Temperature and humidity index (THI)-induced rumen bacterial community changes in goats

Integrated analysis of rumen metabolomics and metataxonomics to understand changes in metabolic and microbial community in Korean native goats under heat stress

Heat stress (HS) is an impactful condition in ruminants that negatively affects their physiological and rumen microbial composition. However, a fundamental understanding of metabolomic and metataxonomic mechanisms in goats under HS conditions is lacking. Here, we analyzed the rumen metabolomics, metataxonomics, and serum metabolomics of goats (n = 10, body weight: 41.08 ± 1.83 kg) under optimum temperature period (OTP) (HS-free, temperature humidity index (THI): 57.13 ± 3.98) and high temperature period (HTP) (HS-exposed, THI: 80.27 ± 1.22) conditions, to identify changes in key metabolites and the rumen microbiome induced by HS. Compared to the OTP and HTP conditions, metabolomic analysis revealed significant changes in rumen metabolites related to energy and amino acid metabolism, with HTP goats showing potential rumen metabolic biomarkers, such as butyrate, isopropanol, phenylacetate, and 2-oxoisocaproate (P < 0.001). Serum analysis revealed significant changes in energy metabolism and immune response, with HTP goats showing potential metabolic biomarkers, including acetate, betaine, glucuronate, and kynurenine (P < 0.05). Metataxonomic analysis revealed that HS affected the alpha diversity measurements, including the Chao1 estimate (P < 0.05) and evenness (P < 0.05) between OTP and HTP groups. Through the metabolic association of the rumen microbiome with the metabolome, we found that Fibrobacter and Ruminococcus were enriched in HTP and positively correlated with ruminal microbial metabolites, such as acetate. In addition, Prevotellaceae UCG-003, which was denoted as the keynote genus in the HTP, co-occurred with acetate-producing bacteria such as Quinella and Ruminococcus. Furthermore, we identified that Oscillospiraceae UCG-002, an enriched bacterial genus in HTP, showed a positive correlation with functional features, such as biotin and sulfur metabolism. Our study provided fundamental insights into how HS affected the physiology and rumen microbial compositions of goats and how both microbiome and host-dependent mechanisms contributed to these changes. These findings could potentially suggest strategies for mitigating the adverse effects of HS, including changes in the microbial population and energy metabolism in goats.

Effects of acute and chronic heat stress on the rumen microbiome in dairy goats

OBJECTIVE

The objective of this study was to reveal the influence of acute and chronic heat stress (HS) on the abundance and function of rumen microbiome and host metabolism.

METHODS

Forty mid-lactation goats were randomly divided into two artificial environments: control group and heat-stressed group. This study was recorded from two periods, 1 day and 28 days. The first day was defined as control 1 (CT1) and HS 1 (acute HS), and the last day was defined as CT28 and HS28 (chronic HS). On the first and last day, 6 dairy goats in each group were randomly selected to collect rumen liquid after the morning feeding through oral stomach tubes. The barn temperature and humidity were recorded every day.

RESULTS

Disruption of the rumen microbiome was observed under chronic HS, represented by an increase in the abundance of Prevotella and Bacteroidales (p<0.05), and upregulation of carbohydrate transport and metabolism functions (p<0.05). Additionally, the abundance of Succinimonas and Ruminobacter in chronic HS is lower than in acute HS (p<0.05), and the functions of intracellular trafficking, secretion and vesicular transport, and the cytoskeleton were downregulated (p<0.05).

CONCLUSION

The HS affected the interaction between the microbiota and host, thereby regulated milk production in dairy goats. These findings increased understanding of the crosstalk between hosts and bacteria.

Invited review: Research on ruminal biohydrogenation-Achievements, gaps in knowledge, and future approaches from the perspective of dairy science

Scientific knowledge about ruminal biohydrogenation (BH) has improved greatly since this metabolic process was empirically confirmed in 1951. For years, BH had mostly been perceived as a process to be avoided to increase the postruminal flow of UFA from the diet. Two milestones changed this perception and stimulated great interest in BH intermediates themselves: In 1987, the in vitro anticarcinogenic properties of CLA were described, and in 2000, the inhibition of milk fat synthesis by trans-10,cis-12 CLA was confirmed. Since then, numerous BH metabolites have been described in small and large ruminants, and the major deviation from the common BH pathway (i.e., the trans-10 shift) has been reasonably well established. However, there are some less well-characterized alterations, and the comprehensive description of new BH intermediates (e.g., using isotopic tracers) has not been coupled with research on their biological effects. In this regard, the low quality of some published fatty acid profiles may also be limiting the advance of knowledge in BH. Furthermore, although BH seems to no longer be considered a metabolic niche inhabited by a few bacterial species with a highly specific metabolic capability, researchers have failed to elucidate which specific microbial groups are involved in the process and the basis for alterations in BH pathways (i.e., changes in microbial populations or their activity). Unraveling both issues may be beneficial for the description of new microbial enzymes involved in ruminal lipid metabolism that have industrial interest. From the perspective of dairy science, other knowledge gaps that require additional research in the coming years are evaluation of the relationship between BH and feed efficiency and enteric methane emissions, as well as improving our understanding of how alterations in BH are involved in milk fat depression. Addressing these issues will have relevant practical implications in dairy science.

Environmental Driving of Adaptation Mechanism on Rumen Microorganisms of Sheep Based on Metagenomics and Metabolomics Data Analysis

Natural or artificial selection causes animals to adapt to their environment. The adaptive changes generated by the rumen population and metabolism form the basis of ruminant evolution. In particular, the adaptive drive for environmental adaptation reflects the high-quality traits of sheep that have migrated from other places or have been distant from their origins for a long time. The Hu sheep is the most representative sheep breed in the humid and low-altitude environments (Tai Lake region) in East Asia and has been widely introduced into the arid and high-altitude environments (Tibetan Plateau and Hotan region), resulting in environmental adaptive changes in the Hu sheep. In this study, a joint analysis of the rumen microbial metagenome and metabolome was conducted on Hu sheep from different regions (area of origin and area of introduction) with the objective of investigating the quality traits of Hu sheep and identifying microorganisms that influence the adaptive drive of ruminants. The results demonstrated that the growth performance of Hu sheep was altered due to changes in rumen tissue and metabolism following their introduction to the arid area at relatively high altitude. Metagenomic and metabolomic analyses (five ramsper area) revealed that 3580 different microorganisms and 732 different metabolites were identified in the rumen fluid of arid sheep. Among these, the representative upregulated metabolites were 4,6-isocanedione, methanesulfonic acid and N2-succinyl-L-arginine, while the dominant microorganism was Prevotella ruminicola. The downregulated metabolites were identified as campesterol, teprenone and dihydroclavaminic acid, while the disadvantaged microorganisms were Dialister_succinatiphilus, Prevotella_sp._AGR2160, Prevotella_multisaccharivorax and Selenomonas_bovis. The results of the Pearson analysis indicated that the rumen microbiota and metabolite content of sheep were significantly altered and highly correlated following their relocation from a humid lowland to an arid upland. In particular, the observed changes in rumen microorganisms led to an acceleration of body metabolism, rendering sheep highly adaptable to environmental stress. Prevotella_ruminicola was identified as playing an important role in this process. These findings provide insights into the environmental adaptation mechanisms of sheep.

