Post-partum uterine involution and oestrus cycle resumption in trypanotolerant Ndama and Baoulé cows

Abstract

This work refers to 30 Ndama and 30 Baoulé cows kept on pasture (Panicum maximum) at the Research and Breeding Centre of Avetonou, Togo (Centre de Recherche et d’Elevage, Avetonou, Togo (CREAT)), which is located in the Sudano-guinean savanna of West Africa. Two calving seasons were observed: 17 Ndama and 15 Baoulé cows gave birth during the dry season (December-January) and 13 Ndama and 15 Baoulé cows at the beginning of the rainy season (February-March). The cows which calved during the dry season lost about 10 % of their bodyweight 30 days post-partum; the cows which had calved at the beginning of the rainy season lost only about 2 % of their average body weight. The duration of the uterine involution was not influenced by the calving season (P > 0.05). On an average, the overall uterine involution was achieved 31 ± 4 days post partum for the Ndama and 30 ± 7 days for the Baoulé cows. The influence of the age of the cows on the uterine involution was significant (P < 0.05). Young cows (4-5 years old) in both breeds had almost all completed their uterine involution by 30 days post-partum. Fifty percent of the Baoulé and Ndama cows had been seen in heats by 49 and 44 days post partum, respectively. According to the examination of the ovarian morphology, 50 % of the cows of both breeds were estimated as cyclic 60 days post-partum. However, the increase in plasma progesterone concentrations (above 0.5 ng/ml) showed that 50 % of the Ndama and Baoulé cows had resumed their sexual cycle 34 and 40 days respectively, post partum. The weight gain depending on the feeding of these trypanotolerant lactating cows on pasture seemed to be the main reason for such variations of resumption of the oestrus cycle after calving and hence for the variation in the calving intervals.