Effect of different seasons (spring vs summer) on the microbiota diversity in the feces of dairy cows

Heat stress has divergent effects on the milk microbiota of Holstein and Brown Swiss cows

Heat stress (HS) is one of the pivotal causes of economic losses in dairy industries and affects welfare and performance, but its effect on milk microbiota remains elusive. It is also unclear if and how different breeds may cope with HS in sustaining productive performance. The objectives of this study were to compare (1) the performance of 2 dairy breeds, namely Holstein and Brown Swiss, subjected to HS and (2) the different effects of HS on the milk microbiota of the 2 breeds in thermal comfort conditions and HS. The study was carried out on 36 dairy cows, 18 per breed. The HS was induced by switching off the cooling system during a natural heat wave for 4 d. In addition to the temperature-humidity index, animal stress was confirmed by measuring respiratory frequency and rectal temperature twice daily at 0400 h and 1500 h. The HS affected the 2 breeds differently. The rectal temperature increased with HS in both breeds. Milk yield recording and sampling were performed during the morning milking of d 1 (at 0400 h) and afternoon milking of d 4 (at 1700 h). Productive parameters were also different: milk yield, FCM, ECM, protein and casein content, and renneting parameters were decreased in Holstein cows but remained unaffected in Brown Swiss cows. The HS also modified the milk microbiota of the 2 breeds differently. During HS, the Brown Swiss cows had milk microbiota that was richer (α diversity) than that of the Holstein cows. Comparing the time points before and during HS within breeds showed that Brown Swiss cow milk microbiota was less affected by HS than Holstein cow milk microbiota. Under the same thermal comfort condition, milk microbiota did not discriminate between Brown Swiss and Holstein. Consistently with α and β diversity, the number of operational taxonomic units (OTU) at the genus level that changed their abundance during HS was higher in Holstein (74 OTU) than in Brown Swiss (only 20 OTU). The most significant changes in abundance affected Acinetobacter, Chryseobacterium, Cutibacterium, Enterococcus, Lactococcus, Prevotella-9, Serratia, and Streptococcus. In conclusion, the present report confirms and extends previous studies by demonstrating that Brown Swiss cows regulate their body temperature better than the Holstein breed. The relative thermal tolerance to HS compared with Holstein cows is also confirmed by changes in milk uncultured microbiota, which were more evident in Holstein cows than in Brown Swiss cows.

Heat stress and feeding effects on the mucosa-associated and digesta microbiome and their relationship to plasma and digesta fluid metabolites in the jejunum of dairy cows

The intestinal microbiota plays a pivotal role in digestive processes and maintains gut health and intestinal homeostasis. These functions may be compromised by increased environmental heat, which in turn reduces feed intake and gut integrity and activates the intestinal immune system. It remains unknown whether high ambient temperatures, which cause heat stress (HS) in dairy cows, disturb the eubiosis of the microbial community, and if so, to which extent the reduction in feed intake and the impairment of circulating and intestinal metabolites account for the alterations of the jejunal microbiota. To address these questions, jejunal digesta, mucosa, and plasma samples were collected from cows exposed to heat stress (HS; 28°C, temperature-humidity index [THI] = 76, n = 10), control conditions (CON; 16°C, THI = 60, n = 10), or pair-fed (PF; 16°C, THI = 60, n = 10) for 7 d. Digesta fluids were examined for pH, acetate, nonesterified fatty acids (NEFA), glucose, and lactate, and plasma samples were analyzed for glucose, lactate, BHB, triglycerides, NEFA, creatinine, and urea. The microbiota of the digesta and mucosa samples were analyzed by 16S rRNA sequencing. The α-diversity was higher in mucosa than digesta but was not affected by high ambient temperatures. However, the mucosa-associated microbiota appeared more responsive to ambient heat than the digesta microbiome. The adaptive responses under HS conditions comprised an increased mucosal abundance of Bifidobacteriaceae, Succinivibrionaceae UCG-001, Clostridia and Lactobacillus. In the digesta, HS has exerted effects on microbial abundance of Colidextribacter, and Lachnospiraceae UCG-008. Several correlations between plasma or intestinal metabolites and microbiota were elucidated, including Methanobacteriaceae correlating positively with plasma BHB and digesta glucose concentrations. Moreover, the reduction in feed intake during HS had non-negligible effects on microbial diversity and the abundance of certain taxa, underpinning the importance of nutrient supply on maintaining intestinal homeostasis.

