The experiment aimed at studying the allometric growth of the different tissues of neck, rib, shoulder blade and leg in relation to the cutting weight of male and female lambs. Twenty-two intact Texel males and 23 Texel females were used. Seven of them were slaughtered at the beginning of the experiment and the others at the weight of 25 or 33kg. Sheep and lambs were distributed into three methods of feeding: M1 - Corn silage and concentrate, only to lambs until weaning at 60 days old; M2 - Corn silage and concentrate, only to lambs until weaning at 45 days old and M3 - Corn silage and concentrate to ewe and lamb until weaning at 60 days old. After weaning, lambs were fed with silage plus concentrate. A completely randomized design outlined in a factorial arrangement 3 x 2 x 2 (3 methods, 2 sexes and 2 slaughter weights) was used. Determination of growth was obtained through the equation log y = log.a + b log.x, by using the logarithm of bone, muscle and fat weight in function of cutting weight logarithm. It was observed that neck and rib bone was precocious (b<1) in both sexes, with allometry coefficients varying from 0.61 to 0.79; 0.81 to 0.88. Muscle was isometric (b = 1) in neck and precocious (b<1) in rib, except for males of methods one and three, which presented isometric growth (b = 1). Fat was late (b>1), regardless of sex and feeding method with allometry coefficients varying from 1.78 to 2.15 (neck) and 1.51 to 1.65 (rib). In shoulder blade, bone was precocious in both sexes, with allometry coefficients varying from 0.76 to 0.79 and 0.54 to 0.58 for males and females, respectively. Muscle presented isometric growth (b = 1), regardless of sex and slaughter weight. Fat was late (b>1), regardless of slaughter weight and sex, with allometry coefficients varying from 1.80 to 2.12. In leg, bone growth was precocious in females and isometric in males, with allometry coefficients varying from 0.57 to 0.63 and 0.78 to 0.80, respectively, for both sexes. Muscle presented isometric growth (b = 1), regardless of sex and slaughter weight. Fat was late (b>1), regardless of slaughter weight and sex, with allometry coefficients varying from 1.80 to 2.12.
allometric coefficients; sheep; sex
