Abstract
Twenty-four lambs between four and five months of age were divided into sex classes: uncastrated males, castrated males and females, eight for each treatment, with an average body weight of 27.00 ± 3.13 kg. dry matter and water intakes were higher for uncastrated males (p < 0.001). final body weight, body weight at slaughter, average daily gain and cold carcass weight were greater for uncastrated, intermediate for castrated and lower for females (p < 0.05). hot and cold carcass yields were higher for castrated males and females, respectively. (p < 0.05). based on principal component analysis, twenty-five variables were selected out of thirty-two, in some of the seven principal components generated, summarizing 21.87% data dimension. Discriminant analysis identified greater discrimination power for body weight at slaughter, thorax width, thorax depth, fatness, dry matter intake and hot carcass weight. All lambs were classified into their respective sex classes. Therefore, uncastrated males have performed better than castrated ones and both showed higher performance than females. Females and castrated males showed higher carcass yield. Discriminant analysis indicated heterogeneity between sex classes.
Funder
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Publisher
Universidade Estadual de Maringa
Reference37 articles.
1. Adam, C. L., & Findlay, P. A. (1997). Effect of nutrition on testicular growth and plasma concentrations of gonadotrophins, testosterone and insulin-like growth factor I (IGF-I) in pubertal male Soay sheep. Journal of Reproduction and Fertility, 111, 121-125. DOI: https://doi.org/10.1530/jrf.0.1110121
2. Association of Official Analytical Chemists [AOAC]. (2000). Official Methods of Analysis. (15th ed.). Arlington, VA: AOAC International.
3. Araújo, T. L. A. C., Pereira, E. S., Mizubuti, I. Y., Campos, A. N. C., Pereira, M. W. F., Heinzen, E., ... Oliveira, R. L. (2017). Effects of quantitative feed restriction and sex on carcass traits, meat quality and meat lipid profile of Morada Nova lambs. Journal of Animal Science and Biotechnology, 8, 1-12. DOI: https://doi.org/10.1186/s40104-017-0175-3
4. Arnold, A. M., & Meyer, H. H. (1988). Effects of gender, time of castration, genotype and feeding regimen on lamb growth and carcass fatness. Journal of Animal Science, 66(10), 2468-2475. DOI: https://doi.org/10.2527/jas1988.66102468x
5. Butterfield, R. M. (1988). New Concepts of Sheep Growth. Austrália, NS: University of Sydney.