Beef cattle

Influence of sire EPD's and genetic rankings on weaning performance of beef calves.

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Abstract

This study aims to evaluate the weaning performance of calves as a function of the Expected Progeny Differences (EPDs) and percentiles (TOP) of Nellore clean-up bulls. Clean-up bull EPDs were produced from one of two distinct genetic evaluation programs (Associaçào Nacional de Criadores e Pesquisadores (ANCP) e GENEPLUS). The EPDs utilized in this study were Birth Weight, Weaning Weight, and Average Daily Gain (ADG). The database was provided by a beef cattle farm in Mato Grosso do Sul, Brazil, breeding Nellore herds. A total of 20 bulls, 482 calves, and 410 dams were evaluated, with 72 being repeat breeders. The dams and calves do not contribute information to the genetic evaluation of the bulls. Reproductive management included two rounds of fixed-time artificial insemination (FTAI) per dam, followed by the use of clean-up bulls (70 days). Dams were randomly assigned to the lots submitted to the clean-up bulls. Nutritional management was conducted under grazing conditions using mineralized salt with pre-partum protein/mineral supplementation, while calf nutrition consisted of nursing and grazing. The statistical model considered the fixed effects of sex, weaning year (2023 and 2024), and the sex by year interaction, in addition to the sires' EPDs, while the effect of dam age was not considered. Each evaluated group is composed of offspring of a bull, and each bull has an EPD (which was used for SIRE selection).The analyzed traits were adjusted weight at 210 days of age (W210, based on the average daily performance from birth to weaning for each animal) and ADG from birth to weaning. Analyses were performed using the least squares method in the PROC GLM procedure of SAS 9.4, with mean contrasts conducted via Tukey's test. The analyses were carried out by trait (EPD and TOP) and by genetic evaluation program (ANCP and GENEPLUS). In almost all analyses, a significant effect of the interaction between sex and weaning year was verified. A pattern was also observed in the behavior of the variables as a function of the weaning years; in 2023, there was greater performance variation, which may be explained by a period of greater climatic instability (drought) compared to 2024, which presented more regular rainfall for the region, resulting in less variation in the performance of the evaluated calves. For the performance of male calves in 2024, no significant difference was verified among the progenies of the bulls used, characterizing lot homogeneity, a pattern observed across all analyzed traits. Based on the results, it is concluded that calf sex, evaluation year, and sire EPDs primarily have a significant effect on calf weaning performance, and an interaction effect between evaluation year and offspring sex may also exist, exept for 2024 male that doesn't have a significant effect.

Keywords: 2026

How to Cite:

Ambrozio Galindo, B., Dos Santos, A., Lopes, L., pinzon, L., Ramos, L., Ruiz, K. & Zardo, L., (2026) “Influence of sire EPD's and genetic rankings on weaning performance of beef calves.”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286390. doi: https://doi.org/10.31274/wcgalp.23976

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