Olive leaves as alternative feed for finishing lambs: evaluation of feed intake, nutrients digestibility, growth performance, and carcase quality

Abstract

This research aims to evaluate how incorporating sun-dried olive leaves (OL) in the diets of Awassi lambs affects production costs, intake and nutrients digestibility, growth performance, and carcase quality. Thirty-six newly weaned male lambs were randomly allocated to one of three diet groups as dry matter (DM) in diets: 1) the control diet (CON), 2) 50 OL g/kg (OL50), and 3) 100 OL g/kg (OL100). On the 50th day, four lambs were randomly selected from each treatment and transported to metabolic cages to evaluate digestibility and N balance. The DM intake was higher (p = .003) in the OL50 and OL100 diets than those on the CON diet. At the same time, the ether extract and metabolisable energy intakes were the highest (p < .0001) in OL100, followed by OL50 and the CON diet. Intake of neutral detergent fibre and acid detergent fibre for lambs fed the OL50 diet surpassed (p < .0001) the other diets. The growth performance parameters were comparable among diets. However, the cost of gain was lower (p = .03) in diets containing OL. The OL incorporation had no treatment effect (p > .05) on the digestibility, N retention, carcase characteristics and meat quality. In conclusion, while the addition of OL at 50 g/kg and 100 g/kg did not affect the growth performance and characteristics of carcase, it did decrease the cost of production, making it a good candidate to replace part of the wheat straw in diets of growing lambs. Highlights Olive leaves percentage substitution of wheat straw improved the nutrients intake in Awassi lambs fed commercial diets. Olive leaves incorporation decreased both the cost of the diet and the cost per kg of gain in Awassi lambs. Olive leaves inclusion did not have a negative effect on digestibility and N Balance, carcase characteristics and meat quality.