NE1941: Environmental Impacts of Equine Operations
(Multistate Research Project)
NE1941: Environmental Impacts of Equine Operations
Duration: 10/01/2019 to 09/30/2024
Statement of Issues and Justification
Statement of Issues and Justification
Overview: Horses are a gateway to the U.S. agriculture industry for millions of youth and families. Horse ownership teaches responsibility, empathy and helps maintain both physical and mental health. Historically, horses helped build the U.S. infrastructure and economy through being a mode of transportation and horsepower. More recently, horses have become an important recreational, performance and therapeutic resource for youth, families and military veterans. In a recent survey, 30% of U.S household included a horse owner, or someone involved in the horse industry (AHC, 2017). Although horses are classified as livestock in the U.S., they are unique when compared to other livestock industries. A clear majority of horse owners are educated women over the age of 40 who have owned horses for more than 15 years. Additionally, 89% of horse farms are consider “small farms” with 19 or fewer horses, which accounts for 60% of all equines in the U.S. (USDA-APHIS, 2017).
- Pasture management
Justification: Pastures offer an economic and nutrient dense feed source for horses. However, owners and managers tend to struggle with pasture and manure management which can lead to negative environmental consequences. Horse farms across the U.S. present unique challenges because of their relatively small size, location near suburban areas, lack of owner knowledge of farm management and available resources, high cost of horse care and ownership, and the complexity of horse health and management. Therefore, collaborative research, outreach and education on pasture and manure management is critical to the health and well-being of horses, the environment, the long-term success of horse ownership and global One Health. Additionally, outreach, education and training are needed for veterinarians, farriers, Extension agents, agency and industry partners who also work closely with horse owners and managers.
The lack of sound grazing- and pasture-management leads to inefficient pasture utilization, poor plant viability, poor soil health, and negative horse-health consequences. Many of these problems occur due to the mismatch between forage supply and demand. Forage supply varies seasonally and depends upon the seasonal type of forage (e.g., warm-season or cool-season). Warm and cool season forages, as the name implies, have peak productivity during warm and cool seasons respectively. Therefore, pastures containing only one seasonal type of forage often have an abundance of forage during peak production, and limited forage during the non-productive season. An overabundance of forage can contribute to overconsumption and obesity related problems (e.g., insulin resistance, laminitis), whereas limited forage production can result in a greater probability of over-grazing. Over-grazing contributes to loss of resources and negative impacts on soil health leading to negative environmental consequences (e.g., erosion, weed invasion, increased susceptibility to drought). Therefore, grazing and pasture management strategies that improve the balance of supply and demand have the potential to improve the efficiency of production, as well as horse and soil health.
- Strategies to extend and improve the grazing season using warm-season grasses, annual grasses, cover crops and stockpiling
- Parasite resistance and management
- Soil quality and nutrient recycling
- Weed control
- Erosion Control
- Outreach to improve the adoption of pasture management BMPs
- Manure disposal and composting
Justification: Adult horses produce over 50 pounds of manure and urine daily along with an additional 15 pounds of bedding. More than one-third of U.S horse farms (35.4%) have no manure disposal plan and leave their manure “to nature” (USDA-APHIS, 2017). Improperly managed manure presents significant environmental consequences including nutrient runoff to bodies of water, fly breeding sites, excessive odors, negative esthetics and localized accumulation of nutrients under stockpiles. Additionally, 39% of owners apply manure to pastures; however, horse owners tend to have high pasture stocking rates which can contribute to excessive parasite loads and anthelmintic use in equines. Research that investigates novel bedding types, composting methods and owner adoptions of BMPs may lead to reduced fly populations and antibiotic use; improved air, soil and water quality; and reduced parasite load and anthelmintic use in horses.
- Fly control
- Ammonia emission
- Bedding type and use
- Antibiotic resistance
- Carcass disposal and composting
Justification: More than half (60%) of the U.S. equine operations have an end of life plan for their equines; however, the plans focus on criteria for euthanasia but not carcass disposal. No data exists on the proportion of horse carcasses disposed of via rendering, composting, burial, cremation and landfill disposal. The high cost of euthanasia and disposal (<$550) along with declining options for carcass disposal presents a significant challenge to all horse owners. Additionally, environmental concerns including protected and endangered wildlife access to carcasses euthanized with barbiturates (or treated with antibiotics and other pharmaceuticals) and associated water quality and public health concerns present additional barriers for horse carcass disposal.
- Method of carcass disposal
- Barbiturates use
- Antibiotic use
- Pasture and manure management BMPs adoption and outreach
Justification: Horse owners commonly rely on their veterinarians and farriers for information related to horse care and management. However, these professionals have limited training and expertise in pasture and manure management. Therefore, this team aims to educate both horse owners and managers in addition to these equine professionals. Education and outreach will include traditional methods of face-to-face to educational offerings (e.g. field days and seminars) along with cutting-edge and novel online learning platforms including social media, online courses, infographics and YouTube videos. These online platforms will be used to better understand current pasture and manure management and carcass disposal options used by horse owners and long-term adoption of new and existing research-based Best Management Practices (BMPs). These efforts should highlight the intimate connection of pasture and manure management and their impacts on environmental, human and horse health.
- Economic analysis of pasture, manure and carcass disposal BMPs
- Survey of U.S. horse owner and manager implementation of BMPs
Related, Current and Previous Work
Related, Current and Previous Work
Allocation of space and time available for grazing have been demonstrated to conserve forage and improve productivity per unit of area. Allocation of space through rotational grazing, as compared to continuous grazing, of both cool (Webb et al., 2009; Kenny, 2016), warm-season plant (Webb et al., 2011), and mixed grass pastures (Daniel et al., 2015) have been demonstrated to increase the amount of forage available for grazing and thus increase the number of grazing days. Positive effects on the proportion of desirable species (Virostek et al., 2015) and ground cover (Kenny, 2016) have also been reported for rotationally grazed horse pasture, as compared to continuous grazing. Allocation of time available for grazing has also been demonstrated to conserve forage. Restricting the time allowed for grazing has been used to regulate horse dry matter/energy intake in effort to match intake with requirements to prevent overconsumption and extend the number of animal grazing days. Available data suggest that mature idle light-breed horses grazing improved pastures for 9 to 12 h/d can meet, but not exceed, maintenance digestible energy requirements (Dowler et al., 2012; Siciliano, 2012; Bowman et al., 2017). The net reduction in pasture intake achieved through restricting time allowed for grazing to 9 to 12 h/d is estimated to be approximately 5 kg DM/d for a 500 kg body weight horse (Siciliano, 2012). Accumulation of the additional 5 kg DM/d is equivalent to approximately 20 additional days of grazing over a one month period for a mature horse weighing 500 kg with maintenance only requirements. Finally, investigating the use of alternative forage species (e.g., teff) under horse grazing has found that annual cool- and warm-season grasses can be successfully used to extend the grazing season in northern climates (DeBoer et al., 2017; Grev et al., 2017). Furthermore, grazing teff, an annual warm-season grass, led to lower glucose and insulin responses in grazing horses during the fall and late-fall in northern climates (DeBoer et al., 2018).
