Effects of the In Ovo Injection of L-Ascorbic Acid on Broiler Hatching Performance †

SIMPLE SUMMARY: Previous studies have shown positive effects of the use of supplementary L-ascorbic acid (L-AA) to mitigate various stressors such as heat and ammonia exposure in the broiler industry. The aim of the current study was to determine the effects of L-AA administrated by in ovo injection on various hatch variables and the embryonic serum L-AA concentrations of Ross 708 broilers. At 18 days of incubation (doi), the following four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA were administrated. An automated multi-egg injector accurately delivered 100 μL solution volumes into the amnion. The in ovo injection of high levels of L-AA (12 and 25 mg) did not affect hatchability, but 12 mg of L-AA in saline and saline alone resulted in a reduction in embryonic mortality. Additionally, serum L-AA did not differ between the in ovo injected treatments at any time period; however, the serum L-AA concentration was numerically higher in males as compared to female hatchlings. In conclusion, the automated in ovo injection of high levels of L-AA may not be detrimental to hatchling quality but may promote embryonic livability. ABSTRACT: Effects of the in ovo injection of various concentrations of L-ascorbic acid (L-AA) on the hatchability and retention levels of L-AA in the serum of broiler embryos were investigated. A total of 960 Ross 708 broilers hatching eggs were randomly divided into four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA. At 18 days of incubation (doi), injected eggs received a 100 μL volume of sterile saline (0.85%) alone or containing one of the two L-AA levels. Percentage egg weight loss was also determined from 0 to 12 and 12 to 18 doi. Hatch residue analysis was conducted after candling to determine the staging of embryo mortality. At approximately 21 doi, hatchability of live embryonated eggs (HI) and hatchling body weight (BW) were determined. Blood samples were taken at 6 and 24 h after L-AA in ovo injection to determine serum L-AA concentrations. Serum L-AA concentrations, HI, and hatchling BW did not differ among all treatment groups. However, chicks in the non-injected group had a higher (p = 0.05) embryonic mortality at hatch in comparison to those in the 12 mg of L-AA in saline and saline alone treatment groups. These results suggest that the in ovo injection of high levels of L-AA (12 and 25 mg) does not negatively affect HI or serum concentrations of L-AA but has the potential to promote embryonic livability. Further research is needed to determine the retention time of L-AA in the other tissues of broilers, including the cornea of the eye, in response to different levels of supplemental L-AA.