Randomized controlled trial investigating the effect of 2 selective dry-cow therapy protocols on udder health and performance in the subsequent lactation.

The objective of this study was to compare culture- and algorithm-guided selective dry-cow therapy (SDCT) programs with blanket dry-cow therapy (BDCT) in a multi-site, randomized, natural exposure clinical trial for the following cow-level outcomes: clinical mastitis, removal from the herd, and Dairy Herd Improvement Association (DHIA) test-day milk yield and SCC measures during the first 120 d in milk (DIM). Two days before planned dry-off, cows in each of 7 herds were randomly allocated to BDCT, culture-guided SDCT (cult-SDCT), or algorithm-guided SDCT (alg-SDCT). At dry-off, BDCT cows received an intramammary antibiotic (500 mg of ceftiofur hydrochloride) in all 4 quarters. Antibiotic treatments were selectively allocated to quarters of cult-SDCT cows by only treating quarters from which aseptically collected milk samples tested positive on a rapid culture system after 30 to 40 h of incubation. For alg-SDCT cows, antibiotic treatments were selectively allocated at the cow level, with all quarters receiving antibiotic treatment if the cow met at least one of the following criteria: (1) any DHIA test with a somatic cell count >200,000 cells/mL during the current lactation, and (2) ≥2 clinical mastitis cases during the current lactation. All quarters of all cows were treated with an internal teat sealant. Clinical mastitis and removal from the herd events (i.e., culling or death) and DHIA test-day data from dry-off to 120 DIM were extracted from herd records. Hazard ratios (HR) for the effect of treatment group on clinical mastitis and removal from the herd during 1 to 120 DIM were determined using Cox proportional hazards regression. The effects of treatment group on test-day loge-transformed SCC and milk yield were determined using linear mixed models. Final models indicated that either SDCT program was unlikely to increase clinical mastitis risk (HRcult-SDCT/BDCT = 0.82, 95% CI: 0.58, 1.15; HRalg-SDCT/BDCT = 0.83, 95% CI: 0.63, 1.09) or test-day logeSCC (cult-SDCT minus BDCT = 0.05, 95% CI: -0.09, 0.18; alg-SDCT minus BDCT = 0.07, 95% CI: -0.07, 0.21). Risk of removal from the herd and test-day milk yield were similar between treatment groups. Findings from this study indicate that culture- or algorithm-guided SDCT can be used at dry-off without negatively affecting cow health and performance in early lactation.

Exposure to antimicrobials through the milk diet or systemic therapy is associated with a transient increase in antimicrobial resistance in fecal Escherichia coli of dairy calves.

The objective of this prospective cohort study was to describe the relationship between exposure to antimicrobials, through both the milk diet and systemic therapy, and to describe antimicrobial resistance of fecal Escherichia coli in dairy calves pre- and postweaning. A convenience sample of 15 Minnesota dairy farms was chosen, representing 3 equal cohorts of milk diet fed to preweaned calves: medicated milk replacer (MMR), nonmedicated milk replacer (NMR), or pasteurized nonsaleable milk (PNM). Five newborn calves were enrolled on each farm, with fecal samples collected from each calf at 1, 3, 5, and 16 wk of age. After isolation, 3 colonies of E. coli were randomly selected from each sample to determine antimicrobial susceptibility by minimum inhibitory concentration (Sensititer, Thermo Scientific, Waltham, MA) to 8 antimicrobials in 8 classes. The isolate was given an antimicrobial resistance score (ARS) according to the number of antimicrobial classes to which it was resistant. Any isolate resistant to 3 or more antimicrobials was defined as being multidrug resistant (MDR). Relationships between ARS and MDR (dependent variables) and possible explanatory variables were analyzed using mixed multivariable linear and logistic regression models, respectively, with critical P-values adjusted for multiple contrasts. Seventy percent of isolates were resistant to sulfadimethoxine. For wk 1 and 3, the mean ARS values were greatest for fecal E. coli from calves fed MMR or PNM compared with NMR, with no difference in ARS values between the MMR and PNM groups at either time point. At wk 5, the mean ARS value was greatest for fecal E. coli from calves fed MMR (3.56 ± 0.45; mean ± SE), intermediate for calves fed PNM (2.64 ± 0.45), and lowest for calves fed NMR (1.54 ± 0.45). However, by wk 16, the mean ARS values were ≤1.0 and did not differ among milk diets. Evaluation of the proportion of isolates with MDR mirrored the results of the ARS analysis (MDR more prevalent in MMR and PNM groups preweaning; no difference among milk diets at 16 wk). There was a tendency for an increase in ARS at wk 5 (1.28 ± 0.70), and the odds for MDR in fecal E. coli were estimated to be 5.2 (95% confidence interval = 0.67, 35.7) and 101.1 (95% confidence interval = 1.15, >999.9) higher at wk 3 and 5 if the calf was treated with a systemic antimicrobial within the 14-d period before sampling. These findings suggest that exposure to antimicrobials through the milk diet or systemic therapy may result in a transient increase in resistance in fecal E. coli, but once the antimicrobial pressure is removed, susceptible E. coli are able to flourish again, resulting in an overall decrease in resistance.

