Abstract
Heterosis plays an important role on yield and profitability of beef production systems. This study evaluates the morphometrics of purebred Nellore (N) and Charolais (C) animals and of the second (G2) and third (G3) generations of their alternating crosses, regarding the effects of genetic group and heterosis from birth to 365 days of age. The experiment comprised 159 calves (C = 29, N = 22, G2 - 3/4C 1/4N = 21, 3/4N 1/4C = 9, G3-5/8C 3/8N = 44 and 5/8N 3/8C = 34). The foreshank girth (FG), thoracic girth (TG), body length (BL), and hip height (HH) were measured after birth, and at 63, 210, and 365 days of age, and the total increases were calculated. The Charolais animals had greater FG, TG, and BL values than Nellore, while the latter had greater HH. For the offspring generations, the predominance of Charolais genes in the genotypes resulted in greater measurements for FG and TG in G2, whereas the predominance of Nellore genes resulted in higher HH values in both generations. The crossbred animals had greater values for all measurements than the purebreds, with more significant differences in FG, TG, and BL compared to Nellore purebreds and in HH compared to Charolais. Charolais animals show higher values for muscularity; while, Nellore animals are taller. Crossbred animals show greater development compared to purebreds, indicating a significant effect of heterosis.
Highlights
Studies on growth performance in animals are based on the assessment of body weight, which is more susceptible to the nutritional fluctuations experienced by animals over time than linear morphometrics (Northcutt et al, 1992)
This study evaluates the morphometrics of purebred Nellore (N) and Charolais (C) animals and of the second (G2) and third (G3) generations of their alternating crosses, regarding the effects of genetic group and heterosis from birth to 365 days of age
The crossbred animals had greater values for all measurements than the purebreds, with more significant differences in foreshank girth (FG), thoracic girth (TG), and body length (BL) compared to Nellore purebreds and in HH compared to Charolais
Summary
Studies on growth performance in animals are based on the assessment of body weight, which is more susceptible to the nutritional fluctuations experienced by animals over time than linear morphometrics (Northcutt et al, 1992). Morphometrics describes an individual or a population more completely than weight alone does (Salako, 2006). It is useful for understanding animal growth (Choy et al, 2017) and used as selection criteria based on growth (Van Marle-Köster et al, 2000). Since morphometric traits of size and shape are indicators of development of an animal body over time (Fernandes et al, 2010), they can be used as good predictors of performance and longevity of animals (Lee and Kim, 2010)
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