Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2013
Publication Date: 8/27/2013
Publication URL: http://handle.nal.usda.gov/10113/57487
Citation: Hales, K.E., Kraich, K.J., Bondurant, R.G., Meyer, B.E., Luebbe, M.K., Brown, M.S., Cole, N.A., MacDonald, J.C. 2013. Effects of glycerin on receiving performance and health status of beef steers and nutrient digestibility and rumen fermentation characteristics of growing steers. Journal of Animal Science. 91(9):4277-4289. Interpretive Summary: Expansion of the biodiesel industry has created an increase in crude glycerin supply, and glycerin has the potential to become a valuable feed ingredient for cattle. One experiment was conducted to evaluate the influence of crude glycerin on animal performance and health when used in receiving cattle diets. Another experiment was conducted in steers fed growing diets to determine the site of nutrient digestion, and ruminal fermentation characteristics when glycerin was included in the diet. The use of glycerin in receiving diets decreases feed intake, yet improves feed efficiency by 5%. Additionally, the use of glycerin had no effect of the number of animals receiving treatment for bovine respiratory disease. Starch digestibility increased as glycerin concentration increased in the diet. The ratio of ruminal volatile fatty acids changed in response to glycerin in the diet, which could have implications on improved feed efficiency. The change in volatile fatty acids as glycerin increased in the diet, in addition to the decrease in feed intake and improvement in feed efficiency implies that glycerin is a viable dietary ingredient in growing and receiving cattle diets.
Technical Abstract: One experiment was conducted to evaluate the influence of crude glycerin (GLY) on animal performance and health when used as a partial replacement for roughage in receiving diets. The second experiment was conducted using ruminally and duodenally cannulated steers in a 4 x 4 Latin square to determine the site of nutrient digestion, and ruminal fermentation characteristics when GLY replaced roughage at 0, 2.5, 5, and 10% of diet DM. In Exp. 1, calves (initial BW=245 kg) were fed treatment diets over a 42-d period that consisted of a control diet based on steam-flaked corn (SFC) with GLY inclusion in replacement of dietary roughage at 0, 5, and 10% of diet DM. A linear reduction in DMI was observed as GLY increased (P=0.01). Crude GLY incorporation tended to improve G:F in a linear manner (P=0.07); efficiency was improved 5.4 and 4.7% at 5 and 10% crude GLY. The number of animals receiving treatment for bovine respiratory disease (BRD) did not differ among treatments (P=0.67). Furthermore, there were no differences among treatments for mortality (P=0.58) or the frequency of calves that were seropositive for serum antibody titers to infectious bovine rhinotracheitis on d 28 (P>0.14). In Exp. 2, apparent OM and apparent and true starch digestibility increased linearly (P<0.05) as GLY concentration increased; whereas, true OM digestibility responded in a quadratic (P<0.01) manner. Bacterial OM and bacterial starch flow responded quadratically (P<0.02) and flow increased from 0 to 5% GLY inclusion and decreased thereafter. Feed OM flow responded quadratically (P<0.05), where it decreased from 0 to 2.5% GLY and increased from 2.5 to 10% GLY inclusion. Feed starch and total starch flow from the duodenum decreased linearly (P<0.02) as the concentration of GLY increased in the diet. Bacterial N flow to the duodenum responded quadratically (P<0.01); it increased with increasing GLY in the diet up to 5% and then decreased from 5 to 10%. The acetate:propionate (A:P) ratio in the ruminal fluid decreased (P<0.05) as the concentration of GLY in the diet increased, which could have implications on improved G:F. The decrease in A:P ratio as GLY increased in the diet, coupled with the linear decrease in DMI and improvement in G:F with GLY addition up to 5% of DM in place of roughage implies that GLY is a viable dietary ingredient in growing and receiving diets.