EFFECT OF DIETARY SELENIUM SOURCES AND LEVELS ON PERFORMANCE OF BROILER CHICKENS

The present study was conducted out to study the effect of dietary supplementation of sources and levels of selenium on growth performance, carcass characteristics, some blood biochemical parameters, antioxidant activity and immunoglobulin levels and economic efficiency of broiler chicks. A total number of 210 unsexed Arbor-Acres chicks, were randomly distributed and divided equally in to seven dietary treatment group; each group was represented by chicks in three replicates of 10 chicks each and kept under similar management conditions basal starter and finisher diets were supplemented with feed additives (two types of selenium) as; T₁: Basal diet (the negative control, with inorganic selenium), T₂: basal diet with 0.1g selenium yeast/ Kg diet,T₃: basal diet with 0.2g selenium yeast/ Kg diet, T₄: basal diet with 0.3g selenium yeast/ Kg diet,T₅: basal diet with 0.1g nano-selenium / Kg diet, T₆: basal diet with 0.2g nano-selenium / Kg diet and T₇: basal diet with 0.3g nano-selenium / Kg diet. Two corn- soybean basal diets were formulated to be fed during starter (1 to 21d, 22.98%cp and 3100 kcal ME/kg diet) and finisher (22 to 35 d, 20%cp and 3100 k cal/kg diet periods. All diets were formulated to meet the nutrient requirements of the chicks according to arbor- acer catalog recommendations through the experimental period; feed and water were provided ad- libitum. Chicks fed diet supplemented with nano -selenium of 0.03g/ Kg diet (T₇) had significantly the highest values of body weight and body weight gain during experimental periods. Feed conversion ratio had significantly improved, while recorded the lowest feed intake by addition of dietary nano-selenium at level of 0.3g/kg diet compared to other treatments. There are highly significant beneficial effects of dietary selenium yeast and nano-selenium on dressing, giblets and some immune organs weights and percentages at 5 weeks of age compared to the negative control group. The best values of dressing percentage and some giblets had significantly increased by 0.03g nano-selenium/ Kg diet, T₇ comparison with the negative control (79.25 and 6.18%) than (74.11 and 5.22%) at 5 weeks of age, respectively. Regarding se concentration in various tissues, the groups receiving se- yeast and nano-selenium showed higher plasma and meat of breast and thigh se contents than the negative control group. Nano-selenium supplementation significantly increase HDL, while HDL-cholesterol concentration were significantly decreased. Activity of GPX- sh in serum blood was significantly improved by supplementation of 0.03 g nano-selenium /kg diet than negative control group. In general, chicks fed 0.03 g nano- selenium had improved growth performance, some carcass and blood parameters. Also GPx activity and selenium concentration in meat and blood during experimental periods.