Substituição do farelo de soja por levedura seca inativa em dietas de bovinos de corte

• Ano de defesa: 2011
• Autor(a) principal: Campos, Andressa Fernanda
• Orientador(a): Pereira, Odilon Gomes
• Banca de defesa: Valadares, Rilene Ferreira Diniz , Marcondes, Marcos Inácio
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Consumo; Digestibilidade; Desempenho animal
• Palavras-chave em Inglês: Consumption; Digestibity; Animal performance
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PASTAGEM E FORRAGICULTURA
• Link de acesso: http://locus.ufv.br/handle/123456789/5700

This work was developed based on two experiments, aiming to evaluate the intake and the total and partial apparent digestibility of nutrients, ruminal pH and ammonia concentration, the microbial efficiency and nitrogen balance (Experiment 1) and the productive performance of beef cattle (Experiment 2) fed with diets containing different levels of substitution (0, 25, 50, 75 and 100%, in dry matter basis) of soybean meal by inactive dry yeast. The roughage: concentrate ratio of 60:40, using as a source of forage the corn silage. In experiment 1, five Nellore steers were used, castrated, with an average initial weight of 320 ± 39 kg, fistulated in the rumen and abomasum, distributed in a 5x5 Square Lattice design. Each experimental period lasted 18 days, 10 for diet adaptation and eight for the sample harvest. The chromic oxide was used as an external marker to estimate fecal and abomasal flows. Spot of blood and urine samples were colleted for determination of the plasmatic urea nitrogen, the microbial efficiency and the nitrogen balance. The collection of rumen fluid for measurements of pH and ammonia were taken (0), 2, 4 and 6 hours after feeding. There was effect of the yeast (P<0.10) on the intake of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber corrected for ashes and protein (NDFap) and total digestible nutrients (TDN). However, there was not effect of the yeast on the intake of non-fibrous carbohydrates (NFC). The total apparent and ruminal and intestinal digestibilies were not affected by yeast levels (P>0.10). It was observed an effect of diet and sampling time for the pH and ruminal ammonia concentration, whose data were fit to the linear and quadratic models, respectively. It was not detected effect of the yeast on the urea urinary excretion (UUE) and urea plasmatic excretion (UPE), concentration of allantoin (ALA), uric acid (ACU), total purine (TP), allantoin in relation to the total purine (ALA/TP) and microbial efficiency (Efmic), yielding averages of 45.79 g/day, 15.55 mg/dL, 115.21; 9.47; 124.68 mmol/day, 92.36% and 157.1gCPmic/kg TDN, respectively. The nitrogen of urine (N-urine) and intake of nitrogen (N-ing) decreased linearly (P<0.10) with increased levels of inactive dry yeast in substitution of soybean meal. There was quadratic effect of the yeast on the nitrogen balance (NB), with estimated minimum value of 21.91 g/day for the level of 52.53% of yeast. In experiment 2, it was assessed the total intake and total apparent digestibility of nutrients, weight gain, average daily gain of carcass, carcass yield and feed conversion of beef cattle receiving the same diets of the experiment 1. The study included 35 Nellore steers, not castrated, with initial weight of 370 ± 42 kg, distributed in a randomized block design with five treatments and seven replications. The intake of DM, OM, CP, EE, kg/day, decreased linearly (P <0.10) with levels of yeast. The intake of NDFap, NFC, and TDN, regardless of the expressed form, were not affected (P> 0.10). There was a quadratic effect (P <0.10) of the yeast on the DM intake, in % of live weight, with estimated maximum value of 2.15% for the diet containing 26.98% of inactive dry yeast. The CP digestibility increased linearly (P <0.10) with the levels of yeast, whereas the apparent digestibility of the other nutrients was not affected (P> 0.10) by the yeast. The average daily gain decreased linearly with increasing levels of yeast. In turn, the average daily gain of carcass, dressing percentage and feed conversion were not affected by the diets (P> 0.10), registering average of 0.91 kg/day, 56.33% and 7.57, respectively. The inactive dry yeast has potential of substitution of soybean meal in diets of beef cattle, because it&#8217;s not affect the total and partial apparent digestibility of nutrients, the nitrogen balance, the microbial efficiency and the average daily gain of carcass. The utilization of this co-product depends of economic factors.