Effect of feeding heat-treated colostrum on risk for infection with Mycobacterium avium ssp. paratuberculosis, milk production, and longevity in Holstein dairy cows.

In summer 2007, a randomized controlled field trial was initiated on 6 large Midwest commercial dairy farms to investigate the effect of feeding heat-treated (HT) colostrum on transmission of Mycobacterium avium ssp. paratuberculosis (MAP) and on future milk production and longevity within the herd. On each farm, colostrum was collected daily from fresh cows, pooled, divided into 2 aliquots, and then 1 aliquot was heat-treated in a commercial batch pasteurizer at 60°C for 60min. A sample from each batch of colostrum was collected for PCR testing (MAP-positive vs. MAP-negative). Newborn heifer calves were removed from the dam within 30 to 60min of birth and systematically assigned to be fed 3.8 L of either fresh (FR; n=434) or heat-treated (HT; n=490) colostrum within 2h of birth. After reaching adulthood (>2 yr old), study animals were tested once annually for 3 yr (2010, 2011, 2012) for infection with MAP using serum ELISA and fecal culture. Lactation records describing milk production data and death or culling events were collected during the 3-yr testing period. Multivariable model logistic and linear regression was used to investigate the effect of feeding HT colostrum on risk for testing positive to MAP during the 3-yr testing period (positive/negative; logistic regression) and on first and second lactation milk yield (kg/cow; linear regression), respectively. Cox proportional hazards regression was used to investigate the effect of feeding HT colostrum on risk and time to removal from the herd. Fifteen percent of all study animals were fed PCR-positive colostrum. By the end of the 3-yr testing period, no difference was noted in the proportion of animals testing positive for MAP, with either serum ELISA or fecal culture, when comparing the HT group (10.5%) versus the FR group (8.1%). There was no effect of treatment on first- (HT=11.797kg; FR=11,671kg) or second-lactation (HT=11,013kg; FR=11,235kg) milk production. The proportion of cows leaving the herd by study conclusion was not different for animals originally fed HT (68.0%) versus FR (71.7%) colostrum. Although a previous study showed that feeding HT colostrum (60°C for 60min) produces short-term benefits, including improved passive transfer of IgG and reduced morbidity in the preweaning period, the current study found no benefit of feeding HT colostrum on long-term outcomes including risk for transmission of Mycobacterium avium ssp. paratuberculosis, milk production in the first and second lactation, and longevity within the herd.

Supplementing fresh bovine colostrum with gut-active carbohydrates reduces passive transfer of immunoglobulin G in Holstein dairy calves.

