Ghiasi Heydar, Piwczyński Dariusz, Sitkowska Beata, González-Recio Oscar
Payame Noor University, Faculty of Agricultural Science, Department of Animal Science, Tehran P.O.Box 19395-3697, Iran.
UTP University of Science and Technology, Faculty of Animal Breeding and Biology, Department of Animal Biotechnology and Genetics, Mazowiecka 28, 85-084 Bydgoszcz, Poland.
Anim Biosci. 2021 Aug;34(8):1303-1308. doi: 10.5713/ab.20.0600. Epub 2021 Mar 2.
The objective of this study was to define a new composite trait for Holstein dairy cows and evaluate the possibility of joint improvement in milk and fertility traits.
A data set consisting 35,882 fertility related records (days open [DO], calving interval [CI], and number of services per conception [NSC], and total milk yield in each lactation [TMY]) was collected from 1998 to 2016 in Polish Holstein-Friesian breed herds. In this study TMY, DO, CI, and lactation length of each cow was used to obtain composite milk and fertility traits (CMF).
Moderate heritability (0.15) was estimated for composite trait that was higher than heritability of female fertility related traits: DO 0.047, CI 0.042, and NSC 0.014, and slightly lower than heritability of TMY 0.19. Favourable genetic correlations (-0.87) were estimated between CMF with TMY. Spearman rank correlation coefficients between breeding value of CMF with DO, CI, and TMY were high (>0.94) but with NSC were moderate (0.64). Selection on CMF caused favourable correlated genetic gains for DO, CI, and TMY. Different selection indices with different emphasis on fertility and milk production were constructed. The amount of correlated genetic gains obtained for DO and total milk production according to selection in CMF were higher than of genetic gains obtained for DO and TMY in selection indices with different emphasis on milk and fertility.
The animal selection only based on a composite trait - CMF proposed in current study would simultaneously lead to favourable genetic gains for both milk and fertility related traits. In this situation CMF introduced in current study can be used to overcome to limitations of selection index and CMF could be useful for countries that have problems in recording traits, especially functional traits.
本研究的目的是为荷斯坦奶牛定义一种新的复合性状，并评估同时改善产奶和繁殖性状的可能性。
收集了1998年至2016年波兰荷斯坦-弗里生奶牛群中35882条与繁殖相关的记录（空怀天数[DO]、产犊间隔[CI]、每次受孕输精次数[NSC]以及各泌乳期总产奶量[TMY]）。本研究中，使用每头奶牛的TMY、DO、CI和泌乳期长度来获得复合产奶和繁殖性状（CMF）。
估计复合性状的遗传力为中等（0.15），高于与母畜繁殖相关性状的遗传力：DO为0.047，CI为0.042，NSC为0.014，略低于TMY的遗传力0.19。估计CMF与TMY之间存在有利的遗传相关性（-0.87）。CMF育种值与DO、CI和TMY之间的斯皮尔曼等级相关系数较高（>0.94），但与NSC的相关系数中等（0.64）。对CMF进行选择会导致DO、CI和TMY产生有利的相关遗传进展。构建了对繁殖力和产奶量有不同侧重的不同选择指数。根据对CMF的选择所获得的DO和总产奶量的相关遗传进展量高于在对产奶和繁殖力有不同侧重的选择指数中获得的DO和TMY的遗传进展量。
仅基于本研究提出的复合性状——CMF进行动物选择，将同时为产奶和繁殖相关性状带来有利的遗传进展。在这种情况下，本研究中引入的CMF可用于克服选择指数的局限性，并且CMF对于在性状记录，尤其是功能性状记录方面存在问题的国家可能有用。
