Treatment of anoestrum in cows by reproductive hormones
Keywords:Anoestrum, cow, estrous cycle, pregnant, reproductive hormone
Anoestrum, a failure in the estrous cycle, in dairy cows causes a reduction in economic efficiency of livestock in Vietnam. My observation showed that dairy cows which have no cycle for the first time (referred to as late estrus) at the age of > 26 months make up 63.22% of population. Animals which have no cycle for
> 5 months (referred to as delayed estrus) after calving make up 40.99% of population. To treat anoestrum, reproductive hormones including Progesterone (PG), Gonadotropin-releasing hormone (GnRH), Pregnant Mare's Serum Gonadotropin (PMSG), Human chorionic gonadotropin (hCG), Estradiol Benzoate (EB) and hormone carriers including Synchromate B (SMB) implanted into the ears and Cue-Mate implanted into the vagina were applied. There are 5 formulas made from these hormones and hormone carriers. Formula I contains PG + GnRH (1st injection i.m.) and PG + GnRH (2nd injection i.m.) 9 days later. Formula II contains PG (1st injection i.m.) and PG + PMSG (2nd injection i.m.) 9 days later. Formula III contains PG (1st injection i.m.) and PG + hCG (2nd injection i.m.) 9 days later. Formula IV contains SMB (ear implantation) + EB (1st injection i.m.) and PG + PMSG (2nd injection i.m.) 7 days later and SMB was removed on day 16. Finally, formula V contains Cue-Mate (intravaginal implantation) + EB (1st injection i.m.) and PG + PMSG (2nd injection i.m.) 7 days later and Cue-Mate was removed on day 16. Treatment of cows inwhich delayed estrous cycle appeared for re-breeding showed that the formula I, II, III, IV, and V induce estrus respectively in 94.82%, 88.46%, 90%, 100%, and 100% of population and promote pregnancy efficiency in respectively 89.66%, 80.77%, 82%, 96%, and 82.14% of population. The data show that formula IV gave the highest efficiency but it is the most costly. In contrast, formula V induces vaginal inflammation in 62.50% of cows. Treatment of cows which have late estrus for the first time with formula I, II, and III showed formula I is efficient in inducing estrus and promoting pregnancy (97.22% and 86.11% respectively). All together, the results indicate that formula I may be the applicable choice for treatment of anoestrum in dairy cows in Vietnam.