The effects of supplemental rumen-protected fat in feedlot rations

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Four experiments were conducted to determine the effects of supplemental rumen-protected fat in feedlot rations. The first experiment tested the effects of supplemental calcium and magnesium salts of fatty acids on ruminal fermentation and duodenal fatty acid flow in beef steers fed forage-free diets. These saponified fatty acids did not disrupt ruminal fermentation but provided little protection from ruminal biohydrogenation under these conditions. The second experiment evaluated the effects of increasing levels of calcium salts on feedlot performance and carcass characteristics. A moderate (6.2%) level of calcium salts had no effect on average daily gain (ADG) or feed efficiency (FE). However, ADG and FE were decreased when calcium salts were fed at 8.7% of the diet. The third experiment evaluated the effects of calcium salt supplementation in traditional and forage-free feedlot diets on feedlot performance and carcass characteristics. Supplemental rumen-protected fat had no effect on ADG or FE but decreased ribeye area (REA) when fed at 6.5% of the diet. The fourth experiment evaluated the effects of feeding calcium salts on feedlot performance, carcass characteristics, and blood metabolites that affect the growth of feedlot animals. Supplemental rumen-protected fat decreased ADG and intake with no effect on FE when fed at 6.5% of the diet. In addition, calcium salts had little effect on carcass measurements and blood metabolites.