The effect of bovine interferon-alpha I1 on pregnancy rate in heifers.

• Autor(a) principal: Barros, C. M.
• Data de Publicação: 1992
• Outros Autores: Newton, G. R., Thatcher, W. W., Drost, M., Plante, C., Hansen, P. J.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.journalofanimalscience.org/content/70/5/1471.long; http://hdl.handle.net/11449/64233
• topic: recombinant interferon; animal; body temperature; cattle; double blind procedure; drug effect; estrus; female; fertility; fertilization; physiology; pregnancy; randomization; Animal; Body Temperature; Cattle; Double-Blind Method; Estrus; Female; Fertility; Fertilization; Interferon Type I, Recombinant; Pregnancy; Random Allocation; Support, Non-U.S. Gov't; Support, U.S. Gov't, Non-P.H.S.

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.