Impact of wheat processing on growth, serum biochemistry, and ruminal microbiota in sheep (Ovis aries)

This study investigated the impact of wheat processing methods (wheat flour vs wheat pellets) on the growth performance, serum biochemical parameters, and rumen microbiome composition in sheep. Results indicated that feeding of wheat flour resulted in significantly higher terminal weight and average daily gain (P < 0.05) and lower cholesterol and ALP04 levels (P < 0.05) in sheep compared to those fed wheat pellets. Analysis of 16s rDNA high-throughput sequencing data revealed significantly higher microbial richness (Chao1 index) in the rumen of sheep fed wheat flour (P < 0.05), even though the phylum-level composition dominated by Firmicutes, Bacteroidetes, and Proteobacteria was similar in both groups of sheep. Notably, sheep fed wheat flour were found to have a significantly higher relative abundance of Bacteroidetes (P < 0.05). At the genus level, Succinivibrionaceae_UCG-001 and Prevotella_1 were significantly more abundant in the rumen of sheep fed wheat flour (P < 0.05). Correlation analysis identified that both terminal weight and average daily gain were positively correlated with ruminal abundance of Bacteroidetes and Prevotella_1, while ALP04 was negatively correlated with the abundance of these taxa. Functional prediction using PICRUSt2 indicated enrichment of pathways related to the ABC-type glycerol-3-phosphate transport system, and periplasmic components in both wheat flour and pellet fed sheep. Overall, these findings suggest that dietary wheat flour modulates rumen microbiota composition, and improves growth performance in sheep.

An Automated Sprinkler Cooling System Effectively Alleviates Heat Stress in Dairy Cows

(1) Background: Heat stress detrimentally restricted economic growth in dairy production. In particular, the cooling mechanism of the spraying system effectively reduced both environmental and shell temperatures. This study was designed to investigate the underlying modulatory mechanism of an automatic cooling system in alleviating heat-stressed dairy cows. (2) Methods: A total of 1208 multiparous dairy cows was randomly allocated into six barns, three of which were equipped with automatic sprinklers (SPs), while the other three were considered the controls (CONs). Each barn was considered a replicate. (3) Results: Body temperatures and milk somatic cell counts significantly decreased, while DMI, milk yield, and milk fat content significantly increased under SP treatment. Rumen fermentability was enhanced, embodied by the increased levels of total VFA, acetate, propionate, and butyrate after SP treatment. The rumen microbiota results showed the relative abundances of fiber-degrading bacteria, including the Fibrobacters, Saccharofermentans, Lachnospira, Pseudobutyrivibrio, Selenomonas, and Succinivibrio, which significantly increased after receiving the SP treatment. (4) Conclusions: This study demonstrated that SP effectively alleviated heat stress and improved production performances and milk quality through modulating the rumen microbiota composition and fermentation function of dairy cows.

Effects of herbal formula on growth performance, apparent digestibility, antioxidant capacity, and rumen microbiome in fattening lambs under heat stress

Heat stress (HS) causes severe economic losses in sheep industry worldwide. The objective of the present study was to investigate the effects of a herbal formula (HF) supplement on growth, digestibility, antioxidant capacity, and rumen microbes in fattening lambs under HS. The HF composed of four herbs was prepared based on the theory of compatibility of Chinese medicine "Jun-Chen-Zuo-Shi". Two-hundred forty 3-month weaned lambs (initial weight 36.61 ± 0.73 kg) were randomly allocated into four groups, supplemented 0% (Control), 0.5%, 1.0%, and 1.5% HF in diets. All lambs were exposed to HS conditions with 79.7 of average temperature-humidity index throughout an experimental period of 35 days. Growth performance, apparent digestibility, and antioxidant activities, involving antioxidant enzymes and heat shock proteins (HSPs), were measured at the end of trial, as well as microbial communities in bacteria and archaea. Results showed that 0.5% HF increased (P = 0.02) average daily gain by 13.80% and decreased feed-to-gain ratio (P = 0.03) by 14.68%, compared to control. With increasing HF doses, the digestibility of ether extract and acid detergent fiber demonstrated a cubical (P < 0.01) and quadratic (P = 0.03) relation, respectively; moreover, glutathione peroxidase and catalase activities demonstrated a quadratic increase (P < 0.01). Serum levels of HSP60, HSP70, and HSP90 for 0.5% HF were lower than that in control (P < 0.05). On the other hand, total volatile fatty acid, acetic acid, butyric acid, valeric acid, and isovaleric acid levels exhibited quadratic increases (P ≤ 0.01) with HF doses. From rumen microbes, the abundance and diversity of bacterial community were improved by HF supplements. Particularly for 0.5% HF group, the operational taxonomic units were the greatest among all groups. Compared to control, Prevotella abundance for HF supplements from 0.5 to 1.5% increased by 35.57 to 60.15%, and Succiniclasticum abundance demonstrated a quadratic pattern (P = 0.02) with doses. Additionally, Methanosphaera abundance in archaeal community raised by 0.2 to 3.3-folds when lambs were fed the HF additions of 0.5 to 1.5%. In summary, dietary HF supplements would contribute to alleviating HS in lambs, and our results suggest the optimal dose of 0.5% HF supplement in diet.

