Malcolm Mottram, Managing Partner
Introduction
As the severity and incidence of cyclic heat events grow it is necessary to improve heat stress management for intensive animal production systems. Physical interventions like environmentally controlled housing, misters & shade all are important or in some cases essential for modern production systems. Under hot conditions no intervention is perfect. Even environmentally controlled poultry housing has its limits. There are several feed additives that can assist in alleviating the impacts of heat. This is important from a production and animal welfare perspective.
What happens to the animal when heat stress occurs?
We tend to think of heat stress as dehydration and that’s sort of right, but the impact is more complicated than that. Certainly, maintaining water balance is very important. While we see feed intake decline, as a response to lowering the heat increment of digestion, the most significant impact of heat stress is the inflammation and degradation of the gut wall causing toxins (lipopolysaccharides) to enter the bloodstream. The innate immune system becomes activated, and energy is spent to fight that “infection”. The loss in production from heat stress can generally be split 50% through a reduction in feed intake and 50% in energy spent on the innate immune system. The more severe impacts of heat stress, including mortality, are associated with toxins entering the bloodstream.
Every heat stress event magnifies the chances of heat damage from the next event.
What is the right approach to alleviating heat stress in animals?
A new paradigm has recently emerged in the field of human medicine, which places damage to the tissues of the gut as the pivot through which the adverse effects of heat load are expressed. This invokes the possibility of novel approaches to the treatment and prevention of heat stress. Instead of treating the symptoms we should stop gut degradation. Maintaining the gut cell hydration and reducing inflammation of the gut are the approaches we recommend focusing on but from an evolutionary perspective what is the best approach.
Cell Hydration
This can generally be described as maintaining osmolarity (water balance) of the cell. The short-term “emergency” response of cells is to use electrolytes like potassium and sodium to maintain water balance. This is energetically costly so instead, cells use organic osmolytes to regulate cell volume. Betaine is an organic osmolyte that is selectively absorbed or secreted by a wide variety of cells including those of the gut, liver and kidney. In fact, betaine is the most widespread osmolyte in nature with single-cell bacteria, plants, animals and humans all using betaine through evolution to maintain cell osmolarity.
It is interesting to note that betaine is preferentially used as the mechanism of gut cells to maintain hydration. That makes sense given electrolytes like potassium and sodium cost energy to move in/out of the cells via the ion pump process. In addition, high levels of intracellular ions also destabilise the cell protein risking degradation and gut damage under heat stress. So, while a short-term “urgent” reaction to heat electrolytes works these ions do not solve the gut damage caused by heat stress.
When applying the use of natural betaine in animals, cell hydration is enhanced and the impacts of heat stress in all animal species are improved (poultry, pigs, cattle, sheep, etc.). We have direct experience and research in each species supported by many years of commercial field application showing any of the improved FCR, growth rate, liveability, reproduction & meat/egg/fibre yield. Not surprising given the effect of heat stress on productivity.
The result of using natural betaine supports the new paradigm on how protecting gut damage from heat stress is so critical to animals’ health, welfare, and production.
Betaine is a natures osmolyte, but an intriguing finding is that natural betaine extracted from sugar beet molasses is far superior to synthetically produced betaine. These synthetic sources have a negative effect themselves on gut inflammation. So, while chemically they appear the same only natural betaine elicits the true osmolyte function expected through evolution.
While there are many good ingredients and additives that can help manage heat stress natural betaine is the one evolutionary tool that is your first line of defence against heat stress.
