Decreasing small ruminant exposure to parasites by reducing slug and snail populations through a sheep/duck grazing system

Project Overview

Project Type: Farmer
Funds awarded in 2016: $10,963.00
Projected End Date: 03/31/2019
Grant Recipient: Wellspring Forest Farm
Region: Northeast
State: New York
Project Leader:
Steve and Elizabeth Gabriel
Wellspring Forest Farm LLC

Annual Reports

Information Products


  • Agronomic: grass (misc. perennial), hay
  • Animals: sheep


  • Animal Production: parasite control, grazing management, grazing - multispecies, grazing - rotational, feed/forage
  • Education and Training: farmer to farmer, on-farm/ranch research
  • Pest Management: biological control, field monitoring/scouting
  • Production Systems: permaculture, integrated crop and livestock systems
  • Sustainable Communities: sustainability measures

    Proposal summary:

    This proposal focuses on Parelaphostrongylus tenuis (P. tenuis, a.k.a brain worm/deer worm). This parasite is on the rise and is especially problematic because there is no effective treatment plan with a strong likelihood of full recovery.  P. tenuis larvae are excreted in deer feces, common grazers of pasture. Larvae infect gastropods, which are consumed by ruminants. Just one larva in a sheep’s spinal cord can cause illness. There is no method for monitoring P. tenuis – producers can only act once an animal shows clinical signs of infection. Anthelmintics and corticosteroids (Ivomec, dexamethasone, Safeguard) can treat the parasite, but have varying effectiveness and don’t meet organic standards. Despite treatment, some animals die or become permanently lame. Rarely is there full recovery. There is no way to predict the outcome. Our farm seeks to establish resilient systems that promote healthy livestock, increase production and reduce costs. We prefer to prevent rather than treat illnesses whenever possible. From previous on-farm research, we know ducks are excellent foragers of gastropods. We propose a two-year multispecies grazing study that adds a complementary stocking rate of ducks to our rotational sheep-grazing plan. If ducks reduce the population of gastropods in the pasture, this reduces exposure of sheep to P. tenuis infected larvae. We will set up gastropod traps in control and treatment paddocks to monitor quantitative gastropod data to determine; Year 1) if the presence of 50 ducks reduces gastropod populations in paddocks and Year 2) the most effective leader-follower timing of duck-sheep rotations.

    Project objectives from proposal:


    A common permaculture principle is “the problem is the solution”. In this case, a gastropod problem means a duck deficiency. We propose to reduce sheep exposure to P. tenuis by reducing the population of host carriers of this parasite (slugs and snails) by adding 50 ducks to our current rotational sheep grazing system. Ducks are excellent foragers and can lay up to 300 eggs/year, thus contributing to farm income. Using gastropod traps in test and control paddocks, we will monitor if 50 grazing ducks reduce gastropod populations in test paddocks. By collecting gastropod data throughout the season, for two years, we aim to determine cycles and patterns in population dynamics, thus helping to determine the most effective leader-follower timing.

    Objective 1: Determine if grazing 50 ducks reduces gastropod populations in paddocks ~12,000 square feet

    Objective 2: Reduce brain worm parasite risk to grazing ruminants, thereby reducing the need for Ivomec, dexamethasone, and Safeguard

    Objective 3: Determine ideal timing of leader-follower rotation that results in low gastropod population, minimal duck poop presence on pasture, and diverse and abundant forage

    We graze sheep on 6 of our 10 acres and graze an additional 10 acres of pasture that we lease from our neighbors, rotating the herd every 3-6 days through paddocks using moveable ElectroNet fencing. For this research, we propose to also rotate 50 Khaki Campbell ducks (+ 2 guard geese) through experimental paddocks, using a similar ElectroNet fence for poultry. We easily move ducks by building their house on top of a trailer, which we pull with our ATV. Duck breed choice and flock size was chosen from experience and demands of the local duck egg market.

