Progress report for LNE22-443
Project Information
Problem and Justification
Gastrointestinal parasites affect virtually all grazing livestock. Traditionally, parasite management involved the single approach of administering dewormer to all animals on the farm multiple times per year. However, this practice has inadvertently resulted in the development of dewormer resistance, which represents a risk to livestock farmers in regards to animal welfare, environmental sustainability, and economic return. The economic loss associated with dewormer resistance is two-fold because it represents a direct cost to the farmer and limits the number of fully effective dewormers available in critical animal health situations. Dewormer resistance has been well-recognized in small ruminants, and the concern for the development of resistance in parasites relevant to other livestock, including cattle and horses, is growing. Therefore, it is necessary for livestock farmers to adopt new ways of controlling parasites in their animals.
Solution and Approach:
To mitigate the development of dewormer resistance and improve the economic return of dewormer administration, farmers must become more selective in their use of dewormers and utilize other management strategies, such as good pasture and animal management, to control the parasite load in their animals. To that end, this program aims to highlight the components of a successful parasite management program and help farmers understand how these strategies can be applicable in their specific situation. We will utilize a combination of one-on-one consultations and field day instruction events in order to help livestock farmers in Maryland learn how to: 1) employ good pasture management practices to control parasite load; 2) monitor parasite load to determine if and when dewormer application is necessary; 3) adopt one of several selective-deworming strategies; 4) utilize appropriate techniques for selecting and administering a dewormer; and 5) evaluate the performance of a dewormer on their farm. One-on-one consultations will focus on building individualized parasite management programs for participants and teaching them to apply these strategies in their own unique situations. On-farm field days will also focus on teaching these strategies and provide an opportunity for participants to ask questions and learn about the experiences of each field-day host farm in the context of parasite management. Post-participation surveys will be conducted to document knowledge gain and behavior changes that occur as a result of this program. Two research studies will be carried out in order to document the effects of 1) improved pasture management on apparent parasite load of pregnant dairy heifers; and 2) forage type (annual vs. perennial) on parasite load of beef cattle and sheep. These studies will provide data to further support the benefits of using pasture management to help control parasites in livestock.
We estimate that 30% of program participants (54 farms) will make at least 1 alteration to their parasite management program, which will affect approximately 1,080 animals and 2,500 acres. Utilizing these practices will reduce the amount of dewormer purchased and applied by each of these farms by 30%, resulting in an annual savings of $3/head/year.
Description of the Problem
Most livestock producers are aware that gastrointestinal parasites can reduce performance, and accordingly, take measures to protect their animals. Gastrointestinal parasites are typically controlled through application of dewormers. Although livestock producers have the best intentions when treating their animals for parasites, routine and frequent treatment is contributing to reduced dewormer efficacy, or resistance. With current practices of routine, non-selective administration of dewormer multiple times per year, it is possible that livestock producers are 1) administering dewormer to animals that do not actually need to be dewormed; or 2) administering a product with reduced efficacy. Both situations perpetuate the development of dewormer resistance and contribute to economic loss. The economic loss associated with dewormer resistance is two-fold because it represents a direct cost to the farmer and limits the number of fully effective dewormers available in critical animal health situations.
Dewormer efficacy is determined by assessing parasite load before and after dewormer administration. A parasite load reduction of ≥95% indicates an effective treatment. Dewormer resistance has been well-documented in small ruminant production systems. While documentation of dewormer resistance is less prevalent in other species, there are reports of resistance in beef cattle (Gasbarre et al., 2015) and horses (Nielsen et al., 2018) across the United States and other countries. A recent study led by USDA APHIS researchers (Gasbarre et al., 2015) indicated that 30% of beef farms located in 19 states across the Central, Southeastern, and Western regions of the U.S. had reduced dewormer efficacy (<90% reduction). In addition, our team recently examined the efficacy of dewormers on Maryland beef farms and observed reduced efficacy on 70% of farms. Thus, it is clear that dewormer resistance is present for beef herds at both national and local levels for beef cattle.
