Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: February 21, 2011
Publication Date: February 28, 2012
Citation: Elsasser, T.H., Li, C., Shaffer, J.F., Collier, R.J. 2012. Effects of Environment on Animal Health: Mechanisms and Regulatory Inputs. In: Collier, R.J. and Collier, J.L., editors. Environmental Physiology of Livestock. Oxford, U.K. Wiley-Blackwell Publications. p. 129-164.
A functional model was developed and presented here to identify critical control points in associated biochemical pathways and further understand that how environmental factors impact the immune system to affect animal health.. A general comparison of the differences in cellular responses to mild versus severe heat stress was summarized. An important detail of the model was the we need to remember that activation of many of the same cell biochemical pathways occurs in response to many different sources of stress. Several small perturbations can become a severe collective stress, if the timing is right! While cellular responses to both mild and severe heat stress share some common ground, given the capacity of physiological processes to adapt, mild heat stress basically reprograms cells and organ processes over time towards a beneficial adaptation whereas the impact of severe heat stress is so immediate that compensatory responses simply can not be activated in time or to a sufficient level to minimize cellular damage.
With the present discussion focused on the biochemical mechanisms through which cellular responses to a variety of environmental and health challenges converge, a few areas stand out as needing additional input to guide future research to the next level of understanding and implementation. Ultimately, this should translate into the development of new and novel management and intervention/stabilization strategies that can be effected in anticipation of environmental impacts on animal health and wellbeing. With the recent sequencing of several domestic animal genomes, we are closer to gaining understanding of how genotype correlates with phenotype. However, with the expression of genes being the critical element in phenotype, this emerging area of epigenetic modulation stands out as having great potential. Not only do we stand a chance of understanding more about how genes react to the environment, but because of the potential to condition animals with induced changes in histone regulation, we may be able to exploit epigenetic modulation in a manner favorable to improved animal health, perhaps while in utero. Secondly, the area of membrane therapy may hold promise as a strategy to modulate animal responses to environmental challenge. While not an easy task to impart changes in basic lipid components of bilayers, some select short-term applications of intercalating agents such as tocopherol isomers or even novel fatty acids may serve to stabilize cell membranes against anticipated changes in environmental exposure or at any rate provide nutritional resources that are beneficial towards maintaining sufficient energy to drive homeostatic compensation.