Heat stress-associated changes in the intestinal barrier, inflammatory signals, and microbiome communities in dairy calves

Recent studies indicate that heat stress pathophysiology is associated with intestinal barrier dysfunction, local and systemic inflammation, and gut dysbiosis. However, inconclusive results and a poor description of tissue-specific changes must be addressed to identify potential intervention targets against heat stress illness in growing calves. Therefore, the objective of this study was to evaluate components of the intestinal barrier, pro- and anti-inflammatory signals, and microbiota community composition in Holstein bull calves exposed to heat stress. Animals (mean age = 12 wk old; mean body weight = 122 kg) penned individually in temperature-controlled rooms were assigned to (1) thermoneutral conditions (constant room temperature at 19.5°C) and restricted offer of feed (TNR, n = 8), or (2) heat stress conditions (cycles of room temperatures ranging from 20 to 37.8°C) along with ad libitum offer of feed (HS, n = 8) for 7 d. Upon treatment completion, sections of the jejunum, ileum, and colon were collected and snap-frozen immediately to evaluate gene and protein expression, cytokine concentrations, and myeloperoxidase activity. Digesta aliquots of the ileum, colon, and rectum were collected to assess bacterial communities. Plasma was harvested on d 2, 5, and 7 to determine cytokine concentrations. Overall, results showed a section-specific effect of HS on intestinal integrity. Jejunal mRNA expression of TJP1 was decreased by 70.9% in HS relative to TNR calves. In agreement, jejunal expression of heat shock transcription factor-1 protein, a known tight junction protein expression regulator, decreased by 48% in HS calves. Jejunal analyses showed that HS decreased concentrations of IL-1α by 36.6% and tended to decrease the concentration of IL-17A. Conversely, HS elicited a 3.5-fold increase in jejunal concentration of anti-inflammatory IL-36 receptor antagonist. Plasma analysis of pro-inflammatory cytokines showed that IL-6 decreased by 51% in HS relative to TNR calves. Heat stress alteration of the large intestine bacterial communities was characterized by increased genus Butyrivibrio_3, a known butyrate-producing organism, and changes in bacteria metabolism of energy and AA. A strong positive correlation between the rectal temperature and pro-inflammatory Eggerthii spp. was detected in HS calves. In conclusion, this work indicates that HS impairs the intestinal barrier function of jejunum. The pro- and anti-inflammatory signal changes may be part of a broader response to restore intestinal homeostasis in jejunum. The changes in large intestine bacterial communities favoring butyrate-producing organisms (e.g., Butyrivibrio spp.) may be part of a successful response to maintain the integrity of the colonic mucosa of HS calves. The alteration of intestinal homeostasis should be the target for heat stress therapies to restore biological functions, and, thus highlights the relevance of this work.

Altered rumen microbiome and correlations of the metabolome in heat-stressed dairy cows at different growth stages

IMPORTANCE

Heat stress is one of the main causes of economic losses in the dairy industry worldwide; however, the mechanisms associated with the metabolic and microbial changes in heat stress remain unclear. Here, we characterized both the changes in metabolites, rumen microbial communities, and their functional potential indices derived from rumen fluid and serum samples from cows at different growth stages and under different climates. This study highlights that the rumen microbe may be involved in the regulation of lipid metabolism by modulating the fatty acyl metabolites. Under heat stress, the changes in the metabolic status of growing heifers, heifers, and lactating cows were closely related to arachidonic acid metabolism, fatty acid biosynthesis, and energy metabolism. Moreover, this study provides new markers for further research to understand the effects of heat stress on the physiological metabolism of Holstein cows and the time-dependent changes associated with growth stages.

Intestinal microbiota dysbiosis and liver metabolomic changes during brain death

Background

Whether a causative link exists between brain death (BD) and intestinal microbiota dysbiosis is unclear, and the distortion in liver metabolism associated with BD requires further exploration.

Methods

A rat model of BD was constructed and sustained for 9 h (BD group, n=6). The sham group (n=6) underwent the same procedures, but the catheter was inserted into the epidural space without ballooning. Intestinal contents and portal vein plasma were collected for microbiota sequencing and microbial metabolite detection. Liver tissue was resected to investigate metabolic alterations, and the results were compared with those of a sham group.

Results

α-diversity indexes showed that BD did not alter bacterial diversity. Microbiota dysbiosis occurred after 9 h of BD. At the family level, Peptostreptococcaceae and Bacteroidaceae were both decreased in the BD group. At the genus level, Romboutsia, Bacteroides, Erysipelotrichaceae_UCG_004, Faecalibacterium, and Barnesiella were enriched in the sham group, whereas Ruminococcaceae_UCG_007, Lachnospiraceae_ND3007_group, and Papillibacter were enriched in the BD group. Short-chain fatty acids, bile acids, and 132 other microbial metabolites remained unchanged in both the intestinal contents and portal vein plasma of the BD group. BD caused alterations in 65 metabolites in the liver, of which, carbohydrates, amino acids, and organic acids accounted for 64.6%. Additionally, 80.0% of the differential metabolites were decreased in the BD group livers. Galactose metabolism was the most significant metabolic pathway in the BD group.

Conclusions

BD resulted in microbiota dysbiosis in rats; however, this dysbiosis did not alter microbial metabolites. Deterioration in liver metabolic function during extended periods of BD may reflect a continuous worsening in energy deficiency.

The Effects of Temperature and Humidity Index on Growth Performance, Colon Microbiota, and Serum Metabolome of Ira Rabbits

This study investigates the effects of different THI values on growth performance, intestinal microbes, and serum metabolism in meat rabbits. The results showed that there were significant differences in THI in different location regions of the rabbit house. The high-THI group (HG) could significantly reduce average daily gain and average daily feed intake in Ira rabbits (p < 0.05). The low-THI group (LG) significantly increased the relative abundance of Blautia (p < 0.05). The HG significantly increased the relative abundance of Lachnospiraceae NK4A136 group and reduced bacterial community interaction (p < 0.05). The cytokine-cytokine receptor interactions, nuclear factor kappa B signaling pathway, and toll-like receptor signaling pathway in each rabbit's gut were activated when the THI was 26.14 (p < 0.05). Metabolic pathways such as the phenylalanine, tyrosine, and tryptophan biosynthesis and phenylalanine metabolisms were activated when the THI was 27.25 (p < 0.05). Meanwhile, the TRPV3 and NGF genes that were associated with heat sensitivity were significantly upregulated (p < 0.05). In addition, five metabolites were found to be able to predict THI levels in the environment with an accuracy of 91.7%. In summary, a THI of 26.14 is more suitable for the growth of meat rabbits than a THI of 27.25, providing a reference for the efficient feeding of meat rabbits.

Heat Stress-Induced Intestinal Barrier Impairment: Current Insights into the Aspects of Oxidative Stress and Endoplasmic Reticulum Stress

Heat stress (HS) occurs when the sensible temperature of animals exceeds their thermoregulatory capacity, a condition that exerts a detrimental impact on health and growth. The intestinal tract, as a highly sensitive organ, has been shown to respond to HS by exhibiting mucosal injury, intestinal leakage, and disturbances in the gut microbiota. Oxidative stress and endoplasmic reticulum stress (ERS) are both potential outcomes of long-term exposure to high temperatures and have been linked to apoptosis, autophagy, and ferroptosis. In addition, HS alters the composition of the gut microbiota accompanied by changed levels of bacterial components and metabolites, rendering the gut more vulnerable to stress-related injury. In this review, we present recent advances in mechanisms of oxidative stress-associated ERS in response to HS, which is destructive to intestinal barrier integrity. The involvement of autophagy and ferroptosis in ERS was highlighted. Further, we summarize the relevant findings regarding the engagement of gut microbiota-derived components and metabolites in modulation of intestinal mucosal injury induced by HS.

