Net Amino Acids Requirements for Weight Gain of Nellore Bulls

Revista Brasileira de Zootecnia

Paulino, Pedro Veiga Rodrigues¹  Ítavo, Luís Carlos Vinhas²  Cecon, Paulo Roberto⁴  Moraes, Eduardo Henrique Bevitori Kling de¹  Valadares Filho, Sebastião de Campos⁴  Silva, Fabiano Ferreira da³  Valadares, Rilene Ferreira Diniz⁴  Veloso, Cristina Mattos³ 

[1] Universidade Católica Dom Bosco, Campo Grande;UESB;UFV, Viçosa

关键词: amino acids;    needs;    Nellore     IntroduçãoNas últimas décadas;    considerável atenção foi dada à determinação de requisitos de proteínas para ruminantes;    tendo sido proposta uma série de sistemas ou modelos baseados;    principalmente;    nas frações protéicas degradáveis e não-degradáveis dos alimentos;    deixando o campo aberto para a predição de exigências em aminoácidos;   

DOI  :  10.1590/S1516-35982002000300028

学科分类：兽医学

来源: Universidade Federal de Vicosa

【 摘 要 】

- Forty Nellore bulls, with 240 kg initial live weight (LW), were used. Four were reference bulls, four were fed for maintenance, and the remaining were allotted to eight treatments, with four different concentrate levels in the diets (20, 40, 60 and 80%) and two levels of crude protein (CP) (15 and 18%). The growing phase was evaluated up to 360 kg of LW and the fattening phase, up to 450 kg of LW. The roughage used was Tyfton bermudagrass hay (Cynodon dactylon). After slaughter, all animal body parts were weighed and sampled. The samples were freeze dried to determine the dry matter, pre-degreased with ether, grinded and the concentrations of amino acids were determined. The net amino acids requirements for gain were calculated according to the factorial method, where the protein gain was multiplied by the empty body amino acids composition. The net amino acids requirements for maintenance were estimated. The sum of the metabolizable requirements for maintenance and gain composed the total metabolizable amino acids requirements. The net amino acids requirements for gain decreased with the increase of the animals live weight. The total metabolizable amino acids requirements, expressed in percentage of the total essential amino acids, did not change a lot as live weight increased, and the mean values were 2.66, 15.11, 6.09, 8.64, 9.26, 18.48, 8.33, 12.01, and 19.41 for methionine, lysine, histidine, phenylalanine, threonine, leucine, isoleucine, valine and arginine, respectively.

【 授权许可】

CC BY-NC