Spatial profiles of the bacterial microbiota throughout the gastrointestinal tract of dairy goats

The gastrointestinal tract (GIT) is stationed by a dynamic and complex microbial community with functions in digestion, metabolism, immunomodulation, and reproduction. However, there is relatively little research on the composition and function of microorganisms in different GIT segments in dairy goats. Herein, 80 chyme samples were taken from ten GIT sites of eight Xinong Saanen dairy goats and then analyzed and identified the microbial composition via 16S rRNA V1-V9 amplicon sequencing. A total of 6669 different operational taxonomic units (OTUs) were clustered, and 187 OTUs were shared by ten GIT segments. We observed 264 species belonging to 23 different phyla scattered across ten GITs, with Firmicutes (52.42%) and Bacteroidetes (22.88%) predominating. The results revealed obvious location differences in the composition, diversity, and function of the GIT microbiota. In LEfSe analysis, unidentified_Lachnospiraceae and unidentified_Succinniclassicum were significantly enriched in the four chambers of stomach, with functions in carbohydrate fermentation to compose short-chain fatty acids. Aeriscardovia, Candidatus_Saccharimonas, and Romboutsia were significantly higher in the foregut, playing an important role in synthesizing enzymes, amino acids, and vitamins and immunomodulation. Akkermansia, Bacteroides, and Alistipes were significantly abundant in the hindgut to degrade polysaccharides and oligosaccharides, etc. From rumen to rectum, α-diversity decreased first and then increased, while β-diversity showed the opposite trend. Metabolism was the major function of the GIT microbiome predicted by PICRUSt2, but with variation in target substrates along the regions. In summary, GIT segments play a decisive role in the composition and functions of microorganisms. KEY POINTS: • The jejunum and ileum were harsh for microorganisms to colonize due to the presence of bile acids, enzymes, faster chyme circulation, etc., exhibiting the lowest α-diversity and the highest β-diversity. • Variability in microbial profiles between the three foregut segments was greater than four chambers of stomach and hindgut, with a higher abundance of Firmicutes dominating than others. • Dairy goats dominated a higher abundance of Kiritimatiellaeota than cows, which was reported to be associated with fatty acid synthesis.

Difference of Microbial Community in the Stream Adjacent to the Mixed Antibiotic Effluent Source

Released antibiotics from source to stream can influence bacterial communities and potentially alter the ecosystem. This research provides a comprehensive examination of the sources, distribution, and bacterial community dynamics associated with varied antibiotic release sources adjacent to the stream. The residual of antibiotics from different sources was determined, and the bacterial community structure was examined to reveal the differences in the bacteria community in the stream. The residual of antibiotics was quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the Illumina MiSeq platform was utilized to sequence bacterial 16S rRNA genes, providing comprehensive insights into the bacterial community structure in the sediment across five different sites. Results indicated that the presence and distribution of antibiotics were significantly influenced by released sources. In the case of the bacterial community, the Proteobacteria and Firmicutes were the most dominant phyla in the sediment, and especially, the Firmicutes showed higher abundance in sites mostly affected by livestock sources. Additionally, livestock gut bacteria such as Clostridium saudiense, Proteiniclasticum ruminis, and Turicibacter sanguinis were prevalent in antibiotic-contaminated sites adjacent to livestock facilities. Overall, this study provides critical insights into the effect of antibiotic contamination by verifying the relationship between the occurrence of antibiotic residuals and the alteration in the bacterial community in the stream.

Plant Extracts to Alleviating Heat Stress in Dairy Cows

Heat stress (HS) in cows is a critical issue in the dairy industry. Dairy cows accumulate heat from body metabolism, along with that imposed by air temperature, humidity, air flow and solar radiation. HS in animals can occur during hot and humid summers when the ambient temperature is extremely high. Dairy cows have relatively high feed intakes and metabolic heat production and are thus susceptible to HS, leading to reductions in feed intake, lower milk yield, affected milk quality, reduced animal health and even shortening the productive lifespan of cows. Therefore, alleviating HS is a top priority for the dairy industry. Suitable plant extracts have advantages in safety, efficiency and few toxic side effects or residues for applications to alleviate HS in dairy cows. This paper reviews the effects of some plant extract products on alleviating HS in dairy cows and briefly discusses their possible mechanisms of action.

Variations in the Physical Properties and Microbial Community of Dairy Cow Manure-Implications for Testing and Efficacy of Footbathing Products

Footbaths containing disinfectants are used on dairy farms to reduce the spread of digital dermatitis; however, they commonly become contaminated with manure. This trial investigated the physical properties and microbial composition of dairy cow manure from two production systems and examined whether the source of manure impacted the efficacy of footbathing disinfectants. Manure was collected from eighteen dairy cows, nine housed and fed grass silage (HOUSED) and nine at pasture (PASTURE). The pH and dry matter content was determined, total DNA was extracted and the region v3-v4 of the 16s rRNA gene sequenced. The efficacy of formalin and two trial products (TP1: peracetic acid and hydrogen peroxide; TP2: chlorocresol and triamine) was evaluated when mixed with manure from the two production systems. Production system differences were found in manure dry matter content, bacterial microbiome and the efficacy of both trial footbathing products but not formalin. The properties of manure affected the results of laboratory testing and therefore have the potential to influence footbathing disinfectant efficacy when footbaths are contaminated with manure. Further research into the impact of organic contaminants on the efficacy of disinfectants could facilitate the development of improved testing programmes and disinfectant products.