Gastro-Intestinal Microbiota in Equines and Its Role in Health and Disease: The Black Box Opens

Horses are large non-ruminant herbivores and rely on microbial fermentation for energy, with more than half of their maintenance energy requirement coming from microbial fermentation occurring in their enlarged caecum and colon. To achieve that, the gastro-intestinal tract (GIT) of horses harbors a broad range of various microorganisms, differing in each GIT segment, which are essential for efficient utilization of feed, especially to use nutrients that are not or little degraded by endogenous enzymes. In addition, like in other animal species, the GIT microbiota is in permanent interplay with the host's cells and is involved in a lot of functions among which inflammation, immune homeostasis, and energy metabolism. As for other animals and humans, the horse gut microbiome is sensitive to diet, especially consumption of starch, fiber, and fat. Age, breeds, stress during competitions, transportation, and exercise may also impact the microbiome. Because of its size and its complexity, the equine GIT microbiota is prone to perturbations caused by external or internal stressors that may result in digestive diseases like gastric ulcer, diarrhea, colic, or colitis, and that are thought to be linked with systemic diseases like laminitis, equine metabolic syndrome or obesity. Thus, in this review we aim at understanding the common core microbiome -in terms of structure and function- in each segment of the GIT, as well as identifying potential microbial biomarkers of health or disease which are crucial to anticipate putative perturbations, optimize global practices and develop adapted nutritional strategies and personalized nutrition.

Microbiome-Metabolome Responses in Ruminal Content and Feces of Lactating Dairy Cows With N-Carbamylglutamate Supplementation Under Heat Stress

The objective of the present study was to investigate the effects of N-carbamylglutamate (NCG) supplementation on metabolic profile and microbiota in ruminal content and feces of lactating dairy cows under heat stress (HS). Forty-eight lactating Holstein cows (154 ± 13.6 days in milk) were assigned randomly to four treatments (n = 12), to receive 0, 15, 20, or 25 g/day of commercial NCG (proportion: 97.7%) for the period of 60 days. The recorded ambient temperature–humidity index (THI) suggested that the cows were exposed to HS for almost the entire experimental period (average THI: 80.6). Samples of ruminal content and feces were collected at the end of the trial (day 60) to determine the biological effects of NCG supplementation on metabolome and microbiota using mass spectrometry-based metabolomics and 16S rRNA gene sequencing techniques, respectively. Results showed that NCG supplementation enhanced the levels of ruminal microbial protein, total volatile fatty acids (VFAs), and the molar proportion of propionate in the rumen, but lowered the ruminal pH, ammonia nitrogen (NH3-N), and the ratio of acetate to propionate. NCG at doses of 20 and 25 g/day reduced the community richness and diversity of ruminal microbiota with the decrease of Shannon and Simpson diversity. Compositions of ruminal and fecal microbiotas were altered by NCG, and the PICRUSt results revealed that metabolic pathways of the bacteria, such as amino acid metabolism, energy metabolism, and pyruvate metabolism, were enriched in NCG groups. Distinct changes in the metabolomic profile of ruminal fluid were observed between the control and NCG groups. Changes of 26 metabolites mainly involved in arginine metabolism, glutamate metabolism, and nitrogen metabolism were observed associated with NCG supplementation. These results provided new insights into the effects of NCG on metabolomic profile and microbiota in ruminal content and feces, and the optimal dose of NCG supplemented to dairy cows was 20 g/hd/day, which contributed to understanding the effects of NCG on HS in lactating dairy cows.

Heat stress impacts the multi-domain ruminal microbiota and some of the functional features independent of its effect on feed intake in lactating dairy cows

Background

Heat stress (HS) affects the ruminal microbiota and decreases the lactation performance of dairy cows. Because HS decreases feed intake, the results of previous studies were confounded by the effect of HS on feed intake. This study examined the direct effect of HS on the ruminal microbiota using lactating Holstein cows that were pair-fed and housed in environmental chambers in a 2 × 2 crossover design. The cows were pair-fed the same amount of identical total mixed ration to eliminate the effect of feed or feed intake. The composition and structure of the microbiota of prokaryotes, fungi, and protozoa were analyzed using metataxonomics and compared between two thermal conditions: pair-fed thermoneutrality (PFTN, thermal humidity index: 65.5) and HS (87.2 for daytime and 81.8 for nighttime).

Results

The HS conditions altered the structure of the prokaryotic microbiota and the protozoal microbiota, but not the fungal microbiota. Heat stress significantly increased the relative abundance of Bacteroidetes (primarily Gram-negative bacteria) while decreasing that of Firmicutes (primarily Gram-positive bacteria) and the Firmicutes-to-Bacteroidetes ratio. Some genera were exclusively found in the heat-stressed cows and thermal control cows. Some co-occurrence and mutual exclusion between some genera were also found exclusively for each thermal condition. Heat stress did not significantly affect the overall functional features predicted using the 16S rRNA gene sequences and ITS1 sequences, but some enzyme-coding genes altered their relative abundance in response to HS.

Conclusions

Overall, HS affected the prokaryotes, fungi, and protozoa of the ruminal microbiota in lactating Holstein cows to a different extent, but the effect on the structure of ruminal microbiota and functional profiles was limited when not confounded by the effect on feed intake. However, some genera and co-occurrence were exclusively found in the rumen of heat-stressed cows. These effects should be attributed to the direct effect of heat stress on the host metabolism, physiology, and behavior. Some of the “heat-stress resistant” microbes may be useful as potential probiotics for cows under heat stress.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00717-z.

Sex differences in rumen fermentation and microbiota of Tibetan goat

BACKGROUND

The gut microbiota play an important role in maintaining host metabolism, the immune system and health, while sex, genotype, diet and health have specific effects on the composition of the gut microbiota. Therefore, to explore the sex differences in the structure and function of rumen microbiota in Tibetan goats, herein we analyzed sex differences in rumen fermentation parameters, rumen microbiota and the expression of genes related to VFA transport in Tibetan goats.

RESULTS

The results showed that the contents of acetic acid and propionic acid in the rumen of TGM (Tibetan goat male) were significantly higher than those in TGFm (Tibetan goat female) (P < 0.05), and total VFAs was significantly higher in TGM than TGFm (P < 0.05). Expression of the VFA transport-related genes DRA, AE2, MCT-1, NHE1, and NHE2 in the rumen epithelium of TGFm was significantly higher than that in TGM. Analysis of the composition and structure of the rumen microbiota revealed significant sex differences. At the phylum level, Firmicutes and Bacteroidetes were the dominant phyla in Tibetan goats. In addition, Fibrobacteres and Spirochaetes had significantly greater relative abundances in TGFm than in TGM (P < 0.05). At the genus level, the relative abundance of Fibrobacter, Ruminococcus_1 and Pyramidobacter was significantly higher in TGFm than in TGM (P < 0.05). The functional prediction results showed that replication, recombination and repair, RNA processing and modification were mainly enriched in TGFm (P < 0.05).

