Kelleher M M, Amer P R, Shalloo L, Evans R D, Byrne T J, Buckley F, Berry D P
Animal & Grassland Research and Innovation Centre, Teagasc, Moorepark, Co. Cork, Ireland; School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
AbacuBio LTD, Dunedin 9016, New Zealand.
J Dairy Sci. 2015 Jun;98(6):4225-39. doi: 10.3168/jds.2014-9073. Epub 2015 Mar 18.
The objective of this study was to develop an index to rank dairy females on expected profit for the remainder of their lifetime, taking cognizance of both additive and nonadditive genetic merit, permanent environmental effects, and current states of the animal including the most recent calving date and cow parity. The cow own worth (COW) index is intended to be used for culling the expected least profitable females in a herd, as well as inform purchase and pricing decisions for trading of females. The framework of the COW index consisted of the profit accruing from (1) the current lactation, (2) future lactations, and (3) net replacement cost differential. The COW index was generated from estimated performance values (sum of additive genetic merit, nonadditive genetic merit, and permanent environmental effects) of traits, their respective net margin values, and transition probability matrices for month of calving, survival, and somatic cell count; the transition matrices were to account for predicted change in a cow's state in the future. Transition matrices were generated from 3,156,109 lactation records from the Irish national database between the years 2010 and 2013. Phenotypic performance records for 162,981 cows in the year 2012 were used to validate the COW index. Genetic and permanent environmental effects (where applicable) were available for these cows from the 2011 national genetic evaluations and used to calculate the COW index and their national breeding index values (includes only additive genetic effects). Cows were stratified per quartile within herd, based on their COW index value and national breeding index value. The correlation between individual animal COW index value and national breeding index value was 0.65. Month of calving of the cow in her current lactation explained 18% of the variation in the COW index, with the parity of the cow explaining an additional 3 percentage units of the variance in the COW index. Females ranking higher on the COW index yielded more milk and milk solids and calved earlier in the calving season than their lower ranking contemporaries. The difference in phenotypic performance between the best and worst quartiles was larger for cows ranked on COW index than cows ranked on the national breeding index. The COW index is useful to rank females before culling or purchasing decisions on expected profit and is complementary to the national breeding index, which identifies the most suitable females for breeding replacements.
本研究的目的是制定一个指数，以便根据奶牛剩余生命周期的预期利润对其进行排名，同时考虑加性和非加性遗传价值、永久环境效应以及奶牛的当前状态，包括最近的产犊日期和胎次。奶牛自身价值（COW）指数旨在用于淘汰牛群中预期利润最低的母牛，并为母牛交易的购买和定价决策提供参考。COW指数的框架包括来自（1）当前泌乳期、（2）未来泌乳期以及（3）净替换成本差异所产生的利润。COW指数是根据性状的估计性能值（加性遗传价值、非加性遗传价值和永久环境效应的总和）、它们各自的净利润值以及产犊月份、存活和体细胞计数的转移概率矩阵生成的；这些转移矩阵用于说明奶牛未来状态的预测变化。转移矩阵是根据2010年至2013年爱尔兰国家数据库中的3,156,109条泌乳记录生成的。2012年162,981头奶牛的表型性能记录用于验证COW指数。这些奶牛的遗传和永久环境效应（如适用）可从2011年国家遗传评估中获得，并用于计算COW指数及其国家育种指数值（仅包括加性遗传效应）。根据奶牛的COW指数值和国家育种指数值，在牛群内将奶牛按四分位数分层。个体奶牛的COW指数值与国家育种指数值之间的相关性为0.65。奶牛当前泌乳期的产犊月份解释了COW指数中18%的变异，奶牛的胎次又额外解释了COW指数中3个百分点的变异。在COW指数上排名较高的母牛比排名较低的同期母牛产奶量和乳固体更多，并且在产犊季节更早产犊。根据COW指数排名的奶牛，最佳和最差四分位数之间的表型性能差异比根据国家育种指数排名的奶牛更大。COW指数对于在基于预期利润进行淘汰或购买决策之前对母牛进行排名很有用，并且是国家育种指数的补充，国家育种指数用于确定最适合作为繁殖后备的母牛。
