The effect of adding ruminally protected fat in fattening diets on nutrient intake, digestibility and growth performance of Awassi lambs

Twenty-one Awassi lambs (initial body weight 20.4±0.4 kg) were used in a completely randomized design to evaluate the effects of adding ruminally protected fat (Ultralac™ 100) to fattening Awassi lambs diets on nutrient intake, digestibility and growth performance. Lambs were fed ad libitum three isonitrogenous high concentrate fattening diets that contained: (1) no added fat (CON); (2) 2.5% added fat (LF); and (3) 5% added fat (HF). Dry matter (DM) intake was higher (P<0.05) for the CON diet than the HF diet and intermediate for the LF diet. Ether extract intake was higher (P<0.05) for the HF (66.7 g per day) diet than for the LF (58.7 g per day) and the CON (20.7 g per day) diets. Metabolizable energy intake was not affected by the dietary treatments (average=10.7 MJ per lamb per day). Dry matter digestibility was higher (P<0.05) for the HF and LF diets (average=76.1%) than for fed the CON (65%) diet. Digestibility results for CP, NDF and energy followed similar patterns to that observed for the DM, although ether extract digestibility was higher (P<0.05) for the HF diet versus the CON and LF diets. There was no difference in weight gain for lambs fed the three experimental diets. There are no advantages to using protected fat in high concentrate fattening diets for Awassi lambs, since the reduced dry matter intake negated the increased dietary energy density.