Plasma progesterone and LH concentrations during oestrous synchronization in female fallow deer ( Dama dama)

Abstract

Fifteen non-lactating adult fallow does were allocated to three treatment regimens ( n = 5 does each) designed to synchronize oestrus on or about 28 May (about 4 weeks after the first natural oestrus during autumn). Does assigned to Treatment 1 (natural oestrus) were initially synchronized with intravaginal progesterone CIDRs and the return oestrus was predicted to occur 21 days later on 28 May. Does assigned to Treatment 2 (prostaglandin-induced oestrus) were also initially synchronized with CIDRs and each doe was given an i.m. injection of cloprostenol on Day 13 (26 May) of the subsequent oestrous cycle. Does assigned to Treatment 3 (CIDR-induced oestrus) each received single intravaginal CIDRs for a 14-day period, with CIDR withdrawal occurring on 26 May. Blood samples from all does were collected at 2-h intervals for 70 h from 06:00 h on 26 May (i.e. cloprostenol injection/CIDR withdrawal) to 04:00 h on 29 May inclusive. Plasma samples were analysed for concentrations of progesterone and LH. Only one doe (Treatment 3) was not observed in oestrus during the intensive blood sampling period. Oestrus synchrony was over a 28-h period for Treatment 1, a 12-h period for Treatment 2 (36–48 h from cloprostenol injection) and a 28-h period for Treatment 3 (32–60 h from CIDR withdrawal). Plasma progesterone concentrations of does allocated to Treatment 1 were low (< 0.5 ng/ml) throughout the blood sampling period but mean values for does allocated to Treatments 2 and 3 were 4–5 ng/ml at the start of the respective synchronization treatments. The decline to basal plasma progesterone concentrations (i.e. < 0.5 ng/ml) was more rapid following CIDR withdrawal (4 h) than following cloprostenol administration (14 h). Does in all 3 treatment groups exhibited similar mean plasma LH profiles, with the onset of the preovulatory LH surge occurring around the onset of oestrus. Maximum mean LH concentrations during the preovulatory surge (∼30 ng/ml) were ∼20 fold higher than basal values and occurred 4–8 h after the onset of oestrus. The doe not observed in oestrus (Treatment 3) exhibited erratic fluctuations in plasma progesterone concentrations throughout the sampling period and failed to exhibit a preovulatory LH surge.