A smart new way to deal with heat stress

Due to climate change, heat stress becomes an increasingly common phenomenon. The consequences for broilers are all too obvious with a significantly lower feed intake and a lower productive efficiency. Many people however are unaware that the intestines suffer considerably from high ambient temperatures. The good news is that dietary inclusion of butyric acid in the form of FRA Butyrin Hybrid could be an effective nutritional tool to alleviate the detrimental effects of heat stress to the broilers’ gut.

Although birds perform well within a relatively wide range of temperatures, optimal performance for growing broilers is found to be between 18 and 22 °C. However, when the temperature in a broiler house rises above their comfort zone, broilers experience physiological stress known as heat stress. In this regard, the effect of relative humidity should not be underestimated. A high environmental temperature in combination with a high humidity is much more detrimental to broilers than a high temperature alone.

While most broiler nutritionists and farmers look with suspicion to depressed feed intakes, much more is happening inside the animal. American researchers recently confirmed not only the negative effect of heat stress on daily gain, feed conversion ratio and meat yield. They also discovered that these effects are not only due to the low feed intake, but also are a direct effect of a damaged gut.

Nutritional strategies to reduce heat stress

What tools do broiler farmers have to minimize the impact of heat stress? Controlling the house temperature and humidity is obviously the most effective way to protect animals from the adverse effects of heat. But management strategies like providing adequate and cool drinking water and feeding smaller and more frequent meals during the cooler parts of the day will stimulate broilers’ appetite and enhance feed intake. One other method to alleviate the effect of high ambient temperature on the performance of broilers is dietary interventions.

From both research and practice, it is well known that butyric acid is highly beneficial to improve intestinal integrity and development. While pure butyric acid is very hard to handle due to its incredible bad smell, FRA Butyrin Hybrid is an effective and easy to handle blend of tributyrin and alpha-monobutyrin. FRA Butyrin Hybrid is designed to improve intestinal integrity and development, such as villi height and villi height to crypt depth ratio. Butyrate increases the expression of tight junction proteins, improving the epithelial barrier which is essential for normal intestinal function.

Proof of concept

To test the effect of FRA Butyrin Hybrid on performance and intestinal health of broilers during chronic heat stress, a broiler study was carried out during the hot-dry season in Nigeria. From rectal temperatures of 42.8 °C and respiratory rates of 96 breaths per minute, it became clear that the Arbor Acres broilers really suffered from heat stress. The control group received a basic commercial starter, grower and finisher diet based on maize and soybean meal. The test group received the basal diet supplemented with FRA Butyrin Hybrid (500 g/ton) during the entire trial period of 42 days.

As expected, the effect of heat stress was seen on all parameters as growth rate, feed intake, feed efficiency and final body weight were negatively affected in both treatment groups compared to the performance objectives of the genetic. However, FRA Butyrin Hybrid was able to alleviate the effects of heat stress as average daily weight gain was improved with 5.1% compared to the control group. As a result, at slaughter these broilers were 70 grams (4.6%) heavier. Remarkably, instead of a higher feed intake, in particular feed was better utilized when FRA Butyrin Hybrid was fed as feed conversion ratio was improved by 13 points.

FRA Butyrin Hybrid significantly improved villi height compared to the control group as well in the duodenum as in the jejunum and ileum, thereby significantly improving villi height to crypt depth ratio (VH:CD ratio) from approximately 3.7 till 6.5 in each intestinal segment compared to the control group. This shows that the favourable effects of FRA Butyrin Hybrid on heat-stressed broilers may have been the result of the gut supporting abilities of the feed additive.

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