Avaliação de diferentes níveis de mistura mineral e uréia na suplementação de novilhas Gir e mestiças recriadas a pasto na região da Zona da Mata mineira durante o período da seca

• Autor(a) principal: Mendonça, Bruno Pietsch Cunha
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5593
• topic: Suplementação; Uréia; Mistura mineral; Supplementation; Urea; Mineral mixture; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

It was evaluated the weight gain, intake and digestibility of nutrients in the diet of crossbred heifers in the period of dry season of Zona da Mata region of Minas Gerais state, Brazil. The experiment was performed in an area of 17.5 hectares formed with Brachiaria decumbens. The area was divided in five paddocks of 3.5 hectares, that were differed in March for mass accumulation enough for use in July of 2007. Thirtyfive Gyr and crossbred heifers were distributed in five treatments, each one with seven repetitions. The heifers were fed with supplement based on corn, urea more ammonia sulfate and mineral mixture, presenting protein levels between 32 and 72 %. The treatments 1 (mineral mix), 2 (10 % mineral mix, 10 % urea and 80 % corn), 3 (10 % mineral mix, 25 % urea and 65 % corn), 4 (25 % mineral mix, 10 % urea and 65 % corn) and 5 (25 % mineral mix, 25 % urea and 50 % corn) were supplied to the heifers everyday around 10:00 a.m. The treatments were evaluated by regression in a completely randomized design, with five treatments and seven repetitions and, in the evaluation of nutrient digestibilities, four treatments and seven repetitions. The treatments consisted of a 2 x 2 + 1 factorial arrangement, being two levels of urea (10 and 25 % of the supplement), two levels of mineral salt (10 and 25 %) and control (only mineral salt), being analyzed by complete orthogonal contrasts at 5 % of probability. The ureia and mineral salt in high levels were effective in controlling the intake of supplements by growing bovine in pasture during the dry season, in which the larger levels decreased the intake of supplements. The treatment containing 25 % of urea and 10 % of mineral salt provided the largest weight gain and the largest ratio weight gain to supplement intake, and one of the largest ratio of weight gain to urea intake, being confirmed when considering the differential of weight gain as a function of the differential of supplement intake. However, supplements containing high urea levels should contain appropriate amount of mineral salt to avoid excessive consumption, as well as appropriate procedures should be followed for the correct use of the urea, to avoid intoxication by excessive consumption.