Bowman, M. A., J. L. Moore, and P. D. Siciliano. 2017. Effect of restricting time allowed for grazing on fecal microbial fermentation parameters. J. Equine Vet. Sci. 52:82. doi:10.1016/j.jevs.2017.03.110.
Daniel, A. D., B. J. McIntosh, J. D. Plunk, M. Webb, D. McIntosh, and A. G. Parks. 2015. Effects of rotational grazing on water-soluble carbohydrate and energy content of horse pastures. J. Equine Vet. Sci. 35: 385-386 (Abstr.). doi: 10.1016/j.jevs.2015.03.014
DeBoer, M. L., M. R. Hathaway, K. J. Kuhle, P. S. D. Weber, A. S. Reiter, C. C. Sheaffer, M. S. Wells, and K. L. Martinson. 2018. Glucose and Insulin Response of Horses Grazing Alfalfa, Perennial Cool-Season Grass, and Teff Across Seasons. J. Equine Vet. Sci. 68:33–38. doi:10.1016/j.jevs.2018.04.008.
DeBoer, M. L., C. C. Sheaffer, A. M. Grev, D. N. Catalano, M. S. Wells, M. R. Hathaway, and K. L. Martinson. 2017. Yield, Nutritive Value, and Preference of Annual Warm-Season Grasses Grazed by Horses. Agron. J. 109:2136. doi:10.2134/agronj2017.02.0099.
Dowler, L. E., P. D. Siciliano, S. E. Pratt-Phillips, and M. Poore. 2012. Determination of Pasture Dry Matter Intake Rates in Different Seasons and Their Application in Grazing Management. J. Equine Vet. Sci. 32:85–92. doi:10.1016/j.jevs.2011.06.006.
Grev, A. M., C. C. Sheaffer, M. L. DeBoer, D. N. Catalano, and K. L. Martinson. 2017. Preference, Yield, and Forage Nutritive Value of Annual Grasses under Horse Grazing. Agron. J. 109:1561. doi:10.2134/agronj2016.11.0684.
Kenny, L. B. 2016. The effects of rotational and continuous grazing on horses, pasture condition, and soil properties. Rutgers University - Graduate School - New Brunswick. Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/49246/
Siciliano, P. D. 2012. Estimation of pasture dry matter intake and its practical application in grazing management for horses. In: Proc. 10th Mid-Atlantic Nutrition Conference. N.G. Zimmermann ed., Timonium, MA.
Virostek, A. M., B. McIntosh, A. Daniel, M. Webb, and J. D. Plunk. 2015. The effects of rotational grazing on forage biomass yield and botanical composition of horse pastures. J. Equine Vet. Sci. 35:386. doi:10.1016/j.jevs.2015.03.015.
Webb, G., C. Duey, and S. Webb. 2009. Continuous vs. Rotational Grazing of Cool Season Pastures by Adult Horses. J. Equine Vet. Sci. 29:388–389. doi:10.1016/j.jevs.2009.04.090.
Webb, G., S. Webb, C. Duey, and K. Minton. 2011. Continuous vs. Rotational Grazing of Cool Season Pastures During the Summer Months. J. Equine Vet. Sci. 31:285. doi:10.1016/j.jevs.2011.03.109.
Adult horses will produce up to 25 kg of manure daily, this converts to about 10 tons per year (each ton contains 4.5 kg of N, 1.7 kg of P2O5 and 2.4 kg of K2O) or 12 cubic yards, soiled bedding will have a volume of 60-80 L per day or about 30 cubic yards per horse per year (ASAE, 2005; Westendorf and Krogmann, 2013; Wheeler et al. 2009).
Composting is conducted on many horse farms. When the temperature of organic materials rises microorganisms (including bacteria, actinomycetes, and fungi) will break down organic constituents (Krogmann et al., 2006). Composting reduces the volume of material and breaks down indigestible material into a plant-usable forms (NRAES, 1999). Compost should be mixed often to ensure the manure pile reaches elevated temperatures (NRAES, 1999; Krogmann et al., 2006). Moisture content (55-60% is ideal) and oxygen can be maintained in a compost pile through regular turning and mixing of the pile. A carbon to nitrogen (C:N) ratio of 20:1 to 30:1 should be maintained. The final product can be spread on crops or pasture for nutrient uptake. Komar et al. (2012) compared wood and straw bedding products and demonstrated that a simple composting system will reduce manure volume and yield a material useful for land application. Proper composting, as demonstrated by increased pile temperatures, occurred after 100-days. Temperatures in the straw materials (long stem and pelleted) and not the wood materials remained elevated long enough to reduce the amount of weed seeds, parasites, and pathogens.
Westendorf et al. (2012) conducted a survey and found that 60% of New Jersey horse farmers balanced equine diets on their own or had no feeding plan at all, the remainder received advice from a veterinarian or a feed store. One third of respondents reduced phosphorus in the diet to reduce excretion, but it was unclear what changes they made. Over 75% rotationally grazed their pastures; 90% of those who rotationally graze also made use of a heavy use area for shelter, exercise, water, and feeding.
Westendorf et al., 2015 developed a feed management plan for horses like the USDA-NRCS 592 Feed Management Program (Harrison et al., 2012). The goal is to encourage producers to reduce overfeeding through environmentally friendly feeding practices. Unfortunately, after a year in the project many were still overfeeding. They concluded that a feed program for horses should assess animal condition, manage pastures, feeds and forages regularly, and encourage consultation with professional nutritionists.
In another study, Westendorf and Williams (2015) found that over-feeding a phosphorus supplement (NaH2PO4) increased fecal phosphorus from 3.6 g/kg in the low phosphorus group to 8.1 g/kg in the high phosphorus group. Samples were also analyzed for Water Extractable Phosphorus (WEP) in horse manure (Wolf et al. 2005), levels increased from 2.1 g/kg in the low P group to 6.8 g/kg in the high P group. They concluded that when horses are overfed phosphorus, the increase in fecal phosphorus and WEP may raise the phosphorus runoff risk. Ammonia levels are often elevated in the air around horse stalls (Williams et al. 2011), ammonia is also elevated in manure when increased crude protein levels are fed. These researchers found that when horses were supplemented with 700 g/d of soybean meal top dressed on a sweet feed to adult horses, the horses receiving the added soybean meal excreted more N and NH3 than horses fed the control diet.
ASAE. 2005. Manure Production and Characteristics. American Society of Agricultural Engineers. ASAE D384.2 Mar2005. http://www.agronext.iastate.edu/immag/pubs/manure-prod-char-d384-2.pdf
Harrison, J., R. White, V. Ishler, G. Erickson, A. Sutton, T. Applegate, B. Richert, T. Nennich, R. Koelsch, R. Burns, D. Meyer, R. Massey, and G. Carpenter. 2012. Case Study: Implementation of feed management as part of whole-farm nutrient management. Prof. Anim. Sci. 28:364–369.