Rumen-protected glucose supplementation alters fecal microbiota and its metabolic profiles in early lactation dairy cows

INTRODUCTION

Negative energy balance (NEB) is the pathological basis of metabolic disorders in early lactation dairy cows. Rumen-protected glucose (RPG) is a feed additive to relieve NEB of cows in early lactation. The aims of the current study were to evaluate the impact of different doses of RPG supply on fecal microbiota and metabolome in early lactation dairy cows, and their correlation with each other.

METHODS

A total of 24 multiparous Holstein dairy cows in early lactation were randomly assigned to one of four treatments for the first 35 days of the early lactation period, as follows: control group, a basal diet without RPG (CON); low RPG, a basal diet plus 200 g/d RPG (LRPG); medium RPG, a basal diet plus 350 g/d RPG (MRPG); or HRPG, high RPG, a basal diet plus 500 g/d RPG (HRPG). After 35 days, fecal samples were obtained from cows in all groups individually and using 16S rRNA gene sequencing to evaluate their microbiotas, while their metabolites were evaluated through metabolomics.

RESULTS

As expected, Firmicutes and Bacteroidetes were the core bacteria phyla. After RPG supplementation, there were an increase in Firmicutes and a decrease in Bacteroidetes. MRPG increased the relative abundance of cellulolytic bacteria, including Ruminococcaceae_UCG-005, Lachnospiraceae_UCG-008, Lachnospiraceae_FCS020_group, and Ruminiclostridium_9, while it decreased the relative abundance of Alistipes, Prevotellaceae_UCG-003, and Dorea. RPG supplementation could regulate the carbohydrate metabolism and amino acid metabolism pathway significantly and relieve lipolysis in dairy cows. Correlation analysis of fecal microbiome and metabolome showed that some major differential bacteria were the crucial contributors to differential metabolites.

CONCLUSION

In conclusion, RPG supplementation can affect the fecal microbial components and microbial metabolism, and 350 g RPG might be the ideal dose as a daily supplement.

Effect of zinc source (zinc sulfate or zinc hydroxychloride) on relative abundance of fecal Treponema spp. in lactating dairy cows

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Cows (n = 24) were fed typical lactating diets that only differed in zinc source inclusion.

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Fecal samples collected from cows were extracted for prokaryotic 16S gene DNA.

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Feeding zinc hydroxychloride decreased the Treponema spp. recovered from fecal samples compared with cows fed zinc sulfate.

Previous research revealed a potential effect of dietary trace mineral source on both ruminal and fecal microbiota. However, the effect of Zn source, specifically, has not previously been considered. Based on reported postruminal solubility, we hypothesized that Zn hydroxychloride would decrease Treponema spp. fecal excretion relative to cows fed Zn sulfate. To test this hypothesis, lactating Holstein cows (n = 24; 685 ± 9 kg of body weight; 159 ± 8 d in milk; parity 3 ± 0.2) were randomly assigned to 1 of 2 dietary treatments: control (75 mg/kg Zn from ZnSO₄) or Zn hydroxychloride (HYD; 75 mg/kg IntelliBond Z; Micronutrients USA LLC). Single fecal grab samples were collected on d 1 before dietary treatments and on d 27 after dietary treatments were applied. Fecal microbial DNA was extracted and sequenced to establish taxonomy using a universal primer for the 16S rRNA gene. Supplementation of HYD decreased the relative abundance of Treponema 2 by 3-fold (14.7% vs. 4.9%). Poor sequencing resolution at the species level limited inference of Treponema spp. toward management or gut health implications of HYD supplementation. However, the inclusion of pathogenic species among Treponema spp. indicates a potential implication of HYD feeding to reduce environmental exposure of the dairy cow to Treponema spp.

Possibility of Using By-Products with High NDF Content to Alter the Fecal Short Chain Fatty Acid Profiles, Bacterial Community, and Digestibility of Lactating Dairy Cows

