Levodopa attenuates the feed intake reduction caused by ergot alkaloids in cattle.

Consumption of ergot alkaloids from endophyte-infected tall fescue results in losses to the livestock industry in many countries and a means to mitigate these losses is needed. The objective of this study was to evaluate intra-abomasal infusion of the dopamine precursor, levodopa (L-DOPA), on dopamine metabolism, feed intake, and serum metabolites of steers exposed to ergot alkaloids. Twelve Holstein steers (344.9 ±â€…9.48 kg) fitted with ruminal cannula were housed with a cycle of heat challenge during the daytime (32 °C) and thermoneutral at night (25 °C). The steers received a basal diet of alfalfa cubes containing equal amounts of tall fescue seed composed of a mixture of endophyte-free (E-) or endophyte-infected tall fescue seeds (E+) equivalent to 15 µg ergovaline/kg body weight (BW) for 9 d followed by intra-abomasal infusion of water (L-DOPA-) or levodopa (L-DOPA+; 2 mg/kg BW) for an additional 9 d. Afterward, the steers were pair-fed for 5 d to conduct a glucose tolerance test. The E+ treatment decreased (P = 0.005) prolactin by approximately 50%. However, prolactin increased (P = 0.050) with L-DOPA+. Steers receiving E+ decreased (P < 0.001) dry matter intake (DMI); however, when supplemented with L-DOPA+ the decrease in DMI was less severe (L-DOPA × E, P = 0.003). Also, L-DOPA+ infusion increased eating duration (L-DOPA × E, P = 0.012) when steers were receiving E+. The number of meals, meal duration, and intake rate were not affected (P > 0.05) by E+ or L-DOPA+. The L-DOPA+ infusion increased (P < 0.05) free L-DOPA, free dopamine, total L-DOPA, and total dopamine. Conversely, free epinephrine and free norepinephrine decreased (P < 0.05) with L-DOPA+. Total epinephrine and total norepinephrine were not affected (P > 0.05) by L-DOPA+. Ergot alkaloids did not affect (P > 0.05) circulating free or total L-DOPA, dopamine, or epinephrine. However, free and total norepinephrine decreased (P = 0.046) with E+. Glucose clearance rates at 15 to 30 min after glucose infusion increased with L-DOPA+ (P < 0.001), but not with E+ (P = 0.280). Administration of L-DOPA as an agonist therapy to treat fescue toxicosis provided a moderate increase in DMI and eating time and increased plasma glucose clearance for cattle dosed with E+ seed.

Fescue has become the dominant cool-season perennial grass in the southeastern region of the United States and is also found in other countries. Endophytes from a plant­fungus symbiotic relationship produce toxic alkaloids that have caused significant annual economic losses to the livestock industry. Treatments to alleviate this toxicosis are still demanded. This study evaluates the infusion of the dopamine precursor, levodopa (L-DOPA), to mitigate the toxicosis caused by ergot alkaloids. When L-DOPA was infused, eating duration increased and the decrease in feed intake caused by ergot alkaloids was less severe. Additionally, circulating dopamine and glucose clearance increased with L-DOPA. These results suggest that L-DOPA has the potential to aid in the mitigation of the toxicosis caused by ergot alkaloids.

5-hydroxytryphophan mitigates ergot alkaloid-induced suppression of serotonin and feed intake in cattle.

The impact of ergot toxicosis on livestock industries is detrimental and treatments are needed in many countries. The objective of this study was to evaluate the effects of acute exposure to ergot alkaloids and 5-hydroxytryptophan (5-HTP) supplementation on feed intake, serotonin metabolism, and blood metabolites in cattle. Eight Holstein steers (538 ±â€…18 kg) fitted with ruminal cannulas were used in a replicated 4 × 4 Latin Square design experiment with a 2 × 2 factorial treatment structure. The treatments were the combination of 0 (E-) or 15 µg ergovaline/kg BW (E+) and 0 (5HTP-) or 0.5 mg of 5-hydroxy-l-tryptophan/kg BW (5HTP+) administered daily for 6 d. Toxic endophyte-infected tall fescue seed was used to supply the daily dose of ergovaline. Endophyte-free seed was used to equalize seed intake between treatments. Ground seed was placed into the rumen immediately before feeding. The 5-HTP was dissolved in water and infused into the abomasum via the reticulo-omasal orifice. Blood was collected from a jugular vein catheter at 0, 1, 2, 4, 8, and 24 h after treatment administration. Ergovaline without 5-HTP (E+/5HTP-) decreased dry matter intake (DMI) in comparison to steers without ergovaline and 5-HTP (E-/5HTP-). However, 5-HTP infusion in association with ergovaline (E+/5HTP+) normalized the DMI. Although E + did not affect (P > 0.05) the area under the curve (AUC) of serum 5-HTP, 5-hydroxyindoleacetic acid, tryptophan, and kynurenine, serum and plasma serotonin concentrations were decreased (P < 0.05). The infusion of 5-HTP increased (P < 0.05) the AUC of serum 5-HTP, serum and plasma serotonin, and serum 5-hydroxyindoleacetic acid. In conclusion, acute exposure to ergot alkaloids reduced DMI and circulating serotonin in cattle but 5-HTP administration showed potential to normalize both circulating serotonin and feed intake.

Some grass species have a symbiotic relationship with an endophytic fungus that produces toxic ergot alkaloids which have detrimental impacts on herbivores. Ergot alkaloids have a significant impact on livestock production causing annual loss to the livestock industry that likely exceeds $1 billion. Effective treatment for this toxicosis is still needed. The objective of this study was to evaluate the effects of acute exposure to ergot alkaloids and 5-hydroxytryptophan supplementation on feed intake, serotonin metabolism, and blood metabolites in cattle. We found that 5-hydroxytryptophan administration has the potential to normalize both circulating serotonin and feed intake reduced by ergot alkaloid consumption.

