A stochastic estimate of the economic impact of oral calcium supplementation in postparturient dairy cows.

The objective was to develop stochastic models to estimate the economic impact in the first 30 d in milk of oral calcium supplementation to multiparous postparturient dairy cows using 4 different strategies: (1) supplementation of cows with a high previous lactation mature-equivalent milk yield, (2) supplementation of lame cows, (3) supplementation of both cows that have a high previous lactation mature-equivalent milk yield and cows that are lame, and (4) supplementation of all cows. Data from current literature were used to model input variables associated with the costs and risks related to milk production, postparturient disease, and culling. The mean net herd impact per 1,000 calvings for each of the 4 supplementation strategies was $4,425, $5,812, $8,313, and $3,065, respectively. Postpartum supplementation of multiparous lame cows had the highest return on investment at 6.5 to 1, followed by supplementation of multiparous high milk yield and lame cows, multiparous high milk yield cows only, and supplementation of all multiparous postpartum cows with returns of 1.8 to 1, 1.1 to 1, and 0.3 to 1, respectively. A herd's average milk yield at first test had the highest influence on the net impact of oral calcium supplementation to all multiparous cows and accounted for 30% of the variation, followed by the decrease in risk of health events in lame cows given oral calcium at 22%, a herd's prevalence of lameness at calving at 13%, and the price of milk at 10%. Each of the remaining stochastic variables contributed to less than 5% of the variation in net herd financial impact of oral calcium administration. Whereas supplementation of all postpartum multiparous cows returned a positive net herd impact approximately 80% of the time, if a herd was willing to devote time to mature-equivalent milk yield calculations and locomotion scoring, supplementation of this subpopulation of postpartum cows with oral calcium was estimated to have a positive economic impact in all iterations. Depending on the supplementation strategy chosen and baseline milk yield and immediate postpartum lameness prevalence in a herd, a herd with 1,000 calvings per year can expect to see an average net impact ranging from approximately $3,000 to $8,000 after postpartum supplementation of oral calcium in multiparous animals.

Effect of oral calcium bolus supplementation on early-lactation health and milk yield in commercial dairy herds.

The objective of this study was to evaluate the effect of supplementation with oral Ca boluses after calving on early-lactation health and milk yield. Cows in their second lactation or greater (n=927) from 2 large dairies in Wisconsin were enrolled during the summer of 2010. Both herds were fed supplemental anions during the prefresh period and less than 1% of fresh cows were treated for clinical milk fever. Cows were scored before calving for lameness and body condition, and then randomly assigned to either a control group or an oral Ca bolus-supplemented group. Control cows received no oral Ca boluses around calving. Cows in the oral Ca bolus group received 2 oral Ca boluses (Bovikalc, Boehringer Ingelheim, St. Joseph, MO), one bolus 0 to 2h after calving and the second 8 to 35 h after calving. The oral Ca bolus administration schedule allowed fresh cows to be restrained in headlocks only once daily. Whole-blood samples were collected immediately before the second oral Ca bolus was given and were analyzed for ionized Ca (Ca(2+)) concentration. Early-lactation health events were recorded and summed for each cow. Only 6 cases (0.6% of calvings) of clinical milk fever occurred during the trial, and only 14% of cows tested were hypocalcemic (Ca(2+) less than 1.0 mmol/L) at 8 to 35 h after calving. Mean Ca(2+) concentrations were not different between the control and oral Ca bolus-supplemented groups. Blood samples from the cows given oral Ca boluses were collected an average of 20.6 h after administration of the first bolus. Subpopulations of cows with significant responses to oral Ca bolus supplementation were identified based on significant interactions between oral Ca bolus supplementation and covariates in mixed multiple regression models. Lame cows supplemented with oral Ca boluses averaged 0.34 fewer health events in the first 30 d in milk compared with lame cows that were not supplemented with oral Ca boluses. Cows with a higher previous lactation mature-equivalent milk production (greater than 105% of herd rank) and supplemented with oral Ca boluses produced 2.9 kg more milk at their first test after calving compared with cows with higher previous lactation milk yields that were not supplemented. Results of this study indicate that lame cows and higher producing cows responded favorably to supplementation with oral Ca boluses. Supplementing targeted subpopulations of cows with oral Ca boluses was beneficial even for dairies with a very low incidence of hypocalcemia.

Direct-fed microbial supplementation and health and performance of pre- and postpartum dairy cattle: a field trial.

