Efeitos de idade e suplementação protéica sobre características de carcaça e qualidade de carne de bovinos criados em pasto

• Ano de defesa: 2010
• Autor(a) principal: Cavali, Jucilene
• Orientador(a): Paulino, Pedro Veiga Rodrigues
• Banca de defesa: Felício, Pedro Eduardo de , Veloso, Cristina Mattos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Maciez; Creep-feeding ultrassom
• Palavras-chave em Inglês: Softness; Creep-feeding ultrassom
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1743

Follow the growth of bulls feeding on pasture, weaning termination, receiving different strategies of supplementation. Fifty two Nellore bulls, grazing Brachiaria decumbens pasture, were used, separated in four groups representing bulls fed ad libitum with mineral salt and tree protein supplementation strategies and thirteen replicates. Strategies T1, T2 and T3 were formulated with corn, soybean meal and composed by the levels of 10, 20 and 30 % of crude protein on creep-feeding ration and by urea levels background ration, keeping isoproteic the ration. The bulls were fed everyday with 1.2, 1.5 and 2.0 kg/animal to calves, growing and finishing bulls, respectively. On each age the animals were slaughtered and a sample of the Longissimus dorsi was taken at the level of the last rib to analyses of meat. The objective was evaluate the effects of strategies protein supplementation strategies on in vivo carcass traits of bulls grazing pasture by ultrasound, avaluate the meat quality according to muscle fibers traits, index of myofibrillar fragmentation, meat shear force, exudative losses and meat color ad fatty acid profile of intramuscular fat of bulls grazing tropical pasture on different ages. The protein supplementation provided greater Longissimus muscle area (AOL), subcutaneous fat thickness (RIB) and rump fat (RUMP) in beef calves fed in a creep feeding system and the RIB were greater when highest levels of crude protein in supplements were offered. The protein supplementation strategies proposed was efficient (P<0.10) to improve gainthe carcass muscularity with increases of the AOL (P<0.10) in 0.0354 cm2/day, from 250 to 446 days old, in addition to promoting greater RIB compared to the animals receiving mineral mix (1.08 mm vs 0.44 mm) even in young bulls in dry season of the year, which allows obtaining bulls with adequate carcass composition to slaughter in lower age. The carcass traits of finishing bulls were better correlated with traits measured by ultrasound on calves phase. The correlations profile of measures in ages was influenced by protein supplementation keeping nutritional restriction and by kind of tissue evaluated, muscle or fat tissues. The different ages of slaughter growing and finishing bulls fed in pasture modify parameters of meat quality as kind of muscle fibers, myofibrillar fragmentation index and intramuscular fat (P<0.10), however didn´t it under shear force (P>0.10), being possible define the meat of young bulls who tender beef. The finishing bulls grazing tropical pasture are defined by red meat color and lower losses of water. The strategies of supplementation favor changes among muscle fibers with increase of white fiber frequency or IIB fibers, to the supplement with most levels of non protein nitrogen (NPN) and decrease defrost losses (P<0.10), don´t modifying another s traits of meat quality. In the last study was to evaluate the fatty acid profile of intramuscular fat (IMF) was determined by gas chromatography. The calf meat has fatty acid profile with high levels of EPA, DPA and DHA, and yet high values to conjugated linoleic acid (CLA), standing all fatty acid with nutraceutical importance. The period of nutritional restriction or dry period favors the ruminal biohydrogenation of fatty acids. The finishing of young bulls in pasture improve monounsaturated fatty acids (MUFA) and decrease polyunsaturated (PUFA) keeping constant the saturated fatty acids (SFA), however decrease the eicosanoids noninflammatory of n-3 series. IMF of bulls of the control group (pasture + mineral mixture) had greater (P<0.10) contents of palmitic (C16:0), oleic (C18:1), linoleic (C18:3) and eicosapentaenoic acid (EPA), more monounsaturated fatty acids (MUFA) and lower estearic acid (C18:0) when compared to the other groups, but did not differ (P>0.10) from the supplemented counterparts regarding total saturated fatty acids (SFA) content. Protein supplementation improved (P<0.10)the amount of polyunsaturated fatty acids (PUFA) and n-6/n-3 ratio of the IMF of the animals, when compared to the control group. However, the MUFA and EPA content of the IMF of the supplemented animals were lower (P<0.10) than the values observed in the animals that received only mineral mixture. Different strategies of protein supplementation of young bulls grazing tropical pastures can modify the fatty acid profile of intramuscular fat and thus be used as a tool to produce beef that meets specific niche markets.