CONCLUSIONS

Correlation analysis revealed significant associations of some rumen microbiota with the fermentation product VFAs and VFA transport-related genes. We concluded that yearling TGM and TGFm have distinct fermentation and metabolism abilities when adapting to the plateau environment, which provides a certain sex reference basis for Tibetan goat adaptation to the plateau environment.

Intestinal Microbial Diversity of Free-Range and Captive Yak in Qinghai Province

BACKGROUND

The gut microbiome is a large and complex organic assemblage with subtle and close relationships with the host. This symbiotic mechanism is important for the health and adaptability of the host to the environment. Compared with other ruminants, there are few studies on yak intestinal microbes. The study of the gut microbiota of the yak will help us better understand the correlation between the microbiota and the environmental adaptability of the host. In this study, we adapted 16S rDNA sequencing technology to investigate the diversity and composition of the intestinal microbial community in free-range yaks and captive yaks living on the Qinghai-Tibet Plateau (QTP).

RESULTS

Sequencing results showed that the intestinal microbial community diversity was significantly different between free-range yaks and captive yaks. Firmicutes and Bacteroidetes were the dominant bacteria in both free-range and captive yaks. However, there were differences between the microbes of the two analyzed feeding styles in different classification levels. Compared with the captive type, free-range yaks had a higher abundance of Ruminococcaceae, Eubacteriaceae, Desulfovibrionaceae, Elusimicrobium, and Oscillibacter, while the abundance of Succinivibrionaceae, Clostridiales, Lachnospiraceae, Prevotellaceae, Roseburia, and Barnesiella was relatively low. The feeding method may be the key factor for the formation of intestinal flora differences in yaks, while altitude did not significantly affect Qinghai yak.

CONCLUSIONS

In this study, we used 16S rDNA sequencing technology to investigate the composition of intestinal flora in free-range and captive yaks living on the QTP. The exploration of dietary factors can provide a theoretical basis for scientifically and rationally breeding yaks and provides a new direction for the development of prebiotics and microecological agents.

Seasonal Differences in Fecal Microbial Community Structure and Metabolism of House-Feeding Chinese Merino Fine-Wool Sheep

The digestive tract microorganisms play a very important role in the host's nutrient intake, environmental suitability, and affect the host's physiological mechanism. Previous studies showed that in different seasons, mammalian gut microbes would be different. However, most of them are concentrated in wild animals. It remains unclear how seasonal change affects the gut microbes of Chinese merino fine-wool Sheep. Therefore, in this experiment, we continuously collected blood and feces samples of 50 Chinese merino fine-wool sheep in different seasons, measured the physiological indicators of blood, and passed 16S rRNA amplicon sequencing, determined the microbial community structure of fecal microorganisms and predicted flora function by PICRUSt. The results of blood physiological indicators showed that WBC, Neu and Bas in spring were significantly higher than those of other seasons. Fecal microbial sequencing revealed seasonal changes in gut microbial diversity and richness. Among them, Chinese merino fine-wool sheep had the highest gut microbes in summer. Firmicutes and Bacteroidetes were the dominant phyla, and they were unaffected by seasonal fluctuations. LEfSE analysis was used to analyze representative microorganisms in different seasons. The Lachnospiraceae and its genera (Lachnospiraceae_NK4A136_group, Lachnospiraceae_AC2044_group, g_unclassified_f_ Lachnospiraceae) were representative microorganisms in the three seasons of spring, summer and winter with harsh environmental conditions; while in autumn with better environmental conditions, the Ruminococcaceae and its genus (Ruminococcaceae_UCG-009 and Ruminococcaceae_UCG-005) were the representative microorganism. In autumn, the ABC transporter and the pyruvate metabolic pathway were significantly higher than other seasons. Correlation analysis results showed that Lachnospiraceae participated in the ABC transporters metabolic pathway, which caused changes in the blood physiological indicators. Overall, our results showed that, in response to seasonal changes, Chinese merino fine-wool sheep under house-feeding have adjusted their own gut microbial community structure, causing changes in the metabolism, and thus changing the physiological conditions of the blood. In the cold season, producers should focus on regulating the nutritional level of feed, enhancing the level of butyric acid in young animals to increase the ABC transporter, resist the external harsh environment, and improve the survival rate.

Heat Stress Affects Faecal Microbial and Metabolic Alterations of Rabbits

Heat stress can impair the rabbit immune system, induce oxidative stress, and cause many complications. These diseases are characterized by metabolic disorders, but the underlying mechanism is unknown. As a result, the current research determines the effects of HS on intestinal microorganisms in rabbits and the metabolic pathway disorders caused by HS. Twelve rabbits were randomly assigned to one of two groups: CON (22–24°C) and HS (30°C–32°C). Both the groups were treated for 15 days. Blood and fecal samples were collected on day 15. Serum immune oxidation indices were determined using a commercial ELISA kit, and the microbiome of rabbit feces was studied using 16S rRNA gene sequencing. Non-targeted metabolomics was analyzed using ultra-high-performance liquid chromatography-mass spectrometry (UHPC MS/MS). The findings revealed that HS significantly increased IgG and T-AOC levels in serum, whereas it decreased TNF-α and IL-10. NMDS analysis revealed a substantial difference in bacterial community composition between HS and CON groups. At the phylum level, the abundance of Firmicutes, Protobacteria, and Verrucomicrobiota was significantly higher in the HS group, whereas the abundance of Bacteriodota was reduced in the CON group. V9D2013 group, Haloplasma, Comamonas, Clostridium sensu stricto 1, Ruminiclostridium, Syntrophus Lutispora, at the genus level Syntrophorhabdus, Paeniclostridium, Clostridium sensu stricto 6, Candidatus Caldatribacterium, Spirochaeta Synergistaceae, Syner-01, [Eubacterium] xylanophilum group, Cellulosilyticum, ADurb.Bin120, and Devosia were significantly upregulated in the HS group. The metabolism of the HS group was considerably upregulated compared with the metabolism of the CON group, according to principal component analysis (PCA) and least-squares discriminant analysis (PLS-DA). HS increased the concentrations of 4-pyridoxic acid, kynurenine, 20-OH-leukotriene B4, and dopamine and decreased the concentration of pyridoxal. In the rabbit gut, these compounds primarily impact the metabolic pathways of vitamin B6, tryptophan, neutrophil activation, and prolactin. 4-Pyridoxic acid, pyridoxal, kynurenine, 20-OH-leukotriene B4, and dopamine are essential inflammatory response markers and oxidative stress.

