Selecting Sheep for Parasite Resistance
PROJECT BACKGROUND AND WORK ACTIVITIES
• Producers participating in this project include:
• Jeff & Kathy Bielek – Misty Oaks Farm – Ohio
• David Coplen – Birch Cove Farm – Missouri
• Doug & Mary Emrick – Lazydae Farm – Ohio
• Richard Gilbert – Mossy Dell Farm – Ohio
• Naomi & Dean Hawkins – Green Pastures Farm – Ohio
• Sue & Dave Ingram – DSI Katahdins – Missouri
• Leah Miller – Bluebird Hill Farm – Ohio
• Jim Orr – Orr Farm – Ohio
• Bill Pope – Ohio
• Donna & Doug Stoneback – Wade Jean Farm – Pennsylvania
Ten producers from three states (Ohio (7), Missouri (2) and Pennsylvania (1)) chose to work together on this NCR-SARE project. Nine of the producers raise Katahdin Hair Sheep, while one used a Katahdin ram on mixed Dorset ewes. Flock sizes ranged from 11 to 900+ ewes. Seven of the producers have registered Katahdin flocks, while three have commercial flocks. All the farms are forage based, and use rotational grazing and selective deworming strategies. Each farm used at least two rams, some closely related to rams used on other farms.
A total of 456 lambs and 31 rams were used in this project.
The method we tested included the use of FAMACHA (a way of classifying sheep based on their level of parasite-induced anemia), body condition scoring and deworming history on all the lambs, with FEC (Fecal Egg Count) done on a randomly selected subset of 15 lambs per sire. Selecting for resistant individual animals can be done using FEC, while FAMACHA is a good indicator of resilience. Body condition scoring provides a way to identify very thin lambs that are more likely to carry heavy worm burdens and to become severely anemic.
All the lambs were identified by sire and managed the same on common pasture on each farm. Lambs were monitored regularly using FAMACHA and drenched based on the typical management of each farm. No changes were made in the management of individual farms. In addition to sire ID, the following information was collected on each lamb whenever possible: sex, birth date, birth weight, type of birth and rearing, deworming history, dam ID and age of dam.
Fecal egg counts, FAMACHA, body condition and vigor scores, and weights if possible, were collected at least twice on each farm: at 8-10 weeks and 12-14 weeks of age. All lambs in the sire groups that required deworming at any time before or during the test period were recorded.
The data was sent to the Bieleks after each collection date, where it was recorded and maintained in an electronic database. Periodic reports were provided to the collaborators, Dr. William Shulaw and Dr. Charles Parker.
All fecal egg counts were performed by the Parasitology Department of the Virginia-Maryland Regional College of Veterinary Medicine (Virginia Tech). Funds from this grant were used to pay for the fecal egg counts, including supplies for collecting the samples, postage and laboratory costs. In addition, each farm was given a stipend to fund a local FFA, 4-H or other interested student to assist with handling the sheep, FAMACHA scoring, weighing, fecal collections and record keeping. This was done to help stimulate an interest in sustainable agriculture and the sheep industry among young people in our local communities.
Although a preliminary analysis of the results has been completed by Drs. Shulaw and Parker, the final results will not be available until after the group meeting in early February 2007. However, some of the things we learned or had reinforced through this project include:
• Adequate numbers of lambs are necessary
* There is significant variation in FEC between lambs
* Total of 15 lambs per sire is ideal; minimum 10 per sire
• Parasite challenge is critical
* A flock average of at least 500 epg, and preferably 1000 epg, is needed to ensure adequate challenge
* Time of year seems to be the most important factor, with higher counts seen from June-August
• Contemporary groups are important
* Lambs of different ages are difficult to compare, even on the same farm
• FAMACHA is a valuable tool, but it takes practice
* Good lighting is essential
* Young lambs are harder to score
* Color blindness can be a problem
* Gets easier (& more accurate) with practice
• Pasture and parasite conditions can change quickly
* Heaviest parasite pressure: June – August in Ohio
WORK PLAN FOR 2007
The data collection portion of the project has been completed.
A group meeting is planned in early February 2007 with our collaborators, Dr. William Shulaw and Dr. Charles Parker. In addition, Dr. David Notter, Professor of Animal Science at Virginia Tech will join the meeting. Dr. Notter directs the National Sheep Improvement Program Genetic Evaluation Center at Virginia Tech and will provide a genetic analysis of the results of our work. This meeting will allow us to share results and experiences, and analyze the data.
Although we won’t have a final report until after the February 2007 meeting, preliminary results were shared at the Farmers Forum at the National Small Farm Trade Show & Conference in Columbia, Missouri on November 4, 2006. In addition, the preliminary results were shared with the Midwest Katahdin Hair Sheep Association for inclusion in their fall newsletter.
Fecal egg count, FAMACHA and performance data have been shared with Dr. William Shulaw for use in his extension work.
A final report will be shared with the Katahdin Hair Sheep International (KHSI), the Ohio State University Sheep Team and Ohio Ecological Food and Farming Association (OEFFA) for inclusion in their newsletters. The information may also be shared through presentations at the KHSI and OEFFA annual meetings, and through a field day on at least one of the farms to share results and practical experience with other farmers.