title: Genetic evaluation of reproduction performance of Jersey × Red Sindhi crossbred cows.
abstract: OBJECTIVE
  The present investigation was undertaken to study the reproduction performance and effect of non-genetic factors on reproduction performance of Jersey crossbred cows.
  
  
  METHODS
  Data on 355 Jersey crossbred cattle maintained at the Post-graduate Research Institute in Animal Sciences, Kattupakkam, Tamil Nadu, distributed over 30 years (1985 to 2014). The effect of various non-genetic factors including the period of birth, season of birth, period of calving, season of calving and parity were analyzed through least-squares analyses using univariate general linear model. The different (co)variance components for calculation of genetic parameters were estimated using restricted maximum likelihood method by fitting an animal model.
  
  
  RESULTS
  The overall least-squares means (±standard error) of age at first service, age at first calving, weight at first calving, service period, calving interval, dry period, and number of services per conception were 848.06±9.72 days, 1204±12.20 days, 289.81±1.71 kg, 210.01±6.41 days, 489.12±6.45 days, 137.96±5.58 days, 2.50±0.07, respectively. Period of calving had either significant (p<0.05) or highly significant (p<0.01) effect on all reproduction traits studied except service period, calving interval, and dry period. Number of services per conception was affected by season of calving. Parity had significant influence (p<0.05) or highly significant (p<0.01) influence on all the traits studied except service period and dry period. Heritability estimates of age at first service, age at first calving, weight at first calving, service period, calving interval, dry period, and number of services per conception were 0.299, 0.220, 0.017, 0.142, 0.222, 0.177, and 0.042, respectively. The estimates of repeatability for service period, calving interval, dry period, and number of services per conception were 0.219, 0.234, 0.420, and 0.001, respectively.
  
  
  CONCLUSIONS
  The reproduction performances of Jersey × Red Sindhi crossbreds were lower when compared to the earlier reports on Jersey crossbreds. Heritability and repeatability values were also low to moderate, indicating limited scope for improvement through selection.
authors.affiliation: Department of Animal Genetics and Breeding, Madras Veterinary College, Vepery, Chennai, Tamil Nadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Vinothraj
authors.affiliation: Department of Animal Genetics and Breeding, Madras Veterinary College, Vepery, Chennai, Tamil Nadu, India.
authors.forename: A
authors.initials: A
authors.lastname: Subramaniyan
authors.affiliation: Department of Animal Genetics and Breeding, Post-graduate Research Institute in Animal Sciences, Kattupakkam - 603 203, Chennai, Tamil Nadu, India.
authors.forename: R
authors.initials: R
authors.lastname: Venkataramanan
authors.affiliation: Department of ARGO, Madras Veterinary College, Vepery, Chennai, Tamil Nadu, India.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Joseph
authors.affiliation: Department of Animal Genetics and Breeding, Madras Veterinary College, Vepery, Chennai, Tamil Nadu, India.
authors.forename: S N
authors.initials: SN
authors.lastname: Sivaselvam
keywords: Jersey crossbred; genetic parameters; reproductive performance