Abstract

Objective: This study aimed to investigate and evaluate the effects of in-ovo injection of vitamin C, L-glutamine and a combination of Vitamin C and L-glutamine on hatchability traits, growth performance, intestinal development, visceral organ weight, thyroid hormones profiles (T3 , T4) and serum malondialdehyde (MDA) levels of broiler chickens after hatching.

Method: Initially, 800 fertile eggs were obtained from Arbor Acres breeder hens older than 50 weeks of age. On the 18th day of incubation, 600 of these fertile eggs were placed in trays for injection at the site of the sterilizing device, weighing, and uniform distribution. In-ovo injection was performed in five experimental groups. The negative control group received no injection, while the positive control group received 0.5 ml of normal physiological serum. The third group was injected with 6 mg of vitamin C in saline, the fourth group with 6 mg of L-glutamine in saline, and the fifth group with a combination of 6 mg of vitamin C and 6 mg of L-glutamine in saline, each in a volume of 0.5 ml. After hatching, the necessary measurements were made in terms of chick weight, number of healthy chicks hatched, and hatching percentage. Then, all chicks were fed a standard pelleted basal diet during the initial, growth, and final stages.

Results The lowest hatchability rate was observed in the in-ovo Vitamin C injection group (P<0.05). Conversely, the control and in-ovo L-glutamine injection groups exhibited the highest hatchability rates (P<0.05). In-ovo Vitamin C injection resulted in the highest mean hatchling weight, whereas the in-ovo L-glutamine group showed the lowest mean hatchling weight (P<0.05). The combined in-ovo injection of Vitamin C and L-glutamine had no positive effect on hatchability or initial chick weight. Regarding performance, in-ovo injection of Vitamin C, L-glutamine, and their combination did not significantly affect feed intake, body weight gain, or feed conversion ratio (FCR); however, L-glutamine injection improved weight gain and FCR from 1 to 10 days of age (P<0.05). Vitamin C injection significantly decreased carcass, breast, and thigh weights and increased mortality (P<0.05). L-glutamine injection and the combination of Vitamin C and L-glutamine resulted in a relative decrease in thigh weight and a decrease in breast and thigh weights, respectively (P<0.05). The effect of Vitamin C injection on T3 levels at 14 days of age, as well as the effect of experimental groups on malondialdehyde (MDA) levels at 42 days of age, were significant (P<0.05). In-ovo injection of Vitamin C and the combination of Vitamin C and L-glutamine had a negative impact on villus height and the villus height-to-crypt depth ratio in the ileum (P<0.05). However, no significant differences were observed in the morphology of the duodenum and jejunum among the groups compared to the control.

Conclusion: In conclusion, despite the enhancement in initial hatchling weight, in-ovo Vitamin C supplementation proved detrimental, as it significantly reduced hatchability, compromised carcass yield, elevated mortality rates, and adversely affected ileal health. Conversely, in-ovo L-glutamine injection effectively preserved hatchability and optimized early-phase feed conversion, ultimately outperforming the other experimental groups in terms of overall performance.