Rumen Microbial Metabolic Responses of Dairy Cows to the Honeycomb Flavonoids Supplement Under Heat-Stress Conditions

Flavonoids played critical roles in stabilizing microbial homoeostasis when animals suffered exoteric stresses. However, whether flavonoids attenuated heat stress of dairy cows is still not clear. Therefore, in the present article, flavonoids extracted from honeycomb were supplemented to investigate the production, digestibility, and rumen microbial metabolism responses of cows under heat stress conditions. A total of 600 multiparous dairy herds were randomly allotted into the control treatment (CON), the heat stress (HS) treatment, and the honeycomb flavonoids supplement under heat stress conditions (HF) treatment for a 30-day-long trial. Each treatment contains 4 replicates, with 50 cows in each replicate. Production performances including dry matter intake (DMI), milk production, and milk quality were measured on the basis of replicate. Furthermore, two cows of each replicate were selected for the measurement of the nutrient digestibility, the ruminal fermentable parameters including ruminal pH, volatile fatty acids, and ammonia-N, and the rumen microbial communities and metabolism. Results showed that HF effectively increased DMI, milk yield, milk fat, and ruminal acetate content (p < 0.05) compared with HS. Likewise, digestibility of NDF was promoted after HF supplement compared with HS. Furthermore, relative abundances of rumen microbial diversities especially Succiniclasticum, Pseudobutyrivibrio, Acetitomaculum, Streptococcus, and Succinivibrio, which mainly participated in energy metabolism, significantly improved after HF supplement. Metabolomic investigation showed that HF supplement significantly upregulated relative content of lipometabolic-related metabolites such as phosphatidylglycerol, phosphatidylinositol, phosphatidylserine, and phosphatidylethanolamine, while it downregulated biogenic amines. In summary, HF supplement helps proliferate microbial abundances, which further promoted fiber digestibility and energy provision, and ultimately enhances the production performances of dairy cows under heat stress conditions.

Alterations in intestinal microbiota composition coincide with impaired intestinal morphology and dysfunctional ileal immune response in growing-finishing pigs under constant chronic heat stress

Background

Previous studies had shown that short-term acute heat stress (HS) affected the host’s metabolism and intestinal microbiota independent of feed intake (FI) reduction, and long-term calorie restriction caused intestinal morphological injuries and gut microbial alterations. However, research on the effects of constant chronic HS on intestinal microbial composition and the roles of FI reduction played in is limited. This study aimed to investigate the effects of 7-day constant chronic HS on the composition of intestinal microbes in growing-finishing pigs, and its relationship with pigs’ performance, intestinal morphology, and ileal immune response. Twenty-four growing-finishing pigs (Duroc × Large White × Landrace, 30 ± 1 kg body weight) were randomly assigned to three treatments (n = 8), 1) thermal neutral (TN) conditions (25 ± 1 °C) with ad libitum FI, 2) HS conditions (35 ± 1 °C) with ad libitum FI, 3) pair-fed (PF) with HS under TN conditions to discriminate the confounding effects of dissimilar FI, and the FI was the previous day’s average FI of HS. The small intestinal segments (duodenum, jejunum, and ileum) and feces were collected on d 8.

Results

Results indicated that HS drastically declined (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) (about 61%) in comparison with TN, and caused hyperpyrexia, meanwhile PF caused hypothermia. Morphological observation by light and electron microscopes showed that both HS and PF treatment decreased (P < 0.05) the villus and microvillus height compared with TN. Additionally, HS increased (P < 0.05) protein expression of heat shock protein 70 in the duodenum, jejunum, and ileum. Furthermore, the expression of tight junction protein zonula occluden-1 (ZO-1) in the duodenum and ileum, and Occludin in the ileum were enhanced (P < 0.05) compared with TN and PF. Moreover, HS significantly enhanced (P < 0.05) the mRNA relative expression of inflammatory cytokines (TLR-2, TLR-4, and tumor necrosis factor-α (TNF-α), IL-6, IL-8, PG1–5, β-defensin 2 (pBD-2)), mucins (mucin-1 and mucin-2) and P65 protein level in the ileal mucosa tissue. Intestinal microbiota analysis by 16S rRNA sequencing showed lower (P < 0.10) α diversity in both HS and PF, and a separated cluster of β diversity among groups. Compared with TN, HS but not PF mainly reduced (FDR < 0.05) Bacteroidetes (phylum), Bacteroidia (class) and elevated the proportions of Proteobacteria (phylum, FDR < 0.05), Bacillales (order, FDR < 0.05), Planococcaceae (family, FDR < 0.05), Kurthia (genus, FDR < 0.05), Streptococcaceae (family, FDR < 0.10) and Streptococcus (genus, FDR < 0.10). Notably, Lactobacillales (order) was decreased (FDR < 0.05) by PF alone. Furthermore, the Spearman correlation analysis indicated that the microbes prevalent in HS were positively (P < 0.05) associated with intestinal morphological injuries indicators and ileal immune response parameters, and the microbes reduced in HS were negatively (P < 0.05) with the performance data.

Conclusions

Intestinal morphological injuries and ileal immune response caused by constant chronic HS independent of FI showed close connections with alterations in intestinal microbiota in growing-finishing pigs.

Microbiota-gut-brain axis and nutritional strategy under heat stress

Heat stress is a very universal stress event in recent years. Various lines of evidence in the past literatures indicate that gut microbiota composition is susceptible to variable temperature. A varied microbiota is necessary for optimal regulation of host signaling pathways and disrupting microbiota-host homeostasis that induces disease pathology. The microbiota–gut–brain axis involves an interactive mode of communication between the microbes colonizing the gut and brain function. This review summarizes the effects of heat stress on intestinal function and microbiota–gut–brain axis. Heat stress negatively affects intestinal immunity and barrier functions. Microbiota-gut-brain axis is involved in the homeostasis of the gut microbiota, at the same time, heat stress affects the metabolites of microbiota which could alter the function of microbiota–gut–brain axis. We aim to bridge the evidence that the microbiota is adapted to survive and thrive in an extreme environment. Additionally, nutritional strategies for alleviating intestinal heat stress are introduced.

Fermentation quality of herbal tea residue and its application in fattening cattle under heat stress

Background

Herbal tea residue (HTR) is generally considered to be the waste of herbal tea beverage production while it still retains rich nutrients and active substances. The main aim of the present study was to investigate the effect of fermentation technology on improving the quality of HTRs, and focus on the fermented HTR-induced alleviation of summer heat stress in fattening cattle.

