US researcher seeks to mitigate the effects of stress in piglets

By Aerin Einstein-Curtis contact

- Last updated on GMT

© iStock
© iStock
A researcher with Texas Tech University is examining the role a cortisol analog can play in improving piglet weaning responses while cutting antibiotic use.

The project received almost $300,000 in funding from the US Department of Agriculture (USDA) with a grant​ from the Agriculture and Food Research Initiative’s Critical Agricultural Research and Extension (CARE​) program. That program announced $4.8m in funding last week.

The study is designed to be done over three years and includes several different trials, said Anoosh Rakhshandeh, assistant professor in swine nutrition and health at Texas Tech University. The initial phase of the project is set to start this summer.

“My research since 2005 has been to observe how stress changes nutrient utilization and how we can enable the physiology of the animal to mitigate the effects of stress – environment stress, immunological stress and social stress,”​ he told FeedNavigator.

The project looks at the use of a cortisol agonist at weaning to improve piglet performance without the need for antibiotics, he said. Goals of the project include tracking what use of a cortisol analog means throughout pig production; identifying the pathway altered by use of the analog; finding the most effective delivery method and running a commercial scale trial.

“The hope is we can understand how it works and replace antibiotics,” ​he said. “Antibiotic resistance is a serious issue, and we’re still dealing with these challenges in terms of capabilities to fight stress, even though there have been lots of developments.”

Foundational research details

The research project is based on findings from several smaller trials, said Rakhshandeh.

Piglets face a good deal of stress at weaning, he said. When piglets are exposed to multiple kinds of stress it can establish an inflammatory or hyper-sensitive immune response that hinders development.

The initial trial looked at ways to down regulate the production or generation of the stress hormone cortisol, he said. “We thought if we can block the hormone cortisol, we might be able to mitigate the stress of weaning in piglets,”​ he added.

However, that practice decreased productivity for the piglets, said Rakhshandeh. “Cortisol is not all bad, it’s needed at some level because it has different functions in the body​,” he added.

At that point the work looked for ways to fill the role cortisol plays without triggering a negative effect from the immune system, he said.

“We did another study with a small number of animals and treated them with cortisol agonists,” ​he said. “We saw a significant increase in the productivity of the animal.”

The new trials seek to examine why that response is generated, he said.

Antibiotic alternatives and piglet performance

The first portion of the trials will in part replicate the earlier work with a larger number of piglets and for a longer period of time, said Rakhshandeh.

In the study, 400 piglets will be given a corn-soybean meal based control diet, or that diet with an in-feed antibiotic; or two doses of the anti-inflammatory cortisol analog, before weaning and 72 hours after weaning, according to the grant. Intestinal samples are set to be taken two weeks after weaning to check for morphology and histopathology.

The influence of the additive on pigs’ immune function will be checked along with activity of digestive enzymes, the research group reported. Blood, manure and ileal digesta samples will be taken and pigs’ body weight and feed intake is set to be recorded.

Information on carcass quality is set to be collected at the end of the study, added Rakhshandeh.

“We hypothesized that the cortisol analog will minimize the negative effect of the immune system during the weaning – as a result we can use it instead of antibiotics,”​ he said. Another hypothesis to be tested is that when used during weaning the supplement would mean antibiotics could be removed from diets, he added.

There is a possibility that after improved initial performance, piglets that do not receive the analog would be able to catch up, he said. The expectation is that it will not happen.

If results are promising from the first study, the second piece of the project is to assess which method of delivery is most effective, he said. These include offering the agonist in feed, water or through injection.

“For industry it would be easier to put in the feed or water,” ​said Rakhshandeh. “[But] what will be the dose? The second year we try to answer these questions.”

The third test again would look at the long-term effectiveness of the cortisol analog for the period from weaning to market, he said. However, it will be on a commercial scale.

The overarching goal of the project is to offer another tool to the pork industry to support production through weaning without relying on antibiotics, he said. “Even through we’ve become better we still have problems with the immunological challenges and obviously antibiotics aren’t the best way,”​ he added.

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