Komar, S., R. Miskewitz, M. Westendorf, and C. A. Williams. 2012. Effects of bedding type on compost quality of equine stall waste: Implications for small horse farms. J. Anim. Sci. 90:1069-1075. doi: 10.2527/jas.2010-3805.
Krogmann, U., M. L. Westendorf, and B. F. Rogers. 2006. Best Management Practices for Horse Manure Composting on Small Farms. Rutgers Cooperative Extension. New Jersey Agricultural Experiment Station. Rutgers University. Bulletin Series. http://njaes.rutgers.edu/pubs/publication.asp?pid=E307 E307.
Westendorf, M.L., C. A. Williams, and L. B. Kenny. 2015. Protection of environmental resources through the implementation of optimum feed management practices on equine farms. Professional Animal Scientist. 31:296-301. (http://pas.fass.org/content/31/3/296.full.pdf+html)
Westendorf, M. L., and C. A. Williams. 2015. Effects of excess dietary phosphorus on fecal phosphorus excretion and water extractable phosphorus in horses. J. Equine Vet. Sci. 35:495-498. doi: 10.1016/j.jevs.2015.01.020
Westendorf, M. L. and U. Krogmann. 2013. Horse Manure Management: Bedding Use. Rutgers Cooperative Extension. New Jersey Agricultural Experiment Station. Rutgers University. FS537.
Wheeler, E. and J. S. Zajaczkowski. 2009. Horse Stable Manure Management. Penn State Cooperative Extension. Pennsylvania State Agricultural Experiment Station. Rutgers University. FS537. Code # UB035.
Williams, C.A., C. Urban, and M.L. Westendorf. 2011. Dietary protein affects nitrogen and ammonia excretion in horses. J. Equine Vet. Sci. 31:305-306.
Wolf, A.M., P.J.A. Kleinman, A.N. Sharpley, and D.B. Beegle. 2005. Development of a water-extractable test for manure: an interlaboratory study. Soil Sci Soc Am J 2005:69:695–700.
According to the 2012 census of Agriculture there were 3.6 million horses in the US, with 72 % (2.6 million) housed on farms with less than 25 horses. A horse averages 50 lbs of raw waste a day with an estimated nine tons per year. Farms are required to have manure management plans and may use manure as fertilizer or a compost feedstock as a route of use. Manure can contain a multitude of bacterial pathogens, antibiotics, and antibiotic resistant genes.
Composting studies to abate pathogenic bacteria (eg. E. coli and Salmonella) have been successful but concluded that temperatures need to be above 55°C. Jiange et. al (2003) states that manure containing E. coli should be composted for a minimum of one week and maintain a compost temperature of 50°C, but preferably composted for two weeks. Sharma et. al (2009) conducted a study to determine antimicrobial resistance during composting manure of cattle administered antibiotics. In this study, compost did not reach the recommended temperature of 55°C for 15 days and antimicrobial resistant E. coli and resistant genes could still be detected after 18 weeks.
Research which analyzes equine manure compost’s ability to remove antibiotic resistant pathogens is lacking. All the aforementioned studies were performed with cattle, swine, or chicken manure.
Horses are rarely given sub-therapeutic doses of antibiotic but they still get treated with antibiotics for a multitude of reasons which can confer antibiotic resistance. Also, horses may be on a farm with other livestock and confer antibiotic resistant pathogens from other animals. Equine manure and compost is used heavily in food production. Antibiotic resistant pathogens have contaminated plants through contaminated irrigation from manure run-off or from contaminated manure of compost application. More than half of the foodborne illnesses in the US are from fresh produce. Therefore, there is a need to determine if horse manure proposes any concern for human health and methods to mitigate antibiotic resistant pathogens from composting.
Jiang, X., Morgan, J. and Doyle, M.P., 2003. Fate of Escherichia coli O157: H7 during composting of bovine manure in a laboratory-scale bioreactor. Journal of food protection, 66(1), pp.25-30.
Sharma, R., Larney, F.J., Chen, J., Yanke, L.J., Morrison, M., Topp, E., McAllister, T.A. and Yu, Z., 2009. Selected antimicrobial resistance during composting of manure from cattle administered sub-therapeutic antimicrobials. Journal of environmental quality, 38(2), pp.567-575.
Within the duration of the previous multistate project, many universities performed outreach work relating to NE1441 research and general education on NE1441 topics.
North Carolina State University developed a 10-day course for USDA-NRCS personnel (Pasture Ecology 1) and a full-day program for farm owners (Grazing and Pasture Management School).
Penn State University offered an annual 2-day course (Equine Environmental Stewardship Short Course) for farm owners, several on-farm Pasture Walk workshops, trainings for USDA-NRCS and Conservation District personnel (Equine Environmental Education and Training Program), and other presentations, webinars, and website articles about various aspects of environmental stewardship.
Rutgers University offered 9 meetings for equine producers and USDA-NRCS staff about conservation and best environmental management procedures. Producers were also informed about New Jersey state animal waste management guidelines and how to sign up for environmental assistance with the USDA-NRCS. Over 150 people signed up for these meetings and over 30 signed up for conservation programs.
Rutgers University conducted a study about feeding horses to benefit the environment (Westendorf et al., 2015). 21 farms participated in this study which developed guidelines for applied nutrition management on horse farms. Subsequently, the state USDA-NRCS developed practice and cost-sharing for those farms implementing feeding management practices.
Rutgers University also produced a Manure Management pamphlet to distribute to Extension Agents and USDA-NRCS personnel along with farmers who attend various environmental focused meetings.
University of Florida offered two county-level BMP workshops focusing on manure and pasture management.
University of Massachusetts offered 21 workshops on composting horse manure, sacrifice lots and footing materials, paradise paddocks, pasture management, managing mud on horse farms, and hay testing. Several projects explored small aerated static composting bins and aerated static composting piles for horse manure, and different footing options for sacrifice lots.
University of Minnesota offered an annual Horse Forage Field Day to publicize the results of forage research to horse owners. In addition, three Extension fact sheets and an easily interpreted infographic were developed for the same purpose. A YouTube video was produced on “When to Initiate Horse Grazing.”
Pasture Management Objective #1
Comments: Conservation of forage through application of grazing schemes that allocate time and space available for grazing may lend to facilitating a greater uniformity of forage supply throughout the year through stock-piling of both cool- and warm-season pasture plants during times of peak production. Additionally, the incorporation of cool- and warm-season annuals to complement perennial pasture may be a useful approach to increasing productivity per acre and extending animal grazing days. An increase in forage productivity per unit of pasture area along with improvement of uniformity of forage supply throughout the year should also decrease chances of overgrazing which in turn should have positive impacts on soil health. Objective Number 1: Pasture Management 1) Identify grazing management schemes that promote uniformity in forage supply across annual grazing cycles, and extend the number of available grazing days. 2) Identify warm- and cool-season forages suitable for stock-pile grazing with horses. 3) Determine the effect of incorporating warm- and cool-season annuals that complement existing perennial pasture productivity per acre and number of horse grazing days. 4) Explore alternative forage species to extend the grazing season.
