Effect of Dietary Supplementation of Lauric Acid on Immunity and Gut Morphometry in Commercial Broilers

An experiment was conducted to evaluate the effect of dietary lauric acid (LA) supplementation as an alternative to antibiotic growth promoter (AGP) at graded levels on immunity, gut pH and morphometry in broilers. Three hundred, day-old commercial broiler chicks were randomly allotted to six dietary treatments with 10 replicates of five chicks in each replicate, raised in battery brooders under uniform management for 42 days. The basal diet (BD) consisted of standard corn-soybean meal without an antibiotic growth promoter (negative control). The positive control diet was the BD having 0.035% chlortetracycline as AGP. The remaining four experimental diets were formulated by supplementing lauric acid to BD at a rate of 0.05% (LA-50), 0.075% (LA-75), 0.1 % (LA-100) and 0.2 % (LA-200), respectively. Blood was collected from one bird per replicate on 35^th d to assess the humoral immune response against the ND vaccine. On the 35^th day, one bird from each replicate was sacrificed for recording of gut pH and histomorphological studies of the gut. On the 40^th day, an inter-digital skin test to phytohaemagglutinin phosphate was done on one randomly selected bird per replicate to assess the cell-mediated immune response (CMI). Lauric acid supplementation (0.05-0.2%) increased antibody (log₂) titers against the ND vaccine more than those on AGP and BD fed birds, and the CMI response improved with LA supplementation, with the highest (P<0.05) response in LA-75 fed birds. Villi height and crypt depth in the duodenum were highest (P<0.05) in LA-50, followed by LA-75, LA-100 and lowest in BD, AGP and LA-200 groups. Ileal pH was not affected, the pH of the duodenum and jejunum gradually lowered with an increase in the level of LA in diets and a significant reduction (P<0.01) was observed at 0.1% and 0.2% of LA supplementation. Based on the results, it could be concluded that lauric acid can be a replacer of antibiotic growth promoter and its supplementation in diets at 0.05% improved immunity and gut health, while higher dietary levels (0.1-0.2%) had no further beneficial effects on these attributes.