Promote Growth and Animal Health with Isoflavones in Red Clover and Other Legumes

The field of nutrition has continued to expand since the 18th century. We once thought that the only important components in foods and feeds were proteins, carbohydrates, fats and salts. Evidence was slowly pieced together to show that certain minor components were essential for life, and the vitamins were discovered. Like the doctors that first suspected vitamins were essential, some cattlemen have long noted advantages in animal performance and health on certain diets in ways that cannot be explained by a simple forage analysis. Today, we are learning the roles that phenolic plant secondary metabolites, sometimes called polyphenols, play in both human and animal nutrition. In particular, our USDA-ARS unit is conducting research on a group of polyphenols called isoflavones, which are found in clovers and other legumes. Isoflavones prevent damage by ultraviolet light in plants. They are also a chemical defense against infection by bacteria and fungi. It has long been recognized that isoflavones also have biological effects on animals that consume the plants. They are antioxidants and estrogens. The estrogenic effects of legumes, well known in ruminants, are due to isoflavones. Much of the early research on isoflavones in ruminant diets is about their negative effects on reproduction. However, new research is showing there are benefits to cattle that consume isoflavones. In this article, we will explore two recently discovered benefits of isoflavones: 1) improved dietary nitrogen efficiency, and 2) improved blood flow during fescue toxicosis

Switchgrass \u3cem\u3e(Panicum virgatum)\u3c/em\u3e Fermentation by \u3cem\u3eClostridium thermocellum\u3c/em\u3e and \u3cem\u3eClostridium saccharoperbutylacetonicum\u3c/em\u3e Sequential Culture in a Continuous Flow Reactor

The study was conducted to evaluate fermentation by Clostridium thermocellum and C. saccharoperbutylacetonicum in a continuous-flow, high-solids reactor. Liquid medium was continuously flowed through switchgrass (2 mm particle size) at one of three flow rates: 83.33 mL h−1 (2 L d−1), 41.66 mL h−1 (1 L d−1), and 20.833 mL h−1 (0.5 L d−1). The cellulolytic phase was initiated by culturing C. thermocellum (63 °C, 24 h). The temperature was decreased (35) and C. saccharoperbutylacetonicum was inoculated. When metabolism decreased (96 h), the temperature was increased (63 °C; 24 h) to permit cellulosome production by C. thermocellum. The C. saccharoperbutylacetonicum was re-inoculated and the temperature returned to 35°C. The average gross production over 9 d was 1480 mg total acids (formic, acetic lactic butyric), 207 mg total solvents (acetone, butanol, ethanol), and average dry matter disappearance was 2.8 g from 25 g non-pretreated switchgrass. There was no effect of flow rate on the product formation. These results indicate that C. thermocellum can survive and produce cellulases with C. saccharoperbutylacetonicumin a continuous-flow, high-solids reactor temperature with temperature cycling

Hops (\u3cem\u3eHumulus lupulus\u3c/em\u3e L.) Bitter Acids: Modulation of Rumen Fermentation and Potential as an Alternative Growth Promoter

Antibiotics can improve ruminant growth and efficiency by altering rumen fermentation via selective inhibition of microorganisms. However, antibiotic use is increasingly restricted due to concerns about the spread of antibiotic-resistance. Plant-based antimicrobials are alternatives to antibiotics in animal production. The hops plant (Humulus lupulus L.) produces a range of bioactive secondary metabolites, including antimicrobial prenylated phloroglucinols, which are commonly called alpha- and beta-acids. These latter compounds can be considered phyto-ionophores, phytochemicals with a similar antimicrobial mechanism of action to ionophore antibiotics (e.g., monensin, lasalocid). Like ionophores, the hop beta-acids inhibit rumen bacteria possessing a classical Gram-positive cell envelope. This selective inhibition causes several effects on rumen fermentation that are beneficial to finishing cattle, such as decreased proteolysis, ammonia production, acetate: propionate ratio, and methane production. This article reviews the effects of hops and hop secondary metabolites on rumen fermentation, including the physiological mechanisms on specific rumen microorganisms, and consequences for the ruminant host and ruminant production. Further, we propose that hop beta-acids are useful model natural products for ruminants because of (1) the ionophore-like mechanism of action and spectrum of activity and (2) the literature available on the plant due to its use in brewing. The purpose of this review is to collect and reexamine experiments that evaluated bitter acids from the hops plant (Humulus lupulus L.) as modifiers of rumen microbiology. These experiments were largely performed and reported over the last decade. However, historical work is drawn upon for context and for the origins of hypotheses. The thesis of the review is that the effects of bitter acids on rumen bacteria are similar to the effects of ionophore antibiotics, which have been used in ruminant nutrition for many years. This similarity and the vast body of current and historical literature on the hops plant make it an ideal model among rumen-active plant secondary metabolites. We have encountered a number of natural products researchers interested in microbiological uses of the bitter acids, but unfamiliar with rumen microbiology and its role in ruminant nutrition. Likewise, there are many ruminant scientists who are unfamiliar with the plant and its biochemistry. Both of these groups are the intended audience. Therefore, the review includes introductions to rumen microbiology and the hops plant