Extrapolating these findings and using data from USDA NASS, we postulate that dewormer resistance affects over 213,000 and 815 beef cattle herds across the U.S. and Maryland, respectively. Data for small ruminants (Kaplan and Vidyashankar, 2012)would indicate that virtually all sheep and goat operations in the US (237,829 farms)and Maryland (1,053 farms) are impacted by dewormer resistance. A conservative estimate of 25% would suggest that 10,000 dairy and 115,000 equine farms are affected nationally, with 84 dairy and 130 equine farms affected in Maryland. Because dewormer resistance is an issue at the parasite-level, farms of all sizes are expected to be impacted.
Solution and Benefits
In order to mitigate the development of dewormer resistance in livestock production systems, farmers should take measures to evaluate and adjust their parasite control program. Adoption of new management strategies will reduce the reliance on dewormers to help preserve dewormer efficacy, reduce costs associated with the development of dewormer resistance, and improve environmental stewardship of livestock operations. Data from small ruminants have indicated that several approaches can both reduce reliance on dewormers and slow the development of dewormer resistance simultaneously (Kaplan, 2020). Such approaches include developing an understanding of current dewormer efficacy on a farm, adopting a selective treatment approach, administering dewormer properly, and utilizing non-drug strategies (Kaplan, 2020). Evaluation and monitoring the current parasite management program is a critical first step to making adjustments to the program. This will be one focal point for the project and participants will be coached individually on how to perform this task. Adoption of selective treatment strategies is another critical aspect of the parasite management program that encourages judicious dewormer use. Program participants will be made aware of the various selection strategies available and the project team will help tailor a strategy as appropriate for each individual. Failure to comply with appropriate dewormer application protocol, especially under-dosing, significantly contributes to the development of dewormer resistance (Kaplan,2020). To that end, explanations for and demonstration of proper dewormer administration will be provided to program participants in order to show how under-dosing can be avoided. Perhaps an over-looked, but nonetheless crucial non-drug component of the parasite management program is pasture management (Burke and Miller, 2020). The project team will assist participants in developing or modifying their pasture management to mitigate parasite exposure. The research component of this project will generate data to highlight two different pasture management strategies and their effects on apparent animal parasite load. Results from these studies will demonstrate for farmers the extent to which these strategies impact parasite load and add to the overall body of literature that pertains to the effect that pasture management has on parasite load. Adoption of these aforementioned parasite management practices will improve the effectiveness of dewormers over time, as indicated through the fecal egg count reduction test, and reduce the amount of dewormer that is unnecessarily applied. At the farm-level, this translates to reduced costs associated with the purchase and application of dewormers.
Objective
This project will teach livestock and equine producers in Maryland how to implement best practices for intestinal parasite management and reduce reliance on dewormers through a combination of direct (on-farm consultations, field days, demonstrations) and indirect (articles, webinars) methods.
Cooperators
- (Educator and Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
- (Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
Research
The goal of this research is to provide data that highlight the impact of different pasture management approaches on apparent parasite load of livestock. We hypothesize that implementing improved pasture management with rotational grazing and improved forage varieties will reduce the apparent parasite load of pregnant dairy heifers relative to heifers managed under a continuous grazing system. We also hypothesize that adopting annual forages will reduce the apparent parasite load for beef cattle and sheep in a mixed species grazing system relative to those managed on perennial pasture only.
Research will take place at two separate sites utilizing either pregnant dairy heifers at the University of Maryland Dairy Farm in Clarksville, MD (Site 1) or a mixed beef cattle/sheep herd at the Western Maryland Research and Education Center in Keedysville, MD (Site 2).
Treatments
At Site 1, pregnant dairy heifers (n=40) will be evenly allocated to one of two treatments: control (continuous pasture) or rotational grazing. The treatments for this study were selected to assess the extent to which implementing improved pasture management practices affect parasite load on dairy heifers. The control treatment is designed to reflect the traditional housing and feeding methods of dairy producers in this region and across the nation. The rotational grazing treatment is designed to utilize good grazing management practices that could reasonably be implemented on many dairy herds.
