A Special Plant Extract Helps Rabbits Stay Healthy in the Heat

Researchers in China found that a natural powder from the Astragalus plant can help mother rabbits stay healthy and have stronger babies in hot weather. The study took place during the summer of 2024 at China Agricultural University. Scientists wanted to find out if adding this plant extract to rabbit food could protect the animals from heat stress. Their results were published in the journal npj Veterinary Sciences.

Heat stress happens when it gets so hot that an animal's body starts to struggle. For farm rabbits, extreme heat can lower pregnancy rates and slow down the growth of baby rabbits, called kits. Scientists were looking for a natural solution that did not involve giving the animals extra medicine. That is why they decided to test Astragalus polysaccharides, also known as APS.

The study included 460 mother rabbits divided into five groups. Each group ate a normal diet, but four groups also received different amounts of APS in their food. The amounts ranged from 200 to 1,000 milligrams per kilogram of feed. One group received no APS and acted as the control group for comparison.

Scientists measured pregnancy rates, litter sizes, and the weight of kits to judge how well the rabbits were reproducing. They also tested the rabbits' blood for hormones like estrogen and progesterone, which are important for pregnancy. In addition, they checked for chemicals that signal whether the body is inflamed or under stress. All of this data helped the team understand how APS was affecting the rabbits.

The researchers also studied the tiny bacteria living inside the rabbits' digestive systems, called gut microbiota. Healthy gut bacteria produce helpful chemicals called short-chain fatty acids, or SCFAs. SCFAs support the immune system and help reduce harmful inflammation. Scientists believed these chemicals might be one reason why APS was helping the rabbits.

The results showed that rabbits fed APS had better pregnancy rates and gave birth to more kits than the control group. The kits born to APS-fed mothers also weighed more and grew faster in their first weeks of life. These positive effects were strongest at doses of around 400 to 800 milligrams per kilogram of feed. Higher doses did not always work better than moderate ones.

Blood tests confirmed that APS lowered levels of IL-6, a chemical linked to inflammation, and raised levels of IL-10, which fights inflammation. Hormone levels also improved in APS-fed rabbits, helping their bodies handle pregnancy more effectively. The gut bacteria analysis showed a healthier balance of microbes and higher levels of short-chain fatty acids in these rabbits. Scientists believe this gut connection is a key part of how APS helps rabbits reproduce in the heat.

This study is important because it shows a natural, drug-free way to protect farm animals from rising temperatures. As climate change makes summers hotter around the world, heat stress is becoming a growing challenge for farmers. Finding plant-based solutions like APS could help improve animal health and farm productivity. Researchers hope to study whether APS works the same way in other farm animals in the future.