Intake and digestibility in sheep fed diets that include waste frying oil

Waste frying oil may serve as a viable alternative to fresh vegetable oils, potentially reducing environmental impacts and animal feed costs. This study aimed to assess the effects of incorporating waste frying oil into sheep diets and to determine the optimal dietary oil concentration. We evaluated intake and apparent digestibility using 25 uncastrated Santa Inês male sheep (average, 90 d of age; 20 ± 3.56 kg) in a randomized block design over a 21-d experimental period. The sheep were housed in individual metabolic cages and fed diets with a 50:50 roughage-to-concentrate ratio twice daily. Diets included waste frying oil at concentrations of 0, 2, 4, 6, and 8% of the total dry matter. Animals receiving higher concentrations of waste frying oil exhibited lower nutrient intake (p < 0.05) compared to those with up to 4% inclusion. Nutrient digestibility decreased linearly (p < 0.05) with increasing oil content, except for ether extract digestibility (p = 0.02), which improved. Although the addition of oil increased the concentration of total digestible nutrients, the intake of total digestible nutrients was not maintained or enhanced at 6% and 8% oil (p = 0.82). Including up to 4% waste frying oil in sheep diets is feasible without compromising nutrient intake and digestibility.