The Influence of Heat Stress on Chicken Immune System and Mitigation of Negative Impacts by Baicalin and Baicalein

Abstract

Heat stress (HS) in poultry husbandry is an important stressor and with increasing global temperatures its importance will increase. The negative effects of stress on the quality and quantity of poultry production are described in a range of research studies. However, a lack of attention is devoted to the impacts of HS on individual chicken immune cells and whole lymphoid tissue in birds. Oxidative stress and increased inflammation are accompanying processes of HS, but with deleterious effects on the whole organism. They play a key role in the inflammation and oxidative stress of the chicken immune system. There are a range of strategies that can help mitigate the adverse effects of HS in poultry. Phytochemicals are well studied and some of them report promising results to mitigate oxidative stress and inflammation, a major consequence of HS. Current studies revealed that mitigating these two main impacts of HS will be a key factor in solving the problem of increasing temperatures in poultry production. Improved function of the chicken immune system is another benefit of using phytochemicals in poultry due to the importance of poultry health management in today’s post pandemic world. Based on the current literature, baicalin and baicalein have proven to have strong anti-inflammatory and antioxidative effects in mammalian and avian models. Taken together, this review is dedicated to collecting the literature about the known effects of HS on chicken immune cells and lymphoid tissue. The second part of the review is dedicated to the potential use of baicalin and baicalein in poultry to mitigate the negative impacts of HS on poultry production.

Early Feeding Strategy Mitigates Major Physiological Dynamics Altered by Heat Stress in Broilers

“…Heat stress exposure is reported to induce immunosuppression in poultry [67,68]. Furthermore, immunosuppression with a significant reduction in immune cytokine levels, such as IL-1β, was reported in heat-stressed broilers [69].…”

“…The current investigated FWD regimes seem to mitigate the undesirable impacts of heat stress on redox status and exhibit an immunomodulation effect. These effects can be justified by the onset of physiological adaptation to heat stress and induction of heat tolerance that restore the redox balance and subsequently immune activation [68]. Furthermore, the increased level of HSP70 with FWD beneficiary enhanced the immune responses as it was reported to boost infectious bursal disease (IBD) resistance in heatstressed broilers [61].…”

Hyperthermia-induced changes in leukocyte survival and phagocytosis: a comparative study in bovine and buffalo leukocytes

“…The challenge of global warming and the resulting negative effects of heat stress on animal health and productivity reinforce the need for intensive research to identify animal species and breeds with greater thermal adaptation (17,18). Profound impact of heat stress on the immune system has been reported for several animal species (19)(20)(21)(22). Research on the immune system of water buffalo has recently gained special interest, leading to the characterization of key elements of the immune system with some similarities and differences from the bovine immune system (23-27).…”

Dietary Peppermint Extract Inhibits Chronic Heat Stress-Induced Activation of Innate Immunity and Inflammatory Response in the Spleen of Broiler Chickens

“…Animals 2024, 14, 1157 2 of 12 Additionally, heat stress can cause poultry immune function dysregulation, which increases mortality and causes broiler producers to incur considerable economic losses [4,5].…”