High concentrations of coliform bacteria in maternal colostrum (MC) have been associated with reduced IgG absorption in calves. Mannan-oligosaccharide, a gut-active carbohydrate (GAC) derived from yeast cell wall, has been shown to adsorb pathogens expressing type-1-fimbriae, reducing their ability to colonize the gastrointestinal tract. The objective of this study was to investigate if addition of a GAC to colostrum would result in increased IgG absorption in newborn calves. Newborn Holstein heifer and bull calves were enrolled in summer 2012 at a commercial transition cow facility in western Wisconsin. Each day, 7.6-L pools of fresh, first milking MC were created, split into 3.8-L aliquots, and refrigerated until feeding. Eligible newborn calves were removed from the dam 30 to 60min after birth, weighed, and randomly assigned to be fed either 3.8 L of the MC pool (control) or 3.8 L of the MC pool with 30 g of GAC mixed in immediately before feeding. Duplicate 10-mL samples of colostrum were collected and frozen at -20°C before feeding (and before addition of GAC) for bacterial culture and IgG determination. A 10-mL venous blood sample was collected from calves before feeding colostrum and 24 h after colostrum feeding, for laboratory determination of serum IgG using radial immunodiffusion analysis. Colostrum and calf characteristics, including colostrum IgG concentration (g/L), colostrum bacteria counts (log10, cfu/mL), calf dystocia scores (1 to 4), birth weights (kg), and age at first feeding (min) were not different between the group fed GAC (n=47) and the control group (n=48). Mixed linear regression analysis showed that calves fed colostrum supplemented with 30 g of GAC had lower mean (standard error) apparent efficiency of absorption of IgG and lower serum IgG concentrations at 24 h [23.9% (1.0); IgG=24.0 (1.1) g/L] than did control calves [30.4% (1.0); IgG=30.8 (1.0) g/L]. Given the negative effect observed in this study, it is not recommended that fresh colostrum be supplemented with 30 g of GAC.

Heat-treated (in single aliquot or batch) colostrum outperforms non-heat-treated colostrum in terms of quality and transfer of immunoglobulin G in neonatal Jersey calves.

The objective of this randomized clinical trial was to describe the effect on colostrum characteristics and passive transfer of IgG in neonatal calves when using the Perfect Udder colostrum management system (single-aliquot treatment; Dairy Tech Inc., Greeley, CO) compared with a negative control (fresh refrigerated or fresh frozen colostrum) and a positive control (batch heat-treated colostrum). First-milking Jersey colostrum was pooled to achieve 31 unique batches with a minimum of 22.8 L per batch. The batch was then divided into 4 with 3.8 L allocated to each treatment group: (1) heat-treated in Perfect Udder bag at 60°C for 60 min and then stored at -20°C (PU); (2) heat-treated in a batch pasteurizer (Dairy Tech Inc.) at 60°C for 60 min and then stored at -20°C in Perfect Udder bag (DTB; positive control); (3) fresh frozen colostrum stored at -20°C in Perfect Udder bag (FF; negative control); and (4) fresh refrigerated colostrum stored at 4°C in Perfect Udder bag (FR; negative control). Colostrum from all treatments was sampled for analysis of IgG concentration and bacterial culture immediately after batch assembly, after processing, and before feeding. Newborn Jersey calves were randomly assigned to be fed 3.8 L of colostrum from 1 of the 4 treatment groups. A prefeeding, 0-h blood sample was collected, calves were fed by esophageal tube within 2 h of birth, and then a 24-h postfeeding blood sample was collected. Paired serum samples from 0- and 24-h blood samples were analyzed for IgG concentration (mg/mL) using radial immunodiffusion analysis. The overall mean IgG concentration in colostrum was 77.9 g/L and was not affected by treatment. Prefeeding total plate counts (log10 cfu/mL) were significantly different for all 4 treatments and were lower for heat-treated colostrum (PU=4.23, DTB=3.63) compared with fresh colostrum (FF=5.68, FR=6.53). Total coliform counts (log10 cfu/mL) were also significantly different for all 4 treatments and were lower for heat-treated colostrum (PU=0.45, DTB=1.08) compared with fresh colostrum (FF=3.82, FR=4.80). Mean 24-h serum IgG concentrations were significantly higher for calves in the PU (41.0 mg/mL) and DTB (40.6 mg/mL) groups compared with FF (35.1 mg/mL) and FR (35.5 mg/mL) groups. Mean apparent efficiency of absorption of IgG was significantly higher for the PU (37%) and DTB (37%) groups compared with the FF (32%) and FR (32%) groups. Calves fed heat-treated colostrum (PU or DTB) experienced significantly improved AEA and serum IgG concentrations.

Addition of gut active carbohydrates to colostrum replacer does not improve passive transfer of immunoglobulin G in Holstein dairy calves.