Interaction of Isoflavones and Endophyte-Infected Tall Fescue Seed Extract on Vasoactivity of Bovine Mesenteric Vasculature

It was hypothesized that isoflavones may attenuate ergot alkaloid-induced vasoconstriction and possibly alleviate diminished contractility of vasculature after exposure to ergot alkaloids. The objective of this study was to determine if prior incubation of bovine mesenteric vasculature with the isoflavones formononetin (F), biochanin A (B), or an ergovaline-containing tall fescue seed extract (EXT) and their combinations affect ergotamine (ERT)-induced contractility. Multiple segments of mesenteric artery and vein supporting the ileal flange of the small intestine were collected from Angus heifers at slaughter (n = 5, bodyweight = 639 ± 39 kg). Duplicates of each vessel type were incubated in tissue culture flasks at 37°C with a 50-mL volume of Krebs–Henseleit buffer containing: only buffer (control); or 1 × 10−6 M EXT; F; or B; and combinations of 1 × 10−6 M EXT + F; 1 × 10−6 M EXT + B; 1 × 10−6 M F + B; or 1 × 10−6 M EXT + F + B. After incubation for 2 h, sections were mounted in a multimyograph chamber. The ERT dose responses were normalized to 0.12 M KCl. Pretreatment with F, B, and F + B without EXT resulted in similar contractile responses to ERT in mesenteric artery and all incubations containing EXT resulted in a complete loss of vasoactivity to ERT. In mesenteric artery pretreated with EXT, treatments that contained B had higher contractile responses (P \u3c 0.05) at ERT concentrations of 1 × 10−7 and 5 × 10−7 M. Also, treatments containing B tended (P \u3c 0.1) to have greater responses than treatments without B at ERT concentrations of 1 × 10−6, 5 × 10−6, and 5 × 10−5 M. In mesenteric vein pretreated with EXT, treatments containing F had greater contractile responses to ERT at 1 × 10−5, 5 × 10−5, and 1 × 10−4 M (P \u3c 0.05). These data indicated that F and B at 1 × 10−6 M and their combination did not impact the overall contractile response to ERT in mesenteric vasculature. However, F and B may offset some of the vasoconstriction caused by prior exposure to ergot alkaloids

Interaction of Isoflavones and Endophyte-Infected Tall Fescue Seed Extract on Vasoactivity of Bovine Mesenteric Vasculature

It was hypothesized that isoflavones may attenuate ergot alkaloid-induced vasoconstriction and possibly alleviate diminished contractility of vasculature after exposure to ergot alkaloids. The objective of this study was to determine if prior incubation of bovine mesenteric vasculature with the isoflavones formononetin (F), biochanin A (B), or an ergovaline-containing tall fescue seed extract (EXT) and their combinations affect ergotamine (ERT)-induced contractility. Multiple segments of mesenteric artery and vein supporting the ileal flange of the small intestine were collected from Angus heifers at slaughter (n = 5, bodyweight = 639 ± 39 kg). Duplicates of each vessel type were incubated in tissue culture flasks at 37°C with a 50-mL volume of Krebs–Henseleit buffer containing: only buffer (control); or 1 × 10−6 M EXT; F; or B; and combinations of 1 × 10−6 M EXT + F; 1 × 10−6 M EXT + B; 1 × 10−6 M F + B; or 1 × 10−6 M EXT + F + B. After incubation for 2 h, sections were mounted in a multimyograph chamber. The ERT dose responses were normalized to 0.12 M KCl. Pretreatment with F, B, and F + B without EXT resulted in similar contractile responses to ERT in mesenteric artery and all incubations containing EXT resulted in a complete loss of vasoactivity to ERT. In mesenteric artery pretreated with EXT, treatments that contained B had higher contractile responses (P \u3c 0.05) at ERT concentrations of 1 × 10−7 and 5 × 10−7 M. Also, treatments containing B tended (P \u3c 0.1) to have greater responses than treatments without B at ERT concentrations of 1 × 10−6, 5 × 10−6, and 5 × 10−5 M. In mesenteric vein pretreated with EXT, treatments containing F had greater contractile responses to ERT at 1 × 10−5, 5 × 10−5, and 1 × 10−4 M (P \u3c 0.05). These data indicated that F and B at 1 × 10−6 M and their combination did not impact the overall contractile response to ERT in mesenteric vasculature. However, F and B may offset some of the vasoconstriction caused by prior exposure to ergot alkaloids

