Effect of an injectable trace mineral supplement on the immune response of dairy calves.

On a spring calving, pastoral dairy farm, the first 40 heifer calves born after calving mid-point (50% of the herd calved) were blood sampled within 24 h. Thirty were selected, using stratified randomisation to form two equal groups (treatment and control) with the same distribution of serum total protein, copper, selenium, zinc, and manganese concentrations, age and breed. From the remaining 10 calves, five were randomly selected into a sentinel group to assess field exposure to Salmonella spp. All calves received two injections of a killed vaccine containing Salmonella spp. antigens at 2 and 6 weeks of age. Concurrently, the treatment group were injected with 1 mL/50 kg trace mineral supplement (TMS) containing 40 mg zinc, 10 mg manganese, 5 mg selenium, 15 mg copper per mL. Sentinel animals received no injections. All animals were bled from 2 to 9 weeks for assay of immune function. At three and four weeks, white blood cells from TMS calves had an increased percentage of cells phagocytosing (effect size = 9.36 and 4.35) and increased number of bacteria ingested per cell (effect size = 0.93 and 1.52). No differences were detected in gamma interferon response (effect size <0.15) or Salmonella sp. antibody titres (effect size <0.20).

Reduction in morbidity and mortality of dairy calves from an injectable trace mineral supplement.

The effect of a multimineral preparation on the health and growth of spring born, dairy calves was investigated on four New Zealand pastoral farms. Calves were randomly allocated injections within 24 hours of birth, 35 days and 70 days after birth. Injections contained 40 mg zinc, 10 mg manganese, 5 mg selenium, 15 mg copper and 5 mg chromium per ml (Multimin+Se+ Cu+Cr Cattle, Virbac South Africa) at 1 ml/50 kg body weight. Morbidity, mortality from natural challenge and growth rates were recorded for 140 days. There were no differences in morbidity and mortality within 48 hours of birth for treated calves compared with controls, P=0.192. Morbidity and mortality were highest at 3-35 days (7.5 per cent [95 per cent CI 5.00 to 9.99] treated calves sick and 15.6 per cent [95 per cent CI 12.48 to 18.73] controls sick, P<0.001). For this period, mortality was lower at 4.4 per cent (95 per cent CI 2.49 to 6.41) treated calves and 10.4 per cent (95 per cent CI 7.78 to 13.03) controls, P<0.001. Allowing for potential confounders, the adjusted OR of treated calves scouring between 3 and 35 days was 0.44 (95 per cent CI 0.24 to 0.82, P=0.009). Allowing for potential confounders, from 0 to 140 days a second model predicted treatment approximately halved the probability of morbidity and mortality (P<0.001). There was no difference in the daily rate of gain (0.67 kg/day [95 per cent CI 0.66 to 0.67] for treated calves).

Effects of dietary supplementation of bentonite and Saccharomyces cerevisiae cell wall on acute-phase protein and liver function in high-producing dairy cows during transition period.

The aim of this study was to investigate the efficacy of dietary endotoxin binders [bentonite (BEN) and Saccharomyces cerevisiae cell wall (SCW)] on acute-phase protein (APP) response and liver function in cows during the transition period. Twenty-four multiparous Holstein cows were randomly assigned to one of four treatment groups. The experimental groups consisted of (1) the basal diet (BD) + SCW, (2) BD + SCW + BEN, (3) BD + BEN, and (4) BD (control). Blood samples were taken at 1, 3 and 4 weeks before and 1 and 3 weeks after parturition and serum concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), glucose, haptoglobin (Hp), serum amyloid A(SAA), albumin, g-glutamyl transferase (GGT), aspartate aminotransferase (AST), cholesterol, iron, and lipopolysaccharide (LPS) were measured. The concentrations of LPS, SAA, albumin, and Hp in the blood were within reference range at all times. The level of blood LPS was not high enough to initiate an APP response. Mean BHBA concentration was highest at 1 week after calving. For NEFA, the pattern was similar, with a peak at 1 week after calving. Cholesterol concentration was lower in the SCW group, probably due to a lower lipoprotein concentration. Mean AST concentration was highest at 1 week after calving, especially in the SCW + BEN group. The results of a current study showed that, if the carbohydrate level is not high in the diet to cause rumen acidosis, it is not profitable to supplement BEN and SCW for adsorbing endotoxins in the diet, in transition cows.