Number of Calves Produced at Specified Age as a Measure of Reproductive Performance in Beef Cattle under Artificially-Inseminated Breeding Scheme

Kenji Oyama, Shinya Fujiwara, Tomohiro Katsuta, Takeshi Honda, Fumio Mukai
2009 Asian-Australasian Journal of Animal Sciences  
Reproductive abilities in beef cattle herds are receiving increased attention due to recent rises in production costs. To achieve more efficient management, a measure of fertility, namely the number of calves produced at k yr of age (NCP k ), was developed and its genetic parameters were estimated from Japanese Black cows by restricted maximum likelihood procedures. The k examined were distributed from 2 to 10 yr of age and NCP 2 averaged 1.077 calves over 43,536 cows. The averages increased by
more » ... erages increased by approximately 0.9 calf with each additional 1 yr increment in k. Heritabilities of NCP k were estimated to be low ranging from 0.083 to 0.162, which seemingly suggested a difficulty of genetic improvement. However, large genetic variation and high accuracy were observed in predicted breeding values of NCP k . For example, the breeding values of NCP 7 were predicted between -0.303 and +0.213 with average accuracy of 0.607 for cows with observations. Genetic correlations among different k were generally high and positive (0.474 to 0.995). The analyses showed that at least NCP 4 was required to maintain the genetic correlations of 0.8 or higher with subsequent NCP k . Also NCP 5 maintained the genetic correlations of 0.9 or higher with subsequent NCP k . The results suggested some possibilities for NCP k to be a selection criterion considering its genetic variation, high accuracy and consistency with subsequent performance. (
doi:10.5713/ajas.2009.80284 fatcat:xtsmbu5jgbhbxn7pvn5mareiya