Desempenho nutricional de bovinos de corte em pastejo suplementados com grão de milho destilado de alta proteína

• Autor(a) principal: Dias, Milene Rodrigues
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFMT
• Texto Completo: http://ri.ufmt.br/handle/1/4872
• topic: Suplementação a pasto; Grão de destilaria; Metabolismo de N; PDR; PNDR; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA; Pasture supplementation; Distillery grain; N metabolism; PDR; PNDR

The objective of this study was to evaluate the effects of including high-protein distilled grain (DDGAP; 43% crude protein (CP), dry matter basis) in supplements for grazing beef cattle, on the intake and nutritional performance of the animals. DDGAP is one of the co-products of ethanol distillation from corn grain, and its production process guarantees DDGAP a high content of crude protein (CP). Five Nellore bulls with initial mean body weight (BW) of 413.5 ± 32 kg, were distributed in a 5 x 5 Latin square design. They were tested in five experimental periods, inclusions of 0, 70, 145, 220 and 330 g DDGAP /kg concentrate supplement (dry matter basis (DM)) for grazing beef cattle (pasture 7.46% crude protein (CP), dry matter basis) in the dry/water transition period. Concentrated supplements were provided in the amount of 6 kg/animal/day (natural matter basis), equivalent to 1.5% BW/day, once a day. The inclusion of DDGAP did not affect total DM (P = 0.76) and forage (P = 0.76) intakes, organic matter digestibilities (P = 0.33) and CP (P = 0.33) , and consequently, did not affect the consumption of digestible organic matter (P = 0.76). The inclusion of DDGAP linearly increased CP intake (P = 0.07) due to increased rumen non-degradable protein intake (PNDR; P < 0.01), as rumen degradable protein intake was not affected (P = 0.07) by the inclusion of DDGAP. Ruminal pH showed a quadratic behavior (P = 0.04) with the inclusion of DDGAP, with a maximum value observed with 220g of DDGAP /kg supplement. Although the inclusion of DDGAP linearly reduced the ruminal concentration of ammoniacal N (P = 0.03), no effects were observed on serum urea-N levels (P = 0.13), urinary urea excretion (P = 0.11), body N retention (P = 0.11), body N retention efficiency (as a proportion of ingested or absorbed N; P > 0.11), and microbial protein intestinal flow. These findings indicate that the lower ruminal ammonia production with the inclusion of DDGAP was not enough to improve the N retention efficiency, as a compensation probably occurred with the higher hepatic urea production via amino acid catabolism in animal tissue. The inclusion of DDGAP in high intake supplements (1.5% of BW/day) although increasing PNDR intake and reducing ruminal ammonia concentration, does not affect intake, diet digestibility and body N retention efficiency. It is recommended the inclusion of up to 330g DDGAP /kg DM of high consumption supplement for beef cattle grazing in the dry-water transition.