Manure Disposal Objective #2
Comments: Improve manure disposal and composting techniques and promote their adoption on equine farms by: 1) Continue the study of different bedding types and effects upon on absorptive capacity, airborne particulate matter distribution, composting characteristics, and final disposition and use. 2) Determine the levels of ammonia emitted on horse farms, especially in stalls, and develop methods for reducing ammonia emissions. 3) Determine the effects of antibiotic use and resistance on the presence of antibiotics in manure piles. Objective 3 also deals with the subject of antibiotic use.
Carcass Disposal and Management Objective #3
Comments: Improve carcass disposal and management by surveying the industry for more information about current practices and developing composting management protocols. 1) Determine the methods of carcass disposal used in the industry. Objective 4 will also deal with a survey. 2) Determine the effects of antibiotic use and resistance on the presence of antibiotics in manure piles. 3) Determine the presence of antibiotic resistant bacteria at equine facilities across the state (ME) and evaluate potential risk factors. 4) Determine the level of barbiturate use in euthanized horses and determine whether compost management will result in the destruction of barbiturates. 5) Develop and promote compost systems that will best meet horse industry needs.
Outreach Objective #4
Comments: 1) Undertake a survey about equine environmental management that can be given in any of the participating states. 2) Educate agency personnel (USDA-NRCS, county Conservation Districts, etc.) about the horse industry, horse farm management, and recommended practices for horse farms to empower them to work more comfortably and effectively with farm owners. 3) Increase access to environmental stewardship information and recommendations from research for horse farm owners and managers through online content and face-to-face trainings and demonstrations.
Sub-Objective 1) Identify grazing management schemes that promote uniformity in forage supply across annual grazing cycles and extend the number of available grazing days. Task 1: Determine the effect of restricting time and space available for grazing on estimated annual forage yield per unit area of pasture. Task 1 Methodology: Two different grazing treatments will be applied to both cool- and warm-season pasture to determine their effect on herbage mass produced per unit area of pasture and total number of animal grazing days per year. Treatments will consist of 1) Restricting grazing time to 10 h/d, 2) restricting pasture space allocated for grazing to contain a target herbage mass of approximately 2% of body weight in dry matter available for grazing assuming a grazing efficiency of 0.5 (i.e., 50% of total forage is available for grazing). Herbage mass within grazing plots will be measured weekly using a falling plate meter. Grazing will continue in each plot until the sward height of plants reaches a lower critical limit (approximately 8 to 10 cm). Grazing will continue when forage reaches an upper critical limit (approximately 20 to 25 cm). The number of grazing days will be recorded.
Sub-Objective 2) Identify warm- and cool-season forages suitable for stockpile grazing with horses. Task 1: Estimate the herbage mass production of stock-piled common crabgrass and Tall fescue. Task 1 Methodology: Replicated plots of common crabgrass and tall fescue will be stockpiled for approximately 60 days and herbage mass production per unit of area will be measured using a falling plate meter. Stockpiling of common crabgrass will occur in the months of August and September; whereas tall fescue will be stockpiled during October and November.
Sub-Objective 3) Determine the effect of incorporating warm- and cool-season grasses that complement existing perennial pasture productivity per acre and number of horse grazing days. Task 1: Evaluate annual cool- and warm-season annual grasses for preference, yield, and forage nutritive value under horse grazing during the early spring, summer and late fall. Task 1 Methodology: Replicated plots of annual cool- (e.g. annual ryegrass, oat, winter wheat) and warm-season grasses (e.g. teff and crabgrass) will be planted in monoculture and grazed in the spring, summer and late-fall. Grazing times were chosen to represent an extended grazing season (spring and late-fall) and options during the “summer slump” (summer). Immediately prior to grazing, forage yield and forage nutritive value samples will be collected by hand-harvesting random duplicate 0.46 by 0.51 m areas to a height of 8 cm. Samples will be dried for 24 h at 60°C in cloth bags and weighed to determine dry matter. After drying, samples will be ground, mixed thoroughly and subsamples will be analyzed for forage nutritive value by a commercial forage testing laboratory. Immediately after grazing, horse preference will be determined by visually assessing the percentage of available forage biomass removal on a scale of 0 (no grazing activity) to 100 (100% of the existing vegetation grazed down to 8 cm). Task 2: Assess pasture yield, production cost and horse preference of integrated warm- and cool-season grass rotational grazing systems. Task 2 Methodology: To determine if warm-season grasses will increase forage availability during summer months, grazing days, yield and persistence and will be equally preferred by horses as compared to a traditional (cool-season grass mix) rotational grazing system. Two integrated systems utilizing utilizing “Wrangler” bermudagrass or “Quick N Big” crabgrass will serve as warm-season test forages. In addition, differences between monoculture and interseeded establishment will be evaluated within test-forage treatments. The number of grazing days in each section of each system will be tracked and recorded. Herbage mass, sward height, vegetative cover and species composition will be measured using previously published methods (Kenny, 2016; Burk et al., 2011). Forage nutrient content of hand-clipped samples will be analyzed (Equi-Analytical Laboratories, Ithaca, NY). Total production costs will be calculated and compared for each system to determine if any economic advantage exists. Relevant costs include cost of establishment, pasture maintenance, and supplemental feeding (if any). Preference of forages for horses will be monitored using the previously validated EquiWatch system (ongoing work). Horses in each of the three rotational systems will be fitted with EquiWatch halters and Garmin GPS monitors for a period of no less than 2 - 24 hour periods over three different grazing periods (1 - early in the grazing season, 2 - mid-grazing season, 3 - late in the grazing season). Horses will be tracked to identify the areas of the rotational systems where they spend the most of their time grazing. This data will be compared to forage nutrient content and sward height.
Sub-Objective 4) Explore alternative forage species to extend the grazing season. Task 1: Evaluate commonly used cover crops for preference, yield, and forage nutritive value under horse grazing. Task 1 Methodology: Replicated plots of cereal ryegrass, annual ryegrass, Berseem clover, Daikon radish and purple top turnip will be planted in monoculture and polycultures and grazed by horses in the fall. Immediately prior to grazing, forage yield and forage nutritive value samples will be collected by hand-harvesting random duplicate 0.46 by 0.51 m areas to a height of 8 cm. For radish and turnips, above and below ground biomass and forage nutritive values will be determined by separating these components at harvest. Samples will be dried for 24 h at 60°C in cloth bags and weighed to determine dry matter. After drying, samples will be ground, mixed thoroughly and subsamples will be analyzed for forage nutritive value by a commercial forage testing laboratory. To determine mixture composition, samples will be separated by species, weighed to determine composition, and then recombined for drying and forage nutritive value analysis. Immediately after grazing, horse preference will be determined by visually assessing the percentage of available forage biomass removal on a scale of 0 (no grazing activity) to 100 (100% of the existing vegetation grazed down to 8 cm).