Exploring the Role of G Protein Expression in Sodium Butyrate-Enhanced Pancreas Development of Dairy Calves: A Proteomic Perspective.

The present study evaluated the effects of sodium butyrate (SB) supplementation on exocrine and endocrine pancreatic development in dairy calves. Fourteen male Holstein calves were alimented with either milk or milk supplemented with SB for 70 days. Pancreases were collected for analysis including staining, immunofluorescence, electron microscopy, qRT-PCR, Western blotting, and proteomics. Results indicated increased development in the SB group with increases in organ size, protein levels, and cell growth. There were also exocrine enhancements manifested as higher enzyme activities and gene expressions along with larger zymogen granules. Endocrine benefits included elevated gene expression, more insulin secretion, and larger islets, indicating a rise in ß-cell proliferation. Proteomics and pathway analyses pinpointed the G protein subunit alpha-15 as a pivotal factor in pancreatic and insulin secretion pathways. Overall, SB supplementation enhances pancreatic development by promoting its exocrine and endocrine functions through G protein regulation in dairy calves.

Postruminal Casein Infusion and Exogenous Glucagon-Like Peptide 2 Administration Differentially Stimulate Pancreatic α-Amylase and Small Intestinal α-Glucosidase Activity in Cattle.

BACKGROUND: Increasing luminal carbohydrate flow decreases pancreatic α-amylase activity but can increase jejunal maltase activity, suggesting that regulation of carbohydrase activity is perhaps uncoordinated in response to luminal carbohydrate flow. Increasing luminal casein flow increases pancreatic α-amylase activity in cattle, and exogenous glucagon-like peptide 2 (GLP-2) has been shown to increase small intestinal α-glucosidase activity in nonruminants. OBJECTIVES: The objective was to evaluate the effects of postruminal casein infusion, exogenous GLP-2, or their combination on endogenous pancreatic and small intestinal carbohydrase activity in cattle postruminally infused with starch. METHODS: Holstein steers [n = 24; 250 ± 23 kg body weight (BW)] received a continuous abomasal infusion of 3.94 g raw corn starch/kg of BW combined with either 0 or 1.30 g casein/kg of BW. Steers received subcutaneous injections in 2 equal portions daily of excipient (0.5% bovine serum albumin) or 100 µg GLP-2/kg of BW per day. At the end of the 7-d treatment period, steers were slaughtered for tissue collection. Data were analyzed using the MIXED procedure of SAS version 9.4 (SAS Institute Inc.). RESULTS: Postruminal casein infusion increased (P ≤ 0.03) pancreatic mass by 12.6%, total pancreatic α-amylase activity by 50%, and postruminal starch disappearance from 96.7% to 99.3%. Exogenous GLP-2 increased (P < 0.01) total small intestinal and mucosal mass by 1.2 kg and 896 g, respectively. Relative to control, GLP-2 and casein + GLP-2 increased (P = 0.04) total small intestinal α-glucosidase activity by 83.5%. Total small intestinal maltase, isomaltase, and glucoamylase activity was 90%, 100%, and 66.7% greater for GLP-2 and casein + GLP-2 steers compared with control. CONCLUSIONS: Casein increased pancreatic α-amylase activity, GLP-2 increased small intestinal α-glucosidase activity, and the combination of casein and GLP-2 increased both pancreatic α-amylase activity and small intestinal α-glucosidase activity. This novel approach provides an in vivo model to evaluate effects of increasing endogenous carbohydrase activity on small intestinal starch digestion.

Influence of Anti-Coccidial Compounds and Phytogenic Saponin Extracts on In Vitro and In Vivo Ruminal Fermentation and Methane Production of Cattle.

Four experiments were conducted to evaluate sources of anti-coccidial compounds and phytogenic saponin extracts on in vitro and in vivo ruminal fermentation and CH4 production at multiple inclusion levels. In experiment 1, eight steers were fed either a finishing diet or a finishing diet supplemented with 0.5 mg/kg BW decoquinate (DCQ) and 3.33 mg/kg BW Yucca schidigera extract (YSE), and respiratory gas exchange was measured. In experiment 2, four ruminally-cannulated steers were fed the same treatments as experiment 1, and ruminal fermentation was evaluated. Anti-coccidial sources (experiment 3; monensin, DCQ, amprolium) and saponin sources (experiment 4; YSE, Quillaja saponaria extract) and levels were evaluated for effects on in vitro ruminal fermentation and CH4 production. DCQ + YSE supplementation did not influence (p ≥ 0.24) in vivo respiratory gas consumption/production, in situ DM degradation, or liquid passage kinetics. Ruminal propionate proportion tended to increase (p = 0.09) with DCQ + YSE. Monensin decreased (p ≤ 0.04) in vitro acetate:propionate and CH4 production; saponin supplementation linearly increased (p < 0.01) propionate proportion but did not influence (p ≥ 0.38) in vitro CH4 production. Saponins and non-antibiotic anti-coccidials did not influence in vitro or in vivo CH4 production with finishing diets.

Duration of ergovaline exposure influences serotonin-mediated vasoactivity of bovine mesenteric vasculature.

