Control of Haemonchus contortus in northern New England sheep and goats through manipulation of its winter ecology

Control of Haemonchus contortus in northern New England sheep and goats through manipulation of its winter ecology

Summary

Over 100 producers in northern New England participated in a grazing season census of parasite species on their farm. Producers received accurate parasite information throughout the 2015 grazing season, and were also given parasite management advice that was tailored to their farm. Over 200 producers and 80 veterinarians attended lectures, short courses and wet labs related to parasite management strategies that work in northern New England. A controlled experiment was completed on the effect of withholding sheep from pastures during the early grazing season. We found that keeping sheep on stored forage until pastures became productive in mid-June caused a significant lowering of parasitism that extended throughout the grazing season.

Objectives/Performance Targets

One hundred NNE sheep and goat producers adopt more effective parasite management strategies, including routine monitoring of Haemonchus levels in their sheep through FAMACHA and fecal egg counts.

Sixty producers will adopt at least three of the following cold weather management techniques to reduce or eliminate the shedding of Haemonchus ova on winter and spring pastures: 1. Winter dewormer treatment; 2. Hasten Spring rise through earlier lambing or increased photoperiod; 3. graze weaned lambs separate from dams on ‘clean’ pastures; 4. utilize appropriate pasture stocking rates and practice rotational grazing; 5. reduce egg shedding on early spring pastures through the use of a ‘mud season’ paddock.

These management changes will positively affect the productivity of 2000 sheep and goats on 1000 acres of pasture, resulting in additional profits of $200.000 per year in the northern New England region.

SPECIFIC OBJECTIVES:

Objective 1a: Determine the prevalence of the major internal parasites of sheep and goats on 120 commercial farms throughout northern New England (Strongyloides, trichostrongylids, tapeworms, Nematodirus). Using a species-specific test for Haemonchus, differentiate the Trichostrongylid nematode species into Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus spp. Monitor the relative abundance of Haemonchus egg production on ten farms each in Maine, New Hampshire and Vermont at biweekly intervals throughout one winter non-grazing season (this will provide us with an estimate in different climatic zones of the comparative timing of spring rise, which will improve our ability to prevent contamination of pastures with Haemonchus eggs during the early spring).

Objective 1b: Identify 30 farms identified in objective 1a to participate in studies of Haemonchus winter ecology.

Objective 2a: Test third-stage (L3) Haemonchus larvae, the long-term infective reservoir of Haemonchiasis in pastures, for their survival after exposure to simulated (in vitro test) and actual (on-farm test) winter environmental conditions at their farm of origin.

Objective 2b: Use the cold-tolerance data to produce a northern New England map of Haemonchus winter-kill zones.

Objective 3: Compare the cold-tolerance of free-living Haemonchus larvae from commercial farms in northern New England with larvae collected from commercial farms in more southern climates (West Virginia and Georgia). The purpose of this comparison is to determine whether Haemonchus has become more cold-tolerant as it has moved north to northern climates.

Objective 4: Test the efficacy of the five winter eradication strategies detailed in Section D on a limited number of northern New England farms (two farms in each State) that have demonstrated zero overwinter survival of Haemonchus L3 larvae, and that have Haemonchus populations that are sensitive to at least one of the three major chemical classes of dewormers. Producers will be trained to implement as many of the management strategies as possible, and livestock production and economic data from the grazing season preceding and following the management changes will be compared.

Accomplishments/Milestones

Summer 2014: Principle Investigators meet to discuss implementation of grant components. A steering Committee is formed from leaders in the sheep and goat industries in northern New England, and holds its first annual meeting in fall 2014. Completed summer of 2014.

Fall 2014: Producer seminars (basic parasitology 101) are held in ME, VT and NH. 60 to 70 producers attend each event. Materials from these seminars are recorded and made available on-line through podcasts and webinars. Completed in September 2015 (five producer-oriented parasite management seminars took place in Maine and New Hampshire in September 2014, October 2014, March 2014 (2 events) and September 2015. Four parasite microscopy and FAMCAHA diagnosis training sessions were held in Maine and New Hampshire in August 2014, March 2015, April 2015, and August 2015. In addition, data from the first year of the NE SARE project was presented to a national audience of veterinarians at the American Association of Small Ruminant Practitioners meeting in New Orleans in September 2015). We have not held any educational events in Vermont to date.