The primary objective of this study was to investigate the effects of supplementing a commercial colostrum replacer (CR) with gut active carbohydrates (GAC) on passive transfer of IgG in commercial dairy calves. A secondary objective was to evaluate the effect of treatment on preweaning health and growth. A total of 240 newborn Holstein dairy calves on a commercial dairy farm were enrolled in this study. Newborn heifer and bull calves were weighed and then randomly assigned to either the treated group [GAC: 30g of GAC mixed into 1.5 doses (150g of IgG) of commercial colostrum replacer; n=119] or the control group [CON: 1.5 doses (150g of IgG) of CR; n=121]. The assigned CR treatment was fed within 3.5h of birth using an esophageal tube feeder. Venous blood samples were collected at 0 and 24h of age and used to measure serum IgG (mg/mL) and serum total protein (g/dL) concentrations and to estimate the apparent efficiency of absorption of IgG (%). The 129 heifers calves enrolled (CON=60; GAC=69) were also followed until weaning to assess the effect of GAC addition on preweaning health and growth. Multivariable linear regression showed that the addition of GAC to CR did not influence passive transfer of IgG, as measured by apparent efficiency of absorption at 24h of age (CON=54.0 vs. GAC=54.3%), serum IgG (CON=20.3 vs. GAC=20.2mg/mL), and serum total protein (CON=5.69 vs. GAC=5.68g/dL). Although study sample sizes were not originally derived to evaluate health outcomes, treatment had no effect on weight gain or incidence of health events (diarrhea, pneumonia, mortality) for heifer calves between birth and 7 wk of age.

Hot topic: investigating the risk of violative meat residues in bob veal calves fed colostrum from cows treated at dry-off with cephapirin benzathine.

The objective was to conduct a study to investigate if violative meat residues are detected in very young bob veal calves that are fed first-milking colostrum harvested from cows that were dry treated, on-label, with cephapirin benzathine. First-milking colostrum was collected from cows that were given intramammary treatment at dry off, on-label, with cephapirin benzathine (ToMORROW, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO). Newborn bull calves meeting study inclusion criteria were removed from their dams shortly after birth and before suckling, and assigned to 1 of 2 trials. For the first trial, 6 treated calves were fed 3.8L of fresh maternal colostrum and 1 control calf was fed 1.5 doses of a plasma-derived colostrum replacer (Secure Calf Colostrum Replacer, VitaPlus Inc., Madison, WI) within 1h after birth. For the second trial, 5 treated calves were fed 3.8L of fresh maternal colostrum and 1 control calf was fed 1.5 doses of Secure Calf Colostrum Replacer within 1h after birth. All calves were humanely euthanized at 24h (trial 1) or 48h (trial 2) of age, and tissues were harvested for antimicrobial residue testing. Samples of maternal colostrum and colostrum replacer were also submitted for antimicrobial residue testing. Kidneys collected from all study calves tested negative for cephapirin benzathine residues when using both the KIS assay (Charm Sciences, Lawrence, MA) and liquid chromatography-tandem mass spectrometry analysis. The potential transfer of cephapirin from cows treated on-label at dry off to calves via colostrum may not be a significant source of cephapirin residues in veal tissues.

Heat-treated colostrum and reduced morbidity in preweaned dairy calves: results of a randomized trial and examination of mechanisms of effectiveness.

A randomized controlled clinical trial was conducted using 1,071 newborn calves from 6 commercial dairy farms in Minnesota and Wisconsin, with the primary objective being to describe the effects of feeding heat-treated colostrum on serum immunoglobulin G concentration and health in the preweaning period. A secondary objective was to complete a path analysis to identify intermediate factors that may explain how feeding heat-treated colostrum reduced the risk for illness. On each farm, colostrum was collected each day, pooled, and divided into 2 aliquots; then, one aliquot was heat-treated in a commercial batch pasteurizer at 60°C for 60 min. Samples of fresh and heat-treated colostrum were collected for standard microbial culture (total plate count and total coliform count, cfu/mL) and for measurement of immunoglobulin G concentrations (mg/mL). Newborn calves were removed from the dam, generally within 30 to 60 min of birth, and systematically assigned to be fed 3.8L of either fresh (FR, n=518) or heat-treated colostrum (HT, n=553) within 2h of birth. Venous blood samples were collected from calves between 1 and 7d of age for measurement of serum IgG concentrations (mg/mL). All treatment and mortality events were recorded by farm staff between birth and weaning. Regression models found that serum IgG concentrations were significantly higher in calves fed HT colostrum (18.0 ± 1.5 mg/mL) compared with calves fed FR colostrum (15.4 ± 1.5 mg/ml). Survival analysis using Cox proportional hazards regression indicated a significant increase in risk for a treatment event (any cause) in calves fed FR colostrum (36.5%, hazard ratio=1.25) compared with calves fed HT colostrum (30.9%). In addition, we observed a significant increase in risk for treatment for scours in calves fed FR colostrum (20.7%, hazard ratio=1.32) compared with calves fed HT colostrum (16.5%). Path analysis suggested that calves fed HT colostrum were at lower risk for illness because the heat-treatment process caused a significant reduction in colostrum total coliform count, which was associated with a reduced risk for illness as a function of improved serum IgG concentrations.