At Site 2, growing beef cattle (n=20) and lambs (n=20) will be managed in two mixed-species groups each consisting of 10 cattle and 10 lambs. Each group will be allocated to one of two treatments: annual pasture (~10 acres) or perennial pasture (~10 acres). Treatments were selected to determine if the current trend of annual forage adoption has implications for parasite load on livestock. It is well-established that certain types of perennial forages, mainly those containing condensed tannins, such as Sericea lespedeza, can help control gastrointestinal parasites. However, it is unknown whether annual forages in general would affect parasite load. Due to the need to reestablish annual stands each year, it could be hypothesized that these forages could limit parasite proliferation and thereby reduce livestock exposure to parasites. These treatments, therefore, are designed to further our understanding of whether annual forages could be used as another tool to manage parasites in grazing livestock systems.
Methods
At Site 1, heifers on the control treatment (n=20) will have unrestricted access to a single pasture consisting of mostly tall fescue forage (~10 acres). In addition to pasture, these heifers will be fed a total mixed ration once daily to meet the majority of nutritional requirements. Heifers on the rotational grazing treatment (n=20) will be managed on a pasture consisting of tall fescue (~10 acres) and annual forage (~8 acres). This pasture will be subdivided into smaller paddocks of approximately 1 acre each to facilitate rotational grazing. The rotational grazing group will be rotationally grazed throughout the study, with rotations occurring approximately every 1 to 3 days depending on forage availability. These heifers will also receive 1 pound of concentrate mix per day consisting of ground corn and mineral mix to ensure adequate mineral consumption. The grazing period will last approximately 40 weeks (April – December) and will take place during year 1 and replicated in year 2.
At Site 2, pastures for both treatment groups will be subdivided into smaller paddocks of approximately 0.5-1 acres each to facilitate rotational grazing. Animals will be rotationally grazed throughout the study, with rotations occurring every 2-3 days depending on forage availability. Animals will have access to free-choice minerals throughout the study. The grazing period will take place for 40 weeks (April – December) and will take place during year 2 and replicated in year 3.
Data Collection and Analysis
Animals at both sites will be weighed every other week throughout the respective grazing seasons in order to monitor performance. During each occasion, samples of manure will be collected from each individual animal for fecal egg count analysis. Samples of manure (~100 grams each) will be collected directly from the rectum of each animal by trained personnel and stored in the refrigerator until overnight shipment to Virginia State University. Personnel at Virginia State University will determine the number of eggs within each sample using the three-chambered McMaster technique (George et al., 2017). Fecal egg count will be statistically analyzed to assess the effect of treatment and species (Site 2 only).
Farmer Input
One member of the advisory committee expressed substantial interest in exploring the effect of forage type or species on parasite load in livestock. Although we are not able to investigate the effect of that specific species on fecal egg counts due to constraints related to pasture establishment, this does indicate that there is interest in exploring the possibility of incorporating different forages as part of the parasite management program. Through interactions with beef farmers during our team’s assessment of dewormer resistance in 2020 (Potts et al., 2021), farmers often inquired about the effect of different pasture management practices on parasite load. These studies would provide data to help justify recommendations for changes in pasture management in the context of parasite control.
Additional Information:
Due to the coordination of body weight measurement and fecal egg count analysis for the animals involved with this research, this study also provides opportunity to conduct a break-point analysis for parasite load in relation to body weight gain. Although this is not the main objective of the study, these data may allow us to determine the parasite load at which animal performance begins to suffer. This information would be useful in helping to establish a threshold at which animals would benefit from deworming.
