Digestibility Studies on Levels of Concentrates in Complete Pelleted Rations for Fattening Lambs

Digestible energy, dry matter and protein, and percent nitrogen retention were determined in a digestion study with nine lambs fed complete pelleted rations containing 10, 20, 30, 40, 50, or 60% sorghum grain, with the remainder of the ration made up of average quality alfalfa hay. The nine lambs averaged 66 lb. at the beginning of the experiment and 107 lb. at the end. Highly significant differences (P<.01) in digestible energy were found, with digestible energy increasing in an almost perfect linear relationship with increasing concentrate in the ration. Digestible dry matter was correlated with digestible energy on each individual ration, and a highly significant relationship between the two measurements was found. Statistical analysis of protein digestion coefficients showed no significant difference between the 10 and 20% concentrate rations or between the 30, 40, 50, or 60% concentrate rations, but a highly significant difference between the 20 and 30% concentrate rations. Percent nitrogen retained showed a highly significant difference due to rations. Wide variability of percent nitrogen retained between individual lambs on any given ration indicated that nitrogen retention may not be an accurate measurement for the evaluation of the rations studied.