In 2016, we completed data collection for our on-farm comparisons of parasite loads and management efficacy during the grazing season, with over 120 ME, NH, and VT producers participating. We initiated a new, more intensive monitoring scheme for regional producers, with 10 farms participating in intensive, individual monitoring of post-lambing ewes to detect and treat animals with large post-parturient increases in Haemonchus contortus egg counts during the early Spring of 2016.
One aspect of this project was to identify the effectiveness of dewormers that were in use on the participating farms. We found that nearly all of the chemical dewormers in current use did not effectively reduce parasite loads, and recommended that producers switch to other, more effective drugs. The intensive spring monitoring, plus the use of effective dewormers by these farmers resulted in significantly lower parasite counts and lower use of dewormers throughout the 2016 grazing season on these farms when compared to the 2015 grazing season.
We developed preliminary data that suggested a positive effect of fall deworming for the control of Haemonchus contortus in sheep during the following grazing season. Our Haemonchus contortus cold-tolerance study was completed in 2016, and we found that parasites originating from sheep living in a northern climate were more tolerant of cold conditions than parasites from sheep on farms in the Deep South (Louisiana). These results are consistent with our hypothesis that H. contortus larvae are becoming increasingly competent to survive winter on pastures in northern climates, and indicate that we may need to adapt our winter management strategies in northern New England to accommodate increased overwintering of this parasite.
We presented basic parasitology information and data generated during the first years of this project to several producer groups in 2016. Overall, we reached >200 producers during 4 separate events. We also taught 40 producers to use microscopy to measure fecal egg counts in their sheep.
Haemonchiasis is one of the most economically important diseases of small ruminant farmers in the United States. In the southern U.S., Haemonchus contortus has become a limiting factor in the production of sheep and goats on pasture. Management of Haemonchus on Southern pastures is hindered by the certainty that animals will rapidly become reinfected after treatment, since the infective stage of Haemonchus persists on pastures from one grazing season to the next.
Historically, northern New England winters have been considered too cold for the survival of Haemonchus on pasture, so years-long infestations should be impossible, at least in theory. However, Haemonchus has adapted to northern climates by undergoing a winter hypobiosis, where larval stages hibernate within adults until conditions become suitable for re-infestation of pastures. Consequently, producers in northern New England are now experiencing long-term infestations of Haemonchus. A 2012 survey of 20 Maine sheep and goat farms diagnosed Haemonchus as the dominant parasite, found in fecal samples on over 90% of tested farms. Estimates of economic losses from Haemonchiasis are not available from northern New England, but an Australian study associated Haemonchus infections with 20% higher mortality, 39% lower weight gain, and 16% lower wool growth. When this production loss, conservatively estimated at 20%, is extrapolated to the 1800 northern New England farms and their 32000 sheep and 17000 goats with a total value of $15 million, (2010 NASS survey) parasitism-related losses in this region could exceed $2 million per year.
New England farmers have been very active in Cooperative Extension and Experiment Station initiatives related to sheep and goat diseases, and their input demonstrates their growing concern about the impact of internal parasitism. Data from a 2008 Integrated Pest Management Survey of Maine sheep and goat producers listed internal parasitism (30%) as the most important disease problem on their farms. In a 2012 UMaine survey, participants were asked to describe how parasitism affected their operation (representative answers follow): “HUGE! hardest part of organic management. Ewe replacement lambs have the worst time during first year.” “Parasites do decrease growth rates which is challenging and causes worry for does who lose condition quickly up to weaning.”
Clearly, our producers are experiencing a significant Haemonchus problem that is impacting their ability to raise sheep or goats profitably on pasture.
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 (completed).
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 (in progress); 2. Hasten Spring rise through earlier lambing or increased photoperiod (planned for 2017); 3. graze weaned lambs separate from dams on 'clean' pastures (planned for 2017, if possible); 4. Use appropriate pasture stocking rates and practice rotational grazing (completed); 5. reduce egg shedding on early spring pastures through the use of a 'mud season' paddock (completed).
These management changes will positively affect the productivity of 2000 sheep and goats on 1000 acres of pasture, resulting in additional profits of $200 per year in the northern New England region.
Winter treatment of small ruminants with effective anthelmintics or increased winter
photoperiod will eliminate 100% of arrested abomasal larvae before the start of the following grazing season.
Two groups of ten Icelandic ewes (one control and one treated) at the University of Maine farm were dosed with 2000 L3 larvae of Haemonchus contortus during early June 2017. Control ewes were maintained on pasture, and were given about 0.5 pounds per day of grain-based concentrate 0.25 pounds each at 8 AM and 5 PM. Treated ewes were also grazed and given grain, but the grain was supplemented with melatonin at the rate of 10 mg per day per ewe. Melatonin treatment was continued until mid-July of 2017. Parasite egg counts and FAMACHA scores were measured weekly on all ewes, and blood samples (taken at ten AM) were collected bi-weekly for measurement of serum melatonin.
