The present study aimed to evaluate the impact of different levels of dietary replacement of barely by prickly pear fruits (PPF) and peel (PPP) on growth performance, carcass traits and antioxidant status of rabbits. A total of 75 weaned male New Zealand White (NZW) rabbits (5 weeks old) with an average initial body weight of (596.00±13.05 g) were randomly assigned to five experimental groups (15 rabbits for each). Five experimental diets were formulated; the first was used as a control diet (0% PPF and PPP). The other four diets were formulated to replace barley with either PPF or PPP at the levels of 25 and 50%.
Results indicated that PPF and PPP are rich sources in vitamins C (2.4, 2.8μg/100g), vitamins E (25, 23μg/100g) and vitamin A (10, 13μg/100g). The content of gross energy (GE) in PPF was higher than that of PPP and barley. The obtained results revealed also that average of BW, BWG, FI and FCR were not affected (P<0.05) by feeding growing rabbits on diet containing either PPF or PPP under each tested level (25 and 50%) compared to rabbits group fed the control diet during (9-13) and (5-13) weeks old.
Feeding growing rabbits on diets contained 50% PPF or 50% PPP resulted in noticeable improvement in both average BWG and FCR in comparison to the other experimental groups including the control group during the whole period (5-13 weeks old). Digestibility of OM, CP, EE and CF were not affected significantly by the inclusion of PPF (25 and 50%) or PPP (25 and 50%)compared to the control group. Besides, there were insignificant differences in TDN and DE among the control group and the other tested groups contained PPF or PPP under each tested level (25 or 50%). Rabbits fed a diet containing 25 and 50% PPP had the lowest (P<0.05) NH3-N concentrations while, rabbits fed 25% PPP supplemented diets had the highest (P<0.05) TVFA value. Rabbits fed diets containing 50% PPF or 50% PPP had heavier (P<0.05) liver, heart and edible giblets compared the control group while, rabbits fed diet containing 50% PPP showed the lowest (P<0.05) abdominal fat and the higher (P<0.05) values of serum antioxidant marker and enzymes (TAC, GSH-Px, SOD and CAT). Plasma triglycerides, cholesterol and LDL concentrations were decreased (P<0.05) while HDL concentration increased (P<0.05) in PPF and PPP supplemented groups compared to the control group. The inclusion of PPF or PPP in rabbit diets at a level of 25 or 50% improved economical efficiency and net revenue compared to the control group.
Conclusively, according to the circumstances of this experiment, PPF or PPP could be incorporated in growing rabbit diets up to 50% as a partial replacement of barley, without any significant impairment of the growth performance and to achieve a better antioxidant status of rabbits and higher economic efficiency of diets.