Impacts of Dietary Supplementations of Orange Peel and Tomato Pomace Extracts as Natural Sources for Ascorbic Acid on Growth Performance, Carcass Characteristics, Plasma Biochemicals and Antioxidant Status of Growing Rabbits

SIMPLE SUMMARY: There has been growing interest in using natural feed additives in to enhance animal performance and meat quality for human consumption. Citrus fruit residues can act as potential natural resources of antioxidants, which comprise a considerable quantity of ascorbic acid. Tomato pomace powder has a good nutritional value because of its content of essential amino acids and fatty acids besides its high content of antioxidants. This work examined the impact of dietary orange peel and tomato pomace extract supplementations at level of 200 mg/kg on growth performance, plasma biochemicals, carcass characteristics and antioxidant status of growing male rabbits. Dietary supplementations of orange peel and tomato pomace extracts could effectively improve growth performance, antioxidative status, modulate ascorbic acid level in plasma and meat and lower the plasma total cholesterol. ABSTRACT: The effect of dietary orange peel (OPE) and tomato pomace extract (TPE) supplementations on growth performance, plasma biochemicals, carcass characteristics and antioxidant status of growing male rabbits were investigated. A total of 96 rabbits (5 weeks old) were distributed into four groups. The first group received untreated pelleted diet (control). The second group was fed a diet containing ascorbic acid (AA; 1.0 g/kg diet), while the third and fourth groups consumed diets supplemented with 200 gm of OPE or (TPE, respectively. Our results indicated that OPE and TPE contained 59, 14.03 mg ascorbic acid/100 g DM, respectively. Growth performance, except feed conversion ratio, and carcass weight were improved by dietary supplementations. Dietary supplementations decreased kidneys, abdominal, back fats and ether extract of meat. Plasma protein and globulin levels were high in rabbits fed AA and TPE-supplemented diets. Low plasma total cholesterol and LDL-cholesterol concentrations were observed in rabbits fed the supplemented diets. Plasma AA was increased in rabbits fed AA and OPE-supplemented diets. Rabbits fed OPE and TPE-supplemented diets had great SOD activity. The best economic efficiency was recorded by rabbits fed the supplemented diets. Dietary supplementations of OPE and TPE could effectively improve growth performance, antioxidative status, modulate AA level in plasma and meat and lower plasma total cholesterol and LDL.