Effects of Weaning, Fasting and B-vitamin Injections on Plasma B-vitamin Concentrations in Beef Calves

Twelve 364 Ib beef calves were weaned, limit-fed and fasted for three days during the 20-day period after weaning, and then inoculated intranasally with live attentuated infectious bovine rhinotracheitis on day 20. Six of these calves were injected intramuscularly with water soluble vitamins every 2 days from day 9 to day 34. Plasma ascorbic acid and pantothenic acid were depressed by weaning and restricted feeding; folic acid and B12 were not. Plasma concentrations of vitamin C, folic acid, pantothenic acid and vitamin BI2 were increased by injections by day 20. Plasma vitamin C, pantothenic acid and BI2 but not folic acid, were markedly reduced 5 days after infectious bovine rhinotracheitis-infection in both control and vitamin-injected calves, but rebounded by day 34 with recovery from infectious bovine rhinotracheitis. Results indicate that stress of weaning and infection can alter blood levels of some vitamins. Plasma vitamin concentrations were consistently high for calves injected with vitamins on the day of inoculation, perhaps reflecting altered tissue release or metabolism and excretion. Whether supplements will reduce severity of infections is not yet known.