الفهرس 
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Abstract
The present study was carried out to study the effect of oral administration of grape seed extract at levels of 0, 75 and 125 mg/kg LBW on growth performance, hematological and blood biochemical parameters and digestibility coefficients of growing APRI rabbits. This experimental was carried out in a private rabbit farm, in cooperation with Department of Animal Production, Faculty of Agriculture, Mansoura University, Egypt, during the period from November to May 2016.A total of 15 rabbit males from APRI line (50% Red Baladi buck x 50 V-line does) aging 8 weeks of age and having ranging between 614 and 626 g live body weight (LBW). The experimental rabbits were divided randomly into 3 groups (5 rabbits in each). Rabbits in the first group were fed basal complete feed diet without treatment and considered as a control group (G1). Rabbits in the second group (G2) and the third group (G3) were fed the same diet and given oral dose of 75 and 125 mg/kg LBW of grape seed extract for the first three weeks an experimental period of 8 weeks up to 16 weeks of age. Rabbit males were fed ad-libitum on a commercial pelleted ration. Live body weight of rabbits and feed intake were weekly recorded, then body weight gain and feed conversion live body weight of rabbits were calculated throughout the experimental period from 8 to 16 wk of age during the last week of the experimental period, three digestibility trails were undertaken on three animals from each group. Values of total digestible nutrients (TDN) were calculated. Blood samples were collected from three rabbits in each group pre-treatment and at the end of experimental. Hematological and blood biochemical concentration were determined. Concentration of total proteins, albumin, glucose, urea, total cholesterol, LDL, HDL and creatinine, and activity of AST and ALT were determined in blood serum. Concentration of globulin was calculated by subtracting. Total antioxidant capacity (TAOC) was determined in blood serum. In whole blood samples, hematological parameters including count of red (RBCs) and white (WBCs) blood cells, and platelets, hemoglobin (Hb) concentration, package cell volume (PCV%), mean corpuscular volume (MCV, fl), mean corpuscular hemoglobin (MCH, pg), mean corpuscular hemoglobin concentration (MCHC, g/dl) as well as leukocyte fraction including percentage of lymphocytes, monocytes, eosinophils and neutrophils were determined. At 16 weeks of age, 3 rabbits from each group were slaughtered and organs weights of liver, heart, and body fat was recorded. Organs weight as a percentage of live body weight was calculated for liver, kidney, spleen, and body fat. The obtained results could be summarized as the following: Results showed significant effect of grape seed extract treatment on LBW of growing rabbits during experimental period from 14 up to 16 weeks of age, being significantly (P<0.05) higher in G3 as compared to rabbits treated with grape seed extract level 75 (G2) and control group (G1). Average daily gain (ADG) of APRI rabbits was significantly (P<0.05) higher in rabbits of G3 treated with 125 mg/kg LBW of grape seed extract as compeered to other groups (G2 and G1) at age intervals 12-16 and 8-16 weeks. While, ADG was not significantly affected by grape seed extract treatment at age interval of 8-12 weeks. Average weekly feed intake (AWFI) of rabbits was significantly (P<0.05) the highest in G3 at 12-13 and 13-14 wk, and in G2 at 14-5 and 15-16 wk, while it was significantly (P<0.05) the lowest in G1 at all age intervals. However, no significant differences were found between G2 and G3 at 13-14, 14-15 and 15-16 wk. Average daily feed intake of APRI rabbits was significantly (P<0.05) higher in rabbits of G3 treated with 125 mg/kg LBW of grape seed extract as compared to control group (G1) at age intervals of 12-16 and 8-16 weeks, but no significant differences were recorded between G2 and G3. Also, no significant effect of treatment with grape seed extract was found on average daily feed intake at age interval of 8-12 weeks. Feed conversion ratio ( FCR) showed a tendency of improvement for treatment groups of rabbits treated with 75 and 125g/kg LBW as compared to control group (G1) at all age intervals, but the significant differences (P<0.05) were observed only at 12-16 wk of age. Feed conversion ratio of rabbits insignificantly improved in G1 as compared to G3, which showed significantly (P<0.05) the poorest FCR as compared to control group. Overall mean of WBC count was significantly (P<0.05) higher in G2 and G3 than in G1. Although, RBC counts was significantly (P<0.05) lower in G2 than in G1 and G3, platelets count was significantly (P<0.05) higher in G1 and G2 than in G3. Concentration of Hb was significantly (P<0.001) lower in G2 and G3 than in control group (G1), while PCV value were not affected significantly by grape seed extract treatment, being similar in all groups. In an opposite trend to the effect of treatment, overall mean of Hb concentration was not affected significantly by sampling time, while overall mean of PCV value significantly (P<0.05) decreased at end as compared to start of the experimental period. There were similar values of MCV, MCH and MCHC in blood of rabbits in all groups. Also, all previous parameters showed insignificant trend of change at both sampling times. Values of MCV, MCH and MCHC insignificantly changed during the experimental period in all groups (Table 16). Percentages of overall mean of monocytes, eosinophils and neutrophils significantly (P<0.05) increased in treatment groups (G2 and G3) as compared to control group (G1). However, percentage of lymphocytes showed significantly (P<0.05) an opposite trend (Table 18). There were insignificant differences in serum total proteins and their fractions, reflecting no effect of grape seed extract treatment on protein metabolism of rabbits Concentration of total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL) were significantly higher (P<0.05) in control group (G1) than in both treatments (G2 and G3). On the other hand, the differences in concentration of glucose and high density lipoprotein (HDL) were not significant. Results also showed that only concentration of triglycerides significantly (P<0.05) decreased at the end as compared to the start of the experiment. Total antioxidants concentration was significantly (P<0.05) higher in G2 and G3 than in G1, while AST activity was significantly (P<0.05) higher in G1 than in G2 and G3. There was tendency of decrease in creatinine and urea concentration in blood serum of rabbits in treatment groups (G2 and G3), but the differences were not significant. Also, both creatinine and urea concentrations showed insignificant decrease at the end than start of treatment. The interaction between grape seed extract treatment and sampling time on creatinine and urea concentrations was also insignificant. All carcass traits were not affected significantly by grape seed extract treatment. Results revealed that oral administration of grape seed extract at both levels significantly (P<0.05) increased digestibility coefficients of DM and CF, while GSE at a level of 75 mg/kg LBW significantly (P<0.05) increased digestibility coefficients of CP. However, digestibility coefficients of OM, EE and NFE were not affected by GSE treatment as compared to control group. Concerning the nutritive values, also rabbits in G2 showed significantly (P<0.05) the highest nutritive values in terms of TDN and DE, while the differences in DCP among the experimental groups were not significant. These results reflected in significantly (P<0.05) the highest values of NB% in G2 as compared to G1 and G3. Generally, treatment of growing rabbits with GSE at a level of 125 mg/kg LBW showed the best economical results in term of increasing relative economic feed efficiency of rabbits to 104% of control rabbits. CONCLUSION: The current findings suggested that grape seed extract at levels of 75 and 125 mg/kg LBW as oral administration for 21 days has significant value in improving the antioxidant status, decreased lipid profile and could serve as a supportive treatment in the nutritional management to improve growth performance of growing rabbits.