Year 1 research at site 1 commenced on April 1, 2022. Dairy heifers (n=51) were enrolled in the study after confirmation of pregnancy and assigned to one of two treatments: control or rotational grazing. Control heifers (n=25) were housed as one group on a single, 6-acre pasture consisting of mostly tall fescue and white clover. These heifers had continuous access to the entire 6-acre pasture for the duration of the season. A total mixed ration consisting of mostly corn silage, small grain silage, and hay was delivered to these heifers in the field once daily to meet nutritional requirements. Rotational grazing heifers (n=26) were housed as a single group on 20 acres of pasture, divided into 0.5-0.75 acre paddocks. Heifers were moved from one paddock to another approximately every 1-3 days and were fed a grain/mineral supplement once daily at a rate of 1 lb/head/day. Approximately 8 acres of this pasture was comprised of annual forages (triticale/ryegrass/oats/crimson clover as a winter annual grazed in spring/fall, sudangrass/cowpeas as a summer annual grazed in summer) and the remainder of the pasture consisted of perennial pasture that was mostly tall fescue. Heifers remained on their respective treatments until approximately 3 weeks before they were due to calve. Because heifers were enrolled and removed from the study according to their stage of pregnancy, the number of animals in each treatment was dynamic throughout the season. However, stocking rates were maintained equally between the control and grazing group so that at any given time, there was a similar number of heifers on each treatment. Heifers were weighed and measured (hip height, BCS) and manure samples were collected for fecal egg count analysis every 2 weeks throughout the study. The final weigh day and last day of grazing for 2022 was December 19, 2022. Preliminary data indicates that the parasite load for both groups of heifers was relatively low, but that heifers on the rotational grazing treatment had a numerically lower parasite load than heifers on the control treatment (9 vs. 16.5 eggs per gram). Final statistical analysis will be completed after Year 2 data are collected, but these preliminary data suggest that implementing rotational grazing can help reduce parasite pressure in dairy heifers.
Year 2 research at site 1 commenced on March 29, 2023. In 2023, a total of 59 heifers were used for the study (n=29 control; n=30 grazing). Methodology remained the same as the previous year (described above). Year 2 research at site 1 was completed on December 21, 2023. This wrapped up the data collection at this site. Moving forward, the project team will be working on compiling all of the data across the study years and completing the statistical analysis on this data.
Year 1 research at site 2 began on May 2, 2023. A total of 19 calves and 30 lambs were brought to the research farm from a local cooperator farm and were rotationally grazed as two mixed-species herds. The perennial-only group (n=15 lambs; n=9 calves) was rotationally grazed on approximately 12 acres of perennial, cool-season grass pasture comprised of mostly orchardgrass, tall fescue, clover, and alfalfa. The perennial/annual group (n=15 lambs; n=10 calves) was rotationally grazed on approximately 13 acres of pasture, part of which was perennial cool-season grass pasture (same forage species as perennial group) and part of which was planted into annual forages for grazing. The portion of the pasture containing annual forages was rotated between winter annuals and summer annuals; while not a main goal of this project, a number of different annual forage mixtures were included to be able to evaluate which annual mixtures performed better and/or were more preferred by the grazing animals. Both groups of animals were weighed and assessed (BCS, FAMACHA score for the lambs) and manure samples were collected for fecal egg count analysis every 2 weeks throughout the study. The original plan was to graze both groups of animals into December; unfortunately, in 2023 there was a fairly severe drought in the area for a good portion of the summer. Due to limited forage growth and a lack of forage for grazing, the final weigh day and last day of grazing for 2023 was September 26, 2023. Preliminary data analysis for 2023 showed greater average daily gains and body condition scores for the lambs on the perennial/annual system and a greater final bodyweight for calves on the perennial/annual system. These indicate a slight growth advantage for both cattle and sheep grazed on this type of system. FAMACHA scores were the same for lambs grazing in both systems in 2023; this was not totally unsurprising, given that these pastures did not have animals on them in 2022 and there was likely low worm burden on the pastures. Additional analysis, including data from fecal egg count results, is currently underway.
Year 2 research at site 2 began on April 1, 2024. In 2024, a total of 19 calves and 35 lambs were again sourced from a local cooperating farm and were brought to the research farm to be rotationally grazed as two mixed-species herds. Methodology remained the same as the previous year (described above), and although it was another dry year we were able to continue grazing through November 12, 2024. The end of 2024 wrapped up the data collection at this site. Over the last month or two, the project team has been compiling all of the data from the two years at this site and moving forward will be working on completing the statistical analysis on this data.
Education
Biannual meetings with the project team will be utilized to keep the advisory committee informed of program progress. Due to the diverse geographic location of committee and project team members, meetings will take place virtually. All members of the advisory committee have received a copy of the project proposal and have provided some feedback on the proposal and program approach. Committee members will be briefed on the outcomes of each milestone and will help recruit participants. Feedback from the committee will be welcomed by the project team and any suggestions they make will be strongly considered in the context of program content and execution. The committee will be given access to the program resource materials provided to participants before they are distributed in order for them to provide feedback or suggestions for additional materials. The following individuals have agreed to serve as members of the advisory committee:
Service Providers:
- Andrew Mast, DVM - Veterinarian with Casselman Veterinary Services in Granstville, MD. Dr. Mast has expertise related to dairy cattle, beef cattle, and livestock health management.
