Animal fat and vitamin E in rabbit diets: Total tract apparent digestibility, growth performance, carcass and meat quality traits
The present study tested the effect of a dietary inclusion with vitamin E and pork lard on the apparent digestibility of the nutrients, the growth performance, the carcass traits, the physical meat quality, and the α-tocopherol content. A total of 60 hybrid rabbits were reared in individual cages from weaning (35 days of age) until slaughter (78 days of age). A control diet with no supplements, one diet supplemented with 2% pork lard, and two diets that used the aforementioned diets supplemented with an additional 200 mg/kg α-tocopheryl acetate were designed. The diets were isoprotein and isoenergy. The fat inclusion increased the crude protein (P < 0.05) and ether extract (P < 0.001) total tract apparent digestibility, and the same was observed for the vitamin E inclusion (P < 0.001 for both variables). This improved the dietary digestible protein content (P < 0.05), which increased the digestible protein to digestible energy ratio (P < 0.001). The fat × vitamin E interaction was observed for the total tract apparent digestibility of the ether extract (P < 0.001), the neutral detergent fibre (P < 0.05) and the acid detergent fibre (P < 0.01). The growth traits were unaffected, with the exception of the feed conversion ratio that improved with the vitamin E addition (P < 0.05). Similarly, the carcass traits remained unaffected, with the exception of the perirenal and total fat incidence that increased with the fat supplement (P < 0.05), and the scapular fat that was reduced with the vitamin E inclusion (P < 0.05). The meat L* (lightness), a* (redness), b* (yellowness) colour values and ultimate pH were unaffected by the experimental treatments, even though a fat × vitamin E interaction was observed for the a* and chroma values of the Longissimus thoracis et lumborum muscle (P < 0.05). Both the fat (P < 0.05) and vitamin E (P < 0.001) dietary inclusion increased the meat α-tocopherol content. Based on the results, it was concluded that the 2% dietary inclusion of animal fat did not provide more benefits for the considered parameters than the sole α-tocopheryl acetate incorporation, but contributed to the increase in the vitamin E content in the meats.
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