Body composition, protein and energy requirements for weight gain of 1/2 boer 1/2 mixed-breed goat kids on pasture/Composicao corporal, exigencias em proteina e energia para ganho de peso de caprinos em pastejo

Body composition, protein and energy requirements for weight gain of 1/2 boer 1/2 mixed-breed goat kids on pasture. The objective of this work was to estimate the body composition and the nutritional requirements in protein and energy for the weight gain of 1/2 Boer and 1/2 Mixed-breed goat kids, during growth phase, on pasture in the semi-arid region. The work was developed at 'Nupearido' farm, in Patos- PB. Twenty-four goat kids were used, with average initial body weigh of 15 kg, distributed into four treatments with increasing levels of concentrate supplementation (0, 0.5, 1.0 and 1.5% of body weight). The animals, maintained under semiconfinement system, received feeding supplementation in individual stalls when they were gathered daily. Whenever one of the animals of each group reached 30 kg of body weigh, all other animals of the group were slaughtered after a 16-hour fast. The body composition varied from 185.3 to 184.0 g of protein; 53.0 to 120.2 g of fat and 1,642 to 2,356 kcal [kg.sup.-1] of empty body. The net requirements in protein and energy on growing varied from 146 to 145 mg and 1.92 to 2.75 kcal [g.sup.-1] of gain, respectively, for animals from 15 to 30 kg of body weigh. Key words: Capra hircus, metabolizable energy, net requirement, metabolizable protein, semi-arid. Objetivou-se com este trabalho estimar a composicao corporal e as exigencias nutricionais em proteina e energia para ganho de peso de cabritos 1/2 Boer 1/2 SRD, na fase de crescimento, em pastejo na regiao semiarida. O experimento foi desenvolvido na fazenda 'Nupearido', no municipio de Patos, Paraiba. Foram utilizados 24 cabritos com peso corporal medio inicial de 15 kg, em pastejo, distribuidos em quatro tratamentos com niveis crescentes de suplementacao concentrada (0; 0,5; 1,0 e 1,5% do peso corporal). Os animais, mantidos em sistema de semiconfinamento, receberam suplementacao alimentar, em baias individuais, ao serem recolhidos diariamente. Quando um dos animais de cada grupo atingia 30 kg de peso corporal, todos os demais animais do grupo eram abatidos apos jejum de 16h. A composicao corporal variou de 185,3 a 184,0 g de proteina; 53,0 a 120,2 g de gordura e 1.642 a 2.356 kcal [kg.sup.-1] de corpo vazio. As exigencias liquidas em proteina e energia variaram de 146 a 145 mg e 1,92 a 2,75 kcal [g.sup.-1] de ganho, respectivamente, para animais de 15 a 30 kg de peso corporal. Palavras-chave: Capra hircus, energia metabolizavel, exigencia liquida, proteina metabolizavel,