Ergovaline (ERV), produced in toxic endophyte-infected tall fescue, causes potent vasoconstriction of bovine peripheral and visceral vasculature. Ergovaline acts as both an agonist and an antagonist in bovine gut blood vessels through serotonin (5-HT) receptors and it appears that the type of action could be influenced by the extent of ERV exposure. Because it was unclear how the duration of ERV exposure influences 5-HT-mediated vasoactivity, experiments were designed to evaluate how simultaneous or prior ERV exposure influenced 5-HT-mediated vasoactivity of mesenteric artery (MA) and vein (MV) segments from Holstein steers (N = 10). Vessels were incubated in Krebs-Henseleit buffer containing 0, 0.01, or 0.1 µM ERV for 24 h prior to the 5-HT dose-response or exposed to fixed concentrations of 0, 0.01, or 0.1 µM ERV simultaneously during the 5-HT dose-response. Vessels were suspended in chambers of a multimyograph containing Krebs-Henseleit buffer and equilibrated to 1 g tension for 90 min. Vessels were exposed to increasing concentrations of 5-HT (5 × 10-8 M to 1 × 10-4 M) every 15 min and contractile responses were normalized as a percentage of the maximum contractile response induced by 120 mM KCl reference addition. Two-way analysis of variance was used to separately analyze data for each vessel type and duration of exposure using the MIXED procedure of SAS. When 5-HT concentration increased from 5 × 10-8 to 1 × 10-6 M, simultaneous addition of 0.1 µM ERV increased (P < 0.01) the contractile response of MV compared with additions of 0 and 0.01 µM ERV. At 1 × 10-4 M 5-HT, the simultaneous presence of 0.01 and 0.1 µM ERV decreased (P < 0.01) the contractile response of both MA and MV compared with 0 µM ERV addition. As 5-HT concentrations increased, the contractile response increased (P < 0.01) in both MA and MV with no previous ERV exposure, but decreased in MA and MV with 24 h prior exposure to 0.01 and 0.1 µM ERV. These data demonstrate that the duration of ERV exposure influences 5-HT-mediated vasoconstriction and likely vasorelaxation in bovine mesenteric vasculature. If ERV and 5-HT exposure occur simultaneously, ERV can act as a partial agonist of 5-HT-mediated vasoconstriction. If 5-HT exposure occurs after blood vessels have had prior ERV exposure, it appears that 5-HT may induce vasorelaxation of blood vessels. More research is needed to identify cellular and molecular mechanisms involved with 5-HT-mediated vasoactivity.

Consumption of ergot alkaloids found in endophyte-infected tall fescue can lead to symptoms of fescue toxicosis, such as vasoconstriction, in ruminant livestock species. Ergovaline is one of the primary ergot alkaloids responsible for causing vasoconstriction when toxic varieties of fescue are consumed. It has been previously shown that ergovaline causes vasoconstriction by interacting with vascular serotonin receptors in cattle and sheep. Depending on when ergovaline exposure occurs, ergovaline can function as an agonist (stimulant) or antagonist (inhibitor) of vascular activity. However, it is unclear how the duration of ergovaline exposure affects vasoconstriction caused by serotonin. Experiments were conducted using the bovine mesenteric artery and mesenteric vein that were exposed to either 0, 0.01, or 0.1 µM ergovaline for 24-h prior to serotonin additions or simultaneously with serotonin additions. Maximum contractile response data were recorded using a multimyograph system and normalized as a percentage of the contractile response produced by the reference compound, KCl. The results of these experiments demonstrated that the duration of ergovaline exposure influences serotonin-mediated vasoconstriction and possibly vasorelaxation in bovine mesenteric vasculature. If ergovaline and serotonin exposure occur simultaneously, ergovaline can act as an agonist or antagonist of serotonin-mediated vasoconstriction. If serotonin exposure occurs after prior ergovaline exposure, serotonin can induce vasorelaxation of blood vessels. Understanding how complex interactions between ergovaline and serotonin occur and affect vascular function will aid in the development of strategies to mitigate sustained vasoconstriction caused during fescue toxicosis.

In vitro gas production kinetics are influenced by grain processing, flake density, starch retrogradation, and Aspergillus oryzae fermentation extract containing α-amylase activity.

Grain processing such as particle size, flake density, or starch retrogradation can influence ruminal degradability characteristics; however, it is unclear how exogenous α-amylase supplementation interacts with different processed grains. Four experiments were conducted to compare the effects of Aspergillus oryzae fermentation extract (Amaize; Alltech Biotechnology Inc., Nicholasville, KY) supplementation on in vitro gas production kinetics of grain substrates with different processing methods that are common in the feedlot industry. In experiment 1, corn processing (dry-rolled, high-moisture, steam-flaked) and Amaize supplementation (0 or 15 U α-amylase activity/100 mL) were evaluated in a 3 × 2 factorial arrangement of treatments. The rate of gas production for dry-rolled corn was higher (P < 0.001) with Amaize supplementation. In experiment 2, flake density (296, 322, 348, 373, and 399 g/L) and starch retrogradation (storage in heat-sealed foil bags for 3 d at 23 or 55°C) were evaluated in a 5 × 2 factorial arrangement of treatments. There was a flake density × starch retrogradation interaction (P < 0.01) for the rate of gas production because the decrease in the rate of gas production with starch retrogradation was greater at lighter flake densities compared with heavier flake densities. In experiment 3, Amaize supplementation was evaluated across flake densities of nonretrograded steam-flaked corn (stored at 23°C) used in experiment 2. There was a flake density × Amaize interaction (P < 0.01) for the rate of gas production where Amaize supplementation resulted in a lower rate of gas production at lighter flake densities (296, 322, and 348 g/L) but a higher rate of gas production at heavier flake densities (373 and 399 g/L). In experiment 4, Amaize supplementation was evaluated across flake densities of retrograded steam-flaked corn (stored at 55°C) used in experiment 2. Gas production was lower after 24 h with Amaize supplementation for retrograded flakes produced to a density of 322 and 399 g/L while Amaize supplementation did not influence gas production at 24 h at other flake densities. There was a flake density × Amaize interaction for the rate of gas production because Amaize supplementation resulted in a faster (P < 0.01) rate of gas production for all flake densities except retrograded flakes produced to a density of 296 g/L. Enzymatic starch availability was positively correlated with the rate of gas production. These data demonstrate that supplementation of 15 U/100 mL of Amaize resulted in greater rates of gas production for dry-rolled corn, corn steam-flaked to heavier densities, and retrograded steam-flaked corn.

