Are animals really stressed?
We normally think of stress as psychophysical fatigue, but stress is medically defined as the functional response of an organism to any kind of stimulus (stressor, that can be of any intensity and duration). Stressors can have different nature (microbial, toxic, thermal, traumatic, emotional) and alter the neurohormonal equilibrium of the organism, leading to an overproduction of cortisol, the “stress hormone”. During their life, reared animals are exposed to many stressors. In mammals, weaning is a really stressful period: changing in the environment, the feed, the group, and birds experience the same kind of stress after hatching. Other causes of stress for all reared animals are transport, crowding, high/low temperature, etc. Therefore, even if they are not clinically sick, animals are really stressed!
What are stress consequences?
It is well documented that high cortisolemia causes a reduction in animal growth. Back in 1965, Bellamy and Leonard observed that cortisol-treated chickens had no muscle and skeletal growth. Stressful periods lead also to immunosuppression and intestinal damages. The gut mucosa integrity is disrupted because of inflammation that decreases the tightness of the intestinal epithelium. Tight junctions are protein structures, that link cells one to each other and are responsible for the correct barrier function of the epithelium. In case of inflammation, these structures lose their integrity and the permeability of the intestinal mucosa is altered. There are several parameters that we can measure through ex vivo and in vitro tests to understand the real condition of the mucosa and the intestinal barrier. For example, one of the most important parameters that we can measure is trans-epithelial electrical resistance (TER): the higher resistance the epithelium opposes to the passage of electricity, the better the barrier works. With the impairment of the physiological gut health, the passage of pathogens and harmful molecules is increased and nutrient absorption can be reduced. This fact, in addition to immunosuppression, leads to a higher risk of infections and pathologies during stressful periods, with consequences in the entire productive cycle of the animal.
What can we do to reduce or prevent stress effects?
Certainly, it is impossible to eliminate all stressors from animal life, but we can follow the good zootechnical practice to reduce them at a minimum level, for example reducing the number of animals for pen avoiding overcrowding. Nutrition is also a powerful tool not to avoid stress, but to mitigate its effects on animal health. As we have seen, intestinal health and mucosa integrity are really important and inflammation alters them during stressful periods. Different feed additives have an anti-inflammatory effect: we tested the ingredients of AviPlus® on enterocytes to determine the effect of this product directly on the mucosal integrity. We conducted two different experiments: the first to determine if AviPlus® can reduce the effect of an inflammatory insult to the epithelium, while the second to evaluate if the use of AviPlus® can prevent intestinal mucosa impairment. Experiments were conducted using Caco-2 cells, enterocytes cell line globally used as a reliable model for intestinal epithelium in all species.
In the first study, epithelial cells were cultured with or without different concentrations of AviPlus® ingredients. At the beginning of the experiment, a cocktail of inflammatory cytokines and bacterial LPS were added to the medium as an inflammatory insult to the epithelium. The challenge strongly affected epithelial functionality within 24 hours. The measurement of the TER and the evaluation of the thigh junction proteins for the three cell lines indicated that treated cells completely restored and even improved the initial barrier function of the epithelium in just 5 days after the inflammatory challenge and had better results than the control. In this experiment, AviPlus® demonstrated to be able to restore the integrity of the intestinal epithelium and to improve it in a very short time and in a dose-dependent manner.
AviPlus® is intended to support animal intestinal health during the whole life, not only as an intervention after an inflammatory challenge. For this reason, the second experiment was set up to evaluate how AviPlus® can prevent the damage of the intestinal epithelium in case of inflammation during the product administration to the animals. Epithelial cells were cultured as before, with or without different concentrations of AviPlus® active ingredients. On the last day of the trial, the inflammatory challenge was done, putting in contact cells with the cocktail of Inflammatory cytokines and bacterial LPS. Results (TER and thigh junction proteins measurements) indicated that treated cells had a better epithelial tightness and a better barrier function than the control over the course of the experiment. After the challenge, the integrity of the control epithelium was strongly affected, while treated cells maintained the same barrier function as the beginning of the experiment. In this case, AviPlus® demonstrated to be useful to prevent all damages caused by inflammation if administered to the animals before the challenge occurs.
The results of the two experiments with AviPlus® active ingredients demonstrate that the specific blend of organic acids and nature identical compounds improve the resistance of intestinal epithelial cells to inflammatory challenge both in a preventive or interventive way.
Conclusion
Even in the best rearing conditions, stress is not completely avoidable and causes a reduction in life performance and consequent economic loss. Intestinal health and gut mucosa integrity have a pivotal role in preventing and facing the effect of stressful periods. Damages of the mucosa cause a higher risk of pathogen translocation, systemic infections, the passage of toxins in the bloodstream, and lower absorption of nutrients. AviPlus® can be a useful tool to reduce the impact of stress on animal live performance, reducing the effect of inflammation on the intestinal mucosa, improving epithelial tightness and barrier function, resulting in better intestinal health.For more information: marketing@vetagro.com