Heat treatment of colostrum on commercial dairy farms decreases colostrum microbial counts while maintaining colostrum immunoglobulin G concentrations.

This study was conducted on 6 commercial dairy farms in Minnesota and Wisconsin to describe the effect of heat treatment (at 60°C for 60 min) on colostrum, on colostrum bacteria counts, and immunoglobulin G concentrations. First-milking colostrum was collected each day, pooled, divided into 2 aliquots, and then 1 aliquot was heat treated in a commercial batch pasteurizer at 60°C for 60 min. Frozen samples of pre- and post- heat-treated colostrum were submitted for standard microbial culture (total plate count and total coliform count, cfu/mL) and testing for immunoglobulin G concentrations (mg/mL). Data were analyzed from 266 unique batches of colostrum. Linear regression showed that heat treatment decreased colostrum total plate counts (-2.25 log(10)) and coliform counts (-2.49 log(10)), but, overall, did not affect colostrum IgG concentration. Though higher-quality batches of colostrum did experience a greater magnitude of loss of IgG as a result of heat treatment as compared with lower- or intermediate-quality batches of colostrum, the colostral IgG concentrations in these batches remained high overall, and within acceptable limits for feeding. This study demonstrates that batch heat treatment of colostrum at 60°C for 60 min can be successfully conducted on commercial dairy farms by farm staff to decrease colostrum microbial counts while maintaining colostrum IgG concentrations.

Short communication: improving passive transfer of immunoglobulins in calves. III. Effect of artificial mothering.

The objective of this study was to investigate the effect of artificial mothering, simulated by verbal and physical stimulation of the newborn, on passive transfer of IgG in the dairy calf. Newborn heifer calves born without dystocia were removed from the dam before suckling and randomly assigned to 1 of 2 treatment groups: no tactile or verbal stimulation other than that required for feeding (group 1; n=20), or artificial mothering, consisting of 15 min of vigorous physical and verbal stimulation conducted within 1 to 2h of birth at the time of colostrum feeding and repeated 1 to 2h later (group 2; n=21). All calves were fed 2.25 L (150 g of IgG) of a commercially available colostrum replacement using an esophageal tube feeder. Blood samples collected at 24h of age showed that serum IgG levels and the apparent efficiency of absorption of the IgG were similar in both groups of calves. Artificial mothering by physical and verbal stimulation had no significant effect on IgG passive transfer in dairy heifers born without dystocia.

The effect of injectable butaphosphan and cyanocobalamin on postpartum serum beta-hydroxybutyrate, calcium, and phosphorus concentrations in dairy cattle.

The objective of this study was to determine the effect of an injection of 10% butaphosphan and cyanocobalamin (Catosal, Bayer, Shawnee Mission, KS) on the day of calving and 1 d later on the prevalence of subclinical ketosis in dairy cattle in the early postpartum period. Cows from 4 herds (n=1,122) were randomized to receive either 25mL of 10% butaphosphan and cyanocobalamin or 25mL of sterile water subcutaneously on both days. Each milliliter of Catosal contained 0.05mg of cyanocobalamin and 100mg of butaphosphan, which provided 17.3mg of P in the form of [1-(butylamino)-1-methylethyl]-phosphonic acid. Serum was sampled for beta-hydroxybutyrate (BHBA) concentration at calving (pretreatment) and again between 3 and 10 d in milk. A subset of samples from mature cows was also evaluated for serum Ca and P concentrations. When cows from all age groups were included in the analysis, there was no difference between the median serum BHBA concentrations of cows in the 2 treatment groups, and no difference in the proportion of hyperketonemic cows (serum BHBA >or=1,200micromol/L) during the first week postpartum. When the analysis was restricted to mature cows (lactation >or=3), both the median BHBA concentration and the proportion of hyperketonemic cows were significantly lower in the treatment group than in the placebo group. Serum Ca and P concentrations did not differ between treatment groups. Our results suggest that injection of butaphosphan and cyanocobalamin on the day of calving and 1 d later may decrease the prevalence of subclinical ketosis during the week after calving in mature dairy cows, but not in first- and second-lactation animals.