Grain processing has been used for decades to improve digestibility of finishing cattle diets, leading to improved growth and feed efficiency. Grain processing methods that result in changes in particle size, flake density, or starch retrogradation have all been shown to affect the degradability characteristics of nutrients in the rumen. Supplementation of feed additives containing exogenous enzyme activity could have the potential to improve digestibility, growth performance, and feed efficiency of livestock. However, it is unknown how supplementation of exogenous α-amylase activity influences degradability characteristics of different processed grains. The objectives of this study were to compare the effects of Aspergillus oryzae fermentation extract supplementation on in vitro gas production kinetics of grain substrates with different processing methods that are common in the feedlot industry. Enzymatic starch availability of steam-flaked corn, but not dry-rolled or high-moisture corn, was reflective of the rate of in vitro gas production. Increasing flake density and increasing starch retrogradation decreased the rate of in vitro gas production. Supplementation of A. oryzae fermentation extract resulted in increased rates of gas production for dry-rolled corn, corn steam-flaked at heavier densities, and retrograded steam-flaked corn.

Corn processing, flake density, and starch retrogradation influence ruminal solubility of starch, fiber, protein, and minerals.

Five ruminally cannulated steers (body weight = 390 ± 7.86 kg) were used in three experiments to evaluate effects of corn processing, flake density, and starch retrogradation on in situ ruminal degradation. In experiment 1, corn was left whole or processed with no screen, ground through a 6-mm screen, or ground through a 1-mm screen. In experiment 2, we produced steam-flaked corn at four densities: 309, 335, 360, and 386 g/L. These four flake densities were sifted for 20 s through a 4-mm screen to produce two particle sizes within each flake density: sifted flakes (>4 mm) and sifted fines (<4 mm). In experiment 3, sifted flakes (335 g/L) were stored for 3-d at either 23 °C (starch availability = 55%) or 55 °C to induce starch retrogradation (starch availability = 41%). All samples for each of the three experiments were weighed into nylon bags and ruminally incubated for 0-h to estimate the soluble fraction. The residue remaining was analyzed for nutrient composition. In experiment 1, whole shelled corn had lesser (P < 0.01) ruminal solubility of all nutrients measured compared with ground corn. Corn ground with a screen (6 and 1 mm) had greater (P < 0.01) ruminal solubility of all nutrients measured compared with corn ground with no screen. Corn ground through a 1-mm screen had greater (P < 0.03) ruminal solubility of DM, total starch, CP, ADF, AHF, P, Mg, K, S, Zn, Fe, and Mn compared with corn ground through a 6-mm screen. In experiment 2, increasing flake density linearly decreased (P < 0.02) the soluble fraction of DM, total starch, CP, ADF, AHF, P, K, S, and Zn of sifted flakes. The soluble DM fraction of sifted fines tended to decrease (P = 0.06) linearly with increasing flake density. Total starch, CP, NDF, and Zn soluble fractions of sifted fines were not influenced by flake density. In experiment 3, storage of sifted flakes in heat-sealed foil bags at 55 °C for 3-d decreased (P < 0.04) the soluble fractions of DM, total starch, CP, NDF, P, Mg, K, S, and Fe. With each increase in the degree of corn processing, there was an increase in the solubility of nutrients. Increasing flake density can decrease ruminal solubility of flakes; however, the soluble fraction of sifted fines is not influenced as much by changes in flake density. Inducing starch retrogradation decreases ruminal solubility of starch, nonstarch OM, and minerals.

Grain processing has been used for decades to improve digestibility of finishing cattle diets, leading to improved growth performance and feed efficiency. The soluble fraction of a feed can be defined as the fraction that disappears immediately in the rumen and its measurement can be useful for understanding kinetic properties of feed digestion. Grain processing methods that result in changes in particle size, flake density, or starch retrogradation have been shown to affect the soluble fraction of dry matter in the rumen. However, it is unknown how the solubility of different nutrients are affected by these changes. The objective of this experiment was to characterize how corn processing, flake density, particle size, and starch retrogradation influence the soluble fraction of starch, protein, fiber, and minerals. With each increase in the degree of corn processing, there was an increase in the solubility of nutrients. Increasing flake density can decrease ruminal solubility of flakes; however, the soluble fraction of sifted fines is not influenced as much by changes in flake density. Inducing starch retrogradation decreases ruminal solubility of starch, nonstarch OM, and minerals. Understanding the factors influencing ruminal solubility of processed corn is important when modeling digestion in beef cattle.

Feeding treats containing cannabidiol (CBD) did not alter canine immune response to immunization with a novel antigen.

Due to the potential risk for cannabidiol (CBD) to negatively impact the immune system, the objective of the current study was to evaluate the effect of CBD on the canine immune response to immunization with a novel antigen, keyhole limpet hemocyanin (KLH). Thirty-two dogs (22.4 ± 6.3 kg BW) were utilized in a completely randomized design with treatments consisting of 5 mg CBD/kg BW/d and a control administered orally via treats. After a 7-d acclimation to treatments, dogs were immunized with 10 mg/dog of KLH via intramuscular injection into the semimembranosus muscle region, which was repeated in 14 d. Blood samples were collected at baseline and weekly for 28 d after initial KLH immunization for analysis of hematology, serum chemistry, and immunoglobulins. Data were analyzed using the MIXED procedure in SAS including the fixed effects of treatment, day, and the treatment by day interaction. Both primary and secondary KLH immunization produced robust immune responses. Most hematological and serum chemistry variables remained within normal reference ranges for dogs across both treatments throughout the study. Alkaline phosphatase, while within normal reference range and similar between treatments at baseline and on d 7 (P = 0.994 and 0.183, respectively), was elevated for CBD-treated dogs versus control on d 14, 21, and 28 (P = 0.006, 0.027, and 0.014, respectively). Both total and KLH-specific IgG and IgM were similar between treatments throughout the study (P > 0.05), although total IgM peaked earlier in control dogs compared to those receiving CBD. Despite the minor shift in the timing of the total IgM peak, CBD did not appear to exhibit humoral immunosuppressive effects when supplemented at 5 mg/kg BW/d. However, this work does highlight the potential for CBD to alter liver function and the need for further safety evaluations of CBD use in dogs utilizing longer-term studies and multiple CBD doses.

