Assessing the influence of feeding olive leaves on the productivity and economic viability of growing Awassi lambs

The goal was to assess the influence of feeding olive leaves (OL) as a roughage source on nutrient intake, nutrient digestibility, N balance, growth performance and carcass characteristics of growing Awassi lambs. Twenty-four male lambs (initial body weight (BW) = 16.82 ± 0.998 kg; age = 70 ± 1.25 days) were randomly assigned to two isonitrogenous diets; OL at 0 (CON) or 150 (OL150) g/kg of dietary dry matter (DM). Diets were fed ad libitum for a period of 60 days after 7 days of adaptation. Feed intake and refusals were recorded daily. Body weights were recorded at the beginning of the study and at biweekly intervals thereafter. Intake of DM and crude protein was similar (P ≥ 0.05) between the two diets. Feeding OL decreased (P ≤ 0.01) intake of neutral detergent fiber and acid detergent fiber whereas it increased (P = 0.001) intake of ether extract compared with the CON diet. No differences (P ≥ 0.05) were observed in the final BW, average daily gain, and total gain between diets. However, the cost of gain was lower (P = 0.05) in lambs fed the OL diet versus the CON diet. None of the carcass characteristics nor meat quality parameters differed between the two diets. In summary, feeding olive leaves at 150 g/kg did not influence growth performance and carcass characteristics and meat quality but improved the economic value of using such products in diets of growing lambs. In addition, the use of this product has a positive impact on reducing environmental pollution.