Effect of heat stress, dietary electrolytes, and vitamins E and C on blood biochemistry of the modern broiler chicken

Authors: LIVINGSTON, MATTHEW - Dsm Nutritional Products, Ltd; Pokoo-Aikins, Anthony; FROST, THOMAS - Dsm Nutritional Products, Ltd; LAPRADE, LISA - Dsm Nutritional Products, Ltd; HOANG, VY - Inside Tracker (SEGTERRA); NOGAL, BARTEK - Inside Tracker (SEGTERRA); PHILLIPS, CHELSEA - Dsm Nutritional Products, Ltd; COWIESON, AARON - Dsm Nutritional Products, Ltd

Submitted to: Frontiers in Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2022
Publication Date: 2/18/2022
Citation: Livingston, M.L., Pokoo-Aikins, A., Frost, T., Laprade, L., Hoang, V., Nogal, B., Phillips, C., Cowieson, A.A. 2022. Effect of heat stress, dietary electrolytes, and vitamins E and C on blood biochemistry of the modern broiler chicken. Frontiers in Animal Science. 3. Article 807267. https://doi.org/10.3389/fanim.2022.807267.
DOI: https://doi.org/10.3389/fanim.2022.807267

Interpretive Summary: Heat stress is a condition in poultry birds where they have difficulty achieving a balance between body heat production and body heat loss. Heat stress has been a great concern in the broiler industry for many years due to its negative impact on production performance and the health status of poultry such as reduced feed consumption, decreased body weight, poor feed efficiency, increased morbidity, poor meat quality, as well as economic losses. This study investigated varying blood physiology of chicks fed diets differing in electrolyte balance while exposed to normal temperature or heat stressed conditions. Birds were fed one of three dietary treatments: a control diet containing primarily sodium chloride (NaCl), a diet containing bicarbonate (NaHCO3), or a diet fortified with 200 ppm vitamin C and E (and containing NaHCO3) and housed in two different temperature-controlled environments (control or heat stressed environment). Performance was measured weekly and blood samples from 2 broilers per pen were analyzed at day 28, 35 and 42 using the i-STAT® Handheld Clinical Analyzer, Abaxis Vetscan VS2, iCheck™ FLUORO devices to measure blood chemistry of the blood samples. Mortality was significantly higher in broilers exposed to heat stress compared to the control. Broilers that received dietary sodium chloride had higher mortality than birds fed bicarbonate. Age created a highly significant linear impact on blood calcium, phosphorus, potassium, sodium, chloride, carotene, aspartate aminotransferase, creatine kinase, uric acid, total protein, albumin, globulin, and hematocrit. Heat stress reduced potassium, hematocrit, uric acid, total protein, globulin, hematocrit and lymphocytes, while increasing sodium and glucose compared to broilers in the control environment. Broilers fed dietary sodium chloride had increased blood potassium and chloride, and reduced sodium compared to those fed bicarbonate and vitamin fortified diets. Total blood carbon dioxide increased in broilers fed bicarbonate and vitamin fortified diets compared to birds fed only sodium chloride. This study demonstrates that blood biochemistry of modern broilers is influenced by dietary intervention and changing environmental conditions. This pattern suggests that a blood biomarker can be used to detect substandard nutrition or heat stress. Additionally, this blood biomarker footprint may help the development of diagnostic tools which in combination with biomarkers can help determine nutrition and health status of individual broiler flocks, for nutritionists, veterinarians and live production managers.

Technical Abstract: A total of 960 broilers were used to determine the effect of heat stress and dietary electrolyte balance on blood biochemistry. Chicks were sex sorted and allocated to 48 pens with 20 chicks per pen (10 males and 10 female) creating 6 treatments (3 diets x 2 house environments) with 8 replicates. Birds were 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) were housed in two different temperature-controlled environments. ( thermoneutral environment (Control) or heat stressed (Heat Stress). Venous blood from 2 broilers per pen were analyzed at day 28, 35 and 42 using the i-STAT® Handheld Clinical Analyzer, Abaxis Vetscan VS2, iCheck™ FLUORO devices, while malondialdehyde, heterophile, and lymphocyte counts were also determined. 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. Age created a highly significant linear impact on blood calcium, phosphorus, potassium, sodium, chloride, carotene, aspartate aminotransferase, creatine kinase, uric acid, total protein, albumin, globulin, and hematocrit. Heat stress reduced potassium, hematocrit, uric acid, total protein, globulin, hematocrit and lymphocytes, while increasing sodium and glucose compared to broilers in a thermoneutral environment. Broilers fed dietary sodium chloride had increased blood potassium and chloride, and reduced sodium compared to those fed bicarbonate and vitamin fortified diets. Total blood carbon dioxide increased in broilers fed bicarbonate and vitamin fortified diets when compared to birds fed only sodium chloride. This study demonstrates that blood biochemistry of modern broilers 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.