Single daily intramuscular injections of low quantities of recombinant ovine interferon-tau extends luteal life-span in Angora goats

The objective of this study was to determine whether single, daily intramus cular injections of low amounts of ovine interferon-tau (ovIFN-tau) would e xtend luteal life-span in nonpregnant Angora goats. Female goats were assig ned randomly to receive a single daily injection of 1) PBS (control; n = 11 ), 2) 125 mug/d ovIFN-tau (n = 11), or 3) 500 mug/d ovIFN-tau (n = 11) from d 14 to 20 after estrus. Luteal life-span was defined as the number of day s from the synchronized estrus until serum progesterone (P-4) declined (< 0 .5 ng/mL) and was of normal duration in controls (19.4 +/- 0.3 d) but was i ncreased (P < 0.05) in goats receiving 125 mug/d (23.2 +/- 1.3 d) and 500 m ug/d (25.5 +/- 1.2 d) ovIFN-tau. Injection of either ovIFN-tau dose caused an initial decrease (P < 0.05) in serum P-4 concentrations relative to cont rols but did not differ from controls thereafter. Rectal temperatures incre ased (P < 0.05) following ovIFN-tau treatment; until d 18 for goats given t he lower dose and throughout the treatment period for those given 500 mug/d . In summary, injections of as little as 125 mug/d of ovIFN-tau extended lu teal life-span in goats. This dose caused a transient reduction in serum P- 4 concentrations and induced hyperthermia.