Effect of Dietary Starch Source and Concentration on Equine Fecal Microbiota

Starch from corn is less susceptible to equine small intestinal digestion than starch from oats, and starch that reaches the hindgut can be utilized by the microbiota. The objective of the current study was to examine the effects of starch source on equine fecal microbiota. Thirty horses were assigned to treatments: control (hay only), HC (high corn), HO (high oats), LC (low corn), LO (low oats), and LW (low pelleted wheat middlings). Horses received an all-forage diet (2 wk; d -14 to d -1) before the treatment diets (2 wk; d 1 to 14). Starch was introduced gradually so that horses received 50% of the assigned starch amount (high = 2 g starch/kg BW; low = 1 g starch/kg BW) by d 4 and 100% by d 11. Fecal samples were obtained at the end of the forage-only period (S0; d -2), and on d 6 (S1) and d 13 (S2) of the treatment period. Cellulolytics, lactobacilli, Group D Gram-positive cocci (GPC), lactate-utilizers and amylolytics were enumerated. Enumeration data were log transformed and analyzed by repeated measures ANOVA. There were sample day × treatment interactions (P \u3c 0.0001) for all bacteria enumerated. Enumerations from control horses did not change during the sampling period (P \u3e 0.05). All treatments except LO resulted in increased amylolytics and decreased cellulolytics, but the changes were larger in horses fed corn and wheat middlings (P \u3c 0.05). Feeding oats resulted in increased lactobacilli and decreased GPC (P \u3c 0.05), while corn had the opposite effects. LW had increased lactobacilli and GPC (P \u3c 0.05). The predominant amylolytic isolates from HC, LC and LW on S2 were identified by 16S RNA gene sequencing as Enterococcus faecalis, but other species were found in oat fed horses. These results demonstrate that starch source can have a differential effect on the equine fecal microbiota

On-Farm Integrated High-Solids Processing System for Biomass

A method for on-farm processing a biomass feedstock into a useful industrial chemicals includes the steps of (a) delignifying the biomass feedstock to produce a delignified biomass, (b) subjecting the deliguified biomass to cellulase production, (c) subjecting the deliguified biomass with attached cellulase to simultaneous cellulolytic and solventogenic reactions to produce useful industrial chemicals (d) collecting and separating the useful industrial chemical from the fermentation broth and (e) collecting the fermentation residues

Effect of Dietary Starch Source and Concentration on Equine Fecal Microbiota

Starch from corn is less susceptible to equine small intestinal digestion than starch from oats, and starch that reaches the hindgut can be utilized by the microbiota. The objective of the current study was to examine the effects of starch source on equine fecal microbiota. Thirty horses were assigned to treatments: control (hay only), HC (high corn), HO (high oats), LC (low corn), LO (low oats), and LW (low pelleted wheat middlings). Horses received an all-forage diet (2 wk; d -14 to d -1) before the treatment diets (2 wk; d 1 to 14). Starch was introduced gradually so that horses received 50% of the assigned starch amount (high = 2 g starch/kg BW; low = 1 g starch/kg BW) by d 4 and 100% by d 11. Fecal samples were obtained at the end of the forage-only period (S0; d -2), and on d 6 (S1) and d 13 (S2) of the treatment period. Cellulolytics, lactobacilli, Group D Gram-positive cocci (GPC), lactate-utilizers and amylolytics were enumerated. Enumeration data were log transformed and analyzed by repeated measures ANOVA. There were sample day × treatment interactions (P \u3c 0.0001) for all bacteria enumerated. Enumerations from control horses did not change during the sampling period (P \u3e 0.05). All treatments except LO resulted in increased amylolytics and decreased cellulolytics, but the changes were larger in horses fed corn and wheat middlings (P \u3c 0.05). Feeding oats resulted in increased lactobacilli and decreased GPC (P \u3c 0.05), while corn had the opposite effects. LW had increased lactobacilli and GPC (P \u3c 0.05). The predominant amylolytic isolates from HC, LC and LW on S2 were identified by 16S RNA gene sequencing as Enterococcus faecalis, but other species were found in oat fed horses. These results demonstrate that starch source can have a differential effect on the equine fecal microbiota

