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Abstract This study was carried out at Sakha Research Center, at Kafrelsheikh, Agricultural Research Center, Ministry of Agriculture, Egypt, during the period from June to August ٢٠١٢. The study was aimed to investigate the effect of different omega-٣ fatty acids sources (fish oil, linseed oil and commercial omega-٣) on body weight, growth rate, meat quality, meat lipid profile, serum lipid peroxidation, antioxidative status and immune response in and New Zealand White and Baladi Black rabbits. Eighty weaning rabbits, (٤٠ Baladi Black rabbits and ٤٠ New Zealand White rabbits) were maintained from weaning to marketing age (٥ to ١٣ weeks of age). Rabbits were randomly divided into five treatments (١٦ animals per treatment of both sexes). Average body weight of rabbits at the beginning of experiment was ٦٨٥±١٠ grams. Animals were healthy and clinically free of external and internal parasites. Experimental diets were formulated to have nearly similar digestible energy (DE) and crude protein (١٧٪ crude protein, ٢٥٥٠ kcal DE per kg diet). The experimental design consisted of five dietary treatments as fallows:- The ١st group was fed the basal diet (control) while the ٢nd,٣rd, ٤thand the ٥th groups were fed the basal diet supplemented with ٢٪ fish oil (FO), ٢٪ linseed oil (LO), ١٪ fish oil plus ١٪ linseed oil and ١٪ Commercial Omega-٣ (CO), respectively. All diets were supplemented with ٢٠٠mg vitamin E/kg as α-tocopherol acetate to protect dietary fatty acid from oxidation. The rabbits were weighted at the start of the experiment and then they were weighted weekly in each treatment. Live body weight, body weight gain, feed intake, feed conversion ratio and mortality rate were recorded. At ١٠ weeks of age, four representative rabbits from each treatment were intravenously injected with ٠٫٢ ml of ١٠٪ suspension of packed Sheep Red Blood Cells (SRBC) to determine humoral immune response (antibody titer production against Sheep Red Blood Cells) and at ١١, ١٢, ١٣ weeks of age blood samples were collected from marginal ear vein of rabbits to determine humoral immune response. At the end of the experimental period (١٣ weeks of age), eight rabbits (٤ males and ٤ females) from each treatment were randomly chosen and fasted approximately for ١٢ hours and weighed before slaughter (pre-slaughtered weight) to study carcass traits. Blood samples were collected after slaughtering to determine some blood constituents, while meat samples were taken from slaughter rabbits for analysis of meat lipid profile, total cholesterol and meat chemical and physical characteristics. The obtained results could be summarized as follows: A. Productive performance traits: ١- Dietary supplementation with different Omega-٣ sources showed insignificant changes in live body weight (LBW) of rabbits al all growing periods. ٢- The heaviest LBW was obtained for rabbits fed fish oil plus linseed oil supplemented diet followed by those fed commercial omega-٣ diet. ٣- Rabbit’s breed has a significant (P≤٠٫٠١) effect on LBW, where Baladi Black rabbits (BB) was heavier than New Zealand White (NZW) ones at ٩ and ١٣ weeks of age (WOA). ٤- No significant effect of dietary treatments on BWG, however, rabbits fed commercial omega-٣ and FO+LO diets gained more weight than then treatments. ٥- The BB rabbits gained significantly (P≤٠٫٠١) more weight than NZW rabbits at the period from ٥-٩ WOA, only. ٦- There were significant decreases in feed consumption for rabbits fed FO+LO – supplemented diets during the periods from ٥ to ٩ and ٥ to ١٣ WOA. ٧- No significant effect of both breed and sex of rabbits on feed intake during all periods. ٨- There were significant decreases in FCR for rabbits that fed commercial omega-٣ and those fed FO+LO diets than the control and other treatments. Moreover, the effect of breed, sex and interaction effect was not significant. ٩- Mortality rate significantly influenced by dietary treatments with the lowest rate value recorded for the commercial omega-٣ and FO treatment followed by those fed LO – supplemented diets. ١٠- There were insignificant effects of different dietary treatments on carcass dressing weight and percentage; hot carcass weight, liver and kidneys weight. ١١- Abdominal fat weight and percentage were significantly decreased in rabbits that fed fish oil-supplemented diet compared with the other treatments along with the control one. ١٢- Data depicted that breeds differ significantly in liver weight and total giblets weight, regardless the effect of omega-٣ sources. However, both hot carcass weight; abdominal fat weight and percent and dressing weight were not significantly affected by rabbit’s breed. ١٣- There were insignificant effects of sex on different carcass traits, except the abdominal fat weight and percentage. In this respect, females had significantly higher values than males. B. Chemical and physical characteristics of meat: ١- There were significant differences in moisture content between different dietary sources of omega-٣, while no significant effect of dietary treatments on protein, Ash, fat, cholesterol, LDL and HDL contents of rabbits meat. ٢- Dietary effect on the physical characteristics of meat was not significant but there were slight variation between treatments in the pH value, tenderness and water holding capacity of meat. ٣- Fish oil, linseed oil and their mixture caused a significant decrease in MDA level of stored meat after ٩٠ days, however, using the commercial omega-٣ product gave the best results in this respect.٤- The effect of rabbit breed and sex on the chemical and physical properties, MDA and vitamin E levels of meat was not significant. C. The fatty acids profile of rabbits meat: ١- Dietary supplementation with FO; LO either singly or in combination, resulted in the PUFAs concentration was significantly higher in the meat of treated groups compared with the control one. ٢- Diets supplemented with LO or FO+LO led to a higher proportion of α-linolenic acid in rabbit meat as compared with fish oil, commercial omega-٣ and the control diet. ٣- The FO and commercial omega-٣ diets resulted in significantly higher proportion of DHA n-٣ and EPA n-٣ fatty acids of rabbits meat. ٤- Baladi Black (BB) rabbits has significantly higher α-linolenic (n-٣) fatty acid and saturated fatty acids (SFAs) than New Zealand White rabbits (NZW). ٥- There were some slight increases in α-linolenic acid, EPA, DHA, PUSFAs and total USFAs in meat samples from females compared with males. D. Blood plasma constituents: ١- Plasma total protein, albumin, globulin, total lipids, cholesterol, HDL and transaminases activity (ALT and AST) were not significantly affected by dietary oil supplements. ٢- Rabbit’s effect of breed and sex had insignificant effect on all plasma parameters investigated. ٣- The effect of sex insignificant effect on all plasma parameters. E. Immunological responses: ١- Dietary sources of omega-٣ PUFAs had a positive effect on humoral immunity response of rabbits as measured by (antibody titer production against Sheep Red Blood Cells) compared with control. ٢- Dietary fish oil supplementation significantly improved the humoral immunity of rabbits at day ٧ post immunization with SRBC.٣- After ١٤ and ٢١ day post immunization, the highest values for antibodies titer (Ab) were recorded for rabbits fed on commercial omega- ٣ fatty acid followed by those fed LO; FO+LO and then the FO supplemented group, while the lowest Ab titer was recorded for the control group.. ٤- There was insignificant effect of breed and sex on immune responses against SRBC at ٧ and ٢١ days post immunization, while at day ١٤ Baladi Black rabbits recorded higher Ab titer than New Zealand White rabbits. |