Factors Affecting Age at First Calving in Kankrej Cattle

The data of 35 years from 1980 to 2014 were analyzed to study the effect of genetic and non-genetic factors viz. period of calving, season of calving as fixed effect and sire as random effect on the reproduction trait (age at first calving) of Kankrej cattle maintained at Livestock Research Station, S.D. Agricultural University, Sardarkrushinagar, Gujarat. The least square mean of age at first calving in Kankrej cows was found to be 1376.0 9 ± 14.55 days. Heritability estimates was 0.44 ± 0.18 for the age at First calving. Genetic correlation of age at first calving (AFC) with first lactation 300 milk yield (F300Y), total milk yield (FLY) and lactation length (FLL) were 0.358 ± 0.218, 0.341± 0.216 and 0.661 ± 0.361, respectively while the phenotypic correlation were 0.055, 0.048 and 0.044, respectively. The effect of period of calving and sire was significant (P<0.01) on age at first calving. 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 indicated breed characteristic for adoption in particular environment. Age at first calving showed a significant variation over the period that indicated some selection measures for age at first calving.