Dietary essential oil feed additive (Biolex™) modulated growth performance, short chain fatty acids and intestinal histomorphology with no effect on immune organ or gastrointestinal tract of broiler chickens

A 42-day study was carried out to evaluate the growth performance, immune organ weight, digestive organ weight, ceca short chain fatty acids (SCFA) profile, and ileum histomorphology responses of broiler chickens fed a blended essential oil, prebiotic, and acidifier product (Biolex™). A total of 540 broiler chicks (Cobb 500) were allocated into three treatments, each with 12 replicates and 15 birds/replicate pen in a randomized complete block design. The three corn-soybean meal dietary treatments were supplemented with 0.0 (Control), 0.5 or 1.0 g/kg of Biolex™ for 42 days. Body weight and feed were recorded on day 0, 14, 28 and 42 of the experiment. On day 42, three birds per pen with body weight closest to the pen average weight were selected and euthanized. Spleen, bursa of Fabricius, gizzard, pancreas, duodenum, jejunum, and ileum were weighed and also expressed relative to body weight of individual bird. The mid-section of ileum was collected for histomorphology measurements. The ceca content from two birds per pen were used to determine the SCFA content. Body weight gain from day 14 to 42 was greater (P < 0.05) in birds fed the 1.0 g per kg premix compared with the control. Total body weight gain and day 42 body weight increased linearly (P < 0.05) with Biolex™ supplementation. There were no treatment effects on absolute or relative digestive or immune organ weights on day 42. The propionate content in the ceca tended to be greater (P = 0.072) in birds fed 0.5 g/kg Biolex™ compared to other treatments. Surface area (µm2 ) of villi in the ileum at day 42 increased linearly (P < 0.05) with Biolex™ supplementation. There were no differences among treatments for other morphological parameters measured in ileum. In conclusion, the data indicate improvements in overall performance of birds receiving diets supplemented with Biolex™. Part of this improvement in growth performance could have resulted from the observed increase in villi surface area which likely enabled enhanced nutrient utilization in the broiler chickens.

Key Words: Broilers, essential oil, short-chain fatty acid, prebiotic, growth performance