Recent studies have shown that resilience indicators based on monitoring voluntary feed intake in pigs also have the potential to demonstrate the resilience to DON mycotoxin in pigs.
Impact of DON on feed intake in pigs
Mycotoxins in pig feed are known to influence pig performance negatively. Studies have shown that the magnitude of the effects varies with the type and concentration of mycotoxin, sex, age of the pig as well as nutritional factors.
When it comes to the mycotoxin deoxynivalenol (DON), meta-analysis studies have highlighted that the greater part of the variation in weight gain was related to the variation in feed intake, more than compared to other mycotoxins (Andretta et al 2011). Some studies reported that DON can induce the release of satiety hormones from endocrine cells found in the gut and others reported that the pro-inflammatory cytokine produced upon exposure to DON can also participate to the observed anorexia.
There are also other responses to DON in pigs, such as oxidative stress and inflammation on the cellular and gut level, which can play an additional role in the impact on pig growth performance as they affect energy maintenance requirements. In contrast to ruminant and poultry, pigs are more sensitive to DON because they have a low ability to detoxify DON to less toxic products.
In a study by Serviento et al (2018) evaluating short- and longterm effects of DON-contaminated diets on the feeding behaviour of finishing pigs (99 to 154 days of age) average daily feed intake was reduced on average by 26% to 32% when compared to the control groups. This was found to be related to a reduction in the rate of feed intake and the meal frequency. Previous DON exposure did not make the pigs resistant to a second interrupted DON challenge. However, based on the faster retrieval rate in feed intake, this previous experience seemed to improve pig response to a repeated DON challenge. The adaptive mechanism of pigs to DON has not been fully understood.
Feed intake as a resilience indicator in pigs
Improving resilience is starting to gain interest for breeding programs. But before we can improve something, we also need to know how to measure it. Several research studies have been underway in different parts of the world to determine what can be measured as a good indicator for resilience in pigs.
The response of a pig to a challenge or perturbation can be characterized by the resistance and resilience potential of the pig. Although the origin of perturbations may not be known, their effect on animal performance can be observed, through changes in voluntary feed intake. The resistance trait describes the immediate reduction in daily feed intake to minimize the impact at the start of the disruption while the resilience trait describes the capacity of the pig to adapt to the perturbation through compensatory feed intake to quickly return to the target trajectory of feed intake.
Feed intake can be very informative about the health and welfare status of the animal and modern monitoring technologies are facilitating the recording of individual feed intake in group-housed pigs.
Nguyen-Ba et al (2020a) developed a modelling and data analysis methodology to quantify the feed intake in response to perturbations in terms of resistance and resilience using voluntary feed intake as a response criterion. The methodology has been employed successfully to identify the target trajectory of feed intake (amount of feed that a pig desires to eat when it is not facing any perturbations) in growing pigs and to quantify the pig’s response to a perturbation in terms of traits related to resistance and resilience.
Measuring resilience to DON mycotoxin in pigs
In a second study Nguyen-Ba et al (2020b) applied the methodology mentioned above to quantify the feed intake response in pigs exposed to DON in the diet. The results showed that the methodology based on measuring feed intake in pigs was able to indicate relatively accurately when the pigs were exposed to DON in the feed by detecting deviations from the target cumulative feed intake resulting from the exposure to a DON-contaminated diet.
Furthermore, results demonstrated that the response of pigs to DON-contaminated diet is influenced by age or body weight as well as previous exposure to the DON-contaminated diet. The researchers thought that this indicates that the adaptation of pigs relies more on resilience than on resistance mechanism.
Older pigs recovered faster than the younger pigs from the DON challenge. Researchers concluded that the greater compensatory feed intake for the heavier pigs is related to the fact that they have a greater gut capacity, as gut capacity increases with body weight.
Nguyen-Ba et al (2020a). A procedure to quantify the feed intake response of growing pigs to perturbations. Animal, 14(2)
Nguyen-Ba et al (2020b). Modelling the feed intake response of growing pigs to diets contaminated with mycotoxins. Animal, 14(5)