Características de carcaça de caprino em função do sexo e da idade do animal: uma visão multivariada

Abstract

The objective of this study was to evaluate the characterization of carcasses of goats originating from the crossing of breeding stock with no defined pattern (Crioulas), with breeders of the Boer breed, on the effect of sex and age in a multivariate view. 32 goats were used (16 males, 8 with 70 days and 8 with 100 days) and (16 females, 8 with 70 days and 8 with 100 days), with initial mean weights of 70 days of 3.11kg ± 0.64 (males) and 3.00 kg ± 0.76 (females); and at 100 days weights of 3.65 kg ± 0.71 (males) and 3.25 kg ± 0.38 (females). In Chapter II, carcass characteristics and age at slaughter influenced (P> 0.05) the total weight gain, slaughter weight and empty body weight, hot carcass weight, and cold carcass weight. There was an effect of age (P> 0.05) for rib eye area, GR measurement, percentage of internal fat and the carcass compactness index. Renal fat had an effect (P> 0.05) for sex and age. Carcass cuts: neck, palette, rib, loin and leg had an effect (P> 0.05) for slaughter age. There was a difference (P> 0.05) in relation to sex for blood. Regarding the tissue composition of the leg, the variables bone and M: O ratio, differed (P> 0.05) for sex and age. The brightness intensity in the meat (L *) and the Shear Force (FC) showed an interaction (P>0.05) sex and age. Conclusion: considering all the characteristics of the carcass, it is observed that the age of slaughter of the animal influences these characteristics of the carcass more strongly than the sex factor of the animal. In chapter III, the data were submitted to Factor Analysis and the factors obtained used as independent variables in Multiple Regression, using the Stepwise method. Biometric measurements showed a high correlation (P <0.05), most of them with correlations above 50%. This behavior also occurred with the characteristics of the carcass and cuts, showing a high correlation with biometric measurements. It was observed that in the prediction equations as the number of variables increases, the value of R² increases, while Cp and RMSE decrease. The data presented an index for the KMO test of 0.80, demonstrating its suitability for factor analysis. The high correlations between the animals 'morphological characteristics with body weight, carcass characteristics and primary commercial cuts suggest the adequacy of morphological characteristics as criteria for early selection of goats' body weight and their carcass characteristics, before slaughter. In Chapter IV, 18 variables were subjected to canonical discriminant analysis, in order to verify possible differences between treatments (sex of animals and slaughter weights). To select the variables with the greatest discriminatory power, the stepwise method was used to compose the discriminant function. Eight variables were selected using the stepwise method: empty body weight, chest depth, chest width, thigh circumference, neck, loin, leg length and croup width. The first three components together explained 100% of the total variation of the variables evaluated. The variable with the greatest weighting power between treatments, selected using standardized canonical coefficients in order of importance was the animal's loin, also selected for presenting the greatest discriminatory power, by the stepwise method.