This study aimed to investigate whether agricultural by-products with a high NDF content and small-particle-size substitute for forage could cause hindgut acidosis and dysbacteriosis in lactating dairy cows. We investigated the impact of soybean hull and beet pulp on the fecal fermentation, bacterial community, and digestibility of cows. Sixteen lactating Holstein cows were treated as follows (% of dry matter (DM)): amount of by-product added was 0 (control, CON), 1.67% (low by-products, LB), 3.33% (medium by-products, MB), and 5% (high by-products, HB). The results showed the fecal pH of cows to be 7.23–7.29, implying no hindgut acidosis. With increased inclusion of by-products in the diets, the proportion of fecal propionate; relative abundance of the phylum Bacteroidetes, the family Lachnospiraceae, and genera unclassified_f_Lachnospiraceae, Acetitomaculum, and Prevotella; and the DM and NDF digestibility of cows all increased linearly. Meanwhile, the fecal genera Turicibacter and Clostridium_sensu_stricto_1 decreased linearly. By-products promoted the abundance of fecal bacteria genes related to energy metabolism, glycolysis/gluconeogenesis, and propanoate metabolism; and correlations between fecal short chain fatty acids, digestibility, and the bacteria genera were seen. Overall, our study suggested that adding 5% by-products could be a viable dietary formulation strategy that promotes digestibility and makes positive changes in hindgut fermentation and bacteria.

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.

Characteristics of Bacterial Microbiota in Different Intestinal Segments of Aohan Fine-Wool Sheep

The microbial community performs vital functions in the intestinal system of animals. Modulation of the gut microbiota structure can indirectly or directly affect gut health and host metabolism. Aohan fine-wool sheep grow in semi-desert grasslands in China and show excellent stress tolerance. In this study, we amplified 16S rRNA gene to investigate the dynamic distribution and adaptability of the gut microbiome in the duodenum, jejunum, ileum, cecum, colon, and rectum of seven Aohan fine-wool sheep at 12 months. The results showed that the microbial composition and diversity of the ileum and the large intestine (collectively termed the hindgut) were close together, and the genetic distance and functional projections between them were similar. Meanwhile, the diversity index results revealed that the bacterial richness and diversity of the hindgut were significantly higher than those of the foregut. We found that from the foregut to the hindgut, the dominant bacteria changed from Proteobacteria to Bacteroidetes. In LEfSe analysis, Succiniclasticum was found to be significantly abundant bacteria in the foregut and was involved in succinic acid metabolism. Ruminococcaceae and Caldicoprobacteraceae were significantly abundant in hindgut, which can degrade cellulose polysaccharides in the large intestine and produce beneficial metabolites. Moreover, Coriobacteriaceae and Eggthellaceae are involved in flavonoid metabolism and polyphenol production. Interestingly, these unique bacteria have not been reported in Mongolian sheep or other sheep breeds. Collectively, the gut microbiota of Aohan fine-wool sheep is one of the keys to adapting to the semi-desert grassland environment. Our results provide new insights into the role of gut microbiota in improving stress tolerance and gut health in sheep.

Effects of Bovine Pichia kudriavzevii T7, Candida glabrata B14, and Lactobacillus plantarum Y9 on Milk Production, Quality and Digestive Tract Microbiome in Dairy Cows

Microbial administration has been used successfully to improve host health. However, the positive effects of endogenous microbials are still underexplored. This study investigated the effects of bovine Lactic acid bacteria and yeast on the milk production, quality and digestive tract microbiome of dairy cows. Lactobacillus plantarum Y9, Pichia kudriavzevii T7 and Candida glabrata B14 isolated from high-yielding dairy cows were selected to feed low-yielding Holstein cows. Pichia kudriavzevii T7 could significantly increase milk yield, meanwhile, Pichia kudriavzevii T7 and Candida glabrata B14 could obviously reduce the number of somatic cell counts (SCC). However, slight differences were found in milk fat, protein, lactose and SNF (solids not fat) percentage. High throughput sequencing showed that the dominant bacteria were Prevotella and Ruminococcaceae in rumen and feces, respectively, and the dominant fungi were Penicillium, Aspergillus and Trichoderma in both samples, before and after feeding the microbial addition. Nonetheless, microbial addition changed the abundance and structure of the microbiome in the digestive tract. Our data showed bovine yeast and LAB were beneficial for improving performance and regulating the microbial structure of dairy cows. This study was expected to enrich the knowledge of the digestive tract microbiome in dairy cows and provide a feasible strategy for the further utilization of bovine microorganisms.

Persistent Circulation of Enterohemorrhagic Escherichia coli (EHEC) O157:H7 in Cattle Farms: Characterization of Enterohemorrhagic Escherichia coli O157:H7 Strains and Fecal Microbial Communities of Bovine Shedders and Non-shedders

