A postbiotic from Aspergillus oryzae attenuates the impact of heat stress in ectothermic and endothermic organisms

Abstract

Heat stress is detrimental to food-producing animals and animal productivity remains suboptimal despite the use of heat abatement strategies during summer. Global warming and the increase of frequency and intensity of heatwaves are likely to continue and, thus, exacerbate the problem of heat stress. Heat stress leads to the impairment of physiological and cellular functions of ectothermic and endothermic animals. Therefore, it is critical to conceive ways of protecting animals against the pathological effects of heat stress. In experiments with endothermic animals highly sensitive to heat (Bos taurus), we have previously reported that heat-induced systemic inflammation can be ameliorated in part by nutritional interventions. The experiments conducted in this report described molecular and physiological adaptations to heat stress using Drosophila melanogaster and dairy cow models. In this report, we expand previous work by first demonstrating that the addition of a postbiotic from Aspergillus oryzae (AO) into the culture medium of ectothermic animals (Drosophila melanogaster) improved survival to heat stress from 30 to 58%. This response was associated with downregulation of genes involved in the modulation of oxidative stress and immunity, most notably metallothionein B, C, and D. In line with these results, we subsequently showed that the supplementation with the AO postbiotic to lactating dairy cows experiencing heat stress decreased plasma concentrations of serum amyloid A and lipopolysaccharide-binding protein, and the expression of interleukin-6 in white blood cells. These alterations were paralleled by increased synthesis of energy-corrected milk and milk components, suggesting enhanced nutrient partitioning to lactogenesis and increased metabolic efficiency. In summary, this work provides evidence that a postbiotic from AO enhances thermal tolerance likely through a mechanism that entails reduced inflammation.

Physiological responses of Holstein calves to prolonged heat stress and dietary supplementation with a postbiotic from Aspergillus oryzae

“…Despite the lack of reduction of inflammatory markers, animal productivity improved in calves receiving the postbiotic. The latter agrees with beneficial effects of supplementing 3 and 6 g/d of AO postbiotic on productivity observed in previous work in heat-stressed lactating cows [11].…”

“…These results agree with previous studies in ruminant and nonruminant animals for which heat stress increased markers of systemic inflammation [18,19,20]. However, our previous study in heat-stressed cows consuming AO postbiotic showed a quadratic reduction of serum amyloid A and lipopolysaccharides binding protein highlighting the effectiveness of 3 but not 6 g/d of postbiotic supplementation on markers of systemic inflammation [11]. Despite the lack of reduction of inflammatory markers, animal productivity improved in calves receiving the postbiotic.…”

“…In line with our experimental objectives, the temperature in the heat stress room mimicked a long-term change that is typically observed in spring and summer dairy regions of the world [3,11]. Under this setting, and contrary to our projections, we found that HS calves showed similar feed intake compared to TN counterparts.…”

Heat Stress-Mediated Activation of Immune–Inflammatory Pathways

“…Several reports have shown an increase in the acute-phase protein haptoglobin, serum albumin A, and serum endotoxins in pigs exposed to heat stress for several hours or days [ 56 , 57 , 58 ]. In agreement with data from pigs, cattle exposed to elevated ambient temperature show greater plasma concentrations of acute-phase proteins (~34 °C 8 h/day for 7 to 21 days) [ 59 , 60 ]. Collectively, these results reveal activation of systemic inflammation during heat stress.…”

“…In recent years, probiotics and prebiotics such as yeast extracts or galacto-oligosaccharides (GOSs) have been promoted as feed additives to enhance immunity and GIT health [ 111 ] in heat-stressed cows [ 60 , 112 , 113 ], birds [ 49 ], and rats [ 108 ]. In most of these studies, the benefits in productive parameters, health, and welfare of the animals as a result of supplementation with pro- and prebiotics were examined.…”