Early-life stressors in piglets can affect the productivity, quality and overall profitability of the adult pig — and their sex is a major determinant of how much they’ll be affected.
Adam Moeser, a professor at the Michigan State Univerity College of Veterinary Medicine, said early weaning leads to persistent leaky gut, chronic low-grade inflammation and altered enteric nervous system function, which increases disease risk.
Sex differences can also play a role in the success of livestock growth and development, he said, noting females exhibit a stronger immune response but are more prone to chronic inflammatory disorders.
WHY IT MATTERS: Producers who manage these stressors may see healthier animals and more profitable operations.
Moeser’s research at East Lansing, Mich., revealed distinct gene expression profiles in males and females, suggesting that early-life androgens play a crucial role in shaping immune responses. These findings underscore the need for sex-specific interventions to improve animal health and productivity.
The gut plays a huge role in both animal and human health, and that’s why it’s a major focus of his research, said Moeser.
“One of the most important concepts … about the gut is its early life development,” he said. “It serves many important functions, not only the efficient digestion and absorption of nutrients, but it must also serve as a barrier between the animal … and the outside world. “
As the largest interface between the outside world and the animal, it also contains the most concentrated and largest immune system in the entire body, the enteric nervous system that independently controls digestion and excretion, and the nutrient transporters that take the vital nourishment from the digestive tract to the cells of the body.
Early development
Because the functions of the gut are so critical, Moeser said they need time to develop in the animal to ensure long-term health. There’s a steep development curve, beginning in the first few days of the pig’s life, and continuing through the first several months.
He said it takes that long until the gut stabilizes in the pig. During this time there are many influences on the normal development trajectory. The gut is responding to outside signals through development that will affect long-term function.
“If anything happens during this critical stage of life, it’s going to shape long-term development and function,” he said, noting that during this stage, there are pathogen challenges such as immune stimulation and vaccines.
“All of these are happening during the first several weeks to months of life, and it can shape a normal life trajectory of disease risk if there’s more stress,” he said.
Some of these stressors are unavoidable in a production agriculture environment and cannot be completely mitigated, he said.
He added, however, that it is important for farmers to understand these stresses. They will play a large role in the animal’s ability to defend itself against other stresses and challenges it will encounter during its life.
Battle of the sexes
One trend that’s shown strongly during Moeser’s research is the gender effect, one that was made clear because of new guidelines that encourage testing on groups that include both male and female animals.
Moeser added that sex is known to shape disease vulnerability and mortality across multiple species. He said research has shown that females typically have higher survivability rates than males, with males dying at a disproportionately higher rate from infection compared with females. That’s likely due to a more robust immune response in female pigs.
It’s not a clear win for the female pigs though, as there’s another area where they seem to be at a disadvantage. When there are chronic and unrelenting stressors, female pigs are more prone to chronic pain and inflammation disorders.
“That may give them a trade-off for survivability versus chronic disease,” Moeser said.
He added that the agriculture industry knows a lot about sex differences, feed efficiency, carcass characteristics and reproduction, but that looking at sex as a biological factor for gut and immune development has been largely overlooked.
It is important to understand that this sex difference or disparity in mortality persists across stages of production, including pre-weaning, nursery and finished phases.
“These are sex differences that are emerging prior to sexual maturity, and that becomes important later,” he said.
Castration effect
One factor that may contribute to higher stress is castration, and that goes beyond the initial pain and trauma of the procedure itself.
“The fact that these differences persist long after the initial event of the castration procedure itself suggests that there’s also something more important underlying this biology,” Moeser said.
A conservative estimate suggests there’s a two to four per cent higher mortality rate in castrated males, which make up virtually the entire male pig population in commercial operations. Those numbers add up fast, and come with dollar signs attached.
“The numbers of pigs that are lost due to this sex difference alone actually become very significant,” Moeser said.
He said his team are continuing to explore what makes castrated males more vulnerable to disease and makes the female more resistant or have higher vulnerability.
“If we can understand the biology, what’s really different between a male and a female, maybe we can come up with some new interventions, or targeted strategies, or sex-specific strategies, that can put a dent in this health disparity,” he said.
His research team is analyzing the systemic response of pigs, tracking the numbers of peritoneal neutrophil (immmune cells that rush to the abdominal lining during infection), which are important to critical immune processes. The team’s research is also exploring a pig’s gene expression pattern, where they’re starting to understand some of the gender differences.
The female animals have very different genetic pathways that are regulated by something known as lipopolysaccharide signalling (or LPS) which regulate immune response. It preserves a higher energy demand, which is reflected in the gut by decreased metabolic processes.
Castrated males, on the other hand, have “unregulated” genetic pathways. They lack a “co-ordinated” defense response that’s seen in females and intact males.
Moeser says the difference between intact males and castrates shows the impact that castration alone can have.
“We know that males and females, they just don’t differ, but they operate different biological systems, and that both stress and immune challenge expose sex differences in the gut, meaning that sometimes, under non-stressful conditions, we may not see a sex difference, but under challenging conditions that sex difference is brought out,” he said.
Making changes
He challenged the industry to look at factors that can intervene and manipulate, from a management standpoint or from a therapeutic standpoint.
“If we learn more about why a male castrate can’t recruit different immune cells as efficiently as a female, if we can boost that, maybe we can improve survival,” he said. “Maybe we need to rethink about the impact of this castration on immune development and health? What are we losing by eliminating these androgens?”
Moeser questioned whether the industry could restore optimal immune function or better immune function in the male by manipulating practices or interventions. He said understanding the sex differences in biology opens new opportunities to better understand pig development.
“Maybe they need a boost. Maybe they need something that intervenes to lessen this mortality gap, which could have significant economic implications,” he said.
For female pigs, he said encouraging gut health, especially in early life, may “set their whole gut and inflammatory tone for life.”
“What is it about females that makes them have a higher, robust immune response? If we knew that, maybe we could optimize boosting immune potential in animals if we could understand the mechanisms of females.”
The post Early life can set health path for pigs appeared first on Farmtario.