Sub-Objective 1) Characterize the environmental impact of manure management practices (stockpiling versus composting) on equine operations. Task 1: Analyze manure nutrient analysis (TKN, Nitrate, Ammonium, TP) at different time points throughout the year (raw/freshly added material to more aged manure and composted stall waste). Task 2: Analyze ground and surface runoff water samples using drainage lysimeters and water runoff collection trenches installed on site to capture effluent and runoff from manure and compost storage areas. Task 3: Analyze additional water samples collected following rain events to characterize bacterial loads (E. coli and fecal coliforms).
Sub-Objective 2) Investigate the use of Poultry Litter Treatment (sodium bisulfate) in equine facilities to help mitigate ammonia in the barn environment. Task 1: Examine the use of sodium bisulfate application in stalls, around manure storage areas, or even incorporated into stall waste to mitigate ammonia losses. Task 2: Look into the potential for additional application for sodium bisulfate use in equine facility manure management to help reduce external parasites and bacteria.
Sub-Objective 3) Explore alternative uses of horse manure such as for energy use. Task 1: Analyze energy content from farm collected samples for energy content. A previous project (Westendorf and Helsel, 2015; https://articles.extension.org/pages/72862/validation-of-near-infrared-reflectance-spectral-data-for-analyzing-horse-manure) described a method for determining energy content (also N, P) of horse manure using Near Infrared Reflectance Spectroscopy (NIRS). Equations were developed using dry, ground samples of horse manure. Gross energy (GE) was predicted after NIRS analysis with a R-Squared value of 0.89. Ash content was also analyzed and is an excellent predictor of GE content, R-Squared value of 0.96. Our first sub-task is to analyze horse manure (including bedding) on New Jersey (NJ) farms for gross energy by NIRS and Ash determination. This survey will help yield a profile of manure energy values on NJ horse farms. The second sub-task is to consider further processing of horse manure, such as pelleting, to determine other disposal methods.
Sub-Objective 4) Work one on one with horse owners on various aspects of manure management including location, covering manure pile, and spreading plan.
Sub-Objective 1 and 2) Determine the methods of carcass disposal used in the industry. Will be determined in survey (see Outreach Objectives). Determine the presence of antibiotic resistant bacteria at equine facilities across the state (ME) and evaluate potential risk factors. Task: A survey and request for manure samples will be sent to local equine facilities (i.e. riding stables, boarding facilities, equine veterinary hospitals, and racing facilities). The survey will inquire on manure management practices, basic medical treatments, transportation frequency, and mortality management. Manure will be sampled using methods previously described.
Sub-Objective 3) Determine the effects of antibiotic use and resistance on the presence of antibiotics in manure piles. To determine if composting can mitigate both antibiotics and antibiotic resistant coliforms. Methods and Tasks: Manure will be collected to determine the prevalence of antibiotic resistant organisms. Subsamples of the manure will be stored in sterile bags with samples being taken at 0, 5, 14, 21, 28, and 35 days. The samples will then be serial diluted and plated onto TSA agar and MacConkey agar with different classes of antibiotics to determine the presence and enumerate total number of antibiotic resistant bacteria and coliforms. The three composting methods that will be used in the compost study are conventional, organic, and organic with increased aeration via turning of the pile. For each of these three methods samples will be taken for analysis after 0, 3, 8, 15, 21, 35, 49, 63, 77, 98, 126 days of composting. Samples will be taken and plated using same methods in determining prevalence of resistant bacteria. Microscopy of samples will also assess parasite eggs per gram and larval viability counts. Using the best determined composting method, a compost study will be conducted with added antibiotics. Samples and temperatures will be taken at the same time points and plated the same way as the previous methods. Additionally, samples will also be tested for the presence of the antibiotics used.
Sub-Objective 4) Determine the level of barbiturate use in euthanized horses and determine whether compost management will result in the destruction of barbiturates. Determine the length of time needed to degrade sodium phenobarbital to undetectable levels in composting and to determine best composting practices to degrade sodium phenobarbital. Methods and Tasks: Five horses requiring euthanasia for health reasons as determined by a licensed veterinarian will be used in this study. Horses will have been euthanized with sodium phenobarbital. Immediately following euthanasia, each carcass will be placed into compost pile constructed by following USDA livestock mortality composting protocol. Three composing turning procedures will be used. One composting pile containing a carcass will not be turned throughout the entire project. The second and third carcass compost piles will be turned after a month and then remain static for the remainder of the project. The last two compost piles will be turned periodically throughout the project. Compost samples from multiple depths and locations throughout the pile will be collected at different time points. Compost leachate will be collected at the same time points. Samples will be assessed using liquid chromatography with tandem mass spectrometry to determine levels of sodium phenobarbital present. Windrow temperatures, atmospheric temperatures and rainfall will be recorded daily.
Sub-Objective 5) Develop and promote compost systems that will best meet horse industry needs. Methods: See Outreach Objective 4, Sub-Objective 1..
Sub-Objective 1) Undertake a survey about equine environmental management that can be given in any of the participating states. This will be an online (Qualtrix) survey and Rutgers University will be the lead institution. Data from survey this will be used to initiate best management education programs, including several of the objectives for this project. Sub-Objective 2) Educate agency personnel (USDA-NRCS, county Conservation Districts, etc) about the horse industry, horse farm management, and recommended practices for horse farms to empower them to work more comfortably and effectively with farm owners. Task 1: NCSU to continue to offer Pasture Ecology 1 School for USDA-NRCS. Task 2: Penn State Extension to continue to offer Equine Environmental Education and Training Program and other trainings for PA USDA-NRCS and Conservation District personnel. Sub-Objective 3) Increase access to environmental stewardship information and recommendations for horse farm owners and managers through online content and face-to-face trainings. Task 1: NSCU to continue to offer Grazing and Pasture Management School for farm owners. Task 2: Penn State to continue to offer Equine Environmental Stewardship Short Course, on-farm workshops, webinars, articles, and fact sheets to farm owners. Task 3: University of Florida to establish a large-scale composting system at a commercial equine facility as a demonstration site for farm owner education; develop tools and a website for farm owners to evaluate manure management BMPS; and hold two BMP workshops. Task 4: University of Massachusetts to offer 4 pasture management workshops per year, 3 composting demonstrations per year, and writing/revising at least 2 fact sheets per year on pasture/mud/manure management. Task 5: University of Massachusetts, on-farm demonstrations, farm visits, and one on one work with horse owners on various aspects of manure management including location, covering manure pile, and spreading plan. Task 6:University of Minnesota to offer field days and workshops to disseminate results of forage research projects to horse owners, industry professionals, and agency officials; develop YouTube videos, social media content, fact sheets, webinars, and infographics.
