Pregnancy and resumption of sexual activity after parturition in “Mossi” Djallonké ewes

Abstract

The present study (July 1990-April 1991) aimed at determining some physiological parameters of pregnancy and resumption of cyclicity after parturition in Djallonké “Mossi” ewes (n = 52). The observation of 20 ewes naturally mated between October and November (dry and cool season) showed a pregnancy length of 149 ± 2.4 days, a fertility rate of 92 %, a prolificacy rate of 118 %, a fecundity rate of 108 and 7.1 % of embryoresorption. Foetal growth and that of its membranes were slow (< 10 g/day) during the first two months. After three months, the growth rate increased (about 27 g/day). The maternal plasma progesterone concentration rose during this period from5.58 ± 0.85 to 13.71 ± 2.32 ng/ml. The study of cyclicity resumption (December-January) conducted in 14 other ewes showed that the first oestrus appeared 56.6 ± 10 days after parturition. A trial made in 18 ewes housed in individual boxes and receiving different levels of feeding (80, 100 and 120 %), and with a suckling period of 4, 5 and 6 weeks showed that the return to heats was related both to the level of feeding and to the suckling length. A dietary regimen meeting all nutrient requirements and a suckling period of 4 weeks led to reducing the interval from parturition to first oestrus by about 3 weeks, i.e. 35 days after lambing. The maternal plasma progesterone levels showed that the first ovulation occured 25 ± 2 days after parturition. In conclusion, these parameters indicate that the reproductive performances of Mossi Djallonké ewes may be improved provided that the feed supply is large enough and that the lambs are weaned early.