Genetic and Phenotypic Parameters of Jersey Cows Reproductive Traits in the Different Calving Numbers
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- Calving Number, Fertility Trait, Genetic and Phenotypic Parameter, Jersey Cow
- Getahun, Kefale
- Genetic parameters of reproductive traits of dairy cows can be evaluated by considering it as the same trait over the calving numbers of a given animal or by treating reproductive performances over calving numbers as different traits. The objectives of this study were to estimate variances, heritabilities genetic as well as phenotypic correlations of some reproductive (calving interval, CI and service per conception, SPC) traits of Jersey cows during their first, second, third, fourth and fifth calving/lactation numbers in Ethiopia considering each calving number as separate trait. Genetic parameters were estimated using multi-variate analysis via AI-REML algorism of the Wombat software. The pedigree file which used to compute the numerator relationship matrix were 782 and 1061, 602 and 787, 458 and 604, 368 and 455 and, 277 and 366 animals for first, second, third, fourth and fifth calving numbers of CI and SPC traits, respectively. Year as a fixed effect and animal and error/residual as random effects were assigned in the model of analysis. The analyzed results showed that higher additive, residual and phenotypic variances of calving interval (CI) were found at the third calving number. For service per conception (SPC), the variances were increased across calving numbers. The estimated heritabilities of CI in the five consecutive calving numbers were 0.15, 0.05, 0.23, 0.22 and 0.08, respectively somewhat higher than the reviewed literature reports. For SPC, the estimates were not different from zero but slightly increased across calving numbers with the values of 0.003, 0.006, 0.01, 0.016 and 0.02, respectively which were lower than the reviewed literature results. Genetic correlations of CI in first and fourth, first and fifth, second and third and, fourth and fifth calving numbers were higher (0.73-0.99) than the other respective calving numbers (-0.33-0.14) whereas, the phenotypic correlations were tended to be of close to very low and some negative values (-0.05-0.19). On the other hand, there were great genetic (0.98-0.99) and phenotypic (0.96-0.99) associations among calving numbers of SPC trait.
Full text: IJRAS_1112_FINAL.pdf