Body weight, oestrous and ovarian activity in local Burundian ewes and goats after parturition in the dry season

To compare body weight losses and post-partum anoestrus, twelve local Burundian ewes and twelve goats which had lambed or kidded at the middle of the dry season were followed from parturition until eight months. Each dam was weighed every month and bled three times a week to assess the ovarian activity resumption by plasma progesterone (P4) profiles. For the two species, the body weight decreased significantly (P<0.05) compared to the body weight at parturition. The mean time during which the body weight decreased was longer (P<0.05) for the ewes (3.2±1.2 months) than for the goats (2.3±1.4 months), however, the relative body weight losses did not significantly differ. The time to oestrous and ovarian activity resumption was highly correlated to the body weight losses for the ewes (r=0.81; P<0.01 and r=0.58; P<0.05) not for the goats. The first oestrus preceded the first ovarian activity by 4 days in the goats, but occurred 36 days later in the ewes. Nevertheless, after the first luteal function, the subsequent ovarian activity was regular and normal in the ewes but not in the goats and in some cases a return to anoestrus could be observed. These data indicate that in the ewe, not in the goat, the body weight losses are one of the major limiting factors of the oestrous and ovarian resumption after parturition during the dry season. Moreover, the occurrence of luteal function does not initiate a regular reproductive cyclicity in the goat in contrast to the ewes.