Improving passive transfer of immunoglobulins in calves. I: dose effect of feeding a commercial colostrum replacer.

The objective of this study was to describe the effects of feeding 1 or 2 doses of a commercially available colostrum-derived colostrum replacer (CR) on passive transfer of immunoglobulins (Ig) in newborn dairy calves, including IgG, IgG1, IgG2, IgA, and IgM. Newborn calves were removed from the dam before suckling and randomly assigned to 1 of 3 treatment groups: group 1 were fed 1 package (100 g of IgG) of CR product, group 2 was fed 2 packages (200 g of IgG) of the same CR product, and group 3 was fed 3.8 L of maternal colostrum. All colostrum treatments were fed using an esophageal tube feeder within 2 h of birth. Blood samples collected before colostrum feeding and at 24 h of age were tested for serum total protein and Ig concentrations. Mean 24-h serum total protein (TP) and IgG concentrations were significantly lower for calves in group 1 (n = 24; TP = 4.9 g/dL, IgG = 9.6 mg/mL) compared with calves in groups 2 or 3. There was no difference in 24-h serum TP or IgG concentrations between calves in group 2 (n = 23; TP = 5.5 g/dL, IgG = 19.0 mg/mL) and calves in group 3 (n = 22; TP = 5.7 g/dL, IgG = 20.7 mg/mL). Fifty-four, 100, and 91% of calves in groups 1, 2 and 3 achieved acceptable passive transfer (24-h serum IgG > or =10 mg/mL), respectively. Statistically significant but numerically small differences existed between calves in groups 2 and 3 for some 24-h serum Ig classes and subclasses (mean serum concentrations of IgG2, IgA, IgM) and for the relative percentages of Ig classes and subclasses (IgA, IgM, and IgG as a percentage of total Ig; IgG1 and IgG2 as a percentage of total IgG).

Improving passive transfer of immunoglobulins in calves. II: interaction between feeding method and volume of colostrum fed.

The objective of this study was to investigate the effect of method of feeding (nipple bottle vs. esophageal tube feeder) on passive transfer of immunoglobulin (Ig) G when either a large or small volume of colostrum was fed. Newborn bull calves were removed from the dam before suckling and randomly assigned to 1 of 4 colostrum replacer (CR) treatment groups: 1.5 L (100 g of IgG) of CR fed using a nipple bottle (group 1; n = 24); 1.5 L (100 g of IgG) of CR fed using an esophageal tube feeder (group 2; n = 24); 3.0 L (200 g of IgG) of CR fed using a nipple bottle (group 3; n = 24), or 3.0 L (200 g of IgG) of CR fed using an esophageal tube feeder (group 4; n = 25). Blood samples collected at 24 h of age showed that serum IgG levels were significantly greater in calves fed large (3 L) volumes of CR compared with calves fed small (1.5 L) volumes of CR, regardless of feeding method. These differences were attributed to the larger mass of IgG ingested by calves fed 3 L of CR (200 g of IgG) compared with calves fed 1.5 L of CR (100 g of IgG). For calves fed small (1.5 L) volumes of colostrum, serum total protein (TP, g/dL), serum IgG (IgG, mg/mL), acceptable passive transfer rates (APT, %), and apparent efficiency of absorption of IgG (AEA, %) were significantly greater for calves fed with a bottle (TP = 5.3 g/dL; IgG = 12.5 mg/mL; APT = 100%; AEA = 51.1%) compared with calves fed with an esophageal tube feeder (TP = 5.0 g/dL; IgG = 9.8 mg/mL; APT = 41.7%; AEA = 40.5%). However, for calves fed large (3 L) volumes of colostrum, there was no difference in passive transfer indices for calves fed with a bottle (TP = 5.8 g/dL; IgG = 19.7 mg/mL; APT = 100%; AEA = 41.1%) compared with calves fed with an esophageal tube feeder (TP = 5.9 g/dL; IgG = 18.7 mg/mL; APT = 100%; AEA = 39.0%).

