Calving rate of cows under caatinga conditions as affected by dry-season suplemmentary grazing on buffel-grass

Abstract

The study was designed to evaluate the effects of buffelgrass (Cenchrus ciliaris, L.) dry-season grazing on seasonal liveweight changes and on annual calving rates of native x Zebu cows, raised extensively on caatinga vegetation. Forty-two mature cows were assigned to two 21-cow treatments: (C) continuous yearlong grazing on caatinga (08 ha/cow), and (CB) continuous rainy-season grazing on caatinga and continuous dry-season grazing on buffel-grass paddock (01 ha/cow). The study was carried out over a three-year period. At the end of the experimental period, CB cows were 85.4 kg heavier (P < 0.05) than the C ones. Annual calving rate showed by CB cows was significantly higher (P < 0.05) than the rate observed for the C cows. In terms of number of calves born, the increase showed by CB group reached 56% indicating the depressive effect on fertility of C cows, caused by heavy liveweight losses, as a result of prolonged periods of undernutrition.