Got Worms? Breeding for Parasite Resistance to Ensure the Sustainability and Resilience of Small Ruminant Operations

Project Overview

Project Type: Research and Education
Funds awarded in 2023: $318,874.00
Projected End Date: 11/30/2026
Grant Recipient: University of Rhode Island
Region: Northeast
State: Rhode Island
Project Leader:
Katherine Petersson
University of Rhode Island


  • Animals: sheep


  • Animal Production: animal protection and health, feed additives, genetics, parasite control, preventive practices
  • Education and Training: demonstration, extension, mentoring, technical assistance, workshop

    Proposal abstract:

    Problem or Opportunity and Justification: Gastrointestinal nematodes (GIN) are associated with increased mortality and reduced performance in pasture based small ruminant (SR) operations.  Although young animals are susceptible to GIN infections, breeding females are particularly susceptible during the transition period due to the sudden emergence of GIN that have overwintered in an arrested state within the ewe. Although SR producers have readily adopted several important IPM tools, there has been limited adoption of the use of estimated breeding values (EBVs) for parasite resistance through the National Sheep Improvement Program (NSIP) to identify animals that are genetically less susceptible to GIN infection.  With the significant increase of new SR producers, continued education and adoption of IPM practices with an emphasis placed on utilizing genetics to select for resistant stock is warranted to ensure the profitability, sustainability and resilience of SR operations in the northeast. This project will increase the number of SR producers utilizing EBVs for parasite resistance to improve on-farm productivity and to enhance breeding decisions. 

    Solution and Approach: We have a three pronged approach towards assisting SR producers with GIN control: 1) Online and in-person IPM/FAMACHA© anemia certification program; 2) Virtual and in-person workshops to promote of the use of EBVs for parasite resistance and; 3) Research into alternative strategies for control of parasites in ewes during the periparturient period (PPP) and their offspring to provide additional effective tools for GIN parasite control. There will be increased effort to reach more producers, particularly from underserved communities, more effectively and equitably and provide them with resources they need to be successful.  To this end we will utilize the following strategies to increase our engagement with SR producers in the Northeast and to remove barriers to adoption of the use of EBVs for genetic selection of parasite resistance. 

    • Coordination with Northeast extension agents and SR veterinarians who visit SR producer farms to identify new communication channels and program delivery options particularly for SR producers with technological limitations.
    • Hold in-person workshops in English and Spanish as needed to support the Spanish speaking community. 
    • Develop a regional mentoring hub with NSIP producer/mentors to facilitate all aspects of collecting, entering and interpreting data with NSIP.
    • Provide financial support, as needed, to support participation of underserved communities in this project. 
    • Launch a genetic selection breeding demonstration project that will be used to showcase the financial benefit that can be achieved from the use of EBVs for economically important traits.
    • We will evaluate the effect of feeding a β-glucan supplement derived from mushrooms to ewes and their offspring during the periparturient period when GIN are a greater challenge.  This product, if proven effective, would be suitable for use by conventional as well as organic SR producers.

    Performance targets from proposal:

    Fifty small ruminant producers will utilize estimated breeding values (EBVs) for parasite resistance across 4,200 ewes and 6,300 lambs. Because of this practice, they will realize a financial gain of $432,088 over 3 years.

    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.