Níveis de grãos úmidos de destilaria desengordurado em dietas para bovinos de corte confinados: desempenho, características de carcaça e qualidade de carne
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Data
2020-12-04
Autores
Ferreira, Mateus Silva [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A oferta de grãos de úmido de destilaria (WDG) para nutrição animal vem crescendo no Brasil, com o aumento da produção de etanol de milho. Assim, este estudo teve como objetivo avaliar os efeitos do WDG de milho desengordurado na dieta de bovinos confinados sobre consumo de matéria seca (CMS), desempenho, características de carcaça, qualidade da carne e expressão de genes envolvidos na lipogênese e metabolismo proteico muscular. Cem machos F1 Angus-Nelore não castrados, com idade entre 20 e 24 meses, com peso corporal inicial médio (PCI) de 369,58 ± 49,17 kg, foram utilizados em um delineamento em blocos casualizado de acordo com o PCI. Os animais foram alimentados com dietas contendo 0, 15, 30 e 45% de WDG desengordurado (4% EE) substituindo o milho e o farelo de soja. Após 129 dias de alimentação, os animais foram abatidos e amostras do músculo Longissimus thoracis (LT) foram coletadas para ensaios de biologia molecular e análises físico-química. Genes lipogênicos (SCD1, PPARγ, FASN e CPT2) e genes do metabolismo proteico muscular (eIF4, IGFR1, mTOR, GSK3β e P70S6K) foram analisados por transcrição reversa seguida de reação em cadeia da polimerase em tempo real (RT-PCR). Os dados foram analisados utilizando contrastes polinomiais (linear, quadrático e controle x WDG). A inclusão do subproduto melhorou o CMS e o peso corporal final – PCF (P < 0,05). Observou-se uma tendência (P < 0,10) para efeito quadrático no CMS e PCF, com maiores valores para animais alimentados com dieta com 30% de WDG. Os animais alimentados com WDG apresentaram maior (P < 0,05) peso da carcaça quente (PCQ) e peso de carcaça fria (PCF), e houve efeito quadrático (P < 0,05) para a área de olho de lombo (AOL), com maiores valores para os animais alimentados com dieta com 30% de WDG. Além disso, não foram observadas diferenças na espessura da gordura subcutânea (EGS) e no pH da carcaça, enquanto as características da qualidade da carne foram semelhantes (P > 0,05) entre os tratamentos (força de cisalhamento, perdas por cozimento, MIF e capacidade de retenção de água). No entanto, a inclusão do WDG levou a uma redução na expressão dos genes lipogênicos (SCD1, PPARγ, FASN e CPT2) e, consequentemente, à quantidade de gordura intramuscular no músculo LT. Além disso, a expressão dos genes eIF4, mTOR e IGFR1 foram menores em animais alimentados com WDG (P < 0,05). No geral, a inclusão de WDG desengordurado em dietas de confinamento melhora o desempenho, características de carcaça e reduz a quantidade de gordura intramuscular, sem afetar outras características de qualidade da carne. Embora o aumento dos níveis de WDG desengodurado tenha influenciado o CMS, PCF, pesos de carcaça e AOL (um indicador de deposição muscular) em resposta à alimentação, não produziu alterações conjuntas nos genes do LT relacionados ao metabolismo proteico muscular.
