Evaluation of Heat Stress Indicators and Biomarkers in Broiler Chickens Supplemented with Varying Amounts of Sodium Bicarbonate in the Semi-Arid Region of Sokoto, Nigeria

Abstract

This study evaluated the efficacy of graded levels of dietary sodium bicarbonate (NaHCO₃) in reducing heat stress in broiler chickens reared in the semi-arid climate. A total of 180-day-old Ross 308 broiler chicks were randomly allotted to four dietary treatments: T1 (0 g NaHCO₃/100 kg feed), T2 (50 g/100 kg), T3 (100 g/100 kg), and T4 (150 g/100 kg), in a completely randomized design. The study lasted 49 days, during which environmental data, respiratory rate, rectal temperature, and blood serum samples for oxidative stress markers were collected. The results confirmed a significantly thermal challenge environment, with THI values frequently within the moderate to severe categories. Analysis of physiological responses showed that sodium bicarbonate supplementation had no significant (P>0.05) effect on respiratory rate or rectal temperature, indicating that the environmental thermal load was the dominant factor driving these primary stress indicators. However, the analysis of oxidative stress biomarkers revealed highly significant (P<0.05) improvements in the values. The T3 and T4 groups showed significantly (P<0.05) increased superoxide dismutase activity, and the T4 group showed a significant boost in Glutathione Peroxidase (GSH-Px) activity compared to the control group. Total Antioxidant Capacity (TAC) was also significantly enhanced in the supplemented groups. It was concluded that while dietary sodium bicarbonate supplementation did not alter the respiratory rate and rectal temperature, it significantly affected the birds' endogenous antioxidant defence system at the cellular level. The highest inclusion level of 150 g/100 kg feed was the most effective. Therefore, it is recommended that broiler diets in semi-arid regions be supplemented with sodium bicarbonate at 150g per 100kg of feed to enhance resilience to heat stress by mitigating oxidative damage