Effect of Using Vitamin C Supplementation on Performance, Blood Parameters, Carcass Characteristics and Meat Quality of Broiler Chickens Under Heat Stress Condition: A Meta-Analysis.

This meta-analysis was performed to evaluate the effects of vitamin C (Vit C) supplementation on broiler performance, blood parameters, carcass characteristics and meat quality under heat stress. Based on searches conducted on PubMed, Scopus, Google Scholar and Web of Science, 35 studies published in authoritative journals from 1985 to 2023 were meta-analysed. Heterogeneity was explored by meta-regression analysis. The results of this meta-analysis showed that the body weight (BW, SMD = +0.339, p = 0.003) and average daily gain (ADG, SMD = +0.381, p = 0.001) were significantly higher in the group receiving Vit C supplementation under heat stress compared to the control group. However, Vit C supplementation did not have a significant effect on feed intake (FI, SMD = +0.084, p = 0.245), but the results were significant for the feed conversion ratio (FCR, SMD = -0.529, p = 0.001). Breast, thigh, abdominal fat, carcass drop loss, liver, gizzard, heart and spleen were not affected by Vit C supplementation, but it has a significant effect on wing weight (SMD = -3.77, p = 0.001). The use of Vit C supplementation decreased triglyceride (SMD = -0.527, p = 0.001), cholesterol (SMD = -0.976, p = 0.001) and blood glucose (SMD = -0.734, p = 0.02) concentrations in the broiler under heat stress. Breast meat quality (L*, a* and b*) was not affected by Vit C supplementation. In the current study, most of the responses had high heterogeneity (I > 50%). The findings of this meta-analysis demonstrated that, in broiler chickens under heat stress, adding Vit C supplementation to the feed can enhance performance. However, Vit C did not have a significant effect on carcass characteristics and the quality of the breast meat of broiler chickens. According to our meta-analysis results, utilisation of 250 mg/kg of Vit C is recommended as an effective growth promoter in broiler under heat stress, and as an antioxidant compound, it had a positive effect on reducing blood TG and TC.