Flake density and starch retrogradation influence in situ ruminal degradability characteristics of steam-flaked corn and predicted starch digestibility and energetic efficiency.

Five ruminally cannulated steers (body weight = 390 ± 7.86 kg) were used in two experiments to evaluate the effects of flake density and starch retrogradation on in situ ruminal degradation of steam-flaked corn. In experiment 1, sifted flakes with flake densities of 257, 296, 335, 373, and 412 g/L (enzymatic starch availabilities: 87%, 76%, 66%, 43%, and 49%, respectively) were evaluated in a randomized complete block design experiment. In experiment 2, the experimental design was a randomized complete block design with a 3 × 2 factorial arrangement of treatments. Three steam-flaked corn fractions corresponding to different particle sizes were used: flakes + fines (not sifted; >4 and <4 mm), sifted flakes (>4 mm), and sifted fines (<4 mm). Particle size fractions were stored for 3 d at either 23 °C or 55 °C (starch availabilities averaged across particle sizes: 53.3% and 25.5%, respectively) in heat-sealed foil bags. Samples were ruminally incubated for 0, 3, 6, 12, 24, 48, 72, or 96 h. Degradation data were modeled to obtain the rate and extent of degradation and passage rate was set to 6% per hour. In experiment 1, the rate of degradation decreased linearly (P < 0.01) and in situ ruminal dry matter (DM) degradability decreased linearly (P < 0.01) from 78.9% to 57.3% as flake density increased from 257 to 412 g/L. In experiment 2, storage of steam-flaked corn samples at 55 °C for 3 d decreased (P < 0.01) the rate of degradation by 37.6% across all particle sizes. Storing samples at 55 °C for 3 d decreased (P < 0.01) in situ ruminal DM degradability of flakes + fines, sifted flakes, and sifted fines by 20.9%, 22.6%, and 14.7%, respectively. Using data from experiment 1 and 2, enzymatic starch availability of sifted flakes was positively correlated (R2 = 0.97; P < 0.01) with in situ ruminal DM degradability. The results demonstrate that decreased starch availability resulting from either starch retrogradation or increased flake density is associated with decreased ruminal digestibility. Decreases in starch availability and in situ ruminal degradability may indicate that increasing flake density or starch retrogradation could potentially alter the site of digestion in cattle. Using prediction equations, decreases in ruminal starch digestibility of steam-flaked corn caused by increasing flake density or increasing starch retrogradation could increase energetic efficiency, depending on the rate of passage and if small intestinal starch digestibility is maintained.

Alteration of the Canine Metabolome After a 3-Week Supplementation of Cannabidiol (CBD) Containing Treats: An Exploratory Study of Healthy Animals.

Despite the increased interest and widespread use of cannabidiol (CBD) in humans and companion animals, much remains to be learned about its effects on health and physiology. Metabolomics is a useful tool to evaluate changes in the health status of animals and to analyze metabolic alterations caused by diet, disease, or other factors. Thus, the purpose of this investigation was to evaluate the impact of CBD supplementation on the canine plasma metabolome. Sixteen dogs (18.2 ± 3.4 kg BW) were utilized in a completely randomized design with treatments consisting of control and 4.5 mg CBD/kg BW/d. After 21 d of treatment, blood was collected ~2 h after treat consumption. Plasma collected from samples was analyzed using CIL/LC-MS-based untargeted metabolomics to analyze amine/phenol- and carbonyl-containing metabolites. Metabolites that differed - fold change (FC) ≥ 1.2 or ≤ 0.83 and false discovery ratio (FDR) ≤ 0.05 - between the two treatments were identified using a volcano plot. Biomarker analysis based on receiver operating characteristic (ROC) curves was performed to identify biomarker candidates (area under ROC ≥ 0.90) of the effects of CBD supplementation. Volcano plot analysis revealed that 32 amine/phenol-containing metabolites and five carbonyl-containing metabolites were differentially altered (FC ≥ 1.2 or ≤ 0.83, FDR ≤ 0.05) by CBD; these metabolites are involved in the metabolism of amino acids, glucose, vitamins, nucleotides, and hydroxycinnamic acid derivatives. Biomarker analysis identified 24 amine/phenol-containing metabolites and 1 carbonyl-containing metabolite as candidate biomarkers of the effects of CBD (area under ROC ≥ 0.90; P < 0.01). Results of this study indicate that 3 weeks of 4.5 mg CBD/kg BW/d supplementation altered the canine metabolome. Additional work is warranted to investigate the physiological relevance of these changes.

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 < 0.05). BCA treatment counteracted the pH, microbiological, and fermentative changes associated with SARA challenge (P < 0.05). Similar results were also observed with MON (P < 0.05). These results indicate that BCA may be an effective alternative to antibiotics for mitigating SARA in cattle production systems.

Feeding Cannabidiol (CBD)-Containing Treats Did Not Affect Canine Daily Voluntary Activity.