Effects of feeding heat-treated colostrum on passive transfer of immune and nutritional parameters in neonatal dairy calves.

The first objective of this study was to describe the effect of on-farm heat treatment of colostrum on colostral bacteria counts and IgG concentrations. The second objective was to describe the effect of feeding heat-treated (vs. raw) colostrum on passive transfer of colostral immune and nutritional parameters in neonatal calves. Pooled batches of colostrum were mixed and divided equally: one half was fed raw whereas the other half was fed after heat treatment at 60 degrees C for 60 min using a commercial on-farm batch pasteurizer. Colostrum samples were cultured for total bacteria count and total coliform count and analyzed for total IgG concentration. Forty-nine Holstein calves were fed either raw colostrum (n = 24) or heat-treated colostrums (n = 25) within 1 to 2 h after birth. Serum samples collected from calves at 0 h (precolostrum) and 24 h (postcolostrum) were assayed for serum total protein; IgG, IgA, and IgM concentrations; peripheral total leukocyte counts; neutrophil counts; lymphocyte counts; lymphocyte phenotypes; vitamin A, vitamin E, cholesterol, and beta-carotene concentrations. Serum samples collected from 2- to 5-d-old calves were tested for immunoglobulin function via a bovine viral diarrhea virus type I serum neutralization titer and for neutrophil bacterial opsonization activity. On-farm batch heat treatment of colostrum at 60 degrees C for 60 min resulted in lower colostrum bacteria concentrations while maintaining colostral IgG concentration. Calves fed heat-treated colostrum had significantly greater serum total protein and IgG concentrations at 24 h, plus greater apparent efficiency of IgG absorption (total protein = 6.3 mg/dL; IgG = 22.3 mg/mL; apparent efficiency of absorption = 35.6%) compared with calves fed raw colostrum (TP = 5.9 mg/dL; IgG = 18.1 mg/mL; apparent efficiency of absorption = 26.1%). There was no effect of treatment on serum concentrations of IgA, IgM, vitamin A, vitamin E, cholesterol, beta-carotene or vitamin E:cholesterol ratio, or on serum bovine viral diarrhea virus type I serum neutralization titers. There was no difference between treatment groups when examining calf plasma total leukocyte counts, neutrophil counts, lymphocyte counts, or neutrophil opsonization activity. However, the latter results were considered inconclusive.

Effect of on-farm commercial batch pasteurization of colostrum on colostrum and serum immunoglobulin concentrations in dairy calves.

The objectives were to describe the effect of on-farm commercial batch pasteurization on immunoglobulin (IgG) concentrations and the fluid and feeding characteristics of colostrum and to compare serum IgG concentrations in calves fed fresh versus pasteurized colostrum. Newborn calves (123) were systematically allocated to dietary treatments of either fresh or pasteurized colostrum at both the first and second colostrum feedings. The IgG concentrations were measured for batches of colostrum fed fresh and in pre and postpasteurized samples for batches of colostrum fed after being pasteurized and in calf serum. Pasteurization reduced colostrum IgG concentration, with the percentage reduction averaging 58.5 and 23.6% for 95-L and 57-L batches, respectively. Pasteurizing high quality colostrum in 57-L (vs. 95-L) batches resulted in higher IgG concentrations in the end product. Pasteurization of 57-L batches produced colostrum of normal or only mildly thickened consistency that could be fed to calves. Serum IgG concentrations were higher for calves fed fresh colostrum and for calves with a shorter time interval (< or = 6 h) between first and second colostrum feedings. After controlling for the time interval between feedings, serum IgG concentrations were significantly higher for 40 calves fed unpasteurized (19.1 mg/ml) vs. 55 calves fed pasteurized colostrum (9.7 mg/ml) for calves fed 2 L at first feeding. By contrast, there was no difference in serum IgG concentrations between 8 calves fed unpasteurized (16.1 mg/ml) and 20 calves fed pasteurized colostrum (13.5 mg/ml) after calves were fed 4 L at the first feeding. While the latter results suggest that pasteurizing colostrum may work for producers with excellent colostrum management, these results are preliminary and should be interpreted with caution, given the fewer number of calves and batches of colostrum involved with this second comparison.