Effects of dietary supplemental zinc and/ or selenium enriched spirulina (Zn-Sp, Se-Sp and Zn-Se-Sp, respectively) as antioxidants on growth performance, nutrient digestibility, plasma biochemicals and antioxidant status of growing rabbits under summer conditions were evaluated. A total of 160 New Zealand White male rabbits at six-weeks-old were randomly assigned to four groups. The first group received untreated diet (control). The other groups received diet supplemented with 100 mg Zn-Sp/kg diet, 0.5 mg Se-Sp/kg diet or 100 mg Zn-Sp+ 0.5 mg Se-Sp, respectively. The findings showed that the supplemented diets enhanced growth performance of rabbits at marketing. Rabbits fed Zn-Sp exhibited high dry and organic matter digestibilities while those fed Zn-Sp and Zn-Se-Sp diet supplemented achieved high crude protein digestibility. Rabbits fed diet supplemented with Zn-Se-Sp gave the highest hot carcass weight when competed with their counterparts. Zn-Sp and Zn-Se-Sp supplemented diets tended to promote dressing percentage. Low concentrations of plasma total cholesterol, LDL-cholesterol and VLDL-cholesterol were recorded by Se-Sp and Zn-Se-Sp groups. Rabbits fed Se-Sp, Zn-Se-Sp had the greatest HDL, plasma TAC and catalase and the lowest TBARs. Conclusively, dietary supplementation of 100 mg Zn-Sp, 0.5 mg Se-Sp or their combination could improve growth performance, nutrients digestibility and antioxidant status of heat stressed growing rabbits.

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.

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.

The present experiment was carried out to evaluate the effects of Zinc-enriched Spirulina (Zn-Sp) supplementation as an organic Zn source on the growth performance, nutrients digestibility, carcass characteristics, blood parameters and economic efficiency of growing rabbits. A total of forty eight male NZW rabbits (35 days old) were allotted to four groups (12 rabbits for each), 4 replicates (3 rabbits for each). Three levels of Zn-Sp (50, 75 and 100 mg Zn-Sp/kg diet) were compared to a control group without Zn-Sp addition.The results have shown that dietary Zn-Sp supplementation caused an increase (P<0.05) in final live body weight at 13 weeks. Supplementation of 75 and 100 mg Zn-Sp improved (P<0.05) body weight gain compared to the control group during the whole experiment period. The increases in body weight gain were 10.93 and 10.63% for 75 and 100 mg Zn-Sp, respectively compared to the control group. On the other hand, at all experimental periods, rabbits fed diets supplemented with 75 and 100 mg Zn-Sp consumed less (P<0.05) feed intake than those fed control diet or 50 mg Zn-Sp. As well as, diets supplemented with Zn at 50, 75 and 100 mg Zn-Sp improved (P<0.05) FCR throughout the experimental period (8weeks). Dietary Zn-Sp supplementation at 100 mg led to a significant increase in all nutrients digestibility In addition; Zn-Sp supplementation had insignificant effect on the CF digestibility. Feeding rabbits on diets supplemented with Zn-Sp at a level of 100 mg/kg DM increased (P<0.05) DCP%, TDN and DE (kcal/kg) compared to the control group. The obtained results also showed that supplementing rabbit diets with Zn-Sp at each tested level increased (P<0.05) hot carcass weight, dressing percentage, total edible parts (%), serum total protein and HDL, serum Zn concentrations, total antioxidant capacity (T-AOC) levels in comparison to the control group. Conversely, a significant decrease (P<0.05) was observed in serum total cholesterol and LDL concentrations compared with the rabbits fed the control diet. The economical efficiency of diets supplanted with 50, 75 and 100 mg Zn-Sp increased by 14.94, 33.0 and 33.48% over the control group. In conclusion, the present results indicated that supplementation of Zn-Sp could be used as an organic source of Zinc for rabbits. It has more bioavailability and caused an improvement in growth performance and digestibility without any adverse effects on the health status of rabbits.

The study was conducted to evaluate the effects of using pomegranate (Punica granatum L.) by-product powder (PBP) as a natural growth promoter in rabbit diets on growth performance. A total of 36 male New Zeeland White (NZW) rabbits was randomly assigned to four groups containing 9 rabbits each in 3 replicates and raised from 5 to 13 weeks of age and nearly equal average initial live body weight (561.67 ± 6.68 g). The experimental groups, the first group was fed basal diet control without PBP as control, while the second, third and fourth groups were supplemented with 1.0, 1.5 and 2.0% of PBP, respectively. The obtained results demonstrated that rabbits fed diet supplemented with1.5% of PBP had the heaviest (P<0.05) final body weight and average daily weight gain followed by those received 2.0, 1.0% and control groups. Rabbit groups fed diets supplemented with 1.0, 1.5 or 2.0% PBP recorded significantly (P<0.05) higher digestibility of DM, OM, CP, and CF compared to the control group. Besides, the digestibility of DM, OM, CP, CF and NFE were higher (P<0.05) with rabbits group fed diet supplemented with 2.0% PBP than the other tested groups. Moreover, data of nutritive values illustrated that rabbit group fed 1.5% or 2.00%PBP recorded the highest (P<0.05) values of DCP, TDN and DE compared to the other tested groups. Supplementation of PBP had no effect on meat CP content. While, there were significantly (P<0.05) decrease in EE meat content of rabbits group fed diet supplemented with 1.0 and 2.0% of PBP than the control group. The supplementation of PBP increased (P<0.05) plasma total protein, albumin and globulin levels compared to those of rabbits fed the control diet. The blood plasma content of glucose, total lipids, total cholesterol and LDL was observed to move down constant with increasing dietary levels of PBP (1.0, 1.5 and 2.0 %), respectively. Also, the values of T-AOC, SOD, CAT and GSH-Px were significantly (p < 0.05) increased with increasing PBP levels in rabbit diets. Additionally, rabbits fed 1.5% PBP diet recorded the best net revenue. Conclusively, the results suggest that the pomegranate (PBP) by-product powder could be supplied in rabbit diets at 1.5% to achieve best performance and economical efficiency without any adverse effect on rabbit's heath.