Dietary supplementation of selenium-enriched olive leaves in fattening rabbits: 1. Productive performance, carcass and meat characteristics

Nowadays, great attention is given to use of by-product in the animal feeding to reduce the cost and the environmental impact of the diets. A good strategy could be the recycling of agricultural by-products, which normally, required an expenditure of resources for disposing. In the present study two different type of olive leaves, enriched or not with selenium (Se) were used, because it could exert an antioxidant defense both in the herbaceous plants, increasing the resistance to water stress, both in animals, improving the health status. Then, the main objective of this study was to evaluated the effect of olive leaves, treated or not with Se, on productive performance of growing rabbits. Thirty weaned New Zealand White rabbits (30 days of age) were allocated in bicellular wire net cages and assigned to three homogeneous groups (970 ± 80 g b.w.; 10 animals/group): control (C) fed standard diet, olive leaves group (OL) fed standard diet þ10% dried olive leaves and selenium group (SE) fed standard diet þ10% dried olive leaves enriched with 2.17 mg/kg of sodium selenate. The feed was provided ad libitum. The productive performance (daily weight gain, daily feed intake) were registered. At 75 days of age the rabbits were slaughtered and the carcass (carcass weights and sizes, edible organs weight, fat content and distribution) and longissimus lumborum meat characteristics (physical: pH, colour, WHC, cooking loss; chemical: moisture, crude proteins, ether extract, ash) were evaluated on refrigerated samples (24 h at 4 C).Data were analyzed with a linear model considering the fixed effect of dietary treatment. Results of this trial showed that the diets did not affect the productive performance of rabbits and the physio-chemical characteristics of meat. However, the rabbits fed olive leaves showed carcass with lower lumbar circumference and intrascapular fat amount. This study confirms the possibility of using olive leaves, enriched or not with selenium, in rabbits feeding and make possible to continue the study (see the companion paper presented at this Congress) evaluating the effect of selenium-enriched olive leaves supplementation on in vivo and meat oxidative status of rabbit.