A method for ELISA determination of serum melatonin in sheep serum was validated in our lab, and the levels in our treated animals were at the high end of the normal range reported for melatonin in the literature. We measured significantly higher melatonin levels in the melatonin-treated ewes than in the control ewes. However, the L3 dosing did not result in a increase in the fecal egg count of Haemonchus contortus in either group of sheep. This result was unexpected, and may have been due to improper handling of the larvae during their culture period.
We plan to re-do this experiment in 2018 with one change to the Methods. Instead of dosing ewes with a measured amount of in vitro-produced larvae, we plan to allow the ewes to graze on a paddock that had been previously contaminated with Haemonchus eggs.
No conclusions yet, as the project has not been completed
A major emphasis of this project was the education of producers to measure and effectively manage parasite populations on their own farms. We achieved this objective through several methods. First, we conducted multiple producer education seminars throughout Northern New England to teach the basic principles of parasite management. We also taught specific skills to producers, including the use of a microscope to identify and enumerate parasite species in manure samples from their farm, and the use of the FAMACHA technique to identify animals with anemia that might be caused by a Haemonchus contortus infestation.
In addition to the formal training coursework, we worked with over 250 producers to identify and solve parasite-related problems on their farms. We set up parasite diagnostics prior to each grazing season, where producers would send us multiple manure samples, and we would identify potential health problems related to parasites found in the samples. Many of the parasite-related problems detected on these farms during the screenings were discussed with the producers on the phone or through email communications. For example, we found that the dewormers used by many of our producers were no longer effective in reducing their parasite populations due to the development of genetic resistance. Once these deficiencies were identified, we would recommend another class of dewormer and work with the producer to test its efficacy on their animals. Most of the potential problems in producer flocks were “solved” prior to the high risk period for Haemonchus (i.e, the mid-summer grazing season).
Producers learn how to measure the extent of parasitism in their individual sheep / goats through FAMACHA scoring or microscopic evaluation of fecal egg counts.
In late 2015 we completed monitoring of pooled fecal egg counts from pooled samples during three critical periods during the early-, mid-, and late-season grazing. Over 120 farms submitted data for an entire grazing season and also completed a survey of their farm metrics and management practices.
We provided hundreds of veterinary consults to producers based on farm-specific data. Many of these farms decreased their Haemonchus counts between the first and second year of monitoring. We changed our field study emphasis in 2016 to more intensive monitoring and treatment of a small subset of farms that were willing to collect individual manure samples from each of their animals at multiple times during early spring, a period that is critical for parasite success in northern New England.
Ten farms from Maine, New Hampshire and Vermont participated in this study. Our plan was to identify, at the time of spring lambing, ewes that had carried heavy burdens of Haemonchus larvae through the winter and were at risk of anemia as these larvae matured into feeding adults. Furthermore, we wanted to identify heavy shedders of Haemonchus ova during the spring, since these ova were likely to develop into infective larvae during early June and increase exposure of ewes and lambs to Haemonchus during the upcoming grazing season.Highly parasitized ewes were identified and communicated to producers, and then were treated with a chemical anthelmintic. Manure samples were again assayed for parasites at 10 to 14 days post-treatment to assess the efficacy of treatments.
We found that many of the participating farms, plus about ten farms that were evaluated for dewormer effectiveness using the Fecal Egg Count Reduction Test (FECRT), did not achieve effective reductions in parasite burdens after the initial anthelmintic treatment. For farms with anthelmintic failure, we reviewed their history of dewormer use and made recommendations on alternative chemical dewormers that might be more effective on their farms. We then followed up with an additional FECRT to ensure that animals were carrying low burdens of parasites, including Haemonchus contortus, onto fields at the beginning of the 2016 grazing season.
A preliminary comparison of fecal egg count data from 2015 (pre-intensive monitoring) to to 2016 (post-monitoring and consultation) showed decreased parasite counts in 2016. In 2016 we completed development work on a quantitative in vitro assay to measure the cold tolerance of the L3 stage of Haemonchus contortus that persists on pastures and infects grazing sheep. We then conducted testing of prolonged (3 to 6 days of exposure) of L3 larvae obtained from farms in Maine, Virginia, Arkansas and Louisiana. We found that the Maine-sourced L3’s were tolerant of cold exposure down to at least 10 degrees C. Parasites from Arkansas and Virginia were not significantly different from the Maine L3’s in cold tolerance, but the Louisiana-based L3’s were killed by significantly warmer temperatures ranging between 20 and 25 degrees C. While these are preliminary results, they indicate that there may be an evolutionary adaptation of the infective L3 stage of Haemonchus to cold that would increase its overwinter survival on pastures in northern climates.