Farmers:
- Hans Kefauver – Owns and operates a cow-calf and lambing operation in Clear Spring, MD. Mr. Kefauver has expertise related to cattle and small ruminant management. He also has expertise related to pasture management.
- Shannon Dill - Horse owner located in Queenstown, MD. Ms. Dill has experience related to the equine industry and management.
Milestones
Biannual meetings with the project team will be utilized to keep the advisory committee informed of program progress. Due to the diverse geographic location of committee and project team members, meetings will take place virtually. All members of the advisory committee have received a copy of the project proposal and have provided some feedback on the proposal and program approach. Committee members will be briefed on the outcomes of each milestone and will help recruit participants. Feedback from the committee will be welcomed by the project team and any suggestions they make will be strongly considered in the context of program content and execution. The committee will be given access to the program resource materials provided to participants before they are distributed in order for them to provide feedback or suggestions for additional materials. The following individuals have agreed to serve as members of the advisory committee:
Service Providers:
- Andrew Mast, DVM - Veterinarian with Casselman Veterinary Services in Granstville, MD. Dr. Mast has expertise related to dairy cattle, beef cattle, and livestock health management.
Farmers:
- Hans Kefauver – Owns and operates a cow-calf and lambing operation in Clear Spring, MD. Mr. Kefauver has expertise related to cattle and small ruminant management. He also has expertise related to pasture management.
- Shannon Dill - Horse owner located in Queenstown, MD. Ms. Dill has experience related to the equine industry and management.
Milestone Activities and Participation Summary
Educational activities:
Participation Summary:
Performance Target Outcomes
Target #1
54
1 change to their parasite management program
1080 animals, 2500 acres
Cost savings of $3/head/year
A large part of this project involves consulting with farmers individually regarding parasite management. Part of these consultations involves collecting and analyzing manure samples for signs of parasites before and after dewormer application. After the consultation visits (2 per farm), we provide each farm with a 3-5 page individualized parasite management report with suggestions for making improvements as well as additional resource literature.
To date, 8 individual farms have participated in the program. These farms consist of beef cattle (n=3), sheep (n=1), dairy cattle (n=1), goats (n=1), and a mixture of sheep and cattle (n=2). Together, these farms collectively manage ~665 animals (365 cattle, 260 sheep, 40 goats). A total of 18 farms completed an interest form in 2022; the farms that we were not able to reach previously will be contacted to see if they are still interested in 2025. One of the benefits of this program targeting multiple livestock species has been our ability to make parasite management recommendations for farms who have more than one species on site. For example, 2 of the 8 farm participants housed both cattle and sheep, and we were able to evaluate parasite programs for both species simultaneously. Furthermore, four of the farms we worked with had large enough herd/flock sizes to enable us to test the efficacy of multiple dewormers, which allows for a more informative parasite management report and recommendations. Individual reports were finalized and sent to these producers in early 2023. The follow-up surveys to year 1 participants will be sent out in early 2025 to document learning outcomes and long-term impacts or changes that have been made. These surveys have been approved by the University of Maryland IRB and are ready to be distributed to our participants.
Additional farms have been recruited to participate in the one-on-one consultation part of this project for 2025. The project team has been in touch with these producers and is working on getting dates lined up for 2025. The team will also continue to advertise and reach out to potential farm participants who may be interested.
In addition to the one-0n-one consultations, we held several on-farm field days and one field day at the research site during 2024. The project team will be following up with participants who attended these events to inquire about and document knowledge gains from those participants. We will also be having some additional field days in 2025 and will be documenting knowledge gains from participants following those programs as well.
Additional Project Outcomes
As a result of the outreach and educational activities from this project, the team has acquired several new working collaborations that will be beneficial in helping with outreach and project advancement moving forward. We look forward to working with these new collaborators.