Growing public interest in the use of cannabidiol (CBD) for companion animals has amplified the need to elucidate potential impacts. The purpose of this investigation was to determine the influence of CBD on the daily activity of adult dogs. Twenty-four dogs (18.0 ± 3.4 kg, 9 months-4 years old) of various mixed breeds were utilized in a randomized complete block design with treatments targeted at 0 and 2.5 mg (LOW) and at 5.0 mg (HIGH) CBD/kg body weight (BW) per day split between two treats administered after twice-daily exercise (0700-0900 and 1,700-1,900 h). Four hours each day [1,000-1,200 h (a.m.) and 1,330-1,530 h (p.m.)] were designated as times when no people entered the kennels, with 2 h designated as Quiet time and the other 2 h as Music time, when calming music played over speakers. Quiet and Music sessions were randomly allotted to daily a.m. or p.m. times. Activity monitors were fitted to dogs' collars for continuous collection of activity data. Data were collected over a 14-day baseline period to establish the activity patterns and block dogs by activity level (high or low) before randomly assigning dogs within each block to treatments. After 7 days of treatment acclimation, activity data were collected for 14 days. Data were examined for differences using the MIXED procedure in SAS including effects of treatment, day, session (Quiet or Music), time of day (a.m. or p.m.), and accompanying interactions. CBD (LOW and HIGH) did not alter the total daily activity points (P = 0.985) or activity duration (P = 0.882). CBD tended (P = 0.071) to reduce total daily scratching compared with the control. Dogs were more active in p.m. sessions than in a.m. sessions (P < 0.001). During the p.m. session, dogs receiving HIGH tended (P = 0.091) to be less active than the control (CON). During the a.m. and p.m. sessions, CBD reduced scratching compared with CON (P = 0.030). CBD did not affect the activity duration during exercise periods (P = 0.143). These results indicate that, when supplemented with up to 4.5 mg CBD/kg BW/day, CBD does not impact the daily activity of adult dogs, but may exert an antipruritic effect.

Influence of air equilibration time, sampling techniques, and storage temperature on enzymatic starch availability of steam-flaked corn.

Measuring enzymatic starch availability is commonly used as a quality control method to ensure steam-flaked corn manufacturing consistency in commercial cattle feeding operations. However, starch availability estimates can be variable. We conducted five experiments to evaluate factors influencing starch availability estimates of steam-flaked corn. In Exp. 1, sample handling methods were evaluated. Sifted flakes were immediately placed into a plastic bag, air equilibrated for 240 min, oven-dried, or freeze-dried. Directly oven-drying samples at 55°C decreased (P < 0.01) starch availability compared to other sample handling methods. In Exp. 2, sifted flakes were air equilibrated for 0, 15, 30, 60, 120, or 240 min. Air equilibration time did not influence (P ≥ 0.54) starch availability. In Exp. 3, samples were evaluated for effects of sifting through a 4-mm screen (flakes + fines vs. sifted flakes) and air equilibration time (0 vs. 240 min). Both sifting steam-flaked corn samples and air equilibration for 240 min increased starch availability (P < 0.01 and P = 0.02, respectively). In Exp. 4, we evaluated the effects of air equilibration time (0 vs. 240 min) on the two sifted portions (sifted flakes vs. sifted fines). There was an air equilibration time × sifted portion interaction for starch availability because air equilibration time increased (P < 0.01) starch availability of sifted fines but did not influence starch availability of sifted flakes. Concentrations of crude protein, soluble crude protein, neutral and acid detergent fiber, ether extract, and acid-hydrolyzed fat, Ca, P, K, Mg, S, Fe, Zn, Mg, and Cu were greater (P < 0.01) for sifted fines compared to sifted flakes. Starch availability and total starch concentration were greater (P < 0.01) for sifted flakes compared to sifted fines. In Exp. 5, effects of air equilibration time (0 vs. 240 min) and storage temperature (23°C vs. 55°ºC) on flakes + fines were evaluated. Storage of flakes + fines in heat-sealed foil bags at 55°C for 3-d decreased (P < 0.01) starch availability by 40.7%. Sifted flakes contained less moisture, greater total starch concentrations, and greater starch availability than sifted fines. Moisture, sifting, air equilibration time, and storage temperature influence starch availability of steam-flaked corn. Adoption of the strategies discussed in the current study will lead to more consistent estimates of starch availability.

Influence of Prolonged Serotonin and Ergovaline Pre-Exposure on Vasoconstriction Ex Vivo.

Ergot alkaloid mycotoxins interfere in many functions associated with serotonergic neurotransmitters. Therefore, the objective was to evaluate whether the association of serotonin (5-hydroxytryptamine, 5-HT) and ergot alkaloids during a 24 h pre-incubation could affect the vascular contractile response to ergot alkaloids. To evaluate the effects of 24 h exposure to 5-HT and ergot alkaloids (ergovaline, ERV), two assays were conducted. The first assay determined the half-maximal inhibitory concentration (IC50) following the 24 h pre-exposure period, while the second assay evaluated the effect of IC50 concentrations of 5-HT and ERV either individually or in combination. There was an interaction between previous exposure to 5-HT and ERV. Previous exposure to 5-HT at the IC50 concentration of 7.57 × 10-7 M reduced the contractile response by more than 50% of control, while the exposure to ERV at IC50 dose of 1.57 × 10-10 M tended to decrease (p = 0.081) vessel contractility with a response higher than 50% of control. The 24 h previous exposure to both 5-HT and ERV did not potentiate the inhibitory response of blood vessels in comparison with incubation with each compound alone. These results suggest receptor competition between 5-HT and ERV. More studies are necessary to determine the potential of 5-HT to treat toxicosis caused by ergot alkaloids.

The Impact of Feeding Cannabidiol (CBD) Containing Treats on Canine Response to a Noise-Induced Fear Response Test.

