Beef cattle maternal and terminal economic selection indices.

摘要

he breeding objective in most livestock operations is to increase profit ability by improving production efficiency. Animals with different purposes are associated with different production systems. The objective of the study is to develop economic selection indices for females and males in three different production systems: maternal, terminal with self-replacement females, and terminal without self-replacement females, based on production characteristics in the intermountain region of the US. Profit equations were constructed to derive economic values under fixed herd size scenario. The parameters used to calculate the cumulative discounted gene expressions (CDGE) and genetic parameters were estimated from 10,007 individual records and 27,165 pedigree records from the Angus herd at the John E. Rouse Beef Improvement Center of Colorado State University. There were 313 sires with an average generation interval of 3.30 years involved in the study, as well as 2,160 dams with an average generation interval of 5.32 years. Sensitivity tests were performed to test the effect of changing production and economic variables on economic selection indices weights. The impacts on selection index for all systems were small with changing production variable. Also, varying economic variables had small effect on selection index of maternal system with correlations among objectives more than 0.80. However, it affects the selection index of two terminal systems a lot with low (-0.05) or even negative (-0.82) correlation between one and another other. The selection responses with considering the cumulative discounted gene expression and based on six economic selection indices were