Effects of selection for post-weaning weights on carcass traits, meat cut yelds and body composition of nellore and caracu bulls, in restrict and ad libitum feeding. / Efeitos da seleção para peso pós-desmame sobre características de carcaça, rendimento de cortes e composição corporal de bovinos nelore e caracu, sob alimentação restrita e Ad Libitum.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Fifty six bulls, born in 1999, from Sertãozinho Experimental Station herds, selected or not for weight at 378 days of age (W 378), were feedlot at Colina Experimental Station. Animals of the genetic groups Nellore (NeS), Control Nellore (NeC) and Caracu (Ca) were utilized. They were randomnly distributed in three experimental groups: initial slaughter group (AI), restricted feeding group (AR) and Ad Libitum feeding group (AL). The AI class had 4 animals for each genetic group and AR and AL had 8 NeS and Ca, and 6 animals NeC. Animals were slaughtered with 4.0 mm of fat thickness measured by ultrasound. After the adaptation period, the AI class was slaughtered and the other classes (AR and AL) started the feedlot period. In each genetic group, when an animal of the AL class attained the desired ultrasonic fat thickness for slaughter, the animal of AR class with similar weight and body conditions score, at the experiment starting point, was also slaughtered. In all animals carcass traits, body composition and meat cuts income were evaluated. Data were analized according to factorial scheme including two type of diets and three genetic groups. The Ca and NeS bulls were heavier at slaughter requiring longer feeding period to attain the desired ultrasonic fat thickness. The heavier weights at slaughter of these animals also changed correlated traits as carcass, hindquater, forequarter and spare ribs weights. The selection for weight in the Nellore promoted higher slaughter, carcass and primary cuts weights, but selected animals had less tender meat, but inside good tender standards. Average values for chemical components of empty body weight, in percentages of water, fat, protein and ash were: Ca (60.4; 15.5; 19.7; 4.4), NeS (58.2; 19.4; 17.8; 4.6) and NeC (57.4; 20.2; 18.3; 4.1). The average rates of empty gain for body weight (kg/day), water (g/day), fat (g/day), protein (g/day), ash (g/day) and energy (Mcal/day) were: Ca (1.01; 409; 382; 150; 70; 4,45), NeS (1.00; 355; 482; 113; 46; 5,19) and NeC (0.91; 301; 457; 103; 52; 4,91). The average rates of empty body gain chemical composition, in percentages of water, fat, protein, ash and energy (Mcal/day) were: Ca (40.1; 36.8; 15.2; 8.0; 4.32), NeS (35.8; 48.1; 11.3; 4.8; 5.19) and NeC (32.7; 49.5; 12.0; 5.8; 5.36). The selection for post-weaning weights, observed by comparing the two Nellore groups, did not promote any change on body composition of these animals, but increased their body size, so they required longer feedlot period. The animals of genetic group Ca, when compared with Nellore, had less fat and more protein, in percentages of empty body. It is due to their larger mature body size.

ASSUNTO(S)

animal breeding. melhoramento genético animal. carne bovina – qualidade composição corporal body composition carcaça carcass bovinos beef quality bovine

ACESSO AO ARTIGO

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