Macedo Mota Lucio Flavio, Pegolo Sara, Bisutti Vittoria, Bittante Giovanni, Cecchinato Alessio
Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, Viale dell' Università 16, 35020 Legnaro, Italy.
Animals (Basel). 2020 Feb 20;10(2):336. doi: 10.3390/ani10020336.
Depending on whether milk protein fractions are evaluated qualitatively or quantitatively, different genetic outcomes may emerge. In this study, we compared the genetic parameters for the major milk protein fractions-caseins (α-, α-, β-, and к-CN), and whey proteins (β-lactoglobulin, β-LG; α-lactalbumin, α-LA)-estimated using the multi-trait genomic best linear unbiased prediction method and expressed variously as milk content (g/100g milk), percentage of milk nitrogen (%N) and daily yield per cow (g/d). The results showed that the genetic parameter estimates varied according to how the milk protein fractions were expressed. Heritability estimates for the caseins and whey protein fractions expressed as daily yields were lower than when they were expressed as proportions and contents, revealing important differences in genetic outcomes. The proportion and the content of β-CN were negatively correlated with the proportions and contents of α-CN, α-CN, and к-CN, while the daily yield of β-CN was negatively correlated with the daily yields of α-CN and α-CN. The Spearman's rank correlations and the coincidence rates between the various predicted genomic breeding values (GEBV) for the milk protein fractions expressed in different ways indicated that these differences had a significant effect on the ranking of the animals. The results suggest that the way milk protein fractions are expressed has implications for breeding programs aimed at improving milk nutritional and technological characteristics.
根据对乳蛋白组分进行定性或定量评估的不同，可能会得出不同的遗传结果。在本研究中，我们比较了主要乳蛋白组分（酪蛋白（α-、α-、β-和κ-酪蛋白）和乳清蛋白（β-乳球蛋白，β-LG；α-乳白蛋白，α-LA））的遗传参数，这些参数是使用多性状基因组最佳线性无偏预测方法估计得出的，并分别以乳含量（克/100克乳）、乳氮百分比（%N）和每头奶牛的日产奶量（克/天）来表示。结果表明，遗传参数估计值因乳蛋白组分的表示方式而异。以日产奶量表示的酪蛋白和乳清蛋白组分的遗传力估计值低于以比例和含量表示时的遗传力估计值，这揭示了遗传结果的重要差异。β-酪蛋白的比例和含量与α-酪蛋白、α-酪蛋白和κ-酪蛋白的比例和含量呈负相关，而β-酪蛋白的日产奶量与α-酪蛋白和α-酪蛋白的日产奶量呈负相关。以不同方式表示的乳蛋白组分的各种预测基因组育种值（GEBV）之间的斯皮尔曼等级相关性和符合率表明，这些差异对动物的排名有显著影响。结果表明，乳蛋白组分的表示方式对旨在改善乳营养和工艺特性的育种计划具有重要意义。
