M. Yossifov, L. Kozelov
Abstract. Two experiments were conducted to investigate effects of rapeseed meal (RSM) vs. sunflower meal (SFM) as a protein source at cereal-based isonitrigenous (at 16 % CP), iso-caloric at gross energy 18 kcal/kg and net (FUG=1) energy diets for fattening lambs. Four wethers (Gygay breed) were used to evaluate the diets’ apparent total tract digestibility (dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), crude fibres (CF), nitrogen free extractives (NFE) and ash) and coefficients (Cd) were used to calculate the diets’ feeding value. Two diets were used: conrol diet (CD) with SFM and experimental diet (ED) with RSM. The results indicated that feeding RSM tended to increase Cd OM (p=0.1), Cd CP (p=0.4), Cd EE (p=0.5) and Cd NFE (p=0.1). The differences were significant at Cd DM (p<0.05), Cd CF (p<0.05) and Cd ash (p<0.001). According to the calculation analysis, diet supplementation with RSM benefits total digestible nutrients (TDN), raised energy values (gross energy, digestible energy and net energy) and improved protein feeding values (protein trully digestible in small intestines (PDI) and balance of protein in rumen (BPR)). Therefore, it’s concluded that, substitution of SFM with RSM in cerealbased ruminant diets significantly (p<0.05) increased in vivo diet digestibility, raised (11 %) TDN and improved its energy and protein feeding value.