    Since 2011, we have raised 6 different breeds of ducks in flock sizes of 8-120. We have raised ducks for meat and for eggs. We have found it most achievable to our farm goals and scale to keep a flock of 50 or less. Meat production was not financially viable in these smaller flock sizes. In contrast, we found that Khaki Cambells are prolific egg layers (up to 300 a year); excellent foragers and are hardy to the cold winter and winds of our landscape. Duck eggs have become a wonderful addition to our farm production. The local butcher and market, a restaurant and shiitake CSA members currently demand more eggs than we can supply.

    Research Question 1: Do ducks reduce gastropod populations in paddocks ~12,000 square feet?


    In year one, we will establish a baseline to determine if there is a reduction in gastropod population if 50 ducks rotate through test paddocks. While know ducks eat gastropods and have documented decreases of slug populations in our forest/shiitake system, the density of ducks per acre was higher.

    We will graze 28 sheep through our pasture in 2016 using our existing sheep grazing plan, in which sheep rotate on average every 4 days. There will be 3 test paddocks and 3 control paddocks, chosen at random from 6 paddocks that have similar characteristics with regards to exposure, slope, moisture, and proximity to pasture edge/woods. These environmental conditions could have a significant effect on gastropod presence. For ease of moving and grazing ducks on the whole paddock, paddocks will be the same size for sheep and ducks, about 12000 square feet by using 3 160’ ElectroNet fences.  Sheep will graze control and test paddocks. Each paddock will have 6-9 slug traps laid out so no more than a 50’ radius will exist from trap to trap. Gastropods can travel about 50 feet in a 24-hour period; so placing traps within this radius should aid in attracting gastropods. Traps involve placing an inch of beer or sugar water with a pinch of yeast in a shallow container – we will use pie pans - partially buried in the ground and easy for the gastropod to access. A wooden plywood board slightly elevated from the rim of the pie pan will keep sheep out and will cover each trap from rain, though still enabling gastropods to slither in. The 51 traps will be set from April 1 – November 1. Each paddock and each trap will be numbered and data collection will be entered in both our farm journal and excel spreadsheet. Data on number of slugs per trap will be collected once a week from all paddocks.

    Ducks and sheep will never share a paddock at the same time. We considered co-mingling grazing for this research, however ducks have high water needs and bathe and defecate in their water, leaving it less than ideal for sheep to drink. We will maintain approximately a 30-day leader-follower relationship with the ducks and sheep, duck grazing the paddock 30-days prior to the sheep. 30 days allows us to gather data from traps between grazing animals for long enough time to see when the gastropod numbers drop and increase, weather data especially precipitation since this increases gastropod populations, what timing allows duck poop to decompose significantly and ducks effect on forage quality. Ducks will graze each paddock for 7 days.

    In 2017, assuming question 1 proves true, we will apply our collected data and create a duck/sheep-grazing plan whereby ducks enter the paddock prior to the sheep when gastropod populations showed to be the lowest and forage quality the highest. If year one research does not determine ducks reduce gastropod populations in paddocks, we will adjust our research for year two accordingly. Though we will work with our technical advisor and assess our data, possible alternative year two research could be to increase stocking rate of ducks by making paddocks sizes smaller and/or letting ducks graze paddocks for longer periods of time.

    Data collection in both year 1 and 2 includes:

    • weekly slug and snail counts from all 18 traps
    • numbers of lambs and ewes in flock, documenting any sickness or loss
    • paddock size (remains constant year 1-2)
    • number of ducks grazing, documenting any losses (remains constant year 1-2)
    • temperature and precipitation via a personal weather station
    • # of days ducks graze each paddock (year 1 = 7, year 2 = adjusted accord to research)
    • # of days sheep graze each paddock
    • # of days each paddock rests between grazing animals (year 1= approximately 30, year 2 = adjusted accordingly)

    In addition to quantitative data, we will keep an observation journal of anecdotal evidence including but limited not to effect of ducks on forage quality of the pasture and farmer enjoyment and well-being during project.

