A very interesting question .... how much and how far will domestic animals respond to temperature stress related natural selection?

These type of experiments are confounded by the complex response of animals to temperature stress, and stress responses will also be dependent on the nature of the stress, the nutrition intake of the animal, and the microbial flora present in the digestive system.

There are different stress responses: acute, immediate, short term, long term and very long term.  Very long term is related to the process of cellular renewal where most of the cell of the body are replaced.

Good studies of this type would need to control for the factors in all the above paragraphs, including microbial flora which most researchers overlook.

Genetic manipulations also act as genetic bottlenecks that reduce precious genetic diversity.

What good would  thermo-tolerant livestock be if you have to feed them antibiotics to survive the microbial pressures of farm life?

An interesting aspect of this type of research would to genetically manipulate livestock for reduced or increased body temperature as a means to confound pathogenic microorganisms adapted  to normal body temperature.

This may have some potential to work against viral pathogens which due to their efficiency and host specific adaptations tend to be sensitive to temperature changes. However, due to the viral generation rate, natural selection can result in dramatic changes in a very short time.  This is a case by case process and nobody can predict this.

Against bacterial pathogens this method is likely to be useless as bacteria will either adapt immediately though their gene regulation pathways, or respond quickly by natural selection.  Also, changing the body temperature of a domestic animal may replace the microbial flora with another community which may have even more pathogenic potential.  Remember, the animal host is an ideal environment with a long history of microbial co-evolution  .... the flora doesn't want to burn down the house to keep warm (some do).

thermoneutrality is caused by metabolic rate(1)   properties of surface(2) haircoat (3) surface tissue insulation(4)  All 4 can have genetic diversity ie (1) physical activity ratio of  protein to  lipid (2) surface ie vascularisation and properties of vaso constriction --dilation haircoat properties (3) thichness and kind of hair tissue insulation (4) thickness of skin and amoiunt of subcutanous fat

thanks Glenn for your briefing. Indeed animals respond in different ways to temperature or any other stress for that matter.

And we can artificially modulate their responses using antibiotics as you rightly mentioned. Changing dietary composition is another approach which I am very conversant with. But more crucial to my interest is the debate if human directed genetical manipulations can be used to alter this evolutionary adaptation.

By this i am thinking about mendellian kind of genetics not the sort of weid fiddling with DNAs at molecular level.

Stated another way is it possible to breed conventional poultry/swine that

that have got their their heat or cold resilience shifted further left or right of the temperature equilibrium of the control population?

And this is not without practical implication, because we will use less fossil fuel in europe to heat animal house. Alternatively, more animal protein will be produced in the tropics. Either way, we will be more sustainable.

Anyhow we know that nature did a good job with naked and frizzle necked

genes which confer heat resistance in poultry. But their gross performance still fall short of what is obtainable in birds used in conventional systems.

thanks @martin for your feedback, but is there potential to drive these genetic bipodiversities you mentioned for the purpose of improving livestock production? We want to cut down on antibiotics in the food-feed chain, but is there any sucess being recorded at hereditary level? Do we even understand the basics of physiological control mechanisms enough to do it in an ethical way?

I think the artificial selection has always be involved in the breeding process. For example, if you go to a tropical country. Let's assume they have a breeding of chicken that thrive in their country. Then by comparing this tropical breeding with breedings from high-latitude countries, there might be implication on which gene expressions are related to thermoneutrality.

The question is if the results are coming close and what the bottlenecks could be, knowing the question of heat or cold stress has being with us a very long time. But I concur that what we need is to identify the individuals or pools that have the traits of interest- in this case heat/cold resilience. But do we know if these properties do segregate at meiosis? Or do we have enough breath of variation within the breeding population to make selection a possibility? More fundamentally, how did nature registered these properties in each species? I am not sure if the primary breeders maintain relevant pure lines acclimatized to these kinds of conditions. We need answers to these issues. With the advent of SNP or marker assisted selection, probably answers will come faster than in previous times.  As a nutritionist it is sometimes frustrating  that our feeds and supplements are not enough to support animals to deal with this subject at the farm level. Despite the abundance of information that is know available in nutritional physiology! The geneticists just have to up their game. Thanks anyhow Zhi.

It is an interesting question. I think most farm animals are equipped with the mechanism that enable them to maintain their body temperature to ideal level by performing behavioral and physiological changes when subjected to variation in ambient temperature beyond thermo-neutral conditions. For example, chickens that are exposed to a few degrees (˚C) above or below thermo-neutral temperature will try to maintain their body temperature by increasing their body surface (Spread wing), shunt blood to body surface (Vasodilation); huddling together, vasoconstriction, and increased feed intake, respectively. Problems will arise when the ambient temperature reaches extreme conditions. I also believe that genes responsible for such behavioral and physiological changes will be up-regulated under such extreme conditions. Depending on the geographic area where the animal exists, anatomical changes such as hair/feather cover, skin thickness, etc. will be modified to adapt the existing condition. You are wright it is time to identify the genes that are up-regulated under adverse climatic conditions in native chickens that thrive very well under harsh temperature and incorporate into modern strain chickens which are also raised in tropical environment.

the problem is well captured in your submission: intensive farming which uses artificial housing systems. In the case of poultry, it began in north america about 50 to 60 years ago. Ever since we have only succeeded in making the housing and temperature lifestyle of the chicken more and more artificial with more and more machines and chemicals. Thus the chicken has not really profited from us in her adaptability to nature. On the other hand we now have a new and growing 'breed' of makind interested in a 'green' feel when they eat poultry. On top our environments are more degraded than ever as we can only effectively run those houses and systems with fossil fuels. A panacea of course would be to have the chickens fundamentally adapted right from their native biology. And this calls for the geneticists to have the correct breeding goals. We need to tell them to give us 'green' chicken, swine, cows and what have you! As nutritionists and producers we can only do our part to release the native inbred potentials of the farm animal, nothing more!