An investigation of the effect of folic acid and its delivery routes on broiler chickens' hatch and growth performance, blood biochemistry, anti-oxidant status, and intestinal morphology.

This study investigated the effect of folic acid (FA) and its delivery routes (in-feed or in ovo) on broiler chicken's hatch and growth performance, blood biochemistry, anti-oxidant status, and intestinal morphology. A total of 1,860 Cobb 500 hatching eggs were incubated for 21 d. On day 12 of incubation, viable eggs were randomly allotted to four groups: the noninjected group, in ovo saline (injected with 0.1 mL/egg of saline solution), in ovo FA 1 (injected with 0.1 ml FA containing 0.1 mg/egg; FA1), and in ovo FA 2 (injected with 0.1 ml FA containing 0.15 mg/egg). All in ovo treatments were delivered via the amnion. At hatch, chicks were re-allotted to five new treatment groups: FA1, FA2, in-feed FA (FA 3; 5mg/kg in feed), in-feed bacitracin methylene disalicylate (BMD; 55 mg/kg in feed), and negative control (NC; corn-wheat-soybean diet) in 6 replicate pens (22 birds/pen) and raised in starter (days 0 to14), grower (days 15 to 24), and finisher (days 25 to 35) phases. Hatch parameters were assessed on day 0, and body weight and feed intake (FI) were determined weekly. On day 25, 1 bird/cage was euthanized, immune organs weighed, and intestinal tissues harvested. Blood samples were collected for biochemistry and anti-oxidant (Superoxide dismutase-SOD and Malondialdehyde-MDA) analysis. Data were analyzed in a randomized complete block design. While FA1 and FA2 decreased (P < 0.001) hatchability in a dose-dependent manner, FA2 caused a 2% increase (P < 0.05) in average chick weight compared to the noninjected group. Compared to the BMD treatment, FA3 decreased (P < 0.05) average FI across all feeding phases. At the end of the trial on day 35, FA2 had similar feed conversion ratio as the BMD treatment while recording less (P < 0.001) FI. FA1 and FA2 recorded a tendency (P < 0.1) to increase MDA levels and SOD activity by 50% and 19%, respectively, compared to the NC treatment. Compared to NC treatment, FA2 increased (P < 0.01) villus height, width, and villus height to crypt depth ratio in the duodenum, and villus width in the jejunum. Besides its negative effect on hatchability, FA2 may help improve embryonic development and anti-oxidant status in broiler chickens.