Measurement of Progress and Results
- Pasture Management Outputs Comments: 1) Grazing management strategies for horses that include the use of both cool and warm season grasses and other alternative forage species. 2) Strategies for increasing the number of days in a grazing season. 3) Management of stockpiled forage for extending the grazing season. 4) Effects of the alternative strategies described above on pasture quality, soil health, and water quality.
- Manure Management Outputs Comments: 1) Manure analysis of fresh, aged, and composted horse manure. 2) Ground and surface water analysis from manure and compost storage areas. E. coli and coliform analysis from manure and compost storage areas. 3) Initial study comparing odor reduction from sodium bi-sulfite reduction in equine facilities. 4) Analysis of energy content from farm collected horse manure samples.
- Mortality Management Outputs Comments: 1) Results of a survey describing industry carcass disposal methods and current practices. 2) Strategies for composting management to mitigate problems with antibiotics and antibiotic resistant coliforms. 3) Strategies for composting management to mitigate problems with barbiturates in euthanized horses and other equine mortalities. 4) Development of compost management systems that will best meet horse industry needs.
- Outreach Outputs Comments: 1) Trainings for agency personnel and horse farm owners based on research findings and general environmental knowledge. 2) Environmental stewardship meetings and outreach materials (both print and digital) to encourage the use of Best Management Practices from the first three objectives. 3) Survey results will help determine current industry practices, help pursue other area objectives, and formulate future outreach programs.
Outcomes or Projected Impacts
- Pasture Manage Impacts 1) Adoption of grazing strategies, including the use of warm-season grasses, and other non-traditional forages for use to extend the grazing season for horses. 2.) Extended grazing season for adopters. 3) Decreased used of purchased feed. 4) Positive observable improvements in pasture quality, soil health, and water quality.
- Manure Management Impacts 1) Strategies for reducing nutrient and bacterial losses around barnyards and manure storages. 2) Odor reduction protocols on farms. 3) Profile of manure energy content. 4) On-farm demonstration projects about best management practices.
- Mortality Management Impacts 1) Increased options for carcass disposal on equine farms. 2) Reduction in antibiotics and barbiturate contamination of watersheds. 3) Useful compost management strategies for producers.
- Outreach Impacts 1) Improved environmental stewardship on horse farms as a result of better understanding of conservation principles and increased adoption of conservation practices. 2) Increased participation in State and Federal conservation management programs such as Comprehensive Nutrient Management Plans on horse farms. 3) A series of workshops related to the Objectives. 4) Best Management Practices education program completed, based on survey results. 5) Adoption of practices that will improve pasture quality, soil health, and water quality.
Milestones(2020):1) Initiation and coordination of multi-state research related to the use of warm-season grasses, stockpiling, and the extension of the grazing season – 2020. This research will be completed between North Carolina State, Penn State, Rutgers, U. of Minnesota, and the U. of Maryland. This work will continue from 2020-2024. 2) Manure analysis for fresh, aged, and composted manure. 2) Completion of survey about carcass disposal methods by 2020. 3) Completion of Outreach Survey by 2020.
(2021):1) Monitor improvements in pasture quality and management, beginning in 2021. 2) Complete study to determine the prevalence of antibiotic resistant organisms in horse manure by 2021. 3) Ground and surface water analysis near barnyards and manure storages, 2021-2022. 4) Complete the study of the use of Poultry Litter Treatment (sodium bisulfate) in equine facilities to help mitigate ammonia in the barn environment, 2021-2023.
(2022):1) Summarize pasture management results, 2022-2024. 2) Design and complete a composting study to determine the best methods for reducing antibiotic prevalence in manure by 2022. 3) Completed outreach educational program by 2022. 4) Completion of the energy content of manure on New Jersey farms, 2022-2023.
(2023):1) Complete in vitro horse manure study to determine the length of time needed to reduce prevalence of barbiturates by 2023. 2) Producer pasture management education program, 2023-2024.
(2024):1) Design and complete a composting study to determine the best methods for reducing barbiturates when present in manure by 2024. 2) Follow-up for producer involvement in State and Federal conservation management programs by 2024. 3) Final producer workshops completed based on research from other objectives by 2024. 4) Completion of on-farm best management practices project.
Projected ParticipationView Appendix E: Participation
To disseminate project results to horse owners and professionals, in-person presentations, field days, YouTube videos, social media posts, online factsheets, webinars and infographics will be developed. Field days will be held at multiple locations and through the duration of the project. Throughout the project, video footage will be taken and a YouTube video demonstrating different components of the project will be developed and added to appropriate University YouTube channels. This information will also be disseminated through posts on University social media pages (e.g. Facebook and Twitter), and Facebook Live videos will be recorded when possible. High resolution photographs throughout the project will also be taken to develop online factsheets and for use in in-person presentations. Finally, webinars will be presented and recorded summarizing the different components of the project and supporting infographics will be developed and posted online. The target audience for all of these educational efforts will be horse owners, industry professionals and agency officials. All educational opportunities will be open to the public and advertised through the various collaborating Universities and their partners.
To determine knowledge gains and changes in behavior as a result of Extension programming, participants will be asked to complete post-program evaluations when attending field days and face-to-face programs where project results are discussed. Social media and website metrics will also be collected to determine the total reach of disseminated project results. Finally, results will be presented at equine-related scientific meetings (e.g. Equine Science Society) and other industry events.
This project is coordinated among the participating states. These are the states that took leadership in this project rewrite
Objective 1 - Pasture Management: North Carolina State, U. of Minnesota, Rutgers, U. of Maryland, Penn State.
Objective 2 - Manure Management: U. of Florida, U. of Massachusetts, Rutgers.
Objective 3 - Mortality Management: U. of Maine, Rutgers.
Objective 4 - Outreach: Penn State, U. of Minnesota, Rutgers.
Dr. Michael Westendorf, Rutgers University, will continue to guide the meetings, reprting etc. He will be assisted on a yearly basis by the faculty from the host institution. A steering committee made up from the members of the folllwing institutions will communicate regularly by tele-conference call and other means: North Carolina State, U. of Minnesota, Rutgers, U. of Maryland, Penn State. U. of Florida, U. of Massachusetts, U. of Maine.
Dr. Westendorf and the committee will communicate regularly with Dr. Mark Rieger, University of Delaware Administrative Advisor for the group and other NERA staff as required.
Related, Current, and Previous Work:
(Outreach activities you have done for previous NE1441 research projects or on NE1441 topics, any impact data you may have on them. If you have any publications about them, please list. Dates and details not necessary.)
