Endophyte-Infected Tall Fescue Affects Rumen Microbiota in Grazing Ewes at Gestation and Lactation

Hepatic transcript profiling in beef cattle: Effects of feeding endophyte-infected tall fescue seeds

The objective of our study was to evaluate the effect of endophyte-infected tall fescue (E+) seeds intake on liver tissue transcriptome in growing Angus × Simmental steers and heifers through RNA-seq analysis. Normal weaned calves (~8 months old) received either endophyte-free tall fescue (E-; n = 3) or infected tall fescue (E+; n = 6) seeds for a 30-d period. The diet offered was ad libitum bermudagrass (Cynodon dactylon) hay combined with a nutritional supplement of 1.61 kg (DM basis) of E+ or E- tall fescue seeds, and 1.61 kg (DM basis) of energy/protein supplement pellets for a 30-d period. Dietary E+ tall fescue seeds were included in a rate of 20 μg of ergovaline/kg BW/day. Liver tissue was individually obtained through biopsy at d 30. After preparation and processing of the liver samples for RNA sequencing, we detected that several metabolic pathways were activated (i.e., upregulated) by the consumption of E+ tall fescue. Among them, oxidative phosphorylation, ribosome biogenesis, protein processing in endoplasmic reticulum and apoptosis, suggesting an active mechanism to cope against impairment in normal liver function. Interestingly, hepatic protein synthesis might increase due to E+ consumption. In addition, there was upregulation of "thermogenesis" KEGG pathway, showing a possible increase in energy expenditure in liver tissue due to consumption of E+ diet. Therefore, results from our study expand the current knowledge related to liver metabolism of growing beef cattle under tall fescue toxicosis.

Ruminal ergovaline and volatile fatty acid dynamics: Association with poor performance and a key growth regulator in steers grazing toxic tall fescue

Fescue toxicosis (FT) is produced by an ergot alkaloid (i.e., ergovaline [EV])-producing fungus residing in toxic fescue plants. Associations between EV, decreased weight gain and ruminal volatile fatty acids are unclear. Feces, rumen fluid, and blood were collected from 12 steers that grazed non-toxic (NT) or toxic (E +) fescue for 28 days. The E + group exhibited decreased propionate (P), increased acetate (A), and increased ruminal A:P ratio, with similar trends in feces. Plasma GASP-1 (G-Protein-Coupled-Receptor-Associated-Sorting-Protein), a myostatin inhibitor, decreased (day 14) only in E + steers. Ergovaline was present only in E + ruminal fluid and peaked on day 14. The lower ruminal propionate and higher A:P ratio might contribute to FT while reduced GASP-1 might be a new mechanism linked to E + -related weight gain reduction. Day 14 ergovaline zenith likely reflects ruminal adaptations favoring EV breakdown and its presence only in rumen points to local, rather than systemic effects.

Risks for animal health related to the presence of ergot alkaloids in feed

The European Commission requested EFSA to provide an update of the 2012 Scientific Opinion of the Panel on Contaminants in the Food Chain (CONTAM) on the risks for animal health related to the presence of ergot alkaloids (EAs) in feed. EAs are produced by several fungi of the Claviceps and Epichloë genera. This Opinion focussed on the 14 EAs produced by C. purpurea (ergocristine, ergotamine, ergocornine, α- and β-ergocryptine, ergometrine, ergosine and their corresponding 'inine' epimers). Effects observed with EAs from C. africana (mainly dihydroergosine) and Epichloë (ergovaline/-inine) were also evaluated. There is limited information on toxicokinetics in food and non-food producing animals. However, transfer from feed to food of animal origin is negligible. The major effects of EAs are related to vasoconstriction and are exaggerated during extreme temperatures. In addition, EAs cause a decrease in prolactin, resulting in a reduced milk production. Based on the sum of the EAs, the Panel considered the following as Reference Points (RPs) in complete feed for adverse animal health effects: for pigs and piglets 0.6 mg/kg, for chickens for fattening and hens 2.1 and 3.7 mg/kg, respectively, for ducks 0.2 mg/kg, bovines 0.1 mg/kg and sheep 0.3 mg/kg. A total of 19,023 analytical results on EAs (only from C. purpurea) in feed materials and compound feeds were available for the exposure assessment (1580 samples). Dietary exposure was assessed using two feeding scenarios (model diets and compound feeds). Risk characterisation was done for the animals for which an RP could be identified. The CONTAM Panel considers that, based on exposure from model diets, the presence of EAs in feed raises a health concern in piglets, pigs for fattening, sows and bovines, while for chickens for fattening, laying hens, ducks, ovines and caprines, the health concern related to EAs in feed is low.