Cattle are carriers, without clinical manifestations, of enterohemorrhagic Escherichia coli (EHEC) O157:H7 responsible for life-threatening infections in humans. A better identification of factors playing a role in maintaining persistence of such strains in cattle is required to develop more effective control measures. Hence, we conducted a study to identify farms with a persistent circulation of EHEC O157:H7. The EHEC O157:H7 herd status of 13 farms, which had previously provided bovine EHEC O157:H7 carriers at slaughter was investigated. Two farms were still housing positive young bulls, and this was true over a 1-year period. Only one fecal sample could be considered from a supershedder, and 60% of the carriers shed concentrations below 10 MPN/g. Moreover, EHEC O157:H7 represented minor subpopulations of E. coli. PFGE analysis of the EHEC O157:H7 strains showed that persistent circulation was due either to the persistence of a few predominant strains or to the repeated exposure of cattle to various strains. Finally, we compared fecal microbial communities of shedders (S) (n = 24) and non-shedders (NS) (n = 28), including 43 young bulls and nine cows, from one farm. Regarding alpha diversity, no significant difference between S vs. NS young bulls (n = 43) was observed. At the genus level, we identified 10 amplicon sequence variant (ASV) indicators of the S or NS groups. The bacterial indicators of S belonged to the family XIII UCG-001, Slackia, and Campylobacter genera, and Ruminococcaceae NK4A21A, Lachnospiraceae-UGC-010, and Lachnospiraceae-GCA-900066575 groups. The NS group indicator ASVs were affiliated to Pirellulaceae-1088-a5 gut group, Anaerovibrio, Victivallis, and Sellimonas genera. In conclusion, the characteristics enhancing the persistence of some predominant strains observed here should be explored further, and studies focused on mechanisms of competition among E. coli strains are also needed.

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.

Heat Stress: Effects on Rumen Microbes and Host Physiology, and Strategies to Alleviate the Negative Impacts on Lactating Dairy Cows

Heat stress (HS) in dairy cows causes considerable losses in the dairy industry worldwide due to reduced animal performance, increased cases of metabolic disorders, altered rumen microbiome, and other health problems. Cows subjected to HS showed decreased ruminal pH and acetate concentration and an increased concentration of ruminal lactate. Heat-stressed cows have an increased abundance of lactate-producing bacteria such as Streptococcus and unclassified Enterobacteriaceae, and soluble carbohydrate utilizers such as Ruminobacter, Treponema, and unclassified Bacteroidaceae. Cellulolytic bacteria, especially Fibrobacteres, increase during HS due to a high heat resistance. Actinobacteria and Acetobacter, both acetate-producing bacteria, decreased under HS conditions. Rumen fermentation functions, blood parameters, and metabolites are also affected by the physiological responses of the animal during HS. Isoleucine, methionine, myo-inositol, lactate, tryptophan, tyrosine, 1,5-anhydro-D-sorbitol, 3-phenylpropionic acid, urea, and valine decreased under these conditions. These responses affect feed consumption and production efficiency in milk yield, growth rate, and reproduction. At the cellular level, activation of heat shock transcription factor (HSF) (located throughout the nucleus and the cytoplasm) and increased expression of heat shock proteins (HSPs) are the usual responses to cope with homeostasis. HSP70 is the most abundant HSP family responsible for the environmental stress response, while HSF1 is essential for increasing cell temperature. The expression of bovine lymphocyte antigen and histocompatibility complex class II (DRB3) is downregulated during HS, while HSP90 beta I and HSP70 1A are upregulated. HS increases the expression of the cytosolic arginine sensor for mTORC1 subunits 1 and 2, phosphorylation of mammalian target of rapamycin and decreases the phosphorylation of Janus kinase-2 (a signal transducer and activator of transcription factor-5). These changes in physiology, metabolism, and microbiomes in heat-stressed dairy cows require urgent alleviation strategies. Establishing control measures to combat HS can be facilitated by elucidating mechanisms, including proper HS assessment, access to cooling facilities, special feeding and care, efficient water systems, and supplementation with vitamins, minerals, plant extracts, and probiotics. Understanding the relationship between HS and the rumen microbiome could contribute to the development of manipulation strategies to alleviate the influence of HS. This review comprehensively elaborates on the impact of HS in dairy cows and introduces different alleviation strategies to minimize HS.

Ultrasonic pre-treatment of Bacillus velezensis for improved electrogenic response in a single chambered microbial fuel cell

Various microbial strains and techniques are being used to improve power production in microbial fuel cells. Cow dung is a peculiar source of anaerobic and micro-aerophilic organisms that were employed in this study to isolate exo-electrogenic microorganisms. To validate their exo-electrogenic nature, all eight visually distinct bacterial single-cell colonies were tested using the ferrocyanide reduction assay, which resulted in the selection of one bacterial strain AD1-ELB with the ability to reduce ferrocyanide for further biochemical, physiological and electrochemical characterization. The selected strain AD1-ELB was identified as Bacillus velezensis by 16 s rRNA gene sequencing. When used in a single-chambered MFC, the isolated AD1-ELB strain produced a maximum open-circuit voltage of 455 mV with a maximum current density of 51.78 µA/cm² and maximum power density of 4.33 µW/cm² on the 16th day. Bacillus velezensis AD1-ELB strain was treated with low-frequency ultrasound (40 kHz) for 1, 2, 3, 4, and 5 min to assess the effect of ultrasonic pre-treatment on an isolated pure culture-based microbial fuel cell. A 3-min exposure to low-frequency ultrasonic therapy resulted in an increase in maximum power of 4.33 µW/cm² with a current density of 51.78 µA/cm² in the MFC, which decreases significantly after 4 and 5 min. Thus, the overall power density achieved was 1.89 times greater than in MFCs with untreated strain. These findings support the use of low-frequency ultrasonic stimulation to improve the performance of microbial fuel cell devices and are restricted to the pure, single-cell strain AD1-ELB, with the potential for variation if some other isolated strain is utilized, hence requiring further study to determine its relative variations.