- Bott, R. C., E. A. Greene, K. Koch, K. L. Martinson, P. D. Siciliano, C. A. Williams, N. L. Trottier, A. Burk, and A. Swinker. 2013. Production and environmental implications of equine grazing. J. Equine Vet. Sci. 33:1031–1043. doi: 10.1016/j.jevs.2013.05.004
- Bott, R. C., E. A. Greene, N. L. Trottier, C. A. Williams, M. L. Westendorf, A. M. Swinker, S. L. Mastellar, and K. L. Martinson. 2016. Environmental implications of nitrogen output on horse operations: A review. J. Equine Vet. Sci. 45:98-106. doi: 10.1016/j.jevs.2015.08.019
- DeBoer, M.L., M.R. Hathaway, K.J. Kuhle, P.S.D. Weber, A.S. Reiter, C.C. Sheaffer, M.S. Wells and K.L. Martinson. 2018. Glucose and insulin response of horses grazing alfalfa, perennial cool-season grass, and teff across seasons. J. Equine Vet. Sci. 68: 33-38.
- DeBoer, M.L., C.C. Sheaffer, A.M Grev, D.N Catalano, M.S. Wells, M.R. Hathaway, and K.L. Martinson. 2017. Yield, nutritive value and preference of annul warm-season grasses grazed by horses. Agronomy J. 109: 2,136-2,148.
- Grev, A.M., C.C. Sheaffer, M.L. DeBoer, D.N. Catalano, and K.L. Martinson. 2017. Preference, yield, and forage nutritive value of annual grasses under horse grazing. Agronomy J. 109: 1,561-1,572.
- Kenny, L. B., D. Ward, M. Robson, and C. A. Williams. 2018. Technical note: Comparing four techniques for estimating desired grass species composition in horse pastures. J. Anim. Sci. 96:2219-2225. doi: 10.1093/jas/sky111
- Martinson, K.L., P.D. Siciliano, C.C. Sheaffer, B.J. McIntosh, A.M. Swinker, and C.A. Williams. 2017. A review of equine grazing research methodologies. J. Equine Vet. Sci. 51: 92-104.
- Martinson, K.L., M.S. Wells, and C.C. Sheaffer. 2016. Horse preference, forage yield and species persistence of twelve perennial cool-season grass mixtures under horse grazing. J. of Equine Vet. Sci. 36: 19-25.
- Nazarenko, Y., M. L. Westendorf, C. A. Williams, and G. Mainelis. 2018. The effects of bedding type in stalls and activity of horses on stall air quality. J. Equine Vet. Sci. 67:91-98. doi: 10.1016/j.jevs.2018.03.014
- Splan, R., M. Spindler, K. Anderson, C. Skelly, M. Westendorf, C. Williams, L. Kenny, and R.C. Bott-Knutson. 2017. Opportunities to Address the Transdisciplinary and Global Challenges of Climate Change in An Equine Science Context. NACTA Journal. March 2018, Vol 62(1).
- Trottier, N. L., R. C. Bott, A. Woodward, E. A. Greene, C. A. Williams, M. L. Westendorf, A. M. Swinker, S. L. Mastellar, and K. L. Martinson. 2016. Gastrointestinal nitrogen metabolism of equids and impact on protein requirement. J. Equine Vet. Sci. 45:78-86. doi: 10.1016/j.jevs.2016.06.002
- Weinert, J. R. and C. A. Williams. 2018. Recovery of pasture forage production following winter rest in continuous and rotational horse grazing systems. J. Equine Vet. Sci. 70:32-37. doi.org/10.1016/j.jevs.2018.06.017
- Westendorf, M.L., C. A. Williams, and L. B. Kenny. 2015. Protection of environmental resources through the implementation of optimum feed-management practices on equine farms. Prof. Anim. Sci. 31:296-301. doi: 10.15232/pas.2014-01379
- Westendorf, M. L., and C. A. Williams. 2015. Effects of excess dietary phosphorus on fecal phosphorus excretion and water extractable phosphorus in horses. J. Equine Vet. Sci. 35:495-498. doi: 10.1016/j.jevs.2015.01.020
- Kenny, L. B., A. O. Burk, and C. A. Williams. 2018. Managing Equine Grazing for Pasture Productivity. In: Equine Pasture Management, edited by P. Sharpe. Elsevier Science, St. Louis, MO (in press). pp. 1-17. doi: 10.1016/B978-0-12-812919-7.00009-3
- Kenny, L. B., M. Westendorf, and C. A. Williams. 2018. Managing Manure, Erosion, and Water Quality in and Around Horse Pastures. In: Equine Pasture Management, edited by P. Sharpe. Elsevier Science, St. Louis, MO (in press). pp. 1-21. doi: 10.1016/B978-0-12-812919-7.00014-7
- Catalano, D. N., C. C. Sheaffer, A. M. Grev, N. J. Ehlke, E. Mousel, and K. L. Martinson. 2018. Yield, Preferencec, and Forage Nutritive Value of Winterhardy Perennial Ryegrass under Animal Grazing. In proceedings: 2018 University of Minnesota Animal Science Showcase. Pg. 14. St. Paul, MN.
- Catalano, D. N., C. C. Sheaffer, A. M. Grev, N. J. Ehlke, E. Mousel, and K. L. Martinson. 2018. Yield, Preference, and Forage Nutritive Value of Winterhardy Perennial Ryegrass under Animal Grazing. In Proceedings: 2018 American Forage and Grassland Council Annual Conference. Louisville, KY.
- Catalano, D.N., C.C. Sheaffer, M.S. Wells, A.M. Grev, M.L. DeBoer, and K.L. Martinson. 2016. Forage nutritive value, yield, and preference of legumes under horse grazing in the establishment year. Proc.,University of Minnesota Excellence in Equine Research Showcase, St. Paul, MN. Pg. 11.
- DeBoer, M.L., M.R. Hathaway, K.J. Kuhle, P.S.D. Weber, C.C. Sheaffer, M.S. Wells and K.L. Martinson. Forage quality and blood metabolites of adult horses grazing alfalfa, teff, and cool-season perennial grasses. In Proceedings: 78th Minnesota Nutrition Conference. Pg. 260. Mankato, MN.
- Catalano, D.N., C.C. Sheaffer, M.S. Wells, A.M. Grev, M.L. DeBoer, and K.L. Martinson. 2016. Forage nutritive value, yield, and preference of legumes of horse grazing in the establishment year. Proc., 2016 North American Alfalfa Improvement Conf., Madison, WI. Available online at: https://www.naaic.org/Meetings/National/2016meeting/Devan%20Catalano%20Abstract.pdf
- DeBoer, M.L., C.C. Sheaffer, M.S. Wells, M.R. Hathaway, A.M. Grev, D.N. Catalano, and K.L. Martinson. 2017. Nitrate-nitrogen content of annual warm-season forages grazed by horses. In Proceedings: 2017 American Forage and Grassland Council Annual Meeting. Roanoke, VA. Available online at http://www.afgc.org/proceedings/2017/DeBoer_Schultz_Michelle%20AFGCInterpretive.pdf.
