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Central Kentucky horse pastures contain significant populations of tall fescue ( Schedonorus arundinacea (Schreb.) Dumort) infected with an endophyte ( Epichloë coenophialum (Morgan-Jones and Gams) Bacon and Schardl) known to produce several ergot alkaloids, with ergovaline in the highest concentration. While most classes of horses are not adversely affected by average levels of ergovaline in pastures, late term pregnant mares have a low tolerance to ergovaline and the related ergot alkaloids. Endophyte-infected tall fescue has been known to cause prolonged gestation, thickened placenta, dystocia, agalactia, and foal and mare mortality. The University of Kentucky Horse Pasture Evaluation Program utilizes ergovaline and endophyte testing, as well as pasture species composition, to calculate ergovaline in the total diet in broodmare pastures. This data is used to develop detailed management recommendations for individual pastures. Application of these recommendations has led to reduced tall fescue toxicity symptoms on these farms, as well as improved pasture management and improved forage quality and quantity.

Ethanol-soluble carbohydrates (ESCs) of cool-season grasses include mono- and disaccharides and sometimes short-chain fructans, which may exacerbate the risk of pasture-associated laminitis. A calibration for prediction of ESC concentrations by near-infrared reflectance spectroscopy (NIRS) was developed from 323 samples of four cool-season grass species (orchardgrass, Kentucky bluegrass, tall fescue, and perennial ryegrass) across 10 cultivars collected in central Kentucky in the morning and afternoon over two growing seasons. The calibration, which had accuracy above 95%, was used to predict ESC concentrations of 1,532 samples from the second growing season. ESC concentrations increased in the afternoon compared to the morning across all cultivars. In the majority of samples, ESC concentrations were not affected by nitrogen application to plots. Use of NIRS has the potential to evaluate management and cultivar effects on ESC concentrations in cool-season grass pastures., (Published by Elsevier Inc.)

Nonstructural carbohydrates of pasture plants, comprising water-soluble carbohydrates (WSCs) and starch, may contribute to excessive consumption of rapidly fermentable carbohydrates by grazing horses. Seasonal and diurnal variation in WSCs were studied in red (Trifolium pratense L.) and white clovers (Trifolium repens L.) subjected to a typical management regime of rotationally grazed horse pastures. Two red and two white clover cultivars from monoculture plots were harvested after 4 weeks of growth from April to October of 2015, in the morning and afternoon of each harvest date. Water-soluble carbohydrates were quantified for each harvest, and starch was quantified for two harvests. Mean monthly WSC concentrations ranged from 80 to 99 mg/g (freeze-dried weight basis), whereas mean starch concentrations were 31 and 40 mg/g. In September, white clover had 14% more WSCs than red clover (P < .0001). Water-soluble carbohydrate concentrations were 10% higher in the afternoon than in the morning (P < .0001). Starch concentrations were 290% higher in the afternoon than in the morning (P < .0001), and nonstructural carbohydrate concentrations in the afternoon averaged 150 mg/g. Further studies are needed to determine whether the mixed grass-legume pastures of central Kentucky accumulate enough nonstructural carbohydrates to present risk factors for equine metabolic or digestive dysfunction., (Published by Elsevier Inc.)

Grasses are a source of nutrients for grazing horses. However, water-soluble carbohydrates (WSCs) of grasses have been implicated in some equine health issues. Grasses also contain phenolic compounds, whose sensory and antimicrobial properties may affect forage intake by horses and horse health. The goals of this study were to assess factors affecting phenolic and WSC concentrations in selected cultivars of cool-season grasses and profile the phenolic compounds. Total phenolics and WSC were quantified in "Linn" and "Calibra" perennial ryegrass (PRG), "Cajun II" tall fescue (Cajun TF), "Persist" orchardgrass (OG), and "Ginger" Kentucky bluegrass (BG), collected in the morning and afternoon of late April, early May, and late May. WSCs were higher in the afternoon (P < .0001), and afternoon concentrations differed among cultivars (P = .011) and decreased by late May (P < .0001). Total phenolics, initially highest in Calibra PRG and Persist OG, decreased or remained constant from late April to late May, except in Persist OG (P < .0001). Total phenolics decreased in the afternoon in Persist OG and Calibra PRG (P = .015). High-performance liquid chromatography revealed similar phenolic profiles in Calibra PRG, Linn PRG, and Cajun TF. These differed from the profiles of Ginger BG and Persist OG. Major peaks were characterized by liquid chromatography coupled to mass spectrometry. The cultivars had a diversity of phenolic compounds possibly worth exploring for properties that may interact with those of WSC to impact equine health., (Published by Elsevier Inc.)