Profile of ingested fatty acids and in the duodenal digest of steers fed different diets

It was evaluated in this study the effect of the type of the diet on duodenal flow of long-chain fatty acids in steers. The tested diets were the following: conventional (feedlot diet composed of 60% corn silage and 40% of concentrate); winter forage silage - rye grass (Lolium multiflorum, Lam); or tropical forage silage - association of millet (Pennisetum americanum, Leeke + alexander grass, Brachiaria plantaginea). Six Charolais × Nellore crossbred steers with cannulas in duodenum were used in a 3 × 3 double Latin square. Dry material intake was similar among the groups (mean of 4,037 g/day), but the intake of total fatty acids and saturated fatty acids were higher in the group fed tropical pasture silage. On the other hand, the animals which received the conventional diet consumed higher quantity of unsaturated fatty acids. Tropical pasture silage provided higher consumption of vacenic acid (C18:1 t-11) and the winter forage silage offered higher consumption of conjugated linoleic acid. The intake of omega-6 fatty acids was higher in the group fed conventional diet and for omega-3, intake was higher in the group fed tropical pasture diet. The total fatty acid flow in the duodenum was not affected by the diets, but in all treatments it was higher than the consumed one. The animals fed diet with concentrate show the greatest changes on the profile of fatty acids during the ruminal fermentation. Conventional diets provide the highest intake of unsaturated fatty acids and the highest availability of vacenic acid in the small intestine, but they do not increase the supply of intestinal conjugated linoleic acid. Foi avaliado o efeito do tipo de dieta sobre o fluxo duodenal de ácidos graxos de cadeia longa em novilhos. As dietas testadas foram: convencional (dieta de confinamento constituída de 60% de silagem de milho e 40% de concentrado); silagem de forrageira temperada - azevém (Lolium multiflorum, Lam); ou silagem de forrageira tropical - associação de milheto (Pennisetum americanum, Leeke + capim-papuã, Brachiaria plantaginea). Foram utilizados seis novilhos mestiços Charolês × Nelore canulados no duodeno, em duplo quadrado latino 3 × 3. O consumo de matéria seca (MS) foi semelhante entre os grupos (média de 4.037 g/dia), mas o consumo de ácidos graxos totais e de ácidos graxos saturados foi mais alto no grupo que recebeu silagem de forrageira tropical. Por outro lado, os animais que receberam a dieta convencional consumiram maior quantidade de ácidos gra