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.

Rumen Bacterial Community of Grazing Lactating Yaks (Poephagus grunniens) Supplemented with Concentrate Feed and/or Rumen-Protected Lysine and Methionine

Simple Summary

Ruminal microorganisms, especially bacteria, play a vital role in utilizing fibrous material in ruminants. The yak is a bovid on the Qinghai-Tibet Plateau that traditionally only grazes natural pasture all year. During lactation, energy intake of yaks is often well below requirements, and yaks lose body weight. Today, to mitigate body weight losses during lactation, suckling yaks are often offered supplementary feed. This study examined the effect of dietary supplements on rumen bacteria in lactating yak. The yaks were offered supplementary concentrate feed (C), rumen-protected Lys and Met (RPA), or both (RPA+C). The ratio of the relative abundance of Firmicutes to Bacteroidetes in RPA+C was greater than in the RPA group, while there was no difference between C and RPA+C. The intakes of supplements resulted in a number of alterations in the abundances of bacteria at the genus level. When supplemented with C, yaks increased the concentration of ruminal total volatile fatty acids (VFAs), acetate, and butyrate. These results demonstrate that supplementary feed: (1) alters the composition of rumen microbiota and VFAs of lactating yaks; and (2) can be used to manipulate the composition of rumen microbiota.

Abstract

Traditionally, yaks graze only natural pasture all year round without supplements. Forage intake of lactating yaks is below energy and protein requirements, even in the summer, and suckling yaks lose a substantial amount of significant body weight. Today, to mitigate the loss in body weight, supplementary feed is being offered to lactating yaks. However, the effects of supplementary feed on ruminal bacterial communities in lactating yaks is unknown. In the current study, we examined the effect of supplementary feed on ruminal microbiota, using 16S rRNA sequencing, and on volatile fatty acids (VFAs). Twenty-four lactating yaks of similar body weight (218 ± 19.5 kg) and grazing natural pasture were divided randomly into four groups and received different supplements: (1) rumen-protected amino acids (RPA); (2) concentrate feed (C); (3) RPA plus C (RPA+C); and (4) no supplements (control-CON). The concentrations of total VFAs, acetate, and butyrate were greater (p < 0.05) when supplemented with concentrate feed (C and RPA+C) than without concentrate feed (CON and RPA). Bacteroidetes (B) and Firmicutes (F) were the dominant ruminal bacterial phyla in all groups. The ratio of relative abundance of F:B in RPA+C was greater than in the RPA group, while there was no difference between CON and RPC (interaction, p = 0.026). At the genus level, the relative abundances of Absconditabacteriales_SR1, Bacteroidales-RF16-group, Bacteroidales_BS11_gut_group, Prevotellaceae, and Rikenellaceae_RC9_gut_group were lesser (p < 0.05) with supplementary concentrate feed (C and RPA+C) than without concentrate feed (CON and RPA), whereas Butyrivibrio_2 and Pseudobutyrivibrio were greater (p < 0.05) with supplementary rumen-protected amino acids (RPA and RPA+C) than without rumen-protected amino acids (CON and C). These results demonstrate that supplementary feed: (1) alters the composition of rumen microbiota and concentrations of ruminal VFAs in lactating yaks; and (2) can be used to manipulate the composition of rumen microbiota.

Inflammation-Associated Microbiota Composition Across Domestic Animals

Domestic animals represent important resources for understanding shared mechanisms underlying complex natural diseases that arise due to both genetic and environmental factors. Intestinal inflammation, particularly inflammatory bowel disease (IBD), is a significant health challenge in humans and domestic animals. While the etiology of IBD is multifactorial, imbalance of symbiotic gut microbiota has been hypothesized to play a central role in disease pathophysiology. Advances in genomic sequencing and analytical pipelines have enabled researchers to decipher the composition of the intestinal microbiota during health and in the context of naturally occurring diseases. This review compiles microbiome genomic data across domestic species and highlights a common occurrence of gut microbiome dysbiosis during idiopathic intestinal inflammation in multiple species, including dogs, cats, horses, cows, and pigs. Current microbiome data obtained from animals with intestinal inflammation are mostly limited to taxonomical analyses in association with broad clinical phenotype. In general, a pathogen or pathosymbiont were not detected. Rather, functional potential of the altered microbiota has been suggested to be one of the key etiologic factors. Among the domestic species studied, canine analyses are currently the most advanced with incorporation of functional profiling of microbiota. Canine IBD parallels features of the disease in humans, thus canines represent a strong natural model for human IBD. While deeper analyses of metagenomic data, coupled with host molecular analyses are needed, comparative studies across domestic species can reveal shared microbial alterations and regulatory mechanisms that will improve our understanding of intestinal inflammation in both animals and humans.