During the winter of 2015 / 2016, we performed a preliminary study, using our university flock, that compared the effectiveness of preventative anthelmintic treatment at different times during the non-grazing season. We found that fall deworming of adult ewes almost completely eliminated their subsequent spring rise. The fall 2015-treated animals were then placed on an aggressive rotational grazing system during 2016, and required no dewormer treatments. In contrast, all of the animals that did not receive a fall deworming experienced spring rise-associated parasitism and anemia that required one or more dewormer treatments, and that likely resulted in significant contamination of their paddocks / fields with Haemonchus ova during the spring of 2016. We are currently repeating this study using larger numbers of animals, and will continue to collect data through the grazing season of 2017.
During 2016, we presented basic parasitology information and data generated during the first years of this project to several producer groups in 2016. Overall, we reached >200 producers during four separate events. We also taught 40 producers to use microscopy to measure fecal egg counts in their sheep. All of these presentations and workshops occurred in northern New England.
Several potentially valuable outcomes have resulted from our 2016 work. First, we implemented a pre-grazing season monitoring and treatment strategy on ten northern New England farms that seemed to reduce Haemonchus contortus parasitism in sheep during the subsequent grazing season. We feel that an intensive period of parasite monitoring and targeted treatment during the immediate post-lambing period may be an effective tool for decreasing parasite burdens in sheep during the subsequent grazing season. Our detection of parasite resistance to ivermectin-type dewormers in multiple northern New England farms built on evidence from multiple published reports that Haemonchus contortus in U.S. sheep is becoming resistant to multiple chemical classes of dewormers. Preliminary results from 2015 / 2016 indicated that fall-based identification and treatment of a sub-population of ewes that are overwintering large burdens of Haemonchus larvae may result in reduced ewe anemia at the time of lambing, when ewes are already at high levels of nutritional stress. Reduction of egg-laying adults in the spring would also decrease spring contamination of pastures. Use of selective fall deworming, combined with delayed entry of sheep onto northern pastures until after “mud season” (2015 results) and effective rotational grazing, appear to reduce the impact of Haemonchus contortus on grazing sheep to levels that do not require interventional dewormer treatment of anemic animals during the relatively short grazing seasons in northern climates.
A cornerstone of effective parasite or pathogen management should be to reduce exposure of target animals to the infectious agent rather than treating them after they become ill. The U.S. sheep industry in northern tier states would certainly benefit from a reduction in the “salvage” treatment of heavily parasitized, anemic sheep and lambs that might result from implementation of our findings. Preliminary information from our in vitro cold tolerance study indicates that Haemonchus contortus may be evolving an increased tolerance of winter cold. if confirmed, this may translate into higher winter survival of infective larval stages on northern New England pastures. Higher overwinter survival on pasture may eventually reduce the effectiveness of winter treatments / management changes that target hypobiotic stages that overwinter in the sheep gut.
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.
Producer seminars (basic parasitology 101) are held in ME, VT and NH. 60 to 70 producers attend each event. Materials form these seminars are recorded and made available on-line through podcasts and webinars.
Parasite species are identified on 100 farms throughout NNE. Producers receive farm-specific information, then are taught effective management techniques based on the parasite species present in their animals. These participants are recruited for further studies.
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.
Regional producers learn about the Haemonchus eradication and winter kill projects. 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.
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 EExtension.
Project data are presented at national and regional conferences. 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 to receive producer feedback.
Milestone Activities and Participation Summary
We identified several areas where producers demonstrated an increased proficiency in the management of parasites on their farms. Many of them learned to diagnose their own parasite infestations through the use of microscopy and parasite egg identification and enumeration, and through the identification of anemia individual animals through FAMACHA scoring. We found that many of our most committed producers were able to intervene and reduce parasite damage before experiencing death or production losses. Currently, we are relying on email communications to identify changes in producer knowledge. During the last year of the grant (2018), we plan to survey producers who participated in our diagnostic outreach projects to quantitate changes in knowledge and proficiency.
Performance Target Outcomes
These farmers will use more non-chemical means to effectively control their Haemonchus infestations during the grazing season, including rotational grazing, Spring-time determination of the severity of spring rise Spring-time determination of their current dewormer's efficacy, and use of dewormers based on individual fecal egg counts.
One hundred farms x an average farm size in Northern New England of about 20 sheep or goats = 2000 adult ewes plus about 3000 lambs per year.
These changes will result in an increase in the number of lambs that survive to either market or reproductive age.
These farmers used non-chemical means to effectively control their Haemonchus infestations during the grazing season, including rotational grazing, Spring-time determination of the severity of spring rise Spring-time determination of their current dewormer's efficacy, and use of dewormers based on individual fecal egg counts.
We estimate that over 4000 lambs on farms in Maine, New Hampshire and Vermont had reduced exposure to Haemonchus contortus parasitism during their first grazing season. This reduced exposure resulted in lower rates of lamb death, and probably increased weight gain for lambs destined for the meat market.
It is reasonable to expect that our farmers experienced a 10% increase in average weight gain and a change in parasitism-related death loss from 20% to 10%,. Based on the values, the measurable benefit would have been an extra 336 lambs that did not die during their first year.