Results

In this study, the waste HTR was fermented and then fed to a total of 45 fattening cattle that were divided into 3 groups (fermented HTR replaced 0, 15, 30% of the forage component of the diet), and the feeding experiment was lasted for 40 days. The physiological indexes, growth performance and fecal microbiota of fattening cattle were evaluated and results showed that fermented HTR could effectively reduce the respiratory rate and rectal temperature of fattening cattle under heat stress, increase the daily feed intake and daily gain, and improve the antioxidant content and blood immune index. In addition, we studied the fecal microbiota composition of 6 fattening cattle in control and 30% HTR substitution groups and found fermented HTR significantly changed the composition of fecal microbiota and increased microbial diversity, and correlation analysis suggested that the bacteria were closely related to fecal SCFA levels of fattening cattle under heat stress.

Conclusions

In this study, fermented HTR replaced 30% of the forage component of the diet that can change the intestine microorganisms, maintain health and alleviate the heat stress of fattening cattle.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03061-y.

Heat Stress Alters the Intestinal Microbiota and Metabolomic Profiles in Mice

Background

Heat stress has negative effects on the intestinal health of humans and animals. However, the impact of heat stress on intestinal microbial and metabolic changes remains elusive. Here, we investigated the cecal microbial and metabolic profiles in mice in response to heat stress.

Methods

The mouse heat stress model was constructed by simulating a high-temperature environment. Twenty mice were randomly assigned to two groups, the control group (CON, 25°C) and the heat treatment group (HS, 40°C from 13:00 to 15:00 every day for 7 days). Serum and cecal contents were collected from the mice for serum biochemical analysis, 16S rRNA high-throughput sequencing, and non-targeted metabolomics.

Results

Both core body temperature and water intake were significantly increased in the HS group. Serum biochemical indicators were also affected, including significantly increased triglyceride and decreased low-density lipoprotein in the heat stress group. The composition and structure of intestinal microbiota were remarkably altered in the HS group. At the species level, the relative abundance of Candidatus Arthromitus sp. SFB-mouse-Japan and Lactobacillus murinus significantly reduced, while that of Lachnospiraceae bacterium 3-1 obviously increased after HS. Metabolomic analysis of the cecal contents clearly distinguished metabolite changes between the groups. The significantly different metabolites identified were mainly involved in the fatty acid synthesis, purine metabolism, fatty acid metabolism, cyanoamino acid metabolism, glyceride metabolism, and plasmalogen synthesis.

Conclusion

In summary, high temperature disrupted the homeostatic balance of the intestinal microbiota in mice and also induced significant alterations in intestinal metabolites. This study provides a basis for treating intestinal disorders caused by elevated temperature in humans and animals and can further formulate nutritional countermeasures to reduce heat stress-induced damage.

Correlation of Breed, Growth Performance, and Rumen Microbiota in Two Rustic Cattle Breeds Reared Under Different Conditions

The use of rustic cattle is desirable to face challenges brought on by climate change. Maremmana (MA) and Aubrac (AU) are rustic cattle breeds that can be successfully used for sustainable production. In this study, correlations between two rearing systems (feedlot and grazing) and the rumen microbiota, the lipid composition of rumen liquor (RL), and the growth performance of MA and AU steers were investigated. Bacterial community composition was characterized by high-throughput sequencing of 16S rRNA gene amplicons, and the RL lipid composition was determined by measuring fatty acid (FA) and the dimethyl acetal profiles. The main factor influencing bacterial community composition was the cattle breed. Some bacterial groups were positively correlated to average daily weight gain for the two breeds (i.e., Rikenellaceae RC9 gut group, Fibrobacter and Succiniclasticum in the rumen of MA steers, and Succinivibrionaceae UCG-002 in the rumen of AU steers); despite this, animal performance appeared to be influenced by short chain FAs production pathways and by the presence of H₂ sinks that divert the H₂ to processes alternative to the methanogenesis.

Changes in Rumen Microbiota Affect Metabolites, Immune Responses and Antioxidant Enzyme Activities of Sheep under Cold Stimulation

Low-temperature environments can strongly affect the normal growth and health of livestock. In winter, cold weather can be accompanied by strong winds that aggravate the effects of cold on livestock. In this study, two experiments were conducted to investigate the effect of low temperature and/or wind speed on physiological indices, rumen microbiota, immune responses and oxidative stress in sheep. When sheep were exposed to cold temperature and/or stronger wind speeds, the average daily gain (ADG) decreased (p < 0.05), and the abundance of Lachnospiraceae was significantly higher (p < 0.05). The acetate and propionate contents and the proportion of propionate in the rumen also significantly reduced (p < 0.05). The immunoglobulin G (IgG) and TH1-related cytokines in the blood were significantly lower (p < 0.05). However, antioxidant enzyme contents were significantly increased and the concentration of malondialdehyde (MDA) was reduced (p < 0.05). In a cold environment, the abundance of Lachnospiraceae in the rumen of sheep was highly enriched, and the decreasing of propionate might be one of the factors affecting the immunity of the animals, the sheep did not suffer from oxidative damage during the experiment.

Heat stress influence the microbiota and organic acids concentration in beef cattle rumen

The objective of this study was to evaluate the effect of heat stress on meta-taxonomic and metabolic profiles of prokaryotes in beef cattle rumen. Six pure-breed Nellore heifers with ruminal cannulas were used in the study. Six treatments were tested in a 6 × 6 Latin Square with six periods of 21days. The treatments were evaluated in a 2 × 2 + 2 factorial arrangement, consisting of 4 combinations: two temperatures conditions (thermoneutral, TN: 24 °C; and heat stress, HS: 34 °C) and two dietary energy concentration [low-energy (37% non-fibrous carbohydrates - NFC, 12 Mcal of metabolizable energy per kg of dry matter) or high-energy concentration (50.5% NFC, 18.49 Mcal of metabolizable energy per kg of dry matter)] plus two additional treatments with animals maintained in TN conditions but with your intake restricted (TN-RI) to the same of the heifers in HS with the two dietary energy concentration. The meta-genome was sequenced by MiSeq Sequencing System platform, and the DNA sequences were analysed using Geneious 10.2.3 software. The metabolic profile was evaluated by liquid and gas chromatography. Animals under HS presented lower (P = 0.04) prokaryote richness than animals under TN conditions. The genera Flavonifractor (1.4%), Treponema (0.6%) and Ruminococcus (0.9%) showed the lowest (P < 0.04) and Carnobacterium (7.7%) the highest (P = 0.02) relative abundance when the animals were submitted to HS, in relation to animals in TN. A total of 49 different metabolites were identified in the ruminal samples. The concentration of isobutyric acid (4.32 mM) was highest in bovine rumen under HS conditions. Heat stress influenced the microbiota and concentration of some organic acids in beef cattle rumen. There was a reduction in the richness of rumen in cattle under heat stress, but the diversity of prokaryotes was not affected.

