Abstract
The present study was conducted to determine the effect of lipid sources with different fatty acid profiles on nutrient digestion and ruminal fermentation. Ten rumen and duodenal fistulated Nellore steers (268 body weight±27 kg) were distributed in a duplicated 5×5 Latin square. Dietary treatments were as follows: without fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The roughage feed was corn silage (600 g/kg on a dry matter [DM] basis) plus concentrate (400 g/kg on a DM basis). The higher intake of DM and organic matter (OM) (p<0.001) was found in animals on the diet with PF and WF (around 4.38 and 4.20 kg/d, respectively). Treatments with PO and LO decreased by around 10% the total digestibility of DM and OM (p<0.05). The addition of LO decreased by around 22.3% the neutral detergent fiber digestibility (p = 0.047) compared with other diets. The higher microbial protein synthesis was found in animals on the diet with LO and WS (33 g N/kg OM apparently digested in the rumen; p = 0.040). The highest C18:0 and linolenic acid intakes occurred in animals fed LO (p<0.001), and the highest intake of oleic (p = 0.002) and C16 acids (p = 0.022) occurred with the diets with LO and PF. Diet with PF decreased biohydrogenation extent (p = 0.05) of C18:1 n9,c, C18:2 n6,c, and total unsaturated fatty acids (UFA; around 20%, 7%, and 13%, respectively). The diet with PF and WF increased the concentration of NH3-N (p<0.001); however, the diet did not change volatile fatty acids (p>0.05), such as the molar percentage of acetate, propionate, butyrate and the acetate:propionate ratio. Treatments PO, LO and with WS decreased by around 50% the concentration of protozoa (p<0.001). Diets with some type of protection (PF and WS) decreased the effects of lipid on ruminal fermentation and presented similar outflow of benefit UFA as LO.
Highlights
The lipid addition in ruminant diets has been used to increase energy density, improve livestock system efficiency and to generate meat quality with human health benefits
We evaluated the influence of several lipid sources on ruminal digestion and fermentation as well as the extent of fatty acid biohydrogenation in the rumen
The decreased dry matter intake (DMI) in diets with linseed oil (LO), PO, and WS was in accordance with the results found in the literature, which show that the reduction in intake with the inclusion of fatty acids may be associated with reduced digestibility, especially in the fiber fraction of the diet (Wanapat et al, 2011)
Summary
The lipid addition in ruminant diets has been used to increase energy density, improve livestock system efficiency and to generate meat quality with human health benefits. Our hypothesis is that sources with a saturated profile (palm oil [PO]) should demonstrate a lower impact on rumen fermentation and in the flow of unsaturated fatty acids (UFA) towards the duodenum. Sci. 28:1583-1591 linseed oil (LO) addition should cause disorders on the ruminal fermentation due to defaunation and negative effects of free UFA on the bacterial membrane, but on the other hand, it could to enhance the flow of UFA to be absorbed in the duodenum. Lipid diets with some types of protection and with UFA profiles (soybean and PF) would be expected to increase the flow of fatty acid through the rumen without disturbing fermentation. The objective of this study was to evaluate these lipid sources with different fatty acid profiles on nutrient digestion and ruminal fermentation in Nellore steers
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