Effect of dietary supplementation of camel hump fat on performance, carcass characteristics, antibody responses and blood metabolites in fattening lambs

The present study aimed to investigate the effects of dietary supplementation of camel hump fat (CHF) in substitution with a conventional ruminally protected fat source (palm fatty acids powder) on performance, carcass traits, blood biochemical parameters and immunological responses in fattening lambs. Twenty five Afshari male lambs were randomly assigned to the five diets in a completely randomized design. Diets were a control group (no fat supplementation) and groups received the supplemental fat levels of 2.5 or 5% of diet from either calcium salt of fatty acids (CSFA) or CHF. All diets were formulated to be isoenergetic and isonitrogenous. Three representative lambs from each group were slaughtered on d 90 of trial to measure carcass traits. Average daily gain was greater (P<0.05) for lambs fed CHF and 2.5% CSFA diets than the control and 5% CSFA diets. The highest feed intake was occurred orderly in groups received 2.5% CSFA, 2.5% and 5% CHF, and the least feed intakes were seen in control and 5% CSFA lambs. Feed conversion ratio was lower in lambs fed CHF- or 2.5% CSFA-diets. Among the carcass characteristics, only hot and cold carcass efficiencies were influenced (P<0.05) by supplemental fat sources. Absolute (P=0.09) and relative (P=0.06) pancreas weights tended to be affected by dietary fat supplementation so that, pancreas weight in control lambs was significantly lower than those in other treatments. Dietary supplementation by CHF and CSFA had no significant effect on blood glucose and triglycerides; however, plasma high-density lipoproteins and cholesterol concentrations were affected (P<0.05) by dietary treatments and supplemental CHF and CSFA increased plasma levels of both variables. Utilization of CHF at the levels of 2.5 and 5% increased (P<0.01) IgG titers against ovalbumin over the time (P<0.05). Serum γ-globulin content was increased (P<0.05) as the result of supplemental fat sources with the highest values assigned to the lambs fed on CHF-diets. The present findings suggest that camel hump fat can be used as a proper alternative for ruminally protected fat sources in fattening lambs with beneficial impacts on performance and immunological responses.