- Grev, A.M., C.C. Sheaffer, D.N. Catalano, M.L. Schultz, and K.L. Martinson. 2016. Yield, preference, and forage nutritive value of small grains under horse grazing. Proc., University of Minnesota Excellence in Equine Research Showcase, St. Paul, MN. Pg. 13.
- Kenny, L., A. O. Burk, and C. A. Williams. 2015. Effects of rotational vs continuous grazing systems on horse condition and vegetation. Waste to Worth Conf. Proc. Seattle, WA. Online: http://create.extension.org/node/100707.
- Reiter, A.S, M.L. DeBoer, M.R. Hathaway, K.J. Kuhle, C.C. Sheaffer, M.S. Wells, K.L. Martinson. 2018. Plasma Amino Acid Concentrations of Horses Grazing Alfalfa, Cool-season Perennial grasses, and Teff. In Proceedings: American Forage and Grassland Council 2018 Annual Meeting. Louisville, KY.
- Schultz, M.L., C.C. Sheaffer, D.N. Catalano, A.M. Grev, and K.L. Martinson. 2016. Forage nutritive value, yield, and preference of warm season grasses grazed by horse in the upper Midwest. IProc., University of Minnesota Excellence in Equine Research Showcase, St. Paul, MN. Pg. 10.
Williams, C. A. 2017. Nutrient cycling in horse pastures. Waste to Worth Conf. Proc. Raleigh, NC. Online: http://articles.extension.org/pages/74361/nutrient-cycling-in-horse-pastures.
Williams, C. A., L. B. Kenny, and M. L. Westendorf. 2015. Protection of environmental resources through the implementation of optimum feed management practices on equine farms. Waste to Worth Conf. Proc. Seattle, WA. Online: http://www.extension.org/pages/72881.
- DeBoer, M.L., K.L. Martinson, K.J. Kuhle, C.C. Sheaffer, M.S. Wells, and M.R. Hathway. 2017. Plasma amino acid concentrations of horses grazing alfalfa, cool-season perennial grasses, and teff. J. Equine Vet. Sci. 52: 83.
- DeBoer, M.L., M.R. Hathaway, K.J. Kuhle, P.S.D. Weber, C.C. Sheaffer, M.S. Wells, R.S. Mottet, and K.L. Martinson. 2017. Glucose response of horses grazing alfalfa, cool-season perennial grasses and teff across seasons. J. Equine Vet. Sci. 52: 79.
- Catalano, D.N., C.C. Sheaffer, A.M. Grev, N.J. Ehlke, and K.L. Martinson. 2017. Yield, preference, and forage nutritive value of winter hardy perennial ryegrass under equine grazing. J. Equine Vet. Sci. 52: 102.
- Kenny, L. and C. A. Williams. 2015. Comparing four techniques for estimating species composition in horse pastures. Mid-Atlantic Nutr. Conf. Proc. 13 https://ansc.umd.edu/extension/mid-atlantic-nutrition-conference/past-proceedings).
- Kenny, L. B., A. O. Burk, and C. A. Williams. 2015. Effects of rotational versus continuous grazing on horse condition and plant performance. J. Equine Vet. Sci. 35:420. Abstract #85.
- Le, A., L. B. Kenny, A. O. Burk, and C. A. Williams. 2016. Impact of grazing system on forage carbohydrates and horse metabolism. Mid-Atlantic Nutr. Conf. Proc. 14 (https://ansc.umd.edu/extension/mid-atlantic-nutrition-conference/past-proceedings).
- Powlowski, C., J. Weinert, and C. A. Williams. 2018. Impact of grazing system on forage carbohydrates and horse metabolism. Mid-Atlantic Nutr. Conf. Proc. 16 (https://ansc.umd.edu/extension/mid-atlantic-nutrition-conference/past-proceedings).
- Reiter, A.S., M.L. DeBoer, K.J. Kuhle, C.C. Sheaffer, M.S. Wells, M.R. Hathaway, and K.L. Martinson. 2017. Variation in nitrate concentration of alfalfa, perennial cool-seasonal grasses, and teff grazed by horses in the upper Midwest. J. Equine Vet. Sci. 52: 45.
- Rizzo, E., A. O. Burk, and C. A. Williams. 2017. The effects of continuous vs. rotational grazing on forage soluble carbohydrate content and blood glucose and insulin concentration in horses. Mid-Atlantic Nutr. Conf. Proc. 15 (https://ansc.umd.edu/extension/mid-atlantic-nutrition-conference/past-proceedings).
- Seeds, C., L. Kenny, and C. A. Williams. 2015. The effects of continuous vs. rotational grazing systems on horse condition and plant performance. Mid-Atlantic Nutr. Conf. Proc. 13 (https://ansc.umd.edu/extension/mid-atlantic-nutrition-conference/past-proceedings).
- Williams, C. A., L. B. Kenny, and A. O. Burk. 2017. Effects of grazing system and season on glucose and insulin dynamics of the grazing horse. J. Equine Vet. Sci. 52:87. Abstract #108.
- DeBoer, M., C. Sheaffer, and K. Martinson. 2017. Grazing horses on teff, alfalfa, and perennial ryegrass. University of Minnesota Extension Factsheet.
- Fojtik, A. and C. A. Williams. 2017. A Guide to More Productive and Nutrient Dense Horse Pastures. Rutgers Cooperative Extension. FS1271. New Brunswick, NJ. pp. 1-4.
- Grev, A., C. Sheaffer, and K. Martinson. 2017. Preference, yield, and forage nutritive value of annual grasses under horse grazing. University of Minnesota Extension Factsheet.
- Martinson, K., C. Sheaffer, and M.S. Wells. 2016. Grass mixtures for Midwest horse pastures. University of Minnesota Extension Factsheet.
- Westendorf, M. L., and C. A. Williams. 2014. Can Animal Feeding Practices Influence Nutrient Runoff? Rutgers Cooperative Extension. FS1191. New Brunswick, NJ. pp. 1-2.
- Westendorf, M. L., and C. A. Williams. 2013. Managing Manure on Horse Farms: Exercise or Sacrifice Lots for Horses. Rutgers Cooperative Extension. FS1190. New Brunswick, NJ. pp. 1-2.
- “When to Initiate Horse Grazing” 3,902 views to date (posted December 12, 2013).
- “Nutrient Cycling in Horse Pastures” Conference presentation at Waste to Worth Conference 2017, Raleigh, NC. Posted May 5, 2017. (https://www.youtube.com/watch?v=i6uLaTe0s8M).
Online Certification Courses
- Pasture Establishment and Management. 2017 enrollment was 31.
- Composting Course. 2014. Available online as a self-certification program for farmers in New Jersey and throughout the US for compost managers. Rutgers Cooperative Extension. http://campus.extension.org/course/view.php?id=897.