Cana-de-açúcar in natura ou ensilada e silagem de milho em dietas para bovinos de corte confinados

• Autor(a) principal: Menezes, Gustavo Chamon de Castro
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5647
• topic: Cana-de-açúcar; Bovinos; Desempenho; Digestibilidade; Sugar cane; Cattle; Performance; Digestibility; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The study was developed from two experiments with the objective of evaluating the consumption and production performance, the total apparent digestibility, ruminal and intestinal microbial efficiency and ruminal parameters in beef cattle fed with diets based on in natura or ensiled sugar cane and corn silage. In experiment 1,35 animals were used, not castrated, with average weight of 350 ± 32 kg and aged between 24 and 36 months, distributed in a randomized block design with five treatments and six replications. The diets consisted of in natura sugar cane grounded at the time of delivery (CIN) or chopped and fed after 72 hours of storage (CAR), sugar cane silage treated with 1% lime (SCT) or not treated (SC) and corn silage (SM) at will. It was used urea / S.A. added on the volume immediately before feeding in sufficient quantity to increase the crude protein (CP) of all forages for approximately 10% DM basis. All animals received 1% of concentrate on the basis of body weight (BW) containing 23% of CP. The experiment was conducted in three periods of 28 days after adjustment of 14 days. Feces were collected twice daily for three days to obtain the flow of fecal DM estimated by the indigestable fiber (iADF). The animals fed with SM were superior (P <0.05) in consumption and in the levels of total digestible nutrients (NDT), which resulted in greater weight gain and fat thickness, without, however, differ in the yield of cuts on the carcass; animals had fewer aproaches to the trough, but with longer exposure time per access, compared to those fed with diets based on in natura or ensiled sugar cane. Animals consuming diets based on in natura sugar cane had higher (P <0.05) intakes of dry matter (DM), non-fiber carbohydrates (NFC) and NDT content, with better weight gain, no differences ( P> 0.05) in the cut income, being the access to the trough lower with longer stays periods in relation to the animals fed on ensiled sugar cane. Animals fed with diets containing ensiled sugar cane did not differ (P> 0.05) for intake and animal performance. Animals fed with diets of in natura sugar cane were similar (P> 0.05) for nutrient intake and animal performance, being that the animals fed with sugar cane stored for 72 hours showed smaller number of accesses with a greater permanence to access the trough. It was concluded that the use of diets containing SM provide superior performance compared to the animals in relation to the animals fed with diets based on in natura or ensiled sugar cane. Animals fed with diets based on in natura sugar cane presented better performances than those fed with diets of ensiled sugar cane. The use of lime in the silage does not result in a better performance of the cattle. The cane sugar stored for 72 hours is an alternative food source. Higher weight gains are correlated with fewer accesses to the trough and with greater length of stays per access. In the second experiment, it was assessed the intake, total apparent digestibility, ruminal and intestinal microbial efficiency and ruminal parameters of cattle fed with diets based on in natura or ensiled sugar cane and corn silage. Five crossbred cattle were used, fistulated in the rumen and abomasum, with body weight (BW) averaging 240 ± 15 kg, not castrated, distributed in a 5 x 5 Latin square. All of the voluminous were corrected with urea / SA to contain approximately 10% CP, in the DM basis, being this mixture sprayed immediately before delivery. The concentrate was offered to all animals on the basis of 1% of body weight containing 23% CP. Each experimental period lasted 14 days and 7 days for diet adaptation and 7 days for data collection. Total feces samples were collected for three days. The collection of abomasal digesta were made during three days at intervals of 15 hours. Abomasal DM flow was estimated using titanium dioxide as an external indicator. Two dissections of the rumen were made (before feeding and after four hours) on alternate days to calculate the ruminal pool and then estimate the rates of digestion and passage of nutrients. Animals fed with diets containing SM had higher total apparent digestibility of organic matter (OM), ruminal crude protein (CP) and intestinal ethereal extract (EE), and higher passage rates of DM, fiber in neutral detergent (NDFcp) and CP compared to animals fed with the other diets. It was observed that the animals fed with diets containing in natura sugar cane had lower (P <0.05) ruminal OM, CP and CNF and higher (P <0.05) in EE, and higher (P <0.05) intestinal digestibility of DM, OM and CNF in relation to animals fed diets based on ensiled sugar cane, and higher rate of transition from DM. There was no difference for the passage rates between the animals fed with diets containing ensiled sugar cane, a repeated characteristic when the animal feeding of in natura sugar cane was compared with the sugar cane stored for 72 hours. It was concluded that the better performance shown by the animals fed with SM can be justified by the increased passage rate of DM and the highest rates of digestion of DM and NDFcp, resulting in greater nutrient intake. The highest passage rate of dry matter observed for the animals fed with diets containing in natura sugar cane justifies the higher consumption and performance achieved compared to those fed with diets containing ensiled sugar cane. The animals fed on ensiled sugar cane diets are similar in all digestive parameters, and the use of lime unable to promote benefits for consumption and digestibility, as well as weight gain in cattle. Animals fed with diets containing sugar cane stored for 72 hours has digestible characteristics similar to those fed with diets containing in natura sugar cane provided immediatel after the harvest.