Valasek Hunter F, Lewis Ronald M, Golden Bruce L, Spangler Matthew L
Department of Animal Science, University of Nebraska, Lincoln, NE 68583, USA.
Theta Solutions, LLC, Olympia, WA 98516, USA.
Transl Anim Sci. 2024 Jun 3;8:txae090. doi: 10.1093/tas/txae090. eCollection 2024.
In beef production herds, unique situations such as breeding system, economic parameters, and current phenotypic performance can affect the emphasis of traits in the breeding goal and consequently the weighting of traits within a selection index. An often overlooked component of breeding goals is the planning horizon, or the time span to consider the economic impact of a selection decision, that varies between enterprises. A platform for constructing economic selection indexes (iGENDEC) was used to determine the impact of planning horizon length, breeding system, and sale endpoint on the relative emphasis of traits in the breeding goal and the re-ranking of selection candidates. As part of this investigation, the adjustment of phenotypic means for hot carcass weight and planning horizons were used to determine the impact of the relative emphasis on hot carcass weight as its mean approached a predetermined discount threshold. General-purpose indexes were created for animals sold at weaning and slaughter for three breeding systems with six different planning horizons (2, 5, 10, 20, 30, and 50 yr). As planning horizon increased, the relative emphasis on weaning weight or hot carcass weight, which affected revenue, decreased while the relative emphasis on stayability and mature weight increased. As the phenotypic mean for hot carcass weight approached and surpassed a predetermined discount threshold, the relative emphasis decreased before increasing again, once the mean weight surpassed the threshold. Rank correlations between indexes with different sale endpoints was 0.71 ± 0.1. Within a slaughter endpoint, re-ranking occurred between short and long planning horizons ( = 0.78 ± 0.09) while that of a weaning endpoint was less substantial ( = 0.85 ± 0.10). Jacard index scores between indexes with different planning horizons ranged from 39.7% to 87.9% and from 47.9% to 78.7% for weaning and carcass endpoints, respectively, for the top 5% of selection candidates. These results illustrate that the determination of a planning horizon can impact the rank of selection candidates and increases in net profit.
在肉牛生产群体中，诸如繁殖系统、经济参数和当前表型性能等独特情况会影响育种目标中性状的重点，进而影响选择指数中各性状的权重。育种目标中一个常常被忽视的组成部分是规划期，即考虑选择决策经济影响的时间跨度，不同企业的规划期各不相同。一个构建经济选择指数的平台（iGENDEC）被用于确定规划期长度、繁殖系统和销售终点对育种目标中性状相对重点以及选择候选个体重新排名的影响。作为这项调查的一部分，利用热胴体重的表型均值调整和规划期来确定当热胴体重均值接近预定折扣阈值时，对其相对重点的影响。针对断奶时出售和屠宰的动物，为三种繁殖系统创建了通用指数，规划期有六种不同时长（2年、5年、10年、20年、30年和50年）。随着规划期增加，对影响收益的断奶体重或热胴体重的相对重点降低，而对繁殖力和成熟体重的相对重点增加。当热胴体重的表型均值接近并超过预定折扣阈值时，相对重点先降低，一旦平均体重超过阈值又再次上升。不同销售终点的指数之间的秩相关系数为0.71±0.1。在屠宰终点内，短期和长期规划期之间会发生重新排名（=0.78±0.09），而断奶终点的重新排名则不太显著（=0.85±0.10）。对于排名前5%的选择候选个体，不同规划期的指数之间的杰卡德指数得分在断奶终点和胴体终点分别为39.7%至87.9%和47.9%至78.7%。这些结果表明，规划期的确定会影响选择候选个体的排名以及净利润的增加。
