Effects of yellow grease or soybean oil on performance, nutrient digestibility and carcass characteristics of finishing Awassi lambs

Twenty-three male Awassi lambs (initial body weight; BW = 18.5 ± 1.72 kg) were individually housed to study effects of using yellow grease (restaurant fat) on lamb performance, nutrient digestibilities and carcass characteristics, and to compare such effects with soybean oil (SO). Lambs were randomly assigned to one of three dietary treatments: no added fat (control; CTL, n = 7), 32 g/kg of yellow grease (YG, n = 8), or 32 g/kg of SO (SO, n = 8) in barley grain-based diets. All diets were formulated to be isonitrogenous, iso-energetic, and to meet all nutrient requirements for finishing lambs. Dietary treatments did not affect intake and digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, or N retention. However, intake and digestibility of ether extract were higher (P<0.05) by YG or SO diets. Lambs fed the YG or SO diets grew faster (P<0.01) and were heavier (P<0.01) than their control counter parts at the completion of the study. Additionally, lambs fed the YG or SO diets had heavier (P<0.05) carcass weights than those offered the control diet. There were no substantial effects on carcass measurements or leg and loin composition, except for tissue depth and rib fat thickness which was higher for lambs offered the YG or SO diets. No histopathological changes occurred in liver, heart and kidneys due to treatments. Under the conditions of the study, dietary restaurant fat improved lamb performance with no detrimental effects on nutrient digestibilities or meat quality, and results were comparable to using soybean oil.