Effects of long-term feeding of crude glycerine on performance, carcass traits, meat quality, and blood and rumen metabolites of finishing bulls

The objective of this study was to examine performance, carcass traits, muscle chemical composition, and blood and rumen metabolites of bulls fed diets with different levels of crude glycerine. A total of 48 Fleckvieh bulls (initial age and live weight 222±16 d and 232±29 kg, respectively) were divided into four dietary treatment groups with different levels of glycerine supplementation: C (without glycerine), G5 (4.7% of glycerine), G10 (9.3% of glycerine) for the entire experimental period (266±38 d), and CG10 (0% for 118 d and then 9.3% of glycerine until slaughter). The diets were similar in their energy and protein contents with glycerine proportionally substituting barley meal. Feed intakes were recorded daily and the bulls were weighed every two weeks until slaughter (592±29 kg of live weight). In addition, blood samples were collected on day 0, 118, and 189 of the experiment. After slaughter, rumen fluid was collected, carcass characteristics were recorded, and m. longissimus lumborum composition was determined. No significant effect of glycerine inclusion was observed in any of the growth performance, carcass and meat quality traits studied. Also, no apparent effects on blood and rumen metabolites were detected. We conclude that crude glycerine can be used as a long-term substitution for barley meal up to the level of approximately 10% of dry matter in the diets of finishing bulls.