Spring 2015: Parasite species are identified during the early, mid and late grazing season of 2015 on 100 farms throughout NNE. Producers received farm-specific information, then were taught effective management techniques based on the parasite species present in their animals. Each producer was involved in a farm-specific consultation with Dr. Weber about management techniques that were best suited for their individual situation. These participants are currently being recruited for further studies. Completed in October 2015.

Fall 2015: Annual seminar is held in ME, VT and NH. Topics include wet labs to train producers how to identify parasites through fecal egg counts and Haemonchus infestations through the FAMACHA technique. Completed in November 2015. Over 200 producers attended 9 parasite management seminars or wet labs between September 2014 and October 2015.

2015-2016: Regional producers learn about the Haemonchus eradication and winter kill projects. Completed in 2015. Over 100 farms in northern New England participated in a 2015 grazing season project that identified and enumerated parasite species on their farms.

Discussions are held with producers to determine identify the parasite management strategies currently in use on their farms. Parasite management strategies currently in use on these farms are identified, and indices related to farm productivity during the 2015 grazing season are recorded. Completed. Farm-specific data was collected through an on-line survey from over 100 producers who took part in the 2015 grazing season survey. Parasite counts on each farm were compared to management practices and analyzed statistically to identify trends and management-related differences in parasite prevalence. Data from this work is being analyzed during the winter of 2015-2016.

Fall 2016: On-farm and controlled research results are communicated to producers throughout northern New England and nationally through Web-based media such as Land Grant Cooperative Extension sites and E- Extension. Partially completed at this time. Our first controlled parasite management study was completed at the University of Maine on our research flock during 2015. The purpose of this study was to determine whether decreased fecal contamination of pastures early in the grazing season, before the first lush forage growth, would reduce subsequent exposure of sheep to Haemonchus contortus.Two groups of animals (five post-partum ewes and 8 lambs per group) were exposed to pastures starting at different times during the spring of 2015, with one group beginning summer grazing on May 15, and the second group being kept off pasture and fed hay until June 15, and fecal egg counts and FAMACHA scores were determined weekly throughout the grazing season. The group held off pasture until mid-June showed significantly lower parasite egg counts and FAMACHA scores throughout the summer, and needed fewer anthelmintic treatments to maintain safe levels of Haemonchus.

Fall / Spring 2016-2017: Project data are presented at national and regional conferences. Completed in September 2015. National presentation s were given at the Annual meetings of the National Dairy Goat Association and the American Association of Small Ruminant Practitiners. Self-learning modules on parasite control are formed. Parasite burdens are monitored on farms that attempted eradication. A final set of regional parasite management conferences are held to receive producer feedback. Not completed at this time.

Impacts and Contributions/Outcomes

We completed the first controlled study of the effect of winter management changes on the severity of Haemonchus parasitism in 2015. We found that delaying the grazing season from mid-May to mid-June resulted in reduced exposure of ewes and lambs to Haemonchus contortus larvae during the entire grazing season, improved animal health, and reduced the need to treat animals with chemical dewormers. We are currently setting up our 2016 study of the effect of preventative winter deworming on the severity of spring rise of Haemonchus on northern new England farms. This project is being approached through a controlled project at U of Maine, and by collection of samples on the farms of participating producers.

We completed a large 2015 survey of parasite species on over 100 farms in Maine, New Hampshire and Vermont. Each farm sent us pooled fecal samples for analysis during early June, late July, and late August of 2015. They also submitted detailed information on their farm management and parasite management strategies. We reported results to all of these producers, and initiated a dialogue about farm-specific management practices that might reduce their parasite burdens. We are currently analyzing the data from this project to identify practices that are associated with consistently low parasitism during the grazing season.

Over 200 producers and 60 practicing veterinarians participated in parasite management seminars during 2015. 80 producers also completed a hands-on wet lab where the principles of parasite identification were taught.

The 2015 work has positively impacted producers in our region by improving their basic knowledge of parasite ecology, and by making them more aware of the actual parasite pressures on their own animals. Many of our producer participants have taken part in seminars, wet labs and the 2015 parasite census, and are much better able to make informed decisions about parasites on their farms.

• Comparison of Haemonchus egg counts of sheep after different spring dates of turn-out to pasture.

Collaborators: