Substituição do farelo de soja por levedura seca inativa em dietas de ovinos

• Ano de defesa: 2011
• Autor(a) principal: Rufino, Leidy Darmony de Almeida
• Orientador(a): Pereira, Odilon Gomes
• Banca de defesa: Marcondes, Marcos Inácio , Cecon, Paulo Roberto
• 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; Ganho de peso; pH ruminal; Qualidade de carne
• Palavras-chave em Inglês: Consumption, Digestibility, Weight gain, Ruminal pH, Meat quality
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PASTAGEM E FORRAGICULTURA::AVALIACAO, PRODUCAO E CONSERVACAO DE FORRAGENS
• Link de acesso: http://locus.ufv.br/handle/123456789/5701

This study was developed based on two experiments, aiming to evaluate the intake and apparent digestibility of nutrients, ruminal pH and ammonia concentration and nitrogen balance (Experiment 1) and the productive performance and meat quality of lambs (Experiment 2) fed diets containing different levels of substitution (0, 33, 67 and 100%, in dry matter basis) of soybean meal by inactive dry yeast. Diets consisted of 60% concentrate and 40% corn silage, formulated to be isonitrogenous (15.5% crude protein, in dry matter basis). In experiment 1, four Santa Ines lambs, non castrated, with initial live weight of 25,6±3,1 kg, fistulated in the rumen, were allocated in a 4 x 4 Latin Square design. Each experimental period lasted 17 days, 10 for diet adaptation and seven for data collection. Fecal and urine total collection was performed from the 11th to the 16th day of each experimental period to determine the apparent digestibility of nutrients and nitrogen balance. The collection of rumen fluid for measurements of pH and ammonia were taken before, 2, 4 and 6 hours after feeding. Dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber corrected for ash and protein (NDFap), non-fibrous carbohydrates (NFC) and total digestible nutrients (TDN) intakes in g/day were not affected (P>0.05) by inactive dry yeast levels. Intakes of DM and NDFap (g/kg) decreased linearly as yeast levels increased in diets (P<0.05). The different levels of inactive dry yeast did not promote changes (P> 0.05) in apparent digestibility of NFC. It was observed a quadratic effect of yeast on apparent digestibility of DM, OM, CP, EE and NDFap as well as on TDN content (P<0.05), estimated maximum values of nutrient digestibility and TDN of 79.30, 81.67, 80.33, 75.52, 63.57 and 80.87%, respectively, at 43.96, 44.71, 44.07, 43.91, 43.27 and 48.06% of inactive dry yeast. It was observed effect of diet and sampling time for ruminal ammonia concentration, whose data were fit to the quadratic model. It was not observed effect of diet (P>0.05) for ruminal pH, but observed effect of time of collection and the data were fit to the quadratic model. Nitrogen balance was not affected (P>0.05) by inactive dry yeast levels. In experiment 2, it was assessed the intake of nutrients, weight gain, average daily gain of carcass, carcass yield, feed conversion and meat quality in lambs receiving the same diets of the previous experiment. The study included 36 Santa Ines lambs, not castrated, with initial live weight of 20,2±0,5 kg, allocated in a randomized block design with four treatments and nine replications. The experiment lasted 78 days, divided in three periods of 21 days after 15 days of adaptation. DM, OM, CP, EE, NDFap, NFC and TDN intakes were not affected (P>0.05) by inactive dry yeast levels. The average daily gain, carcass daily gain, dressing percentage and feed conversion were not affected (P>0.05) by inactive dry yeast levels. The subcutaneous fat thickness decreased linearly (P<0.05) with the increasing levels of yeast replacing the soybean meal in the diet. It was observed a quadratic effect (P<0.01) of yeast on initial temperature of the carcasses showed the highest value of 37.26°C at 48,35% of yeast. It was observed a quadratic effect (P<0.05) of yeast on yellowness of the meat, the minimum values were obtained at 63.29% of replacement of soybean meal by yeast in the diet. The lightness of the meat decreased linearly (P<0.05) with increasing levels of dry yeast to replace soybean meal in diets. The crude protein and ash of meat increased linearly (P<0.05) and the intramuscular fat content of meat decreased linearly (P<0.05) with the increase of dry yeast in the diet. The exudates losses and tenderness of the meat of the animals were not affected by yeast levels (P>0.05). The inactive dry yeast can replace 100% of the soybean meal in diets of sheep. However, the utilization of this co-product depends on economic factors and market availability.