Crescimento, rendimento de carcaça e qualidade da carne de animais Nelore e cruzados com Rubia Gallega, a pasto

Abstract

The aim of this study was to evaluate the growth, carcass yield and meat quality of animals Nellore and with Rubia Gallega. For the study of performance were applied the properties of four nonlinear models, considering the set of growth curves: Von Bertalanffy, Brody, Gompertz and Logistic. The models were adjusted by the method of Gauss Newton through the function "nls", free Software R version 3.1., the data weight-for-age in times 0; 270; 365; 550; and 660 days of age, male and female in Nellore breed and its intersection with the race Rubia Gallega, considering the criteria: Akaike’s Information Criterion (AIC), Bayesian Information Criterion (BIC), mean squared residue (QMR), coefficient of determination (R2) and mean deviation of absolute waste (DMA). It was also applied the likelihood-ratio test for equality of parameters of nonlinear models to determine if a single curve would be adequate to describe the growth of these animals. For the female cross-Nellore and males crossed, the model that best adjusted growth curves was the Brody, while that for males the Nellore breed was the Logistic model. For the test of equality, comparing the curves between females and males Nellore and between males Nellore and crossover, it was found that the hypothesis k1 = k2 = k was rejected by the maximum likelihood ratio test, indicating different growth rate (K). Already for the hypothesis a1 = a2 = a for female and male Nellore, it was found that the female Nellore and the male crossover showed same weight to maturity (A) in relation to the male Nellore. Even with the test of equality of parameters (Â and K), when comparing the data of animals between female and male crusaders and between females Nellore and the crusaders, it was checked that is not rejected by the maximum likelihood ratio test, which indicates that it can be represented by a single equation and that the curves are parallel and identical. This way, neither the sex and the genetic group influenced the estimated parameters. For the evaluation of the income of carcase and meat quality were used 27 male animals whole, being 12 crusaders (Nellore x Rubia Gallega) and 15 pure (Nellore), created and fed grazing Brachiaria brizantha, until the average age of 32 months, and then slaughtered in fridge commercial in the city of Parnamirim - RN. The parameters evaluated were: body weight at slaughter; weights of carcasses hot and cold; income of hot carcasses (WHR) and cold (RCF); body length (CC); index of compactness of the carcasse (ICC); losses by cooling; pH and temperature (T) of the housing in the times 0h, 3h and 24h; weights and yields of front, and hindquarter; area of rib eye); thickness of subcutaneous fat (EGS); color (L*, a* and b*); losses by cooking; and softness. There was no difference (P< 0.05) for WHR; T 0h and 3h; NE; AOL; and color a* and b*. The difference found for these variables, in favor of the animals crossed, proved to be promising for the production of a product potentially superior, by presenting characteristics in order to care for attributes that give meat quality.