Discipline of Genetics, College of Agriculture, Engineering and Science, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
ARC-Animal Production, Private Bag X2, Irene, 0062, South Africa.
Trop Anim Health Prod. 2023 Sep 28;55(5):339. doi: 10.1007/s11250-023-03741-x.
Genetic parameters for daily predicted gross feed efficiency (pGFE) and energy corrected milk (ECM) in the first three parities of South African Holstein cattle were estimated by repeatability animal models. Data comprised of 11,068 test-day milk production records of 1,575 Holstein cows that calved between 2009 and 2019. Heritability estimates for pGFE were 0.12 ± 0.06, 0.09 ± 0.04 and 0.18 ± 0.05 in early, mid and late lactation, respectively. Estimates were moderate for primiparous (0.21 ± 0.05) and low for multiparous (0.10 ± 0.04) cows. Heritability and repeatability across all lactations were 0.14 ± 0.03 and 0.37 ± 0.03, respectively. Genetic correlations between pGFE in different stages of lactation ranged from 0.87 ± 0.24 (early and mid) to 0.97 ± 0.28 (early and late), while a strong genetic correlation (0.90 ± 0.03) was found between pGFE and ECM, across all lactations. The low to moderate heritability estimates for pGFE suggest potential for genetic improvement of the trait through selection, albeit with a modest accuracy of selection. The high genetic correlation of pGFE with ECM may, however, assist to improve accuracy of selection for feed efficiency by including both traits in multi-trait analyses. These genetic parameters may be used to estimate breeding values for pGFE, which will enable the trait to be incorporated in the breeding objective for South African Holstein cattle.
南非荷斯坦奶牛前三个泌乳期的日预测总饲料效率（pGFE）和能量校正奶（ECM）的遗传参数通过重复动物模型进行估计。数据包括 2009 年至 2019 年间分娩的 1575 头荷斯坦奶牛的 11068 个测试日产奶记录。pGFE 的遗传力估计值分别为泌乳早期、中期和晚期的 0.12±0.06、0.09±0.04 和 0.18±0.05。初产牛的估计值适中（0.21±0.05），经产牛的估计值较低（0.10±0.04）。所有泌乳期的遗传力和重复性分别为 0.14±0.03 和 0.37±0.03。不同泌乳阶段的 pGFE 之间的遗传相关性范围为 0.87±0.24（早期和中期）至 0.97±0.28（早期和晚期），而 pGFE 和 ECM 之间存在很强的遗传相关性（0.90±0.03），横跨所有泌乳期。pGFE 的低到中等遗传力估计值表明通过选择可以对该性状进行遗传改良，尽管选择的准确性较低。pGFE 与 ECM 之间的高遗传相关性可能有助于通过在多性状分析中包含这两个性状来提高饲料效率的选择准确性。这些遗传参数可用于估计 pGFE 的育种值，这将使该性状能够纳入南非荷斯坦奶牛的育种目标。
