Estrous and ovarian responses following the administration of different insulin doses following progestagen-cloprostenol treatment in mated does during the dry season

Abstract

Thirty-nine nulliparous and cyclic free-ranging Anglo-nubian goats were synchronized using 60mg MAP intravaginal sponges for 10days and 50μg cloprostenol treatment, 48h before sponge removal (SR). Goats were allocated to 3 groups with 13 animals in each group. The treatment groups, Insulin 0.14 and Insulin 0.20 were treated subcutaneously, for 3 consecutive days – beginning 48h before SR, with 0.14IU/kg BW/day or 0.2IU/kg BW/day of a long-acting insulin, respectively. The Control group received a 0.5ml saline solution (s.c.). The goats were monitored for the occurrence of estrus and mated at the onset of estrus and 24h later. Transrectal ultrasonography was used to monitor the ovarian follicular dynamics, ovulation rate and diagnose pregnancy. Blood samples were collected from 48h before SR to the 12th day of pregnancy for plasma insulin determinations. Insulin administration exhibited an increase (p<0.05) in animals with plasma insulineamia. Insulin treated goats recorded a higher (p<0.05) ovulation rate, when compared to saline control treated goats (1.7±0.23 vs 1.0±0.21). Nulliparous does from the Insulin 0.14 group recorded large follicles at 0, 12 and 18h of the estrous period (p<0.05), a more efficient synchronization of ovulation (p<0.05) and larger size CLs (p<0.05). It was concluded that administration in insulin induced a positive effect on ovarian response in nulliparous goats. Furthermore, in these animals the reproductive performance appeared to be independent of the increase of insulin dosage.