Studies on first lactation reproduction traits of HF × Gir Half Breds

The present investigation was undertaken by utilizing the data maintained at RCDPon Cattle, M.P.K.V., Rahuri fora period of 37 years (1972 to 2008).The data were collected and classified according to generation, period of birth/calving, season of birth/calving and peak milk yield and analyzed by least squares analysis method. Whenever the effects were significant the differences between means were tested by Duncun's Multiple Range Test. Genotypic and phenotypic correlations between traits and heritability of traits were estimated. The overall least squares means of age at first calving, first service period and first calving interval in HF x Gir half breds were 1036.53 ± 15.77, 148.96 ±11.34 and 418.08 ± 11.25 days. The analysis of variance revealed that period of birth and generation had significant effect, and season of birth exerted non-significant effect on age at first calving. The period of calving, peak milk yield and generation had non-significant effect while season of calving had exerted significant effect on first service period and first calving interval. The genetic correlation between AFC and FSP was 0.496 and it was positively significant. The genetic correlation between FSP and FCI (−0.502) was negatively significant. The phenotypic correlation of AFC with FSP and FCI was 0.015 and 0.040, respectively which was positive and non-significant. The phenotypic correlation of FSP with FCI was 0.463 and it was positive and significant. The heritability estimate of AFC, FSP and FCI was 0.279 ±0.151, 0.080 ± 0.010 and 0.082 ±0.012, respectively.