A double-blind field trial was conducted on a commercial dairy to study the effects of feeding a direct-fed microbial (DFM) product consisting of 2 strains of Enterococcus faecium plus Saccharomyces cerevisiae yeast on prepartum and postpartum performance of Holstein cows. Treatments consisted of the normal pre- and post-fresh TMR supplemented with the DFM (2 g/cow per d) or a placebo. Treatments started approximately 10 d prepartum and continued until about 23 d in milk (DIM). A total of 366 Holstein cows were enrolled in 1 of 2 placebo groups or 2 DFM-supplemented groups. Groups were enrolled consecutively, starting with the placebo treatment. Sample size was limited to 4 groups because the cooperating dairy prematurely terminated the study due to increased health problems in one of the groups. Blood samples were taken during the prefresh period between 2 and 10 d prior to calving and at weekly intervals from 3 to 23 DIM. Blood concentrations of nonesterified fatty acids before calving and beta-hydroxy-butyrate after calving were not affected by treatment. Supplementation with the DFM product increased milk fat percentage for the first lactation cows and increased milk protein percentage for the second and greater lactation cows during the first 85 DIM. Second-lactation cows fed the DFM product received fewer antibiotic treatments before 85 DIM than cows receiving the placebo. This validated the dairy producer's concern that cows consuming one of the diets (revealed to be the placebo diet after the study was completed) were experiencing more health problems. Most measures of milk yield were numerically increased by supplementation with the DFM product. However, differences in milk yield were not significant. Key covariates for main study outcomes included milk yield in the previous (first) lactation, body condition score prior to calving, days spent in the maternity pen, and stocking density of the pre-fresh pen.

Management of dry cows for the prevention of milk fever and other mineral disorders.

Mineral disorders in dairy cattle typically occur soon after calving and are often specifically related to nutritional management during the late dry period. The incidence of hypocalcemia, hypophosphatemia, and hypomagnesemia can be minimized by proper diet formulation and good overall nutritional management in the dry period. The addition of anions to the diet during the late dry period may be of particular benefit for preventing hypocalcemia; however, supplementation with anions will reduce dry matter intake if feeding management is not excellent.

Ammonium chloride and ammonium sulfate for prevention of parturient paresis in dairy cows.

Forty-eight Holstein cows with two or more previous lactations and no history of parturient paresis were randomly assigned to one of four prepartum diets in a 2 x 2 factorial design to determine the effect of dietary supplementation with ammonium salts and Ca intake on serum Ca concentrations at calving. Four diets provided either 53 g total dietary Ca/d or 105 g Ca/d and were either supplemented with ammonium salts [100 g/d each of NH4Cl and (NH4)2SO4] or unsupplemented. Anion-cation balance of the diets, calculated as milliequivalents (Na + K)--(Cl + S), was -75 meq/kg DM with ammonium salts and +189 meq/kg DM without ammonium salts. Experimental diets were fed from 21 d prior to expected parturition until calving. Calcium intake during the feeding period did not affect the incidence of parturient paresis or serum concentrations of ionized Ca at calving. The incidence of parturient paresis was 4% with and 17% without the ammonium salts. Cows fed diets containing ammonium salts had higher serum ionized and total Ca concentrations at parturition. Serum concentrations of Mg, P, Na, K, and Cl on the day of parturition were unaffected by dietary treatment.

Parturient paresis and hypocalcemia in ruminant livestock.

Parturient paresis (hypocalcemia) is most likely to affect dairy cattle around the time of parturition. It causes progressive neuromuscular dysfunction and flaccid paralysis. Older dairy cows, cows with a history of parturient paresis during a previous lactation, high-producing cows, and cows from the Jersey and Guernsey breeds are at highest risk for developing parturient paresis. Nonparturient hypocalcemia may also occur and is related to events other than parturition, such as severe stress, that temporarily overwhelm the mechanisms of calcium homeostasis. Beef cattle, sheep, and goats are affected less frequently by hypocalcemia than are dairy cows. Because these species are not as stressed for milk production as dairy cattle, nonparturient hypocalcemia makes up a higher proportion of cases in nondairy ruminants. Clinical signs of hypocalcemia in beef cattle, sheep, and goats tend toward hyperesthesia and tetany rather than the classic flaccid paralysis that occurs in dairy cattle with parturient hypocalcemia. Prompt and effective treatment of hypocalcemia helps to reduce the incidence of secondary complications, such as muscle damage or mastitis. The standard treatment regimen of 500 ml of 23 per cent calcium gluconate, administered intravenously, will elicit a favorable response in approximately 75 per cent of recumbent cows within 2 hours of treatment. Relapses following successful initial therapy are common and may be prevented in part by supplementation of intravenous treatment with an additional 500 ml of 23 per cent calcium gluconate administered subcutaneously. Proper nursing care following treatment speeds recovery and reduces the incidence of secondary complications owing to hypocalcemia.