Selection effect for growth traits on energy requirements in beef Nelore steers

• Published in: Tropical animal health and production Vol. 54; no. 4; p. 213
• Main Authors: Del Pilar Solar Diaz, Iara, Bezerra, Luis Antonio Framartino, Lôbo, Raysildo Barbosa, de Araújo Neto, Francisco Ribeiro, de Camargo, Gregório Miguel Ferreira, da Cruz, Valdecy Aparecida Rocha, Costa, Raphael Bermal, de Oliveira, Henrique Nunes
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2022; Springer Nature B.V
• Subjects: Age; Animals; Beef; Beef cattle; Biomedical and Life Sciences; Body weight; Body weight gain; Energy; Energy requirements; Environmental effects; Feeds; Life Sciences; Maternal effects; Meat production; Pasture; Phenotypes; Polynomials; Regression analysis; Regular Articles; Slaughter; Veterinary Medicine/Veterinary Science; Zoology; Nelore; Profitability; Energy requirement; Correlated response; Growth; Beef cattle production system; Selection criteria
• ISSN: 0049-4747; 1573-7438
• DOI: 10.1007/s11250-022-03210-x

Growth data of 77,372 Nelore steers were used to estimate the selection effect on energy requirements considering two beef production systems: cow-calf and slaughter cycles. All the animals had measures from 120 days to 7 years old. The parameters necessary to evaluate the selection effect on energy requirements were obtained by random regression analysis using Legendre polynomials. The models included additive direct and maternal effects, and animal and maternal permanent environmental effects as random terms. Contemporary group and dam age at calving (linear and quadratic effect) were included as fixed effects, and orthogonal Legendre polynomials of animal age (cubic regression) were considered random covariables. The coefficients from the model M3353_5 were used to calculate the genetic gains necessary to predict the increase in phenotypes. The selection was simulated for body weight (BW) and weight gain (WG) at different ages and energy requirements were calculated using NRC equations. The cost of feed was calculated for a cow-calf and slaughter cycle of production considering a system of
Brachiaria decumbens
pasture without supplementation. In slaughter system, the selection for weight of 365 days of age is the best option. In cow-calf systems, the selection W120 is the best choice.