Do seasonal microbiome changes affect infection susceptibility, contributing to seasonal disease outbreaks?

The aim of the present paper is to explore whether seasonal outbreaks of infectious diseases may be linked to changes in host microbiomes. This is a very important issue, because one way to have more control over seasonal outbreaks is to understand the factors that underlie them. In this paper, I will evaluate the relevance of the microbiome as one of such factors. The paper is based on two pillars of reasoning. Firstly, on the idea that microbiomes play an important role in their hosts' defence against infectious diseases. Secondly, on the idea that microbiomes are not stable, but change seasonally. These two ideas are combined in order to argue that seasonal changes in a given microbiome may influence the functionality of the host's immune system and consequently make it easier for infectious agents to infect the host at certain times of year. I will argue that, while this is only a theoretical possibility, certain studies may back up such claims. Furthermore, I will show that this does not necessarily contradict other hypotheses aimed at explaining seasonal outbreaks; in fact, it may even enhance them.

Exploring the Rumen and Cecum Microbial Community from Fetus to Adulthood in Goat

Simple Summary

The rumen and cecum are two important fermentation organs in ruminants. The acquisition and development of the neonatal microbiome, as well as the difference between these two organs, was important. We performed 16S rRNA gene sequencing to study the diversity, structure and composition of the goat microbial communities between the rumen and cecum from fetus to adulthood. The results revealed the microbial transmission routes from the mother to fetus, and also revealed the establishment and dynamic fluctuations of the gut microbiome from fetus to adulthood in goats.

Abstract

The present study aimed to investigate the colonization process of epithelial bacteria attached to the rumen and intestinal tract tissue during the development of goats after birth. However, this process from fetus to adulthood was very limited. In goats, the rumen and cecum are two important fermentation organs, and it is important to study the acquisition and development of the neonatal microbiome, as well as the difference between these two organs. To characterize the microbial establishment and dynamic changes in the rumen and cecum from fetus to adulthood, we performed 16S rRNA gene sequencing for 106 samples from 47 individuals of nine pregnant mother–fetus pairs and 16 kids from birth up to 6 months. The diversity, structure and composition of the microbial communities were distinct between the rumen and cecum after birth, while they were similar in the fetal period. The study showed a rapid loss and influx of microbes at birth, followed by slight selection after drinking colostrum, and then a strong selection after weaning, suggesting that the establishment and dynamic fluctuations of the gut microbiome undergoes three distinct phases of microbiome progression in life: a conserved phase (during late pregnancy in the fetus), a transitional phase (newborn until weaning), and a stable phase (from weaning to adulthood). The results supported the view that microbes exist in the fetus, and revealed the establishment and dynamic fluctuations of the gut microbiome from fetus to adulthood in goats.

Effect of dietary gossypol supplement on fermentation characteristics and bacterial diversity in the rumen of sheep

The tolerance of ruminants to gossypol, a natural phenolic compound derived from the cotton plant, is greater than that of monogastric animals, partially because of the gossypol-degrading bacteria in the rumen of the ruminants. In this study, we aimed to examine the effect of gossypol supplementation on fermentation characteristics, bacterial α-diversity and community structure in the rumen fluid of sheep to analyse the change of bacterial in response to gossypol. 8 sheep with permanent fistula were randomly divided into 2 groups, a control and gossypol acetate supplementation groups. Sheep in the latter group were supplemented with gossypol acetate at the levels of 600 mg and 1,200 mg/animal per day during the first (S1, days 1 to 27) and subsequent (S2, days 28 to 47) stages. Gossypol supplementation significantly increased the molar proportion of acetate, and decreased the molar proportion of isobutyric acid, butyric acid, and isovaleric acid in the rumen fluid. Gossypol supplementation have no significant effect on bacterial diversity in the rumen fluid. At the phylum level, gossypol had no effect on bacterial community. At the genus level, gossypol supplementation significantly increased the relative abundance of Treponema_2. However, there were no significant differences in the relative abundance of dominant bacterial genera. In conclusion, gossypol supplementation had an effect on molar proportion of acetate, isobutyric acid, butyric acid, and isovaleric acid, but had no significant effect on the bacterial diversity and relative abundance of dominant bacteria in rumen fluid of sheep.

Rumen function in goats, an example of adaptive capacity

The aim of this Research Reflection is to describe the basic rumen function of goats and its modification in response to environmental factors, as well as to discuss similarities and differences when compared to other ruminants. In so doing we shall reveal the adaptive capacity of goats to harsh environments. The basic rumen function in goats is similar to other species of ruminants, as stressed by the opportunity to apply the updates of feeding systems for ruminants to goats. The rumen epithelium acts as a protective barrier between the rumen and the host, but it can be damaged by toxic compounds or acidosis. The rumen also plays an important role in water balance, both for dehydration and rehydration. Recent studies show that the microbiota exhibits a high fractional stability due to functional redundancy and resilience, but this needs more investigation. The microbial community structure differs between goats and cows, which explains the difference in sensitivity to milk fat depression following intake of high lipid diets. Goats also differ from other ruminants by their enhanced ability to feed-sort, but as with cows they can suffer from acidosis. Nevertheless, goats can be considered to be very resistant to environmental factors such as water stress, salt stress or heat stress, and this is especially so in some endogenous breeds. They also are able to detoxify tannins, polyphenols and other secondary metabolites. Some new trials involving feeding behaviour, microbiota and omics or approaches by meta-analyses or modelling will improve our knowledge of rumen function in goats.

Dietary Supplementation of Lysophospholipids Affects Feed Digestion in Lambs

Five experiments were conducted to examine effects of lysophospholipids (LPL) on live weight gain, nutrient digestibility, ruminal fermentation parameters, serum biochemical parameters and rumen bacterial community profile in fattening lambs. Two dietary treatments (pelleted complete feed supplemented without (control diet; CON) or with 0.05% LPL on dry matter basis) were tested in these experiments. Feed and water were provided ad libitum to lambs. The results showed that average daily gain (ADG) tended to increase or was not affected by LPL supplementation. Compared with CON, the supplementation of LPL resulted in an increase in dry matter, crude protein and organic matter digestibilities, and a decrease in neutral detergent fiber and acid detergent fiber digestibilities. Ruminal pH values did not change with LPL supplementation, but the concentrations of ammonia and total short chain fatty acids (SCFAs) were increased. The molar proportion of major individual SCFAs and the ratio of acetate to propionate were not affected by LPL supplementation. While the activity of lipase was decreased with LPL supplementation, all other serum biochemical parameters did not change. Rumen bacterial community was altered by LPL supplementation with the relative abundance of fibrolytic bacteria in the total bacterial population, such as Prevotella, decreased. In conclusion, LPL supplementation can alter feed digestion, but may not result in consistent positive responses in animal growth performance.