Economic selection index development for Beefmaster cattle II: General-purpose breeding objective1

Abstract

An economic selection index was developed for Beefmaster cattle in a general-purpose production system in which bulls are mated to a combination of heifers and mature cows, with resulting progeny retained as replacements or sold at weaning. National average prices from 2010 to 2014 were used to establish income and expenses for the system. Genetic parameters were obtained from the literature. Economic values were estimated by simulating 100,000 animals and approximating the partial derivatives of the profit function by perturbing traits 1 at a time, by 1 unit, while holding the other traits constant at their respective means. Relative economic values for the objective traits calving difficultly direct (CDd), calving difficulty maternal (CDm), weaning weight direct (WWd), weaning weight maternal (WWm), mature cow weight (MW), and heifer pregnancy (HP) were -2.11, -1.53, 18.49, 11.28, -33.46, and 1.19, respectively. Consequently, under the scenario assumed herein, the greatest improvements in profitability could be made by decreasing maintenance energy costs associated with MW followed by improvements in weaning weight. The accuracy of the index lies between 0.218 (phenotypic-based index selection) and 0.428 (breeding values known without error). Implementation of this index would facilitate genetic improvement and increase profitability of Beefmaster cattle operations with a general-purpose breeding objective when replacement females are retained and with weaned calves as the sale end point.

Selection indexes for Nellore production system in the Brazilian Pantanal

“…Most EV for the CW is negative, according to several studies (Wolfová et al, 2005;Ochsner et al, 2017;Simões et al, 2020). Larger animals are not always the most suitable and profitable to production systems, due to the high energy required for their maintenance and the consequent increased feeding costs.…”

“…Although CW and WW are usually reciprocally antagonistic in relation to selection objectives, i.e., it is ideal to increase WW without raising CW, as the correlation assumed between them is not equal to the unit, it is possible to have progress in both traits simultaneously in a balanced way in the selection index (Ochsner et al, 2017). The selection for the direct effect of WW is relevant in the production of beef cattle because it represents the individual growth capacity.…”

“…Several studies include WW as a selection objective (MacNeil et al, 1994;Wolfová et al, 2005;Bittencourt et al, 2006;Matjuda et al, 2014;Ochsner et al, 2017). The RE weighting is variable, according to the systems adopted and the final product.…”

“…Some authors have argued for the use of long-run production costs and product prices in the construction of breeding objectives (e.g., Ochsner et al, 2017;Barron Lopez, 2013) rather than the use of one of the values from a single point in time as was done in this study. Because CW and STAY impact the inputs and outputs and were major contributors to the breeding objectives, the sensitivity of their economic values to changes in prices was evaluated in this study.…”

Management of lethal recessive alleles in beef cattle through the use of mate selection software

“…Ochsner et al [44, 45] outlined procedures on how to develop a maternal economic selection index ($M) given EPD information. These procedures were followed based on selection objective weightings described by MacNeil [46].…”