Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 10, 2012
Publication Date: July 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/56637
Citation: Felver-Gant, J.N., Mack, L.A., Dennis, R.L., Eicher, S.D., Cheng, H. 2012. Genetic variations alter physiological responses following heat stress in two laying hen strains. Poultry Science. 91:1542-1551. Interpretive Summary: Heat stress is a condition in which an animal is exposed to a high temperature environment for an extended period of time. In laying hens, heat stress is a common problem, especially in warm climate areas. Previous studies have shown that the response of chickens to stressors is genetically dependant. The goal of the current research was to determine the genetic variation of the heat stress response in two strains of well studied hens. To achieve this, we separated half of our hens into two adjacent rooms; a control temperature at 24.3 °C and heat stress temperature at 32.6 °C for 2 weeks. The results showed differences in production values, as well as hormone and immune functions between heat stressed hens and their controls. These results are extremely beneficial to the scientific community in better understanding the role genetics have on the heat stress response. These data are useful to egg producers to aid in selecting for hens with genetic backgrounds that are more capable to adapt to heat stress.
Technical Abstract: Heat stress (HS) is a major problem experienced by the poultry industry during high temperature conditions. The ability to manage the detrimental effects of HS can be attributed to multiple factors, including genetic background of flocks. The objective of the present study was to determine the genetic variation in HS effects on the welfare of laying hens. Ninety 28-wk old White Leghorn hens of two strains were used: a commercial line of individually-selected hens for high egg production, DeKalb XL (DXL), and a line of group-selected hens for high productivity and survivability, named kind gentle bird (KGB). Hens were randomly paired by strain and assigned to hot (H) or control (C) treatments for 14 ds. Physical and physiological parameters were analyzed at d 8 and 14 post-treatment. Compared to controls, HS increased core body temperature of hens (P< 0.05), and decreased body weight (P < 0.05) at d 8 and 14. Heat shock protein 70 concentrations in liver were greater in hens exposed to HS (P < 0.05). Compared to DXL hens, KGB hens had higher HSP70 concentrations (P < 0.05). The birds’ liver weight decreased, with less of a response in the KGB line (P < 0.05). The data indicate HS has detrimental effects on the physiology of laying hens due to genetic variations. These data provide evidence that are valuable for determining genetic interventions for laying hens under HS.