Effects of the In Ovo Administration of L-ascorbic Acid on the Performance and Incidence of Corneal Erosion in Ross 708 Broilers Subjected to Elevated Levels of Atmospheric Ammonia †

SIMPLE SUMMARY: Ammonia (NH(3)) is recognized as the most abundant toxic gas in poultry houses, and broilers subjected to elevated NH(3) levels have exhibited negative effects on their growth, immunity, and respiratory systems. The objective of this research was to investigate the in ovo feeding of L-ascorbic acid (L-AA) on the post-hatch performance and corneal erosion incidence in Ross 708 broilers exposed to 50 ppm of atmospheric NH(3). The 4 in ovo treatments that were applied at 17 days of incubation were: non-injected (control), saline-injected (control), or saline containing 12 or 25 mg of L-AA. It was found that the in ovo injection of 12 mg of L-AA improved live performance and lowered corneal erosion incidence relative to those injected with saline. In conclusion, the in ovo administration of 12 mg of L-AA may overcome the negative effects of high atmospheric NH(3) concentrations on broiler live performance and corneal erosion incidence. Further research is needed to determine the physiological and immunological mechanisms that may be involved in the aforementioned improvements in broilers subjected to chronic exposures to elevated levels of atmospheric NH(3). ABSTRACT: Effects of the in ovo injection of various levels of L-ascorbic acid (L-AA) on the performance and corneal erosion incidence in Ross 708 broilers exposed to 50 parts per million (ppm) of atmospheric ammonia (NH(3)) after hatch were determined. A total of 1440 Ross 708 broiler embryos were randomly assigned to 4 treatments: non-injected (control), 0.85% sterile saline-injected (control), or saline containing 12 or 25 mg of L-AA. At hatch, 12 male chicks were randomly assigned to each of 48 battery cages with 12 replicate cages randomly assigned to each treatment group. All birds were exposed to 50 ppm of NH(3) for 35 d and the concentration of NH(3) in the battery cage house was recorded every 20 s. Mortality was determined daily, and mean body weight (BW), BW gain (BWG), average daily BW gain (ADG), and feed intake, as well as feed conversion ratio (FCR), were determined weekly. From 0 to 35 d of post-hatch age (doa), six birds from each cage were selected and sampled for eye erosion scoring. Incidences of corneal erosion were significantly higher at 21 and 28 doa in comparison to those at 14 and 35 doa, and at 21 doa, birds in the saline-injected group exhibited a higher incidence of corneal erosion compared to all other treatment groups. The in ovo injection of 12 mg of L-AA increased BWG (p = 0.043) and ADG (p = 0.041), and decreased FCR (p = 0.043) from 0 to 28 doa in comparison to saline-injected controls. In conclusion the in ovo administration of 12 mg of L-AA may have the potential to improve the live performance of broilers chronically exposed to high aerial NH(3) concentrations, but further study is needed to determine the physiological and immunological factors that may contribute to this improvement.