The effect of lipid sources on intake, rumen fermentation parameters and microbial protein synthesis in Nellore steers supplemented with glycerol

Abstract

The effects of glycerol with fat sources as a feed alternative were investigated in the ration for Nellore steers (Bos indicus). Eight cannulated steers at 30 months of age with initial bodyweight of 554 ± 36.0 kg were used in a double 4 by 4 Latin square design with four consecutive 16-day periods. Treatments were three different diets with lipid sources (soybean, soybean oil and calcium salts of fatty acids) and one diet control without lipid sources. All diets formulated contained 10% crude glycerol and 5% ether extract with a forage:concentrate ratio of 35:65; corn silage was used as forage. The ruminal liquid was sampled for 24 h and ruminal fermentations were monitored by measuring pH, concentrations of ammonia nitrogenand volatile fatty acids in rumen fluid. Urine samples were obtained from the total collection for 24 h for estimation of rumen microbial protein supply using urinary purine derivatives. Our results showed that the use of lipid sources combined with glycerol did not induce significant changes in rumen pH, acetate molar proportion, ruminal microbial protein or dry matter intake. Although the acetate molar proportion was kept constant within normal parameters, the propionate molar proportion was increased by the diet containing lipid sources. Moreover, we found that there was a negative effect of lipid sources on crude protein and neutral detergent fibre corrected for ash and protein intake, and one positive effect on ether extract intake. We believe that association between fat and glycerol may affect rumen fermentation parameters through reducing fibre intake and increasing propionate production and ammonia nitrogen.

Soybean hulls as feed substitute of ground corn can increase the fiber digestibility and bacterial fibrolytic profile of grazing Nellore steers during the rainy season

“…However, when beef cattle are supplemented with lipids, ruminal fermentation can be altered due to the toxicity of long-chain fatty acids, especially unsaturated fatty acids (UFA), to ruminal fibrolytic bacteria and methanogenic archaea (HENDERSON, 1973;JENKINS, 1993), resulting in lower fiber digestibility and DM intake, depending on the composition of basal diet. Thus, different nutritional strategies as whole soybean grain have been used to reduce the UFA effects on rumen microbes or ruminal fermentation parameters in beef cattle (GOMEZ-INSUASTI et al, 2014;GOMEZ-INSUASTI et al, 2018).…”

Effect of soybean oil availabilities on rumen biohydrogenation and duodenal flow of fatty acids in beef cattle fed a diet with crude glycerine

“…Another dietary strategy to reduce rumen BH includes the use of vegetables oils associated with crude glycerine (CG). This combination may increase the UFA duodenal flow in high concentrate diets (Granja-Salcedo et al 2017a), not affecting the dry matter intake (DMI), rumen microbes or ruminal fermentation parameters (Gomez-Insuasti et al 2014;Granja-Salcedo et al 2017b). In addition, this alternative may be a useful strategy for the partial replacement of maize in beef cattle diets, resulting in economic and environmental benefit by reducing the faecal nitrogen excretion (Granja-Salcedo et al 2017b) and increasing the daily gain and feed efficiency (Silva et al 2013).…”