Effect of dietary energy density on growth performance and slaughtering characteristics of fattening Awassi lambs

Abstract

The objective of this study was to evaluate the effect of dietary energy density on nutrient intake, growth performance and slaughtering characteristics of fattening Awassi lambs. Eighteen Lambs (16.7±1.5 kg) housed in individual pens were divided into two groups and offered two finishing diets (nine lambs per diet) that contained 15–85 (HC) and 60–40 (HF) forage to concentrate ratio for 62 days. Experimental diets were isonitrogenous (16% CP) and contained 2.92 and 2.40 Mcal kg −1 for the HC and HF diets, respectively. Feed was offered ad libitum as totally mixed diets. At the end of the experiment, lambs were sacrificed to obtain slaughtering data. Dry matter, OM, and CP intakes were not affected ( P>0.05) by the dietary treatment and averaged 934, 895, and 153 g day −1, respectively. Metabolizable energy intake was higher ( P<0.05) for lambs fed the HC diet (2.8 Mcal day −1) compared with lambs fed the HF diet (2.2 Mcal day −1). Dry matter, OM, and apparent CP digestibilities were higher ( P<0.05) for the HC diet as compared with HF diet. Final body weights for lambs fed HC diet (33.4 kg) was greater ( P<0.05) than lambs fed the HF diet (27.9 kg). Average daily gain (ADG) for lambs fed the HC diet was higher ( P<0.05) as compared to lambs fed the HF diet (258 versus 178 g day −1 for HC and HF diets, respectively). Feed to gain ratio was improved ( P<0.05) with the HC diet (3.8) as compared with the HF diet (5.4). Lambs fed the HC diet had higher ( P<0.05) dressing percentage (48.5%) compared with the HF diet (43.5%). Lambs fed the HC diet had a greater ( P<0.05) carcass weights (15.7 kg) compared with lambs fed the HF diet (12.3 kg). Lambs fed the HC diet had a lower ( P<0.05) GI tract weight (6.0 kg) compared with lambs fed the HF diet (6.8 kg). These results demonstrate that finishing Awassi lambs on high-energy diets improves ME intake, feed efficiency, ADG, nutrient digestibility, slaughtering characteristics, and carcass weight.