Factors Affecting Age at First Calving in Gir Cattle

The production records on 228 Gir cows with 680 lactations sired by 52 bulls, maintained at Cattle Breeding Farm, Junagadh Agricultural University, Junagadh, for 24 years (1987 – 2010) were studied. The data were analyzed to study the effect of period of calving and season of calving as fixed effect on the reproduction trait viz., age at first calving. The average age at first calving in Gir cows was found to be 1490.50 ± 111.04 days. The analysis of variance revealed highly significant effect of period of calving on age at first calving indicating thereby that age at first calving was subjected to non-genetic factors. Season of calving did not affect significantly to this trait under study. Effect of season of calving was not significant on age at first calving indicating breed characteristic to adoption with environment. Age at first calving showed a significant rise over the period that indicate some selection measure require for age at first calving.