Factors influencing gestation length and calving interval of Gir cows under northeast Brazil conditions

Abstract

Data from 129 gestation lengths and 597 calving intervals from a herd of Gir cows in Umbuzeiro, PB, Brazil, were analysed. Gestation lengths was 288.6 ± 0.7 days and was not affected by the factors sire, sex and year, neither by gestation number. Calving interval was 466.6 ± 4.6 days being affected by calving season, sex and year, gestation number and cow age at first calving. Wider calving intervals were observed for cows that calved from July to September with 460 ± 9.4 days and minors from January to March with 430.8 ± 9.5 days. The cows that calved male calves presented calving interval larger than the cows that calved female calves. Average age of cows at first calving was 3.4 years. Cows calved all along the year, but birth concentration was in April-May and November-December.