Effect of service on duration of oestrus and ovulation in dairy goats

In the autumn, Nubian goats (n = 24) were randomly divided into two equal groups after oestrus had been synchronized using fluorogestone acetate intravaginal pessaries (FGA, 30 mg) over a 20 day period. The onset of oestrus was detected at 8 h intervals using either of two vasectomized bucks fitted with an apron during the 5 days following pessary removal. A buck was permitted to mount and serve each doe only twice in 30 min within the first 8 h of oestrus initiation in the SER group. In the CON group, a buck was only permitted to mount. Ovulation was determined by laparoscopy at 8 h intervals starting 24 h after onset of oestrus. Duration of oestrus for SER and CON groups was (mean +/- SD) 26.7 +/- 7.1 and 36.0 +/- 8.0 h, respectively (P < 0.01). The first and last ovulations for SER and CON groups were 34.7 +/- 3.9 and 37.3 +/- 6.2 h, and 35.3 +/- 5.4 and 38.0 +/- 6.0 h from oestrus initiation, respectively (P > 0.05). No differences were found between right and left ovarian activity (P > 0.05). Ovulation rates did not differ (2.17 +/- 0.58 and 2.17 +/- 0.94). Ovulations occurred principally towards the end of oestrus in the CON group and after oestrus had ended in the SER group. Service reduced the duration of oestrus without affecting ovulation times or ovulation rates in Nubian dairy goats.