Análise dos componentes principais das características e composição das carcaças de cordeiros pantaneiros e comerciais

Abstract

The present research aiming to evaluate carcass characteristics and composition of Pantaneiros and Comerciais lambs. Sixty male not castrated lambs (30 Comerciais type and 30 Pantaneiros). In the carcass characteristics correlations of Pantaneiros, the total of 153 correlations, 18 are positive and significant, 5 are negative and significant and 130 are non-significant. Eight components were necessary to reach factor (> or = 0.70), and these 8 first PCs corresponded to 83.34% of the accumulated variance. In this way 10 PCs can be discarded without any significant loss of information. In order to explain the first PC of Pantaneiros sheep, only three carcass characteristics were necessary, which were hot carcass weight, cold carcass weight and carcass compactness index. To explain the first PC of Comerciais sheep, only five characteristics were required, which were hot carcass weight, cold carcass weight, carcass compactness index, conformation, fatness score. For the second PC, only the internal and external housing length were relevant. In the evaluation of the tissue composition for both genetic groups the highly significant and positive correlations were basically concentrated in the fat measurements: subcutaneous fat weight and yield, intermuscular fat weight and yield, total fat weight and yield, others weight and yield. The first four PCA explained 91.37% of the total tissue composition variation of the carcasses. Of this the first PC explained 36.71% and 25.09% was explained by the second PC, adding together 61.81% in the first two PCs. Thus, 11 PCs had a low factor and little explained the total variation of the data. The variables that contribute to explain the total variation within each CP, in a positive way were weight and yield of intermuscular and total fat. The fat muscle ratio contributed negatively to the first PC. The second PC presented a great association with weight and bone yield and muscle yield. The analysis of main components reduced the variables of the characteristics and composition of the carcasses of Pantaneiros and Comerciais lambs with little loss of information. They identified the hot and cold carcass weight, carcass compactness index as the most relevant to explain the characteristics of the carcasses for both genetic groups. In the tissue composition the variables of weight and fat yield were strictly associated to express the first PC. In the second PC only three variables involving bone and muscle tissue were required to accurately determine the tissue composition of the carcasses.