The supply of wet distillers grains (WDG) for animal nutrition has been growing in Brazil, with the increase in corn ethanol production. Thus, this study aimed to evaluate the effect of de-oiled corn WDG in the diet of feedlot cattle on dry matter intake (DMI), performance, carcass traits, meat quality and expression of genes involved in the lipogenesis and muscle protein metabolism. One hundred noncastrated F1 Angus-Nellore bulls, aged 20–24 months, with an average initial body weight (IBW) of 369.58 ± 49.17 kg, were used in a randomized complete block design according to IBW. The animals were fed diets containing 0, 15, 30 and 45% de-oiled WDG (4% EE) replacing corn and soybean meal. After 129 days on feed, the animals were slaughtered and Longissimus thoracis (LT) muscle samples were collected for molecular biology assays and physical-chemical analysis. Lipogenic genes (SCD1, PPARγ, FASN and CPT2) and muscle protein metabolism genes (eIF4, IGFR1, mTOR, GSK3β and P70S6K) were investigated by real-time reverse transcription polymerase chain reaction (RT-PCR). Data were analyzed using polynomial contrasts (linear, quadratic and control x WDG). The inclusion of by-product improved DMI and final body weight – FBW (P < 0.05). A tendency (P < 0.10) to a quadratic effect was observed on DMI and FBW, with greater values for animals fed diet with 30% of WDG. The animals fed WDG presented greater (P < 0.05) hot carcass weight (HCW) and cold carcass weight (CCW), and there was a quadratic effect (P < 0.05) for the ribeye area (REA), with greater values for the animals fed diet with 30% of WDG. Moreover, no differences were observed in backfat thickness (BFT) and carcass pH, while meat quality traits were similar (P > 0.05) among treatments (shear force, cooking losses, MFI, and water-holding capacity). However, the inclusion of WDG led to a reduction in the expression of the lipogenic genes (SCD1, PPARγ, FASN and CPT2) and, consequently, the amount of intramuscular fat in the LT muscle. Moreover, the expression of eIF4, mTOR and IGFR1 genes were lower in animals fed WDG (P < 0.05). Overall, the inclusion of de-oiled WDG in feedlot diets improves performance, carcass traits and reduces the amount of intramuscular fat, without affect other meat quality traits. Although increased levels of de-oiled WDG influenced DMI, FBW, carcass weights and REA (an indicator of muscle deposition) in response to feeding, it did not produce concerted changes in genes of LT related to muscle protein metabolism.
The supply of wet distillers grains (WDG) for animal nutrition has been growing in Brazil, with the increase in corn ethanol production. Thus, this study aimed to evaluate the effect of de-oiled corn WDG in the diet of feedlot cattle on dry matter intake (DMI), performance, carcass traits, meat quality and expression of genes involved in the lipogenesis and muscle protein metabolism. One hundred noncastrated F1 Angus-Nellore bulls, aged 20–24 months, with an average initial body weight (IBW) of 369.58 ± 49.17 kg, were used in a randomized complete block design according to IBW. The animals were fed diets containing 0, 15, 30 and 45% de-oiled WDG (4% EE) replacing corn and soybean meal. After 129 days on feed, the animals were slaughtered and Longissimus thoracis (LT) muscle samples were collected for molecular biology assays and physical-chemical analysis. Lipogenic genes (SCD1, PPARγ, FASN and CPT2) and muscle protein metabolism genes (eIF4, IGFR1, mTOR, GSK3β and P70S6K) were investigated by real-time reverse transcription polymerase chain reaction (RT-PCR). Data were analyzed using polynomial contrasts (linear, quadratic and control x WDG). The inclusion of by-product improved DMI and final body weight – FBW (P < 0.05). A tendency (P < 0.10) to a quadratic effect was observed on DMI and FBW, with greater values for animals fed diet with 30% of WDG. The animals fed WDG presented greater (P < 0.05) hot carcass weight (HCW) and cold carcass weight (CCW), and there was a quadratic effect (P < 0.05) for the ribeye area (REA), with greater values for the animals fed diet with 30% of WDG. Moreover, no differences were observed in backfat thickness (BFT) and carcass pH, while meat quality traits were similar (P > 0.05) among treatments (shear force, cooking losses, MFI, and water-holding capacity). However, the inclusion of WDG led to a reduction in the expression of the lipogenic genes (SCD1, PPARγ, FASN and CPT2) and, consequently, the amount of intramuscular fat in the LT muscle. Moreover, the expression of eIF4, mTOR and IGFR1 genes were lower in animals fed WDG (P < 0.05). Overall, the inclusion of de-oiled WDG in feedlot diets improves performance, carcass traits and reduces the amount of intramuscular fat, without affect other meat quality traits. Although increased levels of de-oiled WDG influenced DMI, FBW, carcass weights and REA (an indicator of muscle deposition) in response to feeding, it did not produce concerted changes in genes of LT related to muscle protein metabolism.
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Palavras-chave
Grão úmido de destilaria, Nutrição animal, Qualidade de carne