The objective of this study was to evaluate the nutritional impacts of the inclusion of different levels of lentil screening by-product (LSB) as unconventional ingredient of protein source as a replacement of soybean meal (SBM) on the growth performance, nutrients digestibility, carcass parameters and plasma constituents and of growing rabbits as well economic efficiency of the diets. Sixty New Zealand White (NZW) growing rabbits, 6 weeks age with an average live body weight 617.9 ±62.4 g were

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... andomly assigned to four dietary treatments as follows: the first used as control diet while the other three diets were formulated to replace LSB for SBM at levels of 25, 50 and 75% (which is equal to 5, 10 and 15% LSB). The results showed that LSB contained 26.6% CP and 12.4% CF on DM basis. LSB was superior in gross energy content than SBM. Lentil screening by-product contains higher concentrations of phytochemicals such as saponnin (26.3 mg/100gDM), phytic acid (610 mg/100g DM), phenolic content (21.01 mg GAE/g DM) and tannins (840 mg catechin equivalent/100 g DM). The rabbits group fed 5% LSB achieved significantly (P<0.05) higher digestibility of CP and value of DCP compared to the control group. Moreover, the same group was higher (P<0.05) in TDN and DE values than the rabbits group fed 15% LSB. They also recorded the highest (P<0.05) final live weight. Daily gain significantly (P<0.05) increased in the groups fed 5, 10 and 15%LSB. The group fed the diet contained 15% LSB achieved the highest (P<0.05) hot carcass weight (g), dressing% and total edible parts%. The group fed 5%LSB recorded the highest (P<0.05) level of globulin. The total cholesterol content, ALT and AST levels tended to be lower (P<0.05) for both groups fed 10 and 15% LSB. Since the use of up to 15% of LSB didn't have a detrimental effect on productive performance, carcass characteristics and plasma constituents as well as economic efficiency in growing rabbit diets; therefore, lentil screening by-product can be recommended as replacement up to 75% of SBM in growing rabbits diets.