Effects of oral vitamin E supplementation during late gestation in beef cattle that calved in late winter and late summer

Effects of maternal natural (RRR alpha-tocopherol acetate) or synthetic (all-rac alpha-tocopherol acetate) vitamin E supplementation on suckling calf performance, colostrum immunoglobulin G, and immune function

The objective of this study was to determine the effects of maternally supplemented natural- or synthetic-source vitamin E on suckling calf performance and immune response. In a 2-yr study, one hundred fifty-two 2- and 3-yr-old, spring-calving, Angus-cross beef cows were blocked by age, BW, and BCS into 1 of 3 isocaloric, corn-based dietary supplements containing 1) no additional vitamin E (CON), 2) 1,000 IU/d of synthetic-source vitamin E (SYN), or 3) 1,000 IU/d of natural-source vitamin E (NAT). Maternal supplementation began approximately 6 wk prepartum and continued until the breeding season. Colostrum from cows and blood from calves was collected 24 h postpartum for analysis of IgG concentration as an indicator of passive transfer and circulating alpha-tocopherol concentration. At 19 d of age, blood was collected from calves to determine the expression of CD14 and CD18 molecules on leukocytes. At 21 and 35 d of age, humoral immune response was measured by a subcutaneous injection, in the neck, with ovalbumin (20 mg; OVA) and blood samples collected weekly until d 63 of age to determine antibodies produced against OVA. At d 63 of age, calves were administered an intradermal injection of OVA (1 mg) in the neck to assess cell-mediated immunity, which was determined on d 65 of age by measuring nodule size with calipers. Circulating alpha-tocopherol concentrations were increased at both 24 h (P = 0.001) and at the day of initial OVA challenge (P < 0.001) in SYN and NAT compared with CON calves. No differences were detected (P > 0.05) for calf birth BW, ADG, or weaning BW. There were no differences (P > 0.05) in calf serum total IgG or cow colostrum total IgG at 24 h or presence of CD14 and CD18 receptors at d 19 of age. The NAT calves had a greater antigen response to OVA at d 63 than SYN calves (P = 0.01; treatment x day interaction). As an indicator of cell-mediated immunity to OVA, nodule size at 65 d of age was not affected (P = 0.92) by maternal dietary supplementation. In conclusion, calves suckling cows supplemented with natural- and synthetic-source vitamin E had increased circulating concentrations of alpha-tocopherol at 24 h, which appeared to continue throughout maternal supplementation; however, calf immune function and performance were not affected.

Mastitis in beef cows and the effects of supplemental β-carotene on milk parameters

Belmont red and Brahman cows (n = 50) were allocated to one of two groups to determine if β-carotene supplementation could reduce the incidence of mastitis and consequently improve calf productivity from birth to weaning. Both groups received a molasses-based supplement ad libitum; the treatment group supplement was fortified with ROVIMIX® β-carotene and ROVIMIX® E50 whereas the control group were provided access to the molasses supplement only. Blood samples were collected from cows pre and post calving and from calves when 84 ± 0.4 days old to measure plasma β-carotene concentration (PCC). Milk samples were collected 7 and 84 days post calving and at weaning and analysed for somatic cell count (SCC) and composition. Supplementation had no significant (P > 0.05) effect on SCC, calf PCC, calf LW gain and LW at weaning. Supplemented cows had significantly (P < 0.05) higher PCC compared with unsupplemented cows (4.9 ± 0.36 v. 3.9 ± 0.24 mg/L, respectively) at weaning. Cows commenced the study in an above-average condition, and combined with unseasonal green forage it is concluded that β-carotene supplementation has no effect on mastitis or calf weaning weight.