Exposure to heat-stress environment affects the physiology, circulation levels of cytokines, and microbiome in dairy cows

Abstract

The microbiome has emerged as a new player on behavior, physiology and stress because of its significant effects on the brain-gut axis. The aim of this study was to increase our understanding of brain-gut function in dairy cows. We investigated the effects of a heat-stress (HS) environment and individual differences of heat sensitivity (IH) on bovine physiological characteristics and microbial composition. Results indicate that both HS and IH increased rectal temperature (RT) (P < 0.05). An HS environment increased plasma, as well as milk cortisol and cytokines in plasma; however, it decreased plasma, and milk oxytocin, triiodothyronine, and thyroxine (P < 0.05) levels. Exposure to an HS environment reduced the diversity of the fecal microbial population, and resulted in a higher expression of diseases, the environmental adaptation pathway, and the immune related pathway, whereas it lowered the expression of metabolic pathways (P < 0.05). High heat sensitive cows have upregulated metabolisms, environmental adaptation and cellular process pathways, and a downregulated neurodegenerative disease pathway (P < 0.05). Thus, we conclude that exposure to an HS environment modulates physiological characteristics, which may interplay with microbial activity, and in turn, alter the circulation levels of cytokines, implicating the role of the brain-gut axis in dairy cows. The HS environment affected physiological characteristics, cytokine levels, and microbial composition, but IH influenced RT and fecal microbial functions.

Differential Dynamics of the Ruminal Microbiome of Jersey Cows in a Heat Stress Environment

“…Although we observed differences in bacterial taxa in minor groups, there is still the possibility that the abundance of functional genes of the ruminal microbiome can be altered by heat stress. Several studies have emphasized that exposure to heat stress conditions results in the downregulation of metabolic pathways in the rumen [26,79,80]. Moreover, heat stress increases the abundance of genes for environmental adaptation [26].…”

“…One potential explanation may be differences in the rumen microbiome. It is noticeable that heat stress conditions alter the rumen microbiome [26]. The rumen harbors highly dense and diverse microbial populations that play important roles in metabolism and health.…”

Heat Shock Alters Mesenchymal Stem Cell Identity and Induces Premature Senescence

“…Moreover, increased ROS levels elicit stem cell depletion and functional defects in several tissues (Burgess et al, 2014). In bovine, the frequency of many chronic inflammation-related diseases is elevated during a hot period (Olde Riekerink et al, 2007;Chen S. et al, 2018), resulting in reduced animal welfare and significant economic losses to the dairy industry (Key et al, 2014). In utero heat stress was recently found to reduce the placental weight and blood flow and decrease birth weight of calves, and they impaired innate and cellular immunity (Dado-Senn et al, 2020).…”

Chronic heat stress regulates the relation between heat shock protein and immunity in broiler small intestine

“…Although, the Ross broiler contained comparatively longer small intestine 8 . Heat stress even alters the appearance of the small intestine 9 as well as negatively impacts on the immune system 10 by triggering the expression of heat shock proteins (HSPs), and, thereby leading to reduce energy metabolism 11 and suppress broiler growth performance.…”