Livestock exclusion reduces the spillover effects of pastoral agriculture on soil bacterial communities in adjacent forest fragments

Forest-to-pasture conversion is known to cause global losses in plant and animal diversity, yet impacts of livestock management after such conversion on vital microbial communities in adjoining natural ecosystems remain poorly understood. We examined how pastoral land management practices impact soil microorganisms in adjacent native forest fragments, by comparing bacterial communities sampled along 21 transects bisecting pasture-forest boundaries. Our results revealed greater bacterial taxon richness in grazed pasture soils and the reduced dispersal of pasture-associated taxa into adjacent forest soils when land uses were separated by a boundary fence. Relative abundance distributions of forest-associated taxa (i.e., Proteobacteria and Nitrospirae) and a pasture-associated taxon (i.e., Firmicutes) also suggest a greater impact of pastoral land uses on forest fragment soil bacterial communities when no fence is present. Bacterial community richness and composition were most related to changes in soil physicochemical variables commonly associated with agricultural fertilization, including concentrations of Olsen P, total P, total Cd, delta ¹⁵ N and the ratio of C:P and N:P. Overall, our findings demonstrate clear, and potentially detrimental effects of agricultural disturbance on bacterial communities in forest soils adjacent to pastoral land. We provide evidence that simple land management decisions, such as livestock exclusion, can mitigate the effects of agriculture on adjacent soil microbial communities.

Seasonal Influence on Rumen Microbiota, Rumen Fermentation, and Enteric Methane Emissions of Holstein and Jersey Steers under the Same Total Mixed Ration

Seasonal effects on rumen microbiome and enteric methane (CH4) emissions are poorly documented. In this study, 6 Holstein and 6 Jersey steers were fed the same total mixed ration diet during winter, spring, and summer seasons under a 2 × 3 factorial arrangement for 30 days per season. The dry matter intake (DMI), rumen fermentation characteristics, enteric CH4 emissions and rumen microbiota were analyzed. Holstein had higher total DMI than Jersey steers regardless of season. However, Holstein steers had the lowest metabolic DMI during summer, while Jersey steers had the lowest total DMI during winter. Jersey steers had higher CH4 yields and intensities than Holstein steers regardless of season. The pH was decreased, while ammonia nitrogen concentration was increased in summer regardless of breed. Total volatile fatty acids concentration and propionate proportions were the highest in winter, while acetate and butyrate proportion were the highest in spring and in summer, respectively, regardless of breed. Moreover, Holstein steers produced a higher proportion of propionate, while Jersey steers produced a higher proportion of butyrate regardless of season. Metataxonomic analysis of rumen microbiota showed that operational taxonomic units and Chao 1 estimates were lower and highly unstable during summer, while winter had the lowest Shannon diversity. Beta diversity analysis suggested that the overall rumen microbiota was shifted according to seasonal changes in both breeds. In winter, the rumen microbiota was dominated by Carnobacterium jeotgali and Ruminococcus bromii, while in summer, Paludibacter propionicigenes was predominant. In Jersey steers, Capnocytophaga cynodegmi, Barnesiella viscericola and Flintibacter butyricus were predominant, whereas in Holstein steers, Succinivibrio dextrinosolvens and Gilliamella bombicola were predominant. Overall results suggest that seasonal changes alter rumen microbiota and fermentation characteristics of both breeds; however, CH4 emissions from steers were significantly influenced by breeds, not by seasons.

Influence of Vertebrate Excreta on Attraction, Oviposition and Development of the Asian Tiger Mosquito, Aedes albopictus (Diptera: Culicidae)

Simple Summary

Commonly known as the Asian tiger mosquito, Aedes albopictus is a vector of dengue worldwide. Knowledge of the behavior of dengue vectors facilitates effective vector control. This is the first comprehensive analysis of selected vertebrate excreta of goat, cow and pig to identify the oviposition attraction and growth performance of Ae. albopictus in Sri Lanka. The current study revealed that Ae. albopictus gravid females are significantly attracted to goat excreta but are repelled by pig excreta. The oviposition preference was highest for the cow excreta and lowest for the pig excreta. For excreta combinations, the Cow+Goat combination increased the oviposition while the Pig+Goat combination reduced the oviposition. The oviposition preference of Ae. albopictus increased with the rate of fermentation. The pig excreta increased the Ae. albopictus larval mortality, larval and pupal duration and reduced adult fecundity, whereas the cow excreta positively affected all these aspects. Additionally, our findings suggest that a high abundance of Ae. albopictus in rural areas of Sri Lanka is possibly due to its oviposition attraction and the growth performance of the vertebrate excreta.

