Growth of and digestibility by sheep fed diets comprising mixtures of grass and legume hay compared with those fed high-grain diets

Abstract

A digestibility trial with 24 mature wethers and a growth trial with 54 weaned lambs were conducted to evaluate the utilization of ground diets containing varying proportions of grass and legume hay relative to a 90% grain diet. The forage and grain diets were (1) 100% crested wheatgrass hay (CWG); (2) 75% CWGand25% alfalfa hay (AA); (3) 50% CWGand50% AA; (4) 25% CWGand75% AA; (5) 100% AA; and (6) 90% barley and 10% barley straw. Even though apparent digestibility of dry matter (DM) and fiber fractions of AA-containing diets was lower than that of the grain diet and the 100% CWG diet, weight gain was similar for all diets. Consumption of the grain and 100% CWG diet was lower (P < 0.05) than that of the 100% AA diet. Conversion of feed DM to liveweight gain for lambs fed the grain diet was only 4.9 and was lower (P < 0.05) than that of the forage diets, which ranged between 6.1 and 7.0. Dressing percentages of lambs at slaughter for the animals fed the grain and 100% AA diet were 45.0 and 43.2%, respectively, which were higher (P < 0.05) than that of animals fed the CWG-containing diets. These data suggest that inclusion of AA in CWG diets did not result in the expected positive associative effect on growth and feed efficiency in sheep. Key words: Sheep, crested wheatgrass, alfalfa, digestibility, growth