The Potential Use of Endophyte-Free inebrians as Sheep Feed Evaluated with In Vitro Fermentation

Endophytic fungal infection is the major reason for intoxication of animals caused by drunken horse grass. Fortunately, it has been established that seed detoxification techniques and isolation of endophytic fungi infect non-endophytic fungi populations with the same genetic background as endophyte-infected Achnatherum inebrians. Moreover, sheep can use endophyte-free Achnatherum inebriants (EF) without obvious toxicity symptoms. The present study selected EF as a representative grass, consisting of five different replacement levels, EF0, EF25, EF50, EF75, and EF100, corresponding to 0%, 25%, 50%, 75%, and 100% of the fermentation substrate, respectively. Simultaneously, in vitro fermentation and the 16S rRNA amplicon sequencing method was used to explore the effect of EF on sheep ruminal fermentation and microbial diversity. The results revealed that EF100 had the highest values for pH, acetate: propionate, the Patescibacteria, Kiritimatiellaeota, and Synergistetes phylum levels, Ruminococcaceae, Prevotellaceae, and Saccharofermentans genus levels than the other treatments (p < 0.05). In contrast, EF25 was associated with higher levels of abundance-based coverage estimator (ACE), Chaol index of the phyla Synergistetes and Bacteroidetes, and of the genus Erysipelotrichaceae, Rikenellaceae, and Prevotella as compared with other treatments (p < 0.05). EF50 resulted in the greatest values for the genus Christensenellaceae and Lachnospiraceae as compared with other treatments (p < 0.05). EF75 resulted in the greatest values for the Shannon index as compared with other treatments (p < 0.05). EF0 resulted in the greatest values for gas production (GP), ammonia nitrogen (NH3-N), total volatile fatty acid (TVFA), acetate, propionate, butyrate, valerate, isobutyrate, isovalerate, and the phyla Firmicutes, Proteobacteria, and Spirochaetes, and the genus Succiniclasticum, Ruminobacter, Family_XIII and Treponema as compared with other treatments (p < 0.05). PICRUSt2 analysis indicated that most of the functional prediction pathways were involved in Carbohydrate metabolism and, Amino acid metabolism. Therefore, the recommended ratio of EF in sheep diet should range from 25% to 50%, and the maximum proportion should not exceed 75%.

Dominant remodelling of cattle rumen microbiome by Schedonorus arundinaceus (tall fescue) KY-31 carrying a fungal endophyte

Tall fescue KY-31 is an important primary forage for beef cattle. It carries a fungal endophyte that produces ergovaline, the main cause of tall fescue toxicosis that leads to major revenue loss for livestock producers. The MaxQ, an engineered cultivar, hosts an ergovaline nonproducing strain of the fungus and consequently is nontoxic. However, it is less attractive economically. It is not known how rumen microbiome processes these two forages towards nutrient generation and ergovaline transformation. We have analysed the rumen microbiome compositions of cattle that grazed MaxQ with an intervening KY-31 grazing period using the 16S rRNA-V4 element as an identifier and found that KY-31 remodelled the microbiome substantially, encompassing both cellulolytic and saccharolytic functions. The effect was not evident at the whole microbiome levels but was identified by analysing the sessile and planktonic fractions separately. A move from MaxQ to KY-31 lowered the Firmicutes abundance in the sessile fraction and increased it in planktonic part and caused an opposite effect for Bacteroidetes, although the total abundances of these dominant rumen organisms remained unchanged. The abundances of Fibrobacter , which degrades less degradable fibres, and certain cellulolytic Firmicutes such as Pseudobutyrivibrio and Butyrivibrio 2, dropped in the sessile fraction, and these losses were apparently compensated by increased occurrences of Eubacterium and specific Ruminococcaceae and Lachnospiraceae . A return to MaxQ restored the original Firmicutes and Bacteroidetes distributions. However, several KY-31 induced changes, such as the low abundance of Fibrobacter and Butyrivibrio two remained in place, and their substitutes maintained significant presence. The rumen microbiome was distinct from previously reported faecal microbiomes. In summary, KY-31 and MaxQ were digested in the cattle rumen with distinct consortia and the KY-31-specific features were dominant. The study also identified candidate ergovaline transforming bacteria. It highlighted the importance of analysing sessile and planktonic fractions separately.

Response of sheep rumen fermentation and microbial communities to feed infected with the endophyte Epichloë gansuensis as evaluated with rumen-simulating technology

Achnatherum inebrians, a perennial grass, is widely distributed in China. When infected by the endophyte Epichloë gansuensis, A. inebrians produces an abundance of alkaloids that enhance plant survival but are toxic to animals. Here we used in vitro fermentation to study the impact of endophyte- infected A. inebrians (E+) addition on rumen fermentation characteristics and on microbial community and diversity as assessed with amplicon sequencing technology. We examined E+ addition at five levels, E0, E25, E50, E75, and E100, corresponding to 0%, 25%, 50%, 75%, and 100% of the fermentation substrate, respectively. Both the fermentation characteristics and rumen microbial community structure differed significantly among treatments. E100 resulted in the highest values for pH, the Shannon index, Kiritimatiellaeota, and Lentisphaerae levels relative to the other treatments. In contrast, E25 was associated with higher levels of ammonia nitrogen, total volatile fatty acid, propionate, butyrate, isobutyrate, valerate, of the phyla Bacteroidetes and Firmicutes, and of the genus Prevotella_1, Succiniclasticum, Family_XIII_AD3011_group, Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG-001, and Pyramidobacter as compared with other treatments. E50 resulted in the greatest values for the abundance-based coverage estimator (ACE) and the Chao1 index as compared with other treatments. E0 resulted in the greatest values for digestibility of dry matter, gas production, acetate, and Ruminobacter as compared with other treatments. This approach avoided animal toxicity experiments and confirmed that rumen fermentation characteristics and rumen microbiota were affected by E+ toxin. Therefore, E25 showed higher abundance in Prevotella_1, Prevotellaceae_ UCG-001, and Lachnospiraceae_XPB1014_group that implied they should play significant roles in E+ alkaloids degradation. And then, we can infer that rumen microorganisms should function as an antidote with respect to this poisoning reaction at moderate dietary percentages of E+.