Interest is increasing regarding use of Cannabidiol (CBD) in companion animals due to anecdotal evidence of beneficial behavioral and health effects. The purpose of this investigation was to evaluate the influence of CBD on behavioral responses to fear-inducing stimuli in dogs. Sixteen dogs (18.1 ± 0.2 kg) were utilized in a replicated 4 × 4 Latin square design experiment with treatments arranged in a 2 × 2 factorial, consisting of control, 25 mg CBD, trazodone (100 mg for 10-20 kg BW, 200 mg for 20.1-40 kg BW), and the combination of CBD and trazodone. A fireworks model of noise-induced fear was used to assess CBD effectiveness after 7 d of supplementation. Each test lasted a total of 6 min and consisted of a 3 min environmental habituation phase with no noise and a 3 min noise phase with a fireworks track. Plasma was collected 1 h before, immediately after, and 1 h following testing for cortisol analysis. Behaviors in each 3 min block were video recorded, and heart rate (HR) sensors were fitted for collection of HR and HR variability parameters. Research personnel administering treats and analyzing behavioral data were blinded as to the treatments administered. Data were tested for normality using the UNIVARIATE procedure in SAS, then differences examined using the MIXED procedure with fixed effects of treatment, period, time, and treatment x time interaction. Inactivity duration and HR increased during the first minute of the fireworks track compared with 1 min prior (P < 0.001 and P = 0.011, respectively), indicating the fireworks model successfully generated a fear response. Trazodone lowered plasma cortisol (P < 0.001), which was unaffected by CBD (P = 0.104) or the combination with CBD (P = 0.238). Neither CBD nor trazodone affected the duration of inactivity (P = 0.918 and 0.329, respectively). Trazodone increased time spent with tail relaxed (P = 0.001). CBD tended to increase HR (P = 0.093) and decreased the peak of low- and high-frequency bands (LF and HF, P = 0.011 and 0.022, respectively). These results do not support an anxiolytic effect of CBD in dogs given 1.4 mg CBD/kg BW/d.

Ergot alkaloids reduce circulating serotonin in the bovine.

Ergot alkaloids can interact with several serotonin (5-hydroxytryptamine [5-HT]) receptors provoking many physiological responses. However, it is unknown whether ergot alkaloid consumption influences 5-HT or its metabolites. Thus, two experiments were performed to evaluate the effect of ergot alkaloid feeding on 5-HT metabolism. In exp. 1, 12 Holstein steers (260 ± 3 kg body weight [BW]) were used in a completely randomized design. The treatments were the dietary concentration of ergovaline: 0, 0.862, and 1.282 mg/kg of diet. The steers were fed ad libitum, kept in light and temperature cycles mimicking the summer, and had blood sampled before and 15 d after receiving the treatments. The consumption of ergot alkaloids provoked a linear decrease (P = 0.004) in serum 5-HT. However, serum 5-hydroxytryptophan and 5-hydroxyindoleacetic acid did not change (P > 0.05) between treatments. In exp. 2, four ruminally cannulated Holstein steers (318 ± 3 kg BW) were used in a 4 × 4 Latin square design to examine the difference between seed sources on 5-HT metabolism. Treatments were: control-tall fescue seeds free of ergovaline, KY 32 seeds (L42-16-2K32); 5Way-endophyte-infected seeds, 5 way (L152-11-1739); KY31-endophyte-infected seeds, KY 31 (M164-16-SOS); and Millennium-endophyte-infected seeds, 3rd Millennium (L108-11-76). The endophyte-infected seed treatments were all adjusted to provide an ergovaline dosage of 15 µg/kg BW. The basal diet provided 1.5-fold the net energy requirement for maintenance. The seed treatments were dosed directly into the rumen before feeding. The experiment lasted 84 d and was divided into four periods. In each period, the steers received seeds for 7 d followed by a 14-d washout. Blood samples were collected on day 0 (baseline) and day 7 for evaluating the treatment response in each period. A 24 h urine collection was performed on day 7. Similar to exp. 1, serum 5-HT decreased (P = 0.008) with the consumption of all endophyte-infected seed treatments. However, there was no difference (P > 0.05) between the infected seeds. The urinary excretion of 5-hydroxyindoleacetic acid in the urine was not affected (P > 0.05) by the presence of ergot alkaloids. In conclusion, the consumption of ergot alkaloids decreases serum 5-HT with no difference between the source of endophyte-infected seeds in the bovine.

Ruminal motility, reticuloruminal fill, and eating patterns in steers exposed to ergovaline.

Fescue toxicosis is problematic for growing steers, causing lower DMI and productivity when fed endophyte-infected (E+) tall fescue. A complete understanding of underlying mechanisms of how fescue toxicosis affects growing steers is lacking. Therefore, the overall objective of this multiexperiment study was to determine whether ruminally dosed ergovaline (ERV) affects rumen motility, rumen contents, and eating patterns. In Exp. 1, an 8-h period to assess ruminal motility began 4 h after feeding by monitoring pressure changes using a wireless system for 21 d. Eight ruminally cannulated steers (283 kg BW) were pair fed with alfalfa cubes (1.5 × NEm) and assigned to endophyte free (E-; 0 µg ERV/kg BW/d) or E+ treatment (20 µg ERV/kg BW/d). Overall, E+ steers had more frequent rumen contractions (Seed P = 0.05 and day of feeding P = 0.02). On days 7 to 9, both treatments showed lower frequencies and E- steers had greater amplitude of contractions (P < 0.001) that corresponded with decreased DMI. In Exp. 2, steers remained in pairs assigned in Exp. 1 (322 kg BW), but reversed seed treatments while increasing ERV levels (titrated 0, 5, 10, 15, and 20 µg ERV/kg BW/d over 57 d). There were no differences between E- and E+ for frequency (P = 0.137) or amplitude of contractions (P = 0.951), but increasing ERV dosage, decreased frequency (P = 0.018) and amplitude (P = 0.005), coinciding with lower DMI. In Exp. 3, 8 steers (589 kg) were pair fed and ruminally dosed 15 µg ERV/kg BW/d, and rumen motility data were collected for 21 d. E- steers showed higher amplitude and lower frequency of contractions than E+ steers with seed (P < 0.001), day (P < 0.001), and seed × day (P < 0.04) effects, but rumen fill was not different between E- and E+ (P > 0.29). Serum prolactin concentrations were lower in E+ steers in Exp. 1 to 3. Eating patterns of pair-fed E- and E+ steers were relatively slower in E+ than E- (Exp. 4) by measuring every 2 h across 24 h. Number of meals were higher in E+ than E- steers, but meal duration and meal size were not different between treatments. Rumen content (DM%) tended to be higher in E+ than in E- when steers were fed once a day (P = 0.07), but there was no difference for rumen content (DM%) when E- and E+ steers were fed 12 times a day (P = 0.13). These results suggest the changes in rumen fill associated with fescue toxicosis may be driven more by changes in feeding behavior and eating pattern rather than by changes in motility.

