The objective of this trial was to characterize the byproduct of lysine production (BLP) and to evaluate performance and carcass traits of confined Santa Gertrudis young bulls receiving increasing dietary levels of BLP. The chemical composition of BLP was the following (dry matter basis): 38% dry matter and 85% crude protein with 79% of this total coming from nonprotein nitrogen; no toxic levels of heavy metals were detected. Twenty-seven young bulls averaging ten months of age and initial body weight of 242 kg were used in this trial. Animals received corn silage plus 80% of concentrate and one of the following levels of BLP: 0, 4.5 or 9.0% on dry matter basis. The experimental period lasted 115 days with 56 days for diet adaptation. Average daily weight gain, dry matter intake, final weight, and carcass weight all responded quadraticaly when the dietary levels of BLP increased from 0 to 9.0%. Feed efficiency and carcass dressing decreased linearly while fat thickness and liver weight increased linearly with incremental levels of BLP in the diet. No significant differences for Longissimus muscle area were observed across treatments. Lower feed intake or dietary sulfur levels did not explain the observed differences in the performance. The maximum recommended dietary level of BLP for finishing young bulls fed high energy diets was 3.7% for expected daily weight gain of 1.23 kg per animal.
aminoacids; beef cattle; feedlot; minerals; residue
