Effect of Bovine Interferon-τ on Body Temperature and Plasma Progesterone Concentrations in Cyclic Dairy Cows

Abstract

We examined the effect of intramuscular injections of recombinant bovine interferon-τ on basal body temperature and plasma concentrations of progesterone in cows. Six mature, nonlactating Holstein cows were synchronized for estrus and assigned randomly to a replicated 3 × 3 Latin square design to receive 0, 1, or 5mg of recombinant bovine interferon-τ intramuscularly on d 9, 12, or 15 of the estrous cycle. Rectal temperatures were measured, and blood was collected just prior to injection, at hourly intervals for 8h, and at 10 and 12h after injection. Treatment with 1 and 5mg of recombinant bovine interferon-τ caused a rise in body temperature that peaked at 6h (39.5±.13°C) and 4h (40.3±.13°C), respectively. Analysis of homogeneity of regression for response curves indicated that 5mg of recombinant bovine interferon-τ decreased plasma progesterone concentrations. This effect was not detected 6for the 1-mg dose of recombinant bovine interferon-τ. Intramuscular administration of 5mg of recombinant bovine interferon-τ caused a hyperthermic response that was temporally associated with the decrease in plasma progesterone. Intramuscular administration of 1mg of recombinant bovine interièron-τ caused a slight rise in temperature occurring 4h later than that caused by 5mg of recombinant bovine interferon-τ, and no decrease in plasma progesterone was detected. Recombinant bovine interferon-τ, administered at a 1-mg dose, warrants further study to determine whether it will alter survival rate of cattle embryos.