Use of lentil screenings in the diets of early weaned lambs and ewes in the second trimester of pregnancy

Commercial lentil screenings (LS) were substituted for barley grain and canola meal, and the resulting experimental diets (0, 12.5, 25 and 33% LS; 17±18% CP dry matter) were evaluated in situ and in digestibility and feedlot studies using Romanov Suffolk lambs. Mature Suffolk, Dorset and Rambouillet ewes were used to evaluate LS or whole barley as protein/energy supplements for ewes in mid-gestation receiving barley silage diets. Lentil screenings included 53.4% lentils, 10.6% weed seeds, 8.27% chaff and dust, with the remainder being a mixture of field peas, barley, wheat and canola. For the lamb trial, the control diet consisted of 62% barley, 12.5% canola meal and 20% alfalfa (as fed), while for the ewe study, the control diet consisted of barley silage with a salt-mineral supplement. Comparing dietary constituents in situ, the rates of protein and dry matter (DM) disappearance were 5±6-fold lower (p < 0.05) and effective ruminal degradability of protein (EDCP) was also lowest (p < 0.05) for LS as compared to alfalfa or barley. Digestibilities of DM, organic matter (OM) and neutral detergent fibre (NDF) as well as N retention (% of N intake) linearly decreased (p < 0.001) with increasing dietary LS. In the lamb feeding trial, average daily gain (ADG; p < 0.01), feed intake (p < 0.01) and feed conversion efficiency (p < 0.05) were all linearly reduced with increasing dietary LS, although such reductions were not significant for ewe lambs. Reduced lamb performance with LS was likely related to antinutritional factors and the reduced digestibility of LS. Valuing LS at 50% the cost of barley, incorporation of up to 25% LS in feeder lamb diets would be cost effective. In the ewe feeding study, although weight gains over the 50 days of feeding were highest (p < 0.05) in barley-supplemented and LS-supplemented as compared to control ewes, LS-supplemented ewes had fewer (p < 0.05) lambs born per ewe and reduced (p < 0.05) weight of lambs weaned breeding per ewe as compared to control ewes. Consequently, supplementation of barley silage diets with LS may not be beneficial for ewes in midgestation. # 1999 Elsevier Science B.V. All rights reserved.