Genetic analysis of reproductive traits of Sahiwal cattle
POONAM RATWAN | A K CHAKRAVARTY | MANOJ KUMAR | A K GUPTA
Data on first lactation reproduction traits of Sahiwal cattle maintained at an organized herd of the institute over a period of 29 years (1988–2016) were analyzed in the present study. Effect of various genetic and non–genetic factors on first lactation reproduction traits in addition to their genetic control was assessed by using mixed model least–square analysis. The overall least–square means for first lactation reproduction traits, viz. age at first service (AFS), age at first calving (AFC), number of services per conception (NSC), conception rate (CR), gestation period (GP), calving to first insemination interval (CFI), service period (SP), calving interval (CI) and pregnancy rate (PR) were 784.84±8.03 days, 1116.18±10.38 days, 1.86±0.11, 0.97±0.06, 287.73±0.60, 84.75±5.01, 119.86±8.31, 420.53±3.33 days and 0.27±0.02, respectively. Analysis of variance revealed that random effect of sire had non– significant influence on all the considered traits in present study. Period of birth significantly influenced AFS and AFC. Differences were statistically significant for effect of period of calving on NSC; season of calving on NSC, CR and PR; age group on NSC and CR. The effect of lactation length used as co–variable had significant influence on CFI, SP and PR. Service period as co–variable significantly affected CI. The magnitudes of heritability estimates were low to medium varying from 0.09 to 0.27 for different reproduction traits indicating large role of environment and management for improvement of these traits.
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