Mitigation of Ergot Vasoconstriction by Clover Isoflavones in Goats (\u3cem\u3eCapra hircus\u3c/em\u3e)

Ergot alkaloids produced by a fungal endophyte (Epichloë coenophiala; formerly Neotyphodium coenophialum) that infects tall fescue (Lolium arundinaceum) can induce persistent constriction of the vasculature in ruminants, hindering their capability to thermo-regulate core body temperature. There is evidence that isoflavones produced by legumes can relax the vasculature, which suggests that they could relieve ergot alkaloid-induced vasoconstriction and mitigate the vulnerability to severe heat stress in ruminants that graze tall fescue. To test if isoflavones can relieve alkaloid-induced vasoconstriction, two pen experiments were conducted with rumen-fistulated goats (Capra hircus) to determine with ultrasonograpy if isoflavones can (1) promote vascular compliance by countering alkaloid-induced vasoconstriction and (2) relieve already imposed alkaloid-induced vasoconstriction. Goats were fed ad libitum chopped orchardgrass (Dactylis glomerata)–timothy (Phleum pratense) hay prior to conducting the experiments. Measures of carotid and interosseous luminal areas were obtained pre- (baseline) and post-ruminal infusions in both experiments with goats being fed the hay, and for blood flow rate in the carotid artery in Experiment 2. Responses to infusion treatments were evaluated as proportionate differences from baseline measures. Peak systolic velocity, pulsatility index, and heart rate were measured on the last day on treatment (DOT) in Experiment 1, and on all imaging sessions during Experiment 2. For Experiment 1, rumens were infused with ground toxic fescue seed and isoflavones in Phase A and with only the toxic seed in Phase B. The infusion treatments were switched between phases in Experiment 2, which employed a fescue seed extract having an ergot alkaloid composition equivalent to that of the ground seed used in Experiment 1. During Experiment 1, luminal areas of carotid and interosseous arteries in Phase A did not deviate (P \u3e 0.1) from baselines over 1, 2, 3, and 4 DOT, but the areas of both declined linearly from baselines over 1, 2, 3, and 4 DOT in Phase B. By 6, 7, and 8 DOT in Experiment 2, luminal areas of the arteries and flow rate declined from baselines with infusions with the only seed extract in Phase A, but luminal areas and flow rate increased over 4, 5, and 6 DOT with the additional infusion of isoflavones. Peak systolic velocity and heart rate were not affected by treatment in either experiment, but were highest when infused with only ergot alkaloids in both experiments. Treatment with isoflavones was demonstrated to relax the carotid and interosseous arteries and reduce resistance to blood flow. Results indicate that isoflavones can relax persistent vasoconstriction in goats caused by consumption of ergot alkaloids, and mitigate the adverse effect that ergot alkaloids have on dry matter intake

Effect of Biochanin A on the Rumen Microbial Community of Holstein Steers Consuming a High Fiber Diet and Subjected to a Subacute Acidosis Challenge

Subacute rumen acidosis (SARA) occurs when highly fermentable carbohydrates are introduced into the diet, decreasing pH and disturbing the microbial ecology of the rumen. Rumen amylolytic bacteria rapidly catabolize starch, fermentation acids accumulate in the rumen and reduce environmental pH. Historically, antibiotics (e.g., monensin, MON) have been used in the prevention and treatment of SARA. Biochanin A (BCA), an isoflavone produced by red clover (Trifolium pratense), mitigates changes associated with starch fermentation ex vivo. The objective of the study was to determine the effect of BCA on amylolytic bacteria and rumen pH during a SARA challenge. Twelve rumen fistulated steers were assigned to 1 of 4 treatments: HF CON (high fiber control), SARA CON, MON (200 mg d-1), or BCA (6 g d-1). The basal diet consisted of corn silage and dried distiller’s grains ad libitum. The study consisted of a 2-wk adaptation, a 1-wk HF period, and an 8-d SARA challenge (d 1–4: 40% corn; d 5–8: 70% cracked corn). Samples for pH and enumeration were taken on the last day of each period (4 h). Amylolytic, cellulolytic, and amino acid/peptide-fermenting bacteria (APB) were enumerated. Enumeration data were normalized by log transformation and data were analyzed by repeated measures ANOVA using the MIXED procedure of SAS. The SARA challenge increased total amylolytics and APB, but decreased pH, cellulolytics, and in situ DMD of hay (P \u3c 0.05). BCA treatment counteracted the pH, microbiological, and fermentative changes associated with SARA challenge (P \u3c 0.05). Similar results were also observed with MON (P \u3c 0.05). These results indicate that BCA may be an effective alternative to antibiotics for mitigating SARA in cattle production systems