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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.

Cool-season grasses (CSGs) accumulate variable amounts of water-soluble carbohydrates (WSCs, monosaccharides and disaccharides, and fructans), depending on climate, time of day and year, and genotype. Fructan concentrations in CSG are sometimes estimated as the difference between concentrations of WSC and ethanol-soluble carbohydrates (ESCs, monosaccharides and disaccharides, and variable amounts of fructan). Characterizing both WSC and ESC may improve understanding of soluble carbohydrate profiles in pastures and inform grazing management decisions, particularly for horses at risk for laminitis. Three CSG cultivars from Kentucky pastures were collected in the morning and afternoon on two springtime dates. Water-soluble carbohydrates and ESC were extracted with water or 80% ethanol, respectively, and analyzed by high-performance liquid chromatography (HPLC) and a colorimetric assay. Method of analysis (HPLC or colorimetry), and extraction solvent, affected the composition of WSC or ESC determined in CSG samples, demonstrating the need to consider methodology when interpreting results. Total soluble carbohydrate (mean of WSC and ESC) concentrations across cultivars and harvests were generally higher in the afternoon than in the morning, based on both HPLC (P = .0023) and colorimetric (P

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.

Botanical composition and forage productivity of mixed cool- and warm-season perennial pastures are important determinants of agricultural sustainability. Effects of three sources of nutrient (inorganic only, organic + inorganic combination, and organic only) and four utilization regimes (unharvested, low and high grazing pressure, and hayed) were evaluated on botanical composition, residual forage mass, and forage production during seven years of management on tall fescue ( Lolium arundinaceum , a cool-season C3 grass) overseeded into existing bermudagrass ( Cynodon dactylon , a warm-season C4 grass) sod in Georgia. Nutrient source had few major impacts on responses, except for greater hay yield with organic fertilization (broiler litter) than with organic + inorganic and inorganic only fertilization. Botanical composition of grazed pastures shifted with time from initial dominance with bermudagrass (∼50% basal area) to mixed composition of tall fescue (60%)/bermudagrass (36%) under low grazing pressure and tall fescue (45%)/bermudagrass (48%) under high grazing pressure. To maintain optimum botanical composition and productivity for year-round sustainable grazing, forage mass needs to be balanced within a maximum threshold to avoid deterioration of forage quality and a minimum threshold to avoid environmental degradation.

Stocker performance and production from mixed cool- and warm-season perennial pastures are important determinants of agricultural sustainability that can be influenced by management. We evaluated the factorial combination of three sources of nutrient application (inorganic only, organic+inorganic combination, and organic only) and two forage utilization regimes [low grazing pressure (LGP) and high grazing pressure (HGP)] on steer stocking density and rate, performance and production during 7 years of pasture management {tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] overseeded into existing Coastal bermudagrass [Cynodon dactylon (L.) Pers.] sod} on a Typic Kanhapludult in Georgia, USA. Nutrient source had few major impacts on responses, except for lower animal performance with organic fertilization (broiler litter) than with organic+inorganic and inorganic only fertilization, especially with LGP. Seasonal changes in stocking weight and rate occurred, not only as expected due to environmental conditions and dominant forage species present, but that also counteracted expected differences imposed by grazing pressure; signaling negative feedback of HGP on forage productivity. Steer performance was greatest in spring and summer under both grazing pressures, but was significantly reduced with increasing grazing pressure in the autumn and winter due to low forage availability. Across years, steer gainha−1 (863kgha−1) was not different between grazing pressures, but gainha−1 declined with time under HGP and was stable with time under LGP. Reducing grazing pressure to a moderate level can lead to equivalent steer production as HGP, and would likely contribute to a more sustainable balance among production, socio-economic and environmental goals. These multi-year results will help cattle producers in warm, moist climates design and implement more sustainable grazing systems.

Parasite-free pastures would improve cattle health and performance, resulting in possible economic return to producers. Our objective was to determine the effect of a single series of anthelmintic treatment of steers prior to stocking on Coastal bermudagrass pastures, during five consecutive summers, on the parasite burden in cattle. The site for this experiment had been conventionally cropped for several decades, with no exposure to cattle, and would be expected to be relatively free of nematode larvae. The experimental design was a randomized complete block (landscape features) with a split plot arrangement of treatments where main plots were pasture fertilization treatments (mineral, clover plus mineral, and broiler litter) and split plots were low and high forage mass. Anthelmintic treatment included pour-on ivermectin on day -21, albendazole on day -7, and injectable ivermectin 48 h prior to stocking of pastures, with the cattle remaining in drylot during the 48-h period prior to being placed on the experimental paddocks. All steers received only one series of treatments during any given year. Yearling Angus steers (Bos taurus) were managed in a put-and-take grazing system with three "tester" steers assigned to each paddock and "grazer" steers added or removed at 28-day intervals. From 1994 to 1998, steers grazed the paddocks for a 140-day period from mid May until early October each year. Fecal samples for worm egg counts were obtained on day 0 and at 28-day intervals, thereafter. On all sampling days after day 0, samples were obtained only from tester animals. Over the 5-year period, the mean eggs per gram of feces (epg) gradually increased from 0 (following treatment) to a mean of 2.2 (range from 0.7 to 3.0) by the end of the grazing season (the last sampling date) in October. Although the epg were not zero, they were below threshold levels that would allow development of a parasite burden in cattle. In traditional management systems, cattle graze parasite-contaminated pastures; therefore, parasites negatively impact growth and productivity throughout the entire grazing period. Periodic anthelmintic treatments simply give a temporary reprieve from those parasitic infections. Conceptually, using the current grazing system, it should be possible to maintain these pastures in a parasite-free status indefinitely; however, from a drug resistance perspective, it would be most applicable in sod-based rotation systems where cattle graze from two to five years before land is returned to row-crops. By removing the effect of parasites, cattle can grow without the physiological constraints that gastrointestinal parasites place on appetite, digestion, nutrient utilization, and general well being.

Bovines spend less time grazing and have reduced intake when grazing endophyte-infected (E +), Neotyphodium coenophialum Glen, Bacon, and Hamlin (comb. novo) Morgan-Jones and Gams vs. endophyte-free (E −) tall fescue (Festuca arundinacea, Shreb.). Because bovine grazing behavior follows series of repeatable cycles, cyclic grazing behavior was studied using spectral analysis to determine if grazing response differed due to endophyte presence. Two 0.81-ha paddocks, one containing E − Kentucky-31 (KY-31) tall fescue and one containing E + KY-31 (100% tiller infection rate) were stocked with yearling Angus steers in the spring and summer for two years. Trained observers monitored steer behavior during two 48-h periods in each year. Spectral analysis, a technique used to detect sinusoidal components in a time series, revealed that steers grazing E − fescue repeated grazing behavior in 12- and 6-h intervals while E + steers exhibited an additional 8-h cycle. Steers grazing E + fescue spent less time (P < 0.05) grazing and lying, and more time standing (P < 0.05), than E − steers for both years. Crosscorrelations between hourly grazing behavior and hourly solar radiation resulted in significant, negative correlations at lag = 0 for E + steers and with correlations near zero for E − steers. We conclude steers grazing E + fescue exhibited different grazing behavior from steers grazing E − fescue and that spectral analysis was valuable in describing grazing behavior.