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Asian-Australas J Anim Sci > Accepted Articles
DOI: https://doi.org/10.5713/ajas.19.0118    [Accepted] Published online May 28, 2019.
Genetics of heifer reproductive traits in Japanese Black cattle
Asep Setiaji1,2,3  , Takuro Oikawa1,2,* 
1United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan., Kagoshima, Japan
2Faculty of Agriculture, University of the Ryukyus,, Okinawa, Japan
3Faculty of Animal and Agricultural Sciences, Diponegoro University, Semarang, Central Java, Indonesia., Semarang, Indonesia
Correspondence:  Takuro Oikawa, Tel: +81-98-895-8756, Fax: +81-98-895-8734, Email: tkroikawa@gmail.com
Received: 8 February 2019   • Revised: 5 April 2019   • Accepted: 7 May 2019
The objective of this study was to identify environmental factors strongly associated with and to estimate genetic parameters of reproductive traits in Japanese Black heifers.
Data included reproduction records of Japanese Black heifers born between 2004 and 2014. First service non-return rate (NRR) to 56 days from first to successful insemination (FS), number of services per conception (IN), age at first calving (AFC) and gestation length (GL) were analyzed with the use of the general linear model (GLM). Genetic parameters were estimated with the use of the univariate animal model of the residual maximum likelihood (REML). Result: Averages of reproductive traits over eleven years were assessed, and the effects of farm, year, month, AI technician and interaction of farm × year on the traits were determined. Estimated heritability of FS was very low and that of AFC was higher than that of the other traits. A close genetic relation was observed among NRR, IN and FS; however, their heritabilities were very low. AFC shows favorable genetic correlation with IN and FS.
Low heritabilities of the most reproductive traits in Japanese Black heifers are strongly influenced by farm management practices, and that large residual variances make genetic evaluation difficult. Among the reproductive traits, AFC is potentially more useful for genetic improvement of heifer reproductive traits because it has high heritability and favorable genetic correlations with IN and FS.
Keywords: Reproductive Traits; Japanese Black Heifer; Heritability; Genetic Correlation

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