The effect of bovine interferon-alpha I1 on pregnancy rate in heifers.
Bovine interferon-alpha I1 (bIFN-alpha) may be useful for enhancing fertility in sheep and cattle because it has extensive sequence homology with ovine and bovine trophoblast protein-1 and, like those proteins, extends corpus luteum lifespan. To test the effectiveness of bIFN-alpha to enhance fertility, several experiments were performed in which inseminated heifers were given i.m. injections of bIFN-alpha approximately at the time of embryo-mediated signals that result in maintenance of the corpus luteum. In Exp. 1, heifers given 20 mg of bIFN-alpha daily from d 14 to 17 tended (P less than .07) to have lower pregnancy rates at d 110 to 112 of gestation (36/75; 48% vs 43/72; 60%). Similar results were obtained in Exp. 2 when heifers received a single injection of 40 mg of bIFN-alpha or placebo at d 13 after estrus; pregnancy rates at d 42 were 39/104 (38%) for bIFN-alpha and 47/98 (48%) for placebo. In Exp. 3, heifers were given gradually increasing doses of bIFN-alpha or placebo from d 11 to 19, because such a regimen had been shown to reduce the number of heifers experiencing hyperthermia after bIFN-alpha injection. Pregnancy rates were 42/95 (44%) for bIFN-alpha and 62/111 (56%) for placebo. Across all three experiments, pregnancy rates were lower (P less than .01) for heifers treated with bIFN-alpha (117/274; 43%) than for heifers treated with placebo (152/281; 54%). In conclusion, these results demonstrate that, under the administration systems used, bIFN-alpha does not increase pregnancy rate, but rather tends to reduce it.
Barros
C M
CM
Departamento de Farmacologia, Universidade Estadual Paulista, São Paulo, Brazil.
Newton
G R
GR
Thatcher
W W
WW
Drost
M
M
Plante
C
C
Hansen
P J
PJ
D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D002417:Cattle / Q000502:physiology*; D004311:Double-Blind Method; D004971:Estrus / Q000187:drug effects*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D005306:Fertilization / Q000187:drug effects*; D007370:Interferon Type I / Q000494:pharmacology*; D011247:Pregnancy; D011897:Random Allocation; D011994:Recombinant Proteins
D007370:Interferon Type I; D011994:Recombinant Proteins