An experiment was conducted to examine the effect of replacing a concentrate supplement with untreated or calcium hydroxide (3% w/w) treated Acacia toritlis leaves in Rhodes grass (Chloris gayana) hay basal diets on feed intake, digestibility, nutrient retention and rumen fermentation parameters of 54 yearling male goats of Arsi-Bale breed (body wt of 13.78 ± 1.9 kg and 12 months old). The experiment was conducted for 84 days in a 2 × 5 factorial design (factor 1: alkali treatment of leaves (treated or untreated) and factor 2: five levels of leaves in concentrate mixture). The treatment diets were: UL-0: hay + 300 g concentrate mixture; UL-25: hay + 225 g concentrate and 75 g untreated dried leaves, UL-50: hay + 150 g concentrate and 150 g untreated dried leaves; UL-75: hay + 75 g concentrate and 225 g untreated dried leaves; UL-100: hay + 300 g untreated dried leaves; TL-0: hay + 300 g concentrate; TL-25: hay + 225 g concentrate and 75 g treated dried leaves; TL-50: hay + 150 g concentrate and 150 g dried treated leaves; TL-75: hay + 75 g concentrate and 225 g treated dried leave and TL-100: hay + 300 g treated dried leaves. Both Ca(OH)2 treatment and partial replacement of the concentrate mixture by Acacia leaf meal (ALM) significantly (P<0.05) reduced ether extract (EE), total phenolics (TP), total tannins (TT) and CT contents of the diets. Whereas, dietary concentrations of ash, acid detergent fibre (ADF), acid detergent lignin (ADL) and calcium (Ca); intakes of dry matter (DM), crude protein (CP), neutral detergent fibre (NDF), nitrogen, Ca and P; digestibility of DM, organic matter (OM), CP and NDF; concentration of rumen ammonia nitrogen and pH of the rumen fluid were significantly (P<0.05) increased by the alkali treatment and partial replacements. In general comparable results of intake, digestibility and balances of nutrients were observed when concentrate ration in the diets was replaced by treated ALM at 75% and untreated 50% in order of importance against untreated leaf meals. It is concluded that partial replacement of acacia leaf meals in the concentrate mixture combined with calcium hydroxide treatment at 75% level gave maximum benefits to goats than other levels of untreated or treated leaves. پرونده مقاله