Randhawa Imtiaz A S, McGowan Michael R, Porto-Neto Laercio R, Hayes Ben J, Lyons Russell E
School of Veterinary Science, University of Queensland, Gatton, QLD 4343, Australia.
CSIRO Agriculture and Food, St Lucia, QLD 4067, Australia.
Animals (Basel). 2021 Mar 18;11(3):870. doi: 10.3390/ani11030870.
Breeding for polled animals is deemed the most practical solution to eradicate horns naturally and circumvent management costs and risks on health and welfare. However, there has been a historical reluctance by some farmers to select polled animals due to perceived lower productivity of their calves. This study has compared estimated breeding values (EBVs) between horned and polled animals (N = 2,466,785) for 12 production and carcass traits to assess historical (before 2000) and recent (2000-2018) genetic implications of poll breeding. Older generations of the polled animals in most breeds had significantly lower (Bonferroni-corrected 0.05) genetic merits for live (birth to maturity) and carcass weights, milk, meat quality, and fat content traits. Substantial gains of genetic potential were achieved during 2000 to 2018 in each breed, such that polled animals have significantly improved for the majority of traits studied. Generally, polled cohorts showed advantageous EBVs for live and carcass weights irrespective of the lower birth weights in some breeds. While Polled Brahman showed inferior production parameters, the poll genetics' effect size () and correlation () were very small on recent birth weight ( = -0.30, = -0.08), 200 days (-0.19, -0.05), 400 days (-0.06, -0.02), 600 days (-0.05, -0.01), mature cow live weight (-0.08, -0.02), and carcass weight (-0.19, -0.05). In conclusion, although there is some evidence that historical selection for polled breeding animals may have reduced productivity, there is strong evidence that more recent selection for polled genotypes in the breeds studied has not resulted in any adverse effects on genetic merit.
培育无角动物被认为是自然根除角并规避健康和福利方面管理成本及风险的最切实可行的解决方案。然而，由于一些农民认为无角动物的犊牛生产力较低，历史上他们一直不愿选择无角动物。本研究比较了有角和无角动物（N = 2,466,785）在12个生产和胴体性状上的估计育种值（EBV），以评估无角育种在历史时期（2000年之前）和近期（2000 - 2018年）的遗传影响。大多数品种的老一代无角动物在活体（出生至成熟）和胴体重量、产奶量、肉质和脂肪含量性状方面的遗传优势显著较低（Bonferroni校正P < 0.05）。2000年至2018年期间，每个品种都实现了遗传潜力的大幅提升，以至于无角动物在所研究的大多数性状上都有显著改善。一般来说，无角群体在活体和胴体重量方面显示出有利的EBV，尽管某些品种的出生体重较低。虽然无角婆罗门牛的生产参数较差，但无角基因对近期出生体重（r = -0.30，ρ = -0.08）、200日龄体重（-0.19，-0.05）、400日龄体重（-0.06，-0.02）、600日龄体重（-0.05，-0.01）、成年母牛活体体重（-0.08，-0.02）和胴体重量（-0.19，-0.05）的效应大小（r）和相关性（ρ）非常小。总之，尽管有一些证据表明历史上对无角种畜的选择可能降低了生产力，但有强有力的证据表明，在所研究的品种中，近期对无角基因型的选择并未对遗传优势产生任何不利影响。
