Levels of mineral mixture and urea in supplementation of crossbred heifers, with Gyr predominance, reared at pasture during the dry season

• Autor(a) principal: Mendonça,Bruno Pietsch Cunha
• Data de Publicação: 2010
• Outros Autores: Lana,Rogério de Paula, Mancio,Antonio Bento, Detmann,Edenio, Barbosa,Analívia Martins, Guimarães,Geicimara
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Revista Brasileira de Zootecnia (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982010001000025
• topic: nitrogen supplement; rearing; weight gain

It was evaluated several levels of mineral mixture and urea for crossbred heifers, with Gyr predominance, in the dry season period in Zona da Mata region in Minas Gerais. The experiment was carried out in a Brachiaria decumbens pasture area, divided in five paddocks of 3.5 hectares. It was used 35 heifers distributed in a 2 õ 2 + 1 factorial scheme, composed of two levels of urea (10 and 25%), two levels of mineral salt (10 and 25%) and a control diet (only mineral salt), totaling five diets, each one evaluated with seven replicates. The supplements were based on ground corn, urea, ammonia sulfate and mineral mixture with 32 to 72% crude protein, and they composed the following diets: MM ( mineral mix), 10:10 (10% mineral mix, 10% urea and 80% corn); 10:25 (10% mineral mix, 25% urea and 65% corn); 25:10 (25% mineral mix, 10% urea and 65% corn), and 25:25 (25% mineral mix, 25% urea and 50% corn). Urea and mineral salt are effective in controlling supplement intake by bovines growing on pastures during dry season because the higher their levels, the lower the intake of supplements. Diets with 25% urea and 10% mineral salt provided higher daily weight gain and higher weight gain:supplemment intake ratio.