO)]; or oral Ca [Ca-Oral (n = 11), 1 oral bolus (Bovikalc bolus, Boehringer Ingelheim, St. Joseph, MO) containing CaCl2 and CaSO4 (43 g of Ca) 2 times 12h apart]. Total serum Ca levels were evaluated at 0, 1, 2, 4, 8, 12, 16, 20, 24, 36, and 48 h, and urine pH was evaluated at 0, 1, 12, 24, 36, and 4 8h after treatment initiation. Total serum Ca levels were higher for Ca-IV than for control and Ca-Oral cows at 1, 2, and 4h after treatment initiation, but lower than Ca-Oral cows at 20, 24, and 36 h and lower than control cows at 36 and 48 h. At 1h after treatment initiation, when serum Ca levels for Ca-IV cows peaked (11.4 mg/dL), a greater proportion of Ca-IV (n = 8) cows had total serum Ca levels >10mg/dL than control (n = 0) and Ca-Oral (n = 1) cows. At 24h after treatment initiation, when Ca-IV cows reached the total serum Ca nadir (6.4 mg/dL), a greater proportion of Ca-IV (n = 10) cows had serum Ca levels <8 mg/dL than control (n = 5) and Ca-Oral (n = 2) cows. Treatment, time, and treatment × time interaction were significant for urine pH. Mean urine pH was lower for Ca-Oral cows (6.69) than for control (7.52) and Ca-IV (7.19) cows. Urine pH levels at 1h after treatment were lower for Ca-IV cows compared with both control and Ca-Oral cows, a finding likely associated with the iatrogenic administration of boric acid added as a solubilizing agent of the intravenous Ca solution used. At 12, 24, and 36 h, urine pH levels were lower for Ca-Oral cows compared with both control and Ca-IV cows. This was expected because the oral Ca supplementation used (Bovikalc) is designed as an acidifying agent. Wide fluctuations in blood Ca were observed after prophylactic intravenous Ca supplementation. The implications for milk production and animal health, if any, of these transient changes in total serum Ca have yet to be evaluated.

The effects of calcitonin on the development of and Ca2+ levels in heat-shocked bovine preimplantation embryos in vitro

Intracellular calcium homeostasis is essential for proper cell function. We investigated the effects of heat shock on the development of and the intracellular Ca²⁺ levels in bovine preimplantation embryos in vitro and the effects of calcitonin (CT), a receptor-mediated Ca²⁺ regulator, on heat shock-induced events. Heat shock (40.5 C for 10 h between 20 and 30 h postinsemination) of in vitro-produced bovine embryos did not affect the cleavage rate; however, it significantly decreased the rates of development to the 5- to 8-cell and blastocyst stages as compared with those of the control cultured for the entire period at 38.5 C (P < 0.05). The relative intracellular Ca²⁺ levels at the 1-cell stage (5 h after the start of heat shock), as assessed by Fluo-8 AM, a fluorescent probe for Ca²⁺, indicated that heat shock significantly lowered the Ca²⁺ level as compared with the control level. Semiquantitative reverse transcription PCR and western blot analyses revealed the expression of CT receptor in bovine preimplantation embryos. The addition of CT (10 nM) to the culture medium ameliorated the heat shock-induced impairment of embryonic development beyond the 5- to 8-cell stage. The Ca²⁺ level in the heat-shocked embryos cultured with CT was similar to that of the control embryos, suggesting that heat shock lowers the Ca²⁺ level in fertilized embryos in vitro and that a lower Ca²⁺ level is implicated in heat shock-induced impairment of embryonic development. Intracellular Ca²⁺-mobilizing agents, e.g., CT, may effectively circumvent the detrimental effects of heat shock on early embryonic development.

Changes in serum copper and zinc levels in peripartum healthy and subclinically hypocalcemic dairy cows

The objective of this study was to determine the levels of serum copper and zinc in subclinically hypocalcemic peripartum dairy cows in comparison to healthy animals. Blood samples were taken from 219 multiparous Holstein cows near parturition (from 4 weeks prepartum to 4 weeks postpartum) and 51 cows with subclinical hypocalcemia. The results showed that the serum copper concentration increased gradually at 1 week prepartum and remained high for the first 4 weeks postpartum in the healthy periparturient dairy cows. The serum zinc concentration reached a nadir at 1 week postpartum and subsequently increased gradually to baseline. The serum zinc concentration was significantly decreased (P<0.01) in dairy cows with subclinical hypocalcemia compared with healthy cows. There was no significant difference in the serum copper concentration between cows with subclinical hypocalcemia and healthy cows. These data demonstrate that the concentrations of copper and zinc in serum change dramatically during the peripartum period in dairy cows, which is a tremendous challenge for the body and for the maintenance of dairy cow health. The present study further suggests that a decreased serum zinc concentration could be a cause of decreased productive performance and increased susceptibility to other diseases due to immunosuppression in dairy cows with subclinical hypocalcemia. Additionally, this decreased zinc concentration may be involved in the pathogenesis of subclinical hypocalcemia.

Effects of feeding various dosages of Saccharomyces cerevisiae fermentation product in transition dairy cows

Feeding 56 versus 0 g/d of Saccharomyces cerevisiae fermentation product (SCFP; Diamond V Original XP; Diamond V, Cedar Rapids, IA) can increase feed intake and milk production in transition dairy cows. To evaluate the effects of various dosages of SCFP, Holstein cows were given individually a supplement containing 0 (n=14), 56 (n=15), or 112 g (n=13) of SCFP daily during morning lockup as a topdressing to their total mixed ration. The supplement consisted of 0, 56, or 112 g of SCFP mixed with 84 g of molasses and 168, 112, or 56 g of corn meal, respectively. Supplement feeding began 28 d before predicted calving date (no less than 14 d) and ended 28 d postpartum, and supplement intake was evaluated daily. Blood samples were collected at d -21, -14, -7, -3, -1, 0, 1, 3, 7, 14, 21, and 28 to measure serum concentrations of macrominerals, metabolites, acute-phase proteins, immunoglobulin, and hormones. Milk weights were measured and milk samples were collected 2 times/wk on nonconsecutive days and analyzed for milk fat, protein, lactose, and somatic cell count (SCC). During the first day after calving, feeding SCFP versus no SCFP decreased serum cortisol concentrations and at least tended to increase supplement intake and serum concentrations of calcium, glucose, urea N, and serum amyloid A. During the first 4 wk postpartum, feeding SCFP versus no SCFP decreased milk SCC and increased milk production and serum phosphorus concentrations. Feeding 112 versus 56 g of SCFP/d did not show additional effects. Feeding SCFP may have a dosage-independent beneficial effect in supporting the physiologic adaptations after parturition, resulting in higher milk production and lower milk SCC.