Peso al nacimiento de terneros Red Poll puros y cruzas con Angus en un sistema pastoril del norte de Uruguay

Birth weight is the first recorded measurement of a productive animal, such as beef cattle. Its importance lies in its direct correlation with attributes crucial to beef producers, such as ease of calving and its relationship to weaning weight. In our country, numerous studies have been conducted on crossbreeding and improvement of the two main beef breeds, Hereford and Aberdeen Angus. However, there is potential for improvement through the use of other, less common beef breeds, such as Red Poll. The objective of this study is to analyze the birth weight of purebred Red Poll calves and those crossbred with Aberdeen Angus. As various studies have indicated, the lack of assistance required during calving, due to its inherent ease, is one of the many strengths of the Red Poll breed, among others. This study aimed to analyze the birth weights of purebred Red Poll (RP100%) and Angus-crossbred (RP x AA) calves in a herd in northern Uruguay. Birth weights were recorded for 30 calves, both RP100% and RP x AA. Weight was measured within the first 24 hours of life during the spring of 2025. The animals belonged to the "San Florencio" farm and ranch owned by Mr. Mariano Fernandez, located in Artigas. Subsequently, Analysis of Variance (ANOVA) was performed for birth weight, including genotype and sex as fixed effects, and the effect of birth date as a covariate.

The results showed average birth weights of 33.2 kg for RP100% and 34.2 kg for the RP x AA crossbred. Female calves, on the other hand, averaged 33.8 kg compared to 33.7 kg for male calves.

No significant differences in birth weight were found for the evaluated factors of sex, genotype, or date of birth, and it is concluded that the sample size used for this thesis was insufficient to demonstrate such differences.