Effects of a blend of Saccharomyces cerevisiae-based direct-fed microbial and fermentation products in the diet of newly weaned beef steers: growth performance, whole-blood immune gene expression, serum biochemistry, and plasma metabolome1.

We examined the effects of dietary supplementation of a Saccharomyces cerevisiae-based direct-fed microbial (DFM) on the growth performance, whole-blood immune gene expression, serum biochemistry, and plasma metabolome of newly weaned beef steers during a 42 d receiving period. Forty newly weaned Angus crossbred steers (7 d post-weaning; 210 ± 12 kg of BW; 180 ± 17 d of age) from a single source were stratified by BW and randomly assigned to 1 of 2 treatments: basal diet with no additive (CON; n = 20) or a basal diet top-dressed with 19 g of the DFM (PROB; n = 20). Daily DMI and weekly body weights were measured to calculate average daily gain (ADG) and feed efficiency (FE). Expression of 84 immune-related genes was analyzed on blood samples collected on days 21 and 42. Serum biochemical parameters and plasma metabolome were analyzed on days 0, 21, and 42. On day 40, fecal grab samples were collected for pH measurement. Compared with CON, dietary supplementation of PROB increased final body weight (P = 0.01) and ADG (1.42 vs. 1.23 kg; P = 0.04) over the 42 d feeding trial. There was a tendency for improved FE with PROB supplementation (P = 0.10). No treatment effect (P = 0.24) on DMI was observed. Supplementation with PROB increased (P ≤ 0.05) the concentrations of serum calcium, total protein, and albumin. Compared with CON, dietary supplementation with PROB increased (P ≤ 0.05) the expression of some immune-related genes involved in detecting pathogen-associated molecular patterns (such as TLR1, TLR2, and TLR6), T-cell differentiation (such as STAT6, ICAM1, RORC, TBX21, and CXCR3) and others such as TNF and CASP1, on day 21 and/or day 42. Conversely, IL-8 was upregulated (P = 0.01) in beef steers fed CON diet on day 21. Plasma untargeted plasma metabolome analysis revealed an increase (P ≤ 0.05) in the concentration of metabolites, 5-methylcytosine and indoleacrylic acid involved in protecting the animals against inflammation in steers fed PROB diet. There was a tendency for lower fecal pH in steers fed PROB diet (P = 0.08), a possible indication of increased hindgut fermentation. This study demonstrated that supplementation of PROB diet improved the performance, nutritional status, and health of newly weaned beef steers during a 42 d receiving period.

Interaction of ergovaline with serotonin receptor 5-HT2A in bovine ruminal and mesenteric vasculature.

Ergot alkaloids from endophyte-infected (Epichloë coenophiala) tall fescue (Lolium arundinaceum) induce vasoconstriction. Previous work has shown that serotonin receptor subtype, 5HT2A, is present in bovine ruminal (R) and mesenteric (M) vasculature, plays a role in vasoconstriction, and could be influenced by ergot alkaloids. To determine the influence of ergot alkaloids on 5HT2A, the vasoactivity of an agonist selective for 5HT2A, (4-bromo-3,6-dimethoxybenzocyclobuten-1-yl) methylamine HCl (TCB-2), was evaluated using bovine ruminal and mesenteric arteries and veins (RA, RV, MA, MV) that were exposed to ergovaline (ERV) prior to or during the TCB-2 additions. Ruminal and mesenteric blood vessel segments were collected, cleaned, and cut into 2- to 3-mm cross-sections. Vessel segments were incubated in Krebs-Henseleit buffer containing 0, 0.01 or 1 µM ERV for 2 h prior to TCB-2 dose response or exposed to ERV concentrations simultaneously during TCB-2 dose response. For the dose response portion of the study, vessels were suspended in a multimyograph containing 5 mL of continuously oxygenated Krebs-Henseleit buffer and equilibrated to 1 g tension for 90 min. Vessels were exposed to increasing concentrations of TCB-2 every 15 min and contractile response data were normalized as a percentage of the maximum contractile response induced by 120 mM KCl reference. Analysis of variance was evaluated separately for each vessel and each ERV exposure experiment using the mixed models procedure of SAS for effects of TCB-2 and ERV concentrations. All blood vessels with previous ERV exposure had significantly lower contractile responses to TCB-2 (P < 0.01). All blood vessels with simultaneous exposure to 1 µM ERV had higher (P < 0.01) contractile responses at lower concentrations of TCB-2. Simultaneous ERV addition at 1 × 10-4 M TCB-2 did not affect contractility of RV, MA, MV (P > 0.05), but decreased contractility of RA (P < 0.01). These results indicate that ergopeptine alkaloid exposure influences contractility of bovine ruminal and mesenteric blood vessels through serotonin receptor subtype 5HT2A by acting as both an agonist and antagonist. Additional work is needed to determine if ergot alkaloids like ERV simply occupy receptor binding sites competitively, or influence receptor internalization to cause the observed divergent responses.