During the recent decades, rain reduction and consequently water shortage in Iran had an impact effect on crop cultivation program. Therefore, considering these factors, it is necessary to plan for crop production, which needs less water. Grass pea (Lathyrus sativus), is a high-quality forage in animal feeding and has unique biological traits like drought tolerance. Hence, this experiment was conducted to study the effect of alfalfa substitution with grass pea hay on performance and carcass quality of Kurdish growing lambs. Twenty-four Kurdish male lambs with an average body weight of 30.23 kg and seven months age were used in this experiment. Experimental diets included: (1) diet without grass pea hay (control), (2) diet containing 10% grass pea hay, (3) diet containing 20% grass pea hay, and (4) diet containing 30% grass pea hay. The results showed that neutral detergent fiber, crude protein, and ash contents of grass pea hay were 32.67%, 19.66%, and 11.70% of dry matter, respectively. Experimental diets had no significant effect on dry matter intake and feed efficiency, carcass parameters, carcass cuts, and meat chemical compositions of the lambs (P ≥ 0.05). Orthogonal comparisons showed that lambs fed diets containing grass pea hay had the higher average daily gain (P < 0.05). It was concluded that diet inclusion of grass pea hay up to 30% of dry matter, had no adverse effect on lambs healthy status.
