Effect of service and oxytocin on estrus duration in goats

The object of this experiment was to determine the effect of service and oxytocin injection on estrus duration in dairy goats. Eighteen Nubian goats were randomly divided into service (SER), oxytocin (OXY) and control (CON) groups of six animals each. Estrus was synchronized by using medroxyprogesterone acetate intravaginal sponges (MAP, 60 mg) over a 12 day period. Estrus was detected by using a vasectomized buck (also called sterile service) with an apron at 6 h intervals (at 06:00, 12:00, 18:00 and 24:00 h) during the 5 days after sponge removal. In the SER group the male was permitted to mount and to service each doe only once. The OXY group was injected with 25 IU of oxytocin and mounting was permitted. Both treatments were done during the first hours of estrus. The CON group was only permitted to be mounted. Estrus duration for groups SER, OXY and CON was (mean +/- SD) 24.0 +/- 5.4 h, 37.0 +/- 12.2 h and 40.0 +/- 9.8 h, respectively. The SER group was different from the OXY and CON groups (P < 0.05). There was no difference in estrus duration between the OXY and CON groups (P > 0.05). It is concluded that service shortens estrus duration and 25IU oxytocin injected intramuscularly had no effect on its duration.