The effects of feeding olive cake and Saccharomyces cerevisiae supplementation on performance, nutrient digestibility and blood metabolites of Awassi lambs

Throughout a 63 day-period, thirty fat-tailed Awassi ram lambs were used to determine the influence of feeding olive cake (OC) and Saccharomyces cerevisiae (SC) supplementation on performance and blood metabolites. Intact male lambs with an average initial body weight (BW) of 25.0 kg ± 1.91 were randomly assigned to 3 dietary treatments; lambs fed the conventional diet (CON; n = 10; group 1) or OC containing diets (n = 20). Within the OC diet, 10 of the lambs received a diet containing 150 g/kg dietary dry matter (DM) OC (OC; group 2) and the other 10 received OC diet plus 0.5 g/head/day SC (OCSC; group 3). Lambs were offered ad libitum access to the assigned diets until the end of the study. On day 0, 21, 42, and 63, lamb BW was measured before the morning feeding to evaluate average daily gain (ADG) and feed:gain ratio (feed efficiency). Additionally, on the same days, ten milliliters of blood were collected before feeding from the jugular vein and analyzed for blood metabolite concentrations and liver enzymes. With the exception of ether extract (EE) intake, which was greater (P < 0.01) in OC containing diets than CON diet, no differences (P ≥ 0.11) were observed in DM, crude protein (CP), neutral detergent fiber (aNDF) and acid detergent fiber (ADF) intakes among dietary treatments. Digestibility of DM, CP, aNDF and ADF decreased (P ≤ 0.04) in OC and OCSC diets vs the CON diet. However, digestibility of EE increased (P < 0.01) in OC containing diets over the CON diet. No significant differences were noticed in total gain, ADG and feed efficiency among dietary treatments. No differences were observed in serum content of urea N, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase among treatments. However, serum content of glucose tended to be greater (P = 0.07) in the OC and OCSC groups than in the CON group. In all measured variables, SC supplementation did not show any differences over the OC diet alone. In summary, results of the current study indicate that feeding olive cake for growing Awassi lambs could replace the conventional feeds at 150 g/kg of dietary DM; whereas Saccharomyces cerevisiae supplementation did not show any significant benefits.