title: Short communication: Genetic analysis for fertility traits of heifers and cows from smallholder dairy farms in a tropical environment.
abstract: The objective of this study was to estimate genetic parameters for various fertility traits on Holstein upgraded dairy heifers and cows in a smallholder system under tropical conditions using data sets from the Thailand national recording scheme. The investigated traits were age at first service (AFS), age at first calving (AFC), days from calving to first service (DTFS), days between first and last service (DFLS), days open (DO), calving interval (CI), number of services per conception (NSPC), and conception at first service (FSC). The data consisted of 68,555, 34,401, and 54,004 records on heifers, primiparous, and multiparous cows, respectively, calving between 1996 and 2011. Gibbs sampling was employed to obtain (co)variance components using both univariate and bivariate analyses with linear and threshold animal models. Virgin heifers had better fertility performance than primiparous and multiparous cows. The reproductive performance in primiparous cows was inferior compared with multiparous cows. Cows with higher Holstein-Friesian blood showed lower reproductive efficiency. Estimated heritabilities for most of the fertility traits were 0.04 or less except for AFS (0.26) and AFC (0.25). The estimated genetic correlations among fertility traits within parity indicated that selection for cows with high conception rate could lead to shortened DO and CI, as well as DTFS. The FSC and NSPC could be used as the best indicators for heifer and cow fertility and could be complemented by other traits, which were genetically considered as different traits such as DTFS and DFLS in terms of a fertility index. This would enable efficient selection for better fertility. Genetic correlations for fertility traits in primiparous and multiparous cows were very high (>0.90), but those between heifers and cows were lower (0.03 to 0.83). The latter results indicated that fertility traits of heifers and cows should be considered as different traits.
authors.affiliation: The Bureau of Biotechnology in Livestock Production, Department of Livestock Development, Pratumtani 12000, Thailand. Electronic address: buaban_ai@hotmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Buaban
authors.affiliation: Department of Animal Science, Khon Kaen University, Meaung, Khon Kaen 40002, Thailand.
authors.forename: M
authors.initials: M
authors.lastname: Duangjinda
authors.affiliation: Department of Life Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Life Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Masuda
authors.affiliation: The Bureau of Biotechnology in Livestock Production, Department of Livestock Development, Pratumtani 12000, Thailand.
authors.forename: J
authors.initials: J
authors.lastname: Sanpote
authors.affiliation: Department of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kuchida
mesh_terms: D000818:Animals; D002417:Cattle / Q000235:genetics / Q000502:physiology*; D003612:Dairying; D005260:Female; D005298:Fertility; D006824:Hybridization, Genetic; D007315:Insemination, Artificial / Q000662:veterinary; D013785:Thailand; D014329:Tropical Climate
keywords: Holstein upgraded; genetic parameters; reproduction; tropics