Abstract

Aedes albopictus is an important vector of dengue worldwide. Eliminating dengue in Sri Lanka depends entirely on controlling the vector and human-vector contact. Thus, studying the bionomics and behavior of Ae. albopictus is paramount. The objective of this study was to evaluate the effect of the excreta of cow, goat and pig on the attraction, oviposition and development of Ae. albopictus. Bioassay chambers determined the mosquito stimulatory response. Ovitraps determined Ae. albopictus oviposition preference to excreta singly, in combination and on fermentation. The excreta effect on larval development was also determined. The results revealed that Ae. albopictus gravid females were significantly attracted to goat excreta but were repelled by pig excreta. The oviposition preference was highest for cow excreta and lowest for pig excreta. For excreta combinations, the Cow+Goat combination increased the oviposition while the Pig+Goat combination reduced the oviposition. The oviposition preference of Ae. albopictus increased with the rate of fermentation. The pig excreta increased the Ae. albopictus larval mortality, larval and pupal duration and reduced adult fecundity, whereas the cow excreta positively affected all these aspects. Our findings additionally suggest that a high abundance of Ae. albopictus in rural areas of Sri Lanka may be due to its oviposition attraction and growth performance for vertebrate excreta.

The specific enthalpy of air as an indicator of heat stress in livestock animals

Along with recognition of environmental effects on the performance and welfare of livestock animals, studies have been proposing new methodologies and parameters to diagnose the heat stress of animals through the physical properties of air. This article aims to present the state-of-the-art on the use of the specific enthalpy of air as an indicator of heat stress in livestock animals. As a starting point, conceptual considerations were made about the connection between homoeothermic animals and the environment. Variables for heat stress evaluation based on psychrometric air properties are then described, including dry bulb temperature and relative humidity, which are often used microclimate variables, and the specific enthalpy of dry air, which acts as a thermal comfort index. Final considerations highlight the recent history of the use of specific enthalpy of air equations as indicators of heat stress in livestock animals, with the intention of better understanding the relationship between animals and the environment. As a conclusion, the specific enthalpy of air is recommended as an indicator in the assessment of livestock housing conditions as, unlike other indices, it is based on thermodynamic air properties and not on linear regressions.

A multi-kingdom metabarcoding study on cattle grazing Alpine pastures discloses intra-seasonal shifts in plant selection and faecal microbiota

Diet selection by grazing livestock may affect animal performance as well as the biodiversity of grazed areas. Recent DNA barcoding techniques allow to assess dietary plant composition in faecal samples, which may be additionally integrated by the description of gut microbiota. In this high throughput metabarcoding study, we investigated the diversity of plant, fungal and bacterial taxa in faecal samples of lactating cows of two breeds grazing an Alpine semi-natural grassland during summer. The estimated plant composition of the diet comprised 67 genera and 39 species, which varied remarkably during summer, suggesting a decline of the diet forage value with the advancing of the vegetative season. The fungal community included Neocallimastigomycota gut symbionts, but also Ascomycota and Basidiomycota plant parasite and coprophilous taxa, likely ingested during grazing. The proportion of ingested fungi was remarkably higher than in other studies, and varied during summer, although less than that observed for plants. Some variation related to breed was also detected. The gut bacterial taxa remained stable through the summer but displayed a breed-specific composition. The study provided insights in the reciprocal organisms' interactions affecting, and being affected by, the foraging behaviour: plants showed a high temporal variation, fungi a smaller one, while bacteria had practically none; conversely, the same kingdoms showed the opposite gradient of variation as respect to the animal host breed, as bacteria revealed to be the group mostly characterized by host-specificity.

An Overview of the Elusive Passenger in the Gastrointestinal Tract of Cattle: The Shiga Toxin Producing Escherichia coli

For approximately 10,000 years, cattle have been our major source of meat and dairy. However, cattle are also a major reservoir for dangerous foodborne pathogens that belong to the Shiga toxin-producing Escherichia coli (STEC) group. Even though STEC infections in humans are rare, they are often lethal, as treatment options are limited. In cattle, STEC infections are typically asymptomatic and STEC is able to survive and persist in the cattle GIT by escaping the immune defenses of the host. Interactions with members of the native gut microbiota can favor or inhibit its persistence in cattle, but research in this direction is still in its infancy. Diet, temperature and season but also industrialized animal husbandry practices have a profound effect on STEC prevalence and the native gut microbiota composition. Thus, exploring the native cattle gut microbiota in depth, its interactions with STEC and the factors that affect them could offer viable solutions against STEC carriage in cattle.