The objective of this trial was to characterizethe byproduct of lysine production (BLP) and to evaluate performance and carcasstraits of confined Santa Gertrudis young bulls receiving increasing dietarylevels of BLP. The chemical composition of BLP was the following (dry matterbasis): 38% dry matter and 85% crude protein with 79% of this total coming fromnonprotein nitrogen; no toxic levels of heavy metals were detected. Twenty-sevenyoung bulls averaging ten months of age and initial body weight of 242 kg wereused in this trial. Animals received corn silage plus 80% of concentrate andone of the following levels of BLP: 0, 4.5 or 9.0% on dry matter basis. Theexperimental period lasted 115 days with 56 days for diet adaptation. Averagedaily weight gain, dry matter intake, final weight, and carcass weight all respondedquadraticaly when the dietary levels of BLP increased from 0 to 9.0%. Feed efficiencyand carcass dressing decreased linearly while fat thickness and liver weightincreased linearly with incremental levels of BLP in the diet. No significantdifferences for Longissimus muscle area were observed across treatments.Lower feed intake or dietary sulfur levels did not explain the observed differencesin the performance. The maximum recommended dietary level of BLP for finishingyoung bulls fed high energy diets was 3.7% for expected daily weight gain of1.23 kg per animal.
