EFFECT OF SILYMARIN ON PERFORMANCES AND MEAT QUALITY OF BROILER CHICKEN

Silymarin is a poliphenolic compound extract from Silybum marianum and Cynara cardunculus. Its components, the flavonolignans silybin, silydianin and silycristin, improve liver glucuronidation of xenobiotics and reduce hepatic glutatione consumption. Moreover, silymarin shows antioxidant effects, reducing free radical-mediated damage in tissues and plays an important role in hepatic protein synthesis by DNA-dependent RNA polymerase I activation. Toxic substances in feedstuff and the rapid growth rate of recent broiler breeds led to a relevant hepatic metabolic stress, which can reduce feed conversion efficiency and meat quality. The aim of this study is to evaluate the effects of different doses of silymarin in diet on broiler performances and meat quality. For the trial, 180 chicks (type ROSS 508), were allocated in 3 groups (1 to 3) of 60 animals. Each groups was divided into two replicates of 30 chicks (A and B). All the animals were fed ad libitum with commercial feedstuffs of first (from d 1 to d 21) and second (from d 22 to d 60) period. Animals of group 1 (A and B), control, were fed base feedstuff, while animals of groups 2 and 3, experimental, received the same feedstuff added with 40 and 80 ppm of silymarin respectively. During the trial, health status was evaluated daily, while live weight and feed intake were measured every 20 days. At d 60, 20 animals from each group were sacrificed, and pectoralis major (PM) and gastrocnemio (G) muscolar tissue were sampled on 10 animals for Malonil Di-Aldeid (MDA) and chemical analysis, while on the remaining animals, dressing percentages were evaluated. From table 1, silymarin at the doses of 40 ppm (group 2) and 80 ppm (group 3) did not modified significantly growth performances and dressing percentages, but reduced feed intake, with a sparing of feedstuff of 3,68% and 2,63% respectively. Silymarin at the doses of 40 ppm significantly reduced (P<0,05) MDA values at T30 (30 minutes after slaughtering) in both muscles tested, while at the doses of 80 ppm only MDA of pectoralis major was affected (P<0,05) at T0 and T30. Any significative difference was recovered with regard to meat composition. Silymarin at the doses tested improved feed conversion rate, without affecting growth performances and meat composition. Treatments increased muscles resistance to oxidative stress reducing slaughtering waste. The use of silymarin seems to be more advantageous at the dose of 40 ppm.