Efeito do DDG sobre os parâmetros ruminais de bovinos de corte em confinamento

Abstract

Beef catlle production in confined systems increased the production efficiency, but necessities a great quantity of feed. Co-products are a feed alternative with high quality and economic viability in ruminant diets, highlighting the co-products of ethanol production. This work aimed to evaluated ruminal parameters of confined beef cattle supplemented or not with DDG. There was used eight Nelore bulls, with 400 kg of body weight, and 18 – 20 months of age. The experimental design used was crossover with switch back, composed by two treatments (control and dried distillers grains – DDG) and 12 repetitions by treatment (n=24). At 0, 2, 4, 6, 8, 10 and 12 hours post-feeding, ruminal content was collected, filtered and the pH determined. Two aliquots of 50 mL of ruminal content were acidified (0.1 mL of sulfuric acid) and stored at - 15ºC. Statistical analyses was performed with the PROC MIXED of the SAS software, and the means were compared by Tukey test (p<0.10). The diet did not influenced ruminal parameters pH and N-NH3. The mean values found in conventional and DDG diets for pH were 6.11 and 6.18 and for N-NH3 were 22.96 and 21.04, respectively. The DDG inclusion increased the concentrations of three principal SCFA (Acetate, propionate and butirate), and decreased acetate:propionate relationship, from 3.91 in conventional diet to 3.07 in the DDG diet. Postfeeding time influences all parameters, but there was no significant interaction between diets and post-feeding time. The supplementation of confined animals is a strategy to provide the essential nutrients, and ensure a great body weight gain of animals. The inclusion of DDG on the confined beef cattle diets was positive, once that increased SCFA production without pH modification. Considering 5.5 the value of pH that limit ruminal bacterial growth and can alter ruminal fermentation, DDG diet did not reach this value (> 5.75), even with the highest production of SCFA. These results indicated a higher feed degradability without interferences on the ruminal dynamic. The decrease on acetate:propionate relationship also indicates a better feed energy use, with more propionate produced in relation to acetate for DDG diet. In conclusion, the replacement of cottonseed meal by DDG in diets of confined beef cattle did not influence the ruminal environment and was able to increase the SCFA production. Therefore, the DDG utilization is recommended for feeding confined beef cattle.