NUTRITIONAL EFFECT OF LINSEED OIL ON PRODUCTIVE PERFORMANCE, CARCASS CHARACTERISTICS AND BLOOD PICTURE OF GROWING RABBITS

A number of eighty growing NZW rabbits at 5 weeks age and 620 ± 30 g average live body weight were weighed and distributed into five experimental groups. The experiment aimed at studying the effect of linseed oil at the rate of 1,2, 3 and 4% on their productive performance, carcass characteristics, some blood parameters, T3 and T4 as well as histological changes in the liver and testis of the tested animals. Adding linseed oil to rabbit diets at the level of 2% improved significantly (P≤0.05) LBW compared to the control one as well as the other 3 levels of oil. The DWG showed no significant differences among the five experimental groups, except for the treatment of 2% linseed oil which significantly differed (P≤0.05) compared to the control group and the other 3 treatments of linseed oil. The highest significant BWG value (P≤0.05) was obtained with adding 2% linseed oil to the diet, while the lowest value obtained with the 4% oil treatment, but without significant difference with other 2 oil levels or the control one. The increase in BWG came in a descending order with increasing oil % in the diet. The amount of daily feed intake remarkably (P≤0.05) decreased than the control one with age when diets contained 2 and 3% linseed oil. The pest (P≤0.05) FCR (3.58) was obtained in the group of 2% linseed oil, while the worst (4.36) was recorded with adding 4% linseed oil to the diets. Live body weight at slaughtering time as well as carcass weight insignificantly differed among the five tested groups. Adding linseed oil to the diets of tested rabbits improved carcass weight generally over that of the control one. The group fed 2% linseed oil diet gave the highest carcass weight. Regarding weights of carcass organs, i.e. head, heart, abdominal fat and back quarters, except back quarters yield, showed no significant differences among the 5 different treatments. Weights of liver, kidney and testis and their yield as well as dressing percentage and back quarters yield noticeably increased (P≤0.05) in the group of 2% linseed oil diet compared to the control one and other 3 linseed oil treatment groups. Diet supplemented with linseed oil generally increased blood TP, Alb. , HDL, LDL, T3 and T4 values compared to the control group, while it decreased glob. and cholesterol as well as TG in the two high levels of oil supplementation only. The experimental dietary treatments showed beneficial effect of omega-3-PUFA on liver and testis structures of rabbits fed diet supplemented with linseed oil at the rate of 2 and 3% since it did not show any abnormality in the histological structure of both organs. Conclusively, on the light of the aforementioned results, it could be concluded that addition of linseed oil to growing rabbit diets at the rate of 2 followed by 3% resulted in lowering daily feed intake accompanied by improved feed conversion ratio and increase in body weight gain without adverse effects on hematological aspects. Moreover, the same treatments induced the most noticeable changes in carcass characteristics as well as structural changes in the histology of both liver and testis of males.