    Note - Project manager Elizabeth Gabriel will carry out all of the listed tasks below and in some cases, in collaboration with other people as listed.

    Timeline of project


    • March – Notify the professional experts who provided advice to this proposal of the receipt of funding and forward movement of research
    • March – Expand current grazing plan to include duck rotation, showing paddock size, trap placement and order of rotation
    • March to End of Study – Maintain a journal of anecdotal observations and happenings –Steve Gabriel & Hired Labor
    • April – Start rotationally grazing sheep and ducks
    • April – Set-up gastropod traps in control and test paddocks
    • May – Start rotating ducks through paddocks 30 days prior to sheep – Steve
    • May – November – Collect weekly data on gastropod population, # of days ducks are in each paddock, # of days paddock rests, # of days sheep are in paddocks, weather variables – Hired Labor
    • May- November – Maintain gastropod traps, refreshing bait as needed – Hired Labor
    • June – Host Groundswell CRAFT Tour
    • June/July – Technical Advisor visits to help with data collection, animal rotation, and review research practices – Brett Chedzoy
    • May – November – Observe and monitor how long it takes for duck poop to decompose and forage quality to bounce back if trampled by duck feet – Hired Labor
    • August – host site for Finger Lakes Permaculture Open House – Steve
    • December 2016 – January 2017 – analyze research and collected data. Identify any major areas of improvement, need for change or unexpected research errors. Determine duck-sheep leader-following timing for 2017 – Brett and Steve


    • February – Update base map of paddocks for year 2, including leader-follower timing
    • February - April – If duck flock loss, reorder birds to maintain a flock size of 50, set-up housing and care for ducklings
    • April – Set-up gastropod traps in all paddocks, begin rotating sheep and ducks with determined leader-follower variable – Steve
    • April – November – Collect weekly data on gastropod population, # of days ducks are in each paddock, # of days paddock rests, # of days sheep are in paddocks, weather variables – Hired Labor
    • May- November – Maintain gastropod traps, refreshing bait as needed – Hired Labor
    • August/September – Set-up and Host Cooperative Extension Field Day – Brett, Steve
    • August – host site for Finger Lakes Permaculture Open House – Steve
    • May – November – Observe and monitor how long it takes for duck poop to decompose and forage quality to bounce back if trampled by duck feet – Hired Labor
    • November - December – analyze research and collected data. Write a final report that includes conclusion of research, effectiveness and applicability – Brett and Steve
    • January 2018 – Give presentation on research and results at NOFA-NY


    Wellspring Forest Farm maintains a Facebook page and blog via our website which reach about 750 people. We will post our research, interesting updates, events we are hosting and our final report to both of these mediums. In June 2016, we are hosting the Finger Lakes CRAFT on a tour of our farm. This group of interested beginning farmers is managed by Groundswell Center for Food and Farming and has 20-30 active participants. In 2014, we were part of The Finger Lakes Permaculture Institute’s ‘Permaculture Site Open House’. In 2014, there were 200 attendees, in 2015 over 300, of which over 150 visited Wellspring Forest Farm. Additionally, after each year, we will share the report summary on several applicable list serves including managed by Brett Chedzoy and Small Ruminant Marketing hosted by Tatiana Stanton, each host over 500 participants. With Brett, we will organize a Cornell Cooperative Extension Field Day and pasture walk with the Tri-County Grazing group in the fall of 2017. Marketing through CCE networks and local farmers, these events are well attended with 50-100 people. In the fall of 2017, we will submit a proposal to present at the NOFA-NY annual winter conference for Elizabeth to present on the research and results at the January 2018 NOFA-NY Winter Conference. We also plan to send the final report to all of the professional experts who gave advice to prepare this research plan and encourage them to share the information with their networks.


    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.