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

Abstract

-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.

Meat lipid profile of steers finished in pearl millet pasture with different rates of concentrate

“…A factor that may have contributed to reduce the w-6/w-3 ratio in treatments without supplementation and with 0.5 concentrate supplementation (Table 4) was the high content of linolenic acid (C18: 3 n-3) in pearl millet (22.74 g 100g -1 of total lipids of forage). In their study, Menezes et al (2010) found that animals fed a restricted diet with tropical pasture silage (pearl millet + Alexander grass) ingested a higher amount of omega-3 fatty acids (9.5 g per day) compared to those fed ryegrass silage (3.43 g d -1 ) or a diet containing 60% corn silage and 40% concentrate (5.89 g d -1 ), and showed relations omega-6:omega-3, 1.55, 1.13 and 5.72, respectively.…”

“…Using stored forage, Menezes et al (2010) observed that the consumption of pearl millet silage, compared to annual ryegrass silage, promotes a higher intake of SFA; however, the total of SFA that reaches the small intestine for absorption is similar. This may explain the insignificant change in the levels of SFA in meat from cattle, in the present and in other studies, such as that by Prado et al (2003).…”

“…This fatty acid is considered the precursor of the conjugated linoleic acids (CLA) that can be formed from the action of the enzyme Delta 9-desaturase, which is present in the adipose tissue of animals (Ledoux et al, 2000). The reducing effects of the total biohydrogenation process seem to be more intense, when the inclusion of concentrate in the diet is elevated, which results in the increase of duodenal flow of C18:0 trans-11 (Menezes et al, 2010). Therefore, energy supplementation used in the present study seems not to have been effective on ruminal biohydrogenation, since it caused no changes of the concentrations of vaccenic acid and CLA cis-9-trans-11.…”

“…Therefore, supplementation with grain predisposes to lower rates of biohydrogenation and larger input of UFA which reach the small intestine to be absorbed (Martínez Marín, 2007). Even so, the pasture type appears to be an important factor in the process of lipid deposition in beef, since tropical pastures show a lipid profile with lower levels of polyunsaturated fatty acids (PUFA), mainly C18:3 and smaller amounts of C14:0, in comparison to temperate pastures (Menezes et al, 2010).…”

The Effects of Grass-Based versus Grain-Based Feeding of Ruminants on the Human Hygienic Status, a Review.

“…Regarding grain-based feeding, the biohydrogenation process was found to be inhibited by a decrease in the ruminal pH and ultimately growth inhibition of the CLA-producing bacteria (Wood et al, 2008) (Figure 1B). The reduction in the pH values is typically linked with this sort of diet, as the presence of concentrated food components reduces lipolysis, which is a fundamental step in biohydrogenation (Menezes et al, 2010). If ruminal biohydrogenation of UFA can be controlled, it may be possible to enhance the quality of ruminant meats via generally increasing UFA, CLA, and n-3 FAs in particular.…”