Brown seaweed supplementation may help broilers handle heat stress - Interpretive Summary

   

Chickens don’t do well in the heat. In fact, birds experiencing heat stress tend to eat less, grow slower, and even have compromised immune function. Heat stress is also a major cause of mortality for chickens and leads to considerable economic losses each year in the poultry industry.

In a new study, poultry scientists based at Dalhousie University, report a promising way to counter heat stress: seaweed. Their new findings, published in the journal Poultry Science^®, suggest that providing brown seaweed supplementation, via extract in drinking water or seaweed meal, can lead broiler chickens to eat more and grow better—despite high temperatures.

“Seaweed contains unique bioactive compounds and has been applied in poultry feed because of its richness in carbohydrates, minerals, protein, vitamins, and dietary fibers, with relatively stable amino acid profiles and growth-stimulating properties,” write the study authors

As the study leaders point out, recent studies have shown benefits of brown seaweed for ruminant livestock in times of heat stress and benefits of marine algae on production in older hens. The new study is the first look at how brown seaweed might counteract the harmful effects of blood chemistry changes and oxidative-induced damage during heat stress.

For their investigation, the scientists worked with 336 day-old, mixed-sex Ross 308 broiler chicks. Chicks were divided into four treatments: a control group received no brown seaweed supplementation, one group received 1 mL seaweed extract (SWE) in drinking water, one group received 2 mL SWE in drinking water, and the last group received 2% seaweed meal in feed.

Given seaweed meal, heat-stressed birds showed higher average body weight gain (ABWG), average feed intake (AFI), average water intake (AWI), and a better feed conversion ratio (FCR). These data are in line with previous studies showing that the fiber content of brown seaweed meal can lead to better growth. The researchers uncovered further health benefits by examining the blood chemistry in these broilers.

The researchers discovered that the seaweed meal and 1 mL SWE treatments resulted in lower levels of harmful liver enzymes that can flood the bloodstream during heat stress. “Brown seaweed meal and extract also increased plasma albumin concentration among heat-stressed birds in our study, indicating better liver functioning,” they report. Digestive enzymes also stayed closer to healthy levels in the birds given brown seaweed products.

Benefits to immune function were less clear. While the researchers report no negative effects on immune organ function or immune molecule secretion, they didn’t see a significant benefit either. Nor did they find a benefit to antioxidant enzymes either. The researchers did note the possibility that the antioxidant effects of seaweed may be dose dependent.

Overall, the researchers concluded that brown seaweed supplementation improved broiler growth performance regardless of heat stress-related health changes.

    

The full paper, titled “Effects of brown seaweed products on growth performance, plasma biochemistry, immune response, and antioxidant capacity of broiler chickens challenged with heat stress,” can be found in Poultry Science^® and online here.

DOI: 10.1016/j.psj.2022.102215