Effect of Heat Stress, Dietary Electrolytes, and Vitamins E and C on Growth Performance and Blood Biochemistry of the Broiler Chicken

Abstract

Environmental heat stress creates a detriment to the welfare and performance in broiler chickens. While there are some dietary mineral and vitamin supplements that mitigate this condition, a rapid, plasma-based detection method would improve management response and broaden the scientific understanding of heat stress. A total of 960 broilers were used to determine the effect of heat stress and dietary electrolyte balance on blood biochemistry. Sex sorted chicks were allocated to 48 pens with 20 chicks per pen creating 6 treatments (3 diets x 2 house environments) with eight replicates and fed one of three dietary treatments: a control containing primarily sodium chloride (NaCl), a heat stress formulation containing bicarbonate (NaHCO3), or heat stress fortified with 200 ppm vitamin C and E (NaHCO3 Fortified). Birds were housed in two different temperature-controlled environments either a thermoneutral (Control) or heat stressed (Heat Stress) environment. At day 28, 35 and 42 venous blood was collected and analyzed using rapid detection methods followed by post-mortem veterinary evaluations. Performance was measured at weekly intervals. Mortality was significantly higher in broilers exposed to heat stress as compared to thermoneutral, while broilers that received dietary sodium chloride also had higher mortality than bicarbonate fed birds. Heat stress significantly impacted potassium, hematocrit, uric acid, total protein, globulin, hematocrit, lymphocytes, sodium, and glucose. This study demonstrates that blood biochemistry of broiler chickens is influenced by dietary intervention and changing environmental conditions. This pattern suggests a blood biomarker footprint of sub-optimal nutrition or poor environmental conditions that may provide valuable information into physiological changes in response to dietary electrolytes, vitamins, and heat stress. Furthermore, this footprint may potentiate the development of diagnostic tools, combining biomarkers to determine nutrition and health status of individual broiler flocks, for nutritionists, veterinarians, and live production managers to manage flocks for environmental, humane, and productive purposes.

Changes in Japanese quail (Coturnix coturnix japonica) blood gases and electrolytes in response to multigenerational heat stress

“…The results of the current study disagree with the results of others because iCa was significantly lower in chronic random-bred heat stressed females [39]. Typically, an increase in iCa in the blood could be due to bone growth demands at the time of sampling or mobilization of iCa to activate calcium-dependent ionic channels involved in maintaining homeostasis during periods of increased temperature [39,40]. However, decreased iCa at 31.1˚C may mean that vascular dilation develops later and at a higher temperature which allows for conservation of iCa until a threshold for activation of certain homeostatic mechanisms is reached.…”

“…This difference was not driven by pH differences because the pH of chronic TN females and chronic HS females were not significantly different from each other. Another study using 35˚C determined that iCa increased as broilers chicks aged, and this increase was higher in heat stressed birds than those housed at thermoneutral temperatures (21 to 22˚C) [39]. The results of the current study disagree with the results of others because iCa was significantly lower in chronic random-bred heat stressed females [39].…”

“…Others have found that male broiler chicks subjected to heat stress at 35˚C for 8 hours per day increased blood K + levels [38]. However, researchers have also found decreases in K + levels, uric acid, total protein, and globulin levels in heat stressed broilers at 35˚C for 6 hours per day [39]. In this study, K + levels did not seem affected by treatment, indicating that the heat stress may not have been severe enough to metabolize protein or glycogen stores.…”

“…Another study using 35˚C determined that iCa increased as broilers chicks aged, and this increase was higher in heat stressed birds than those housed at thermoneutral temperatures (21 to 22˚C) [39]. The results of the current study disagree with the results of others because iCa was significantly lower in chronic random-bred heat stressed females [39]. Typically, an increase in iCa in the blood could be due to bone growth demands at the time of sampling or mobilization of iCa to activate calcium-dependent ionic channels involved in maintaining homeostasis during periods of increased temperature [39,40].…”

Effect of dietary supplementation of some antioxidant combinations on nutrient digestibility in heat-stressed broilers

“…There is evidence that heat stress increases the need for vitamins and minerals for broilers (Calik, 2022;Livingston et al, 2022). Research has supported the use of Cr supplements as a nutritional strategy to improve growth performance (Ghazi et al, 2012), nutrient metabolism (Jahanian and Rasouli, 2015), antioxidant status, and stress response (Khan et al, 2016) in chickens exposed to heat stress.…”