Avaliação de medidas biométricas em ovinos e efeito de raça sobre o desempenho pós parto de cordeiros

Abstract

Breed is one of the main factors influencing the weight performance of lambs, especially during the suckling phase. Understanding the phenotypic differences among sires and the growth of lambs from different breeds contributes to improving animal selection and management. This study aimed to evaluate the effect of purebred sires (Dorper and Santa Inês) on the weight growth of lambs up to weaning and to characterize the morphostructural changes of the sires before and after the breeding season. Twenty-three lambs from twenty crossbred ewes, belonging to the Small Ruminant Sector of IFAL – Satuba Campus, and two sires (one from each breed) were monitored. Weighings were carried out at birth and from 10 to 90 days of age. The study lasted 11 months (March 2024 to February 2025). Analyses included phenotypic description of the sires (via radar charts), descriptive statistics of lamb weights, normality tests (Shapiro–Wilk) and homogeneity of variance tests (Levene), comparisons over time (Student’s t-test), and fitting of a linear mixed-effects model (Weight ~ Days × Breed), with random effect for Lamb. Both breeds showed progressive growth. A significant difference between breeds was observed only at 20 days (p < 0.05). The mixed-effects model indicated significance for time (p < 0.001) and for the interaction Days × Breed (p = 0.009), demonstrating that the lambs’ growth rate differed between breeds. Although mean weights were similar at several time points, the longitudinal analysis revealed that Dorper and Santa Inês presented distinct growth curves, reinforcing the importance of using appropriate statistical models to detect complex patterns of animal development.