Influence of environmental temperature on the physiological, endocrine, and immune responses in livestock exposed to a provocative immune challenge

Authors: Carroll, Jeffery - Jeff Carroll; Sanchez, Nicole; Chase, Chadwick - Chad; Coleman, Samuel; SPIERS, DON - University Of Missouri

Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2011
Publication Date: 3/16/2012
Citation: Carroll, J.A., Sanchez, N.C., Chase, C.C., Coleman, S.W., Spiers, D.E. 2012. Influence of environmental temperature on the physiological, endocrine, and immune responses in livestock exposed to a provocative immune challenge. Domestic Animal Endocrinology. 43:146-153.

Interpretive Summary: While livestock experience many stressors throughout the production cycle, one of the most commonly experienced and most difficult to control, is stress caused by fluctuations in environmental temperatures that extend beyond the thermoneutral zone for an animal. In swine, cold stress has long been recognized as a major cause of neonatal morbidity and mortality. A possible explanation for the increased morbidity and mortality associated with cold stress in neonatal pigs may be related to their inability to generate a febrile response. Previously, we have demonstrated that the acute phase immune response, including the generation of fever, following exposure to an immune challenge is substantially altered in neonatal pigs maintained in a cold environment. In fact, neonatal pigs that were maintained in a cold environment and administered a gram-negative bacterial endotoxin (i.e., lipopolysaccharide: LPS) experienced a period of hypothermia which in and of itself could prove detrimental in a production environment. In cattle, we have previously reported differences in the acute phase immune response in two diverse breeds of Bos taurus (Angus and Romosinuano) cattle when maintained under thermoneutral (TN) conditions and exposed to LPS. In a more recent study evaluating these two breeds of cattle, Angus heifers displayed greater rectal temperature than Romosinuano heifers when housed at either TN or heat stress (HS) air temperatures and produced a greater temperature response to LPS. However, when housed in a HS environment, Romosinuano heifers displayed greater sickness behavior scores compared to Angus heifers following LPS administration. Additionally, HS increased the release of pro-inflammatory cytokines following LPS administration. These data clearly demonstrate that even intermittent periods of HS similar to that experienced in production environments can have significant effects on the stress and innate immune responses of cattle. Understanding the impact of thermal stress on the immunological responses of livestock is critical to developing and implementing alternative management practices that would improve the overall health and well-being of animals in production systems. This data will be of interest to scientists in the fields of stress physiology and immunology, as well as swine and cattle producers and can be used to modify management practices in order to enhance livestock health and well-being.

Technical Abstract: While livestock experience many stressors throughout the production cycle, one of the most commonly experienced, and most difficult to control, is stress caused by fluctuations in environmental temperatures (ET) that extend beyond the thermoneutral zone for an animal. In swine, cold stress has long been recognized as a major cause of neonatal morbidity and mortality. A possible explanation for the increased morbidity and mortality associated with cold stress in neonatal pigs may be related to their inability to generate a febrile response. Previously, we have demonstrated that the acute phase immune response, including the generation of fever, following exposure to a provocative immune challenge is substantially altered in neonatal pigs maintained in a cold environment. In fact, neonatal pigs that were maintained in a cold environment and administered a gram-negative bacterial endotoxin (i.e., lipopolysaccharide: LPS) experienced a period of hypothermia which, in and of itself, could prove detrimental in a production environment. In cattle, we have previously reported differences in the acute phase immune response in two diverse breeds of Bos taurus (Angus and Romosinuano) cattle when maintained under thermoneutral (TN) conditions and exposed to LPS. In a more recent study evaluating these two breeds of cattle, Angus heifers displayed greater rectal temperature than Romosinuano heifers when housed at either TN or heat stress (HS) air temperatures and produced a greater febrile response to LPS. However, when housed in a HS environment, Romosinuano heifers displayed greater sickness behavior scores compared to Angus heifers following LPS administration. Environmental temperature also played a significant role in the release of pro-inflammatory cytokines following LPS administration. For example, heifers housed in a HS environment produced greater concentrations of interleukin-6 after LPS administration than heifers housed at TN. These data clearly demonstrate that even intermittent periods of HS similar to that experienced in production environments can have significant effects on the stress and innate immune responses of cattle. Understanding the impact of thermal stress on the immunological responses of livestock is critical to developing and implementing alternative management practices that would improve the overall health and well-being of animals in production systems.