2006 SARE Group FarmerRancher Grant Selecting Sheep for

2006 SARE Group Farmer/Rancher Grant Selecting Sheep for Parasite Resistance SARE Project Number: FNC 05 -583 Kathy Bielek Misty Oaks Farm 1130 Kimber Road Wooster, OH 44691 330 -264 -5281 bielek@bright. net

Outline v The Parasite Problem v Background v 2006 SARE Producer Grant v Selecting Sheep for Parasite Resistance v Questions & Answers

Courtesy of William Shulaw, DVM, MS

The Parasite Problem v Parasites affect the health and productivity of sheep Ø Reduced lamb growth Ø Potential death of lambs and ewes Ø Require v Most ewes expensive chemical dewormers susceptible are lambs & lactating v Parasites are developing resistance to dewormers

RESISTANCE SELECTION IN ADULT WORMS TREATMENT Courtesy of William Shulaw, DVM, MS

Why Selection Works v Parasite numbers not evenly distributed among all animals in flock v Roughly 20% of animals harbor 80% of parasites v Treating only those 20% helps avoid developing parasites resistant to dewormers v Identifying and selecting less susceptible replacement animals will help increase flock’s resistance to parasites over time

Fall 2000 103, 546, 200 eggs per day for just 46 sheep Just 10 (21%) of the lambs excreted 77% of the eggs !!

150 epg 600 epg 1850 epg 650 epg 2450 epg 17, 300 epg

Misty Oaks Farm - 2004

Participants v Jeff & Kathy Bielek - Misty Oaks Farm - Ohio v David Coplen - Birch Cove Farm - Missouri v Doug & Mary Emrick - Lazydae Farm - Ohio v Richard Gilbert - Mossy Dell Farm - Ohio v Naomi & Dean Hawkins - Green Pastures Farm - Ohio v Sue & Dave Ingram - DSI Katahdins - Missouri v Leah Miller - Bluebird Hill Farm - Ohio v Jim Orr - Orr Farm - Ohio v Bill Pope - Ohio v Donna & Doug Stoneback - Wade Jean Farm - Pennsylvania Total of 456 lambs and 31 rams in project

Katahdins: The Low Maintenance Meat Sheep v Excellent v No mothers shearing v Medium v 200% v Single size lamb crop purpose: Meat v Natural parasite resistance

Our Collaborators v William Shulaw, DVM, MS Extension Veterinarian, Beef/Sheep Ohio State University v Charles Parker, Ph. D Professor Emeritus, Dept of Animal Science Ohio State University New Cooperator v David Notter, Ph. D Professor of Animal Science Virginia Tech Ø Dr. Notter directs the National Sheep Improvement Program (NSIP) Genetic Evaluation Center at Virginia Tech

Objectives of The Grant v Identify rams with ability to transmit parasite resistance to offspring v Compare effect of different management systems v Investigate method to identify potential replacement seed stock Tools v FAMACHA v Body Condition Scoring (BCS) v Vigor Scoring v Fecal Egg Counts (FEC)

The FAMACHA© System v v Compare eye color chart with color of mucous membranes of sheep Ø 1 – not anemic Ø 5 -- severely anemic Eye color is an indirect measure of the worm burden – applies to Hemonchus contortus only Courtesy of William Shulaw, DVM, MS

FAMACHA – How it Works

Fecal egg counts (FEC) using Mc. Master Technique 1 egg = 50 epg

Method v All lambs identified by sire v All lambs managed together in single group on each farm v FEC, FAMACHA & BCS done twice: at 810 weeks & 12 -14 weeks v No changes made to management of each farm

Detailed Record Keeping v Collected on all 456 lambs: v Collected at least twice (8 -10 and 12 -14 weeks of age; some at 16 -18 weeks) on 15 lambs per sire: Ø Lamb ID Ø Date of birth Ø Sex Ø Date Ø Birth type & rearing Ø Weight Ø Birth weight Ø Body condition score Ø Sire ID Ø FAMACHA Ø Dam ID Ø Vigor score Ø Age of Dam Ø Fecal egg count Ø Deworming history

Results v Identified several rams that APPEAR to show greater ability to transmit parasite resistance to offspring v Management Ø Time of lambing Ø Pasture v All practices had major impact management farms able to identify potential replacement ewe and ram lambs

Adequate Numbers Are Necessary for Valid Comparisons Avg = 1605 epg Avg = 3280 epg Avg Ram A

Management Example: Pasture Management Matters v Farm #1 v Farm #2 Ø All dewormed 7/20/06 Ø All dewormed 7/16/06 Ø Rotated across previously grazed pastures Ø Moved to clean pasture every week

Management Example: Pasture Conditions Can Change Quickly

Management Example: Nutrition

Management Example: Time of Lambing At 2 nd collection (13 weeks of age): v older and heavier lambs had lower FEC. v a 10 day increase in lamb age resulted in 21% decrease in FEC. v a 10 pound increase in lamb weight resulted in 18% decrease in FEC.

Probable Sire Differences ØOffspring of Sire A probably show more parasite resistance than Sire B. ØBut, dams of Sire B offspring mainly ewes lambing as yearlings – confounds results.

Selecting Parasite Resistant Service Sires Based on FEC v Be sure there is a challenge Ø v v Group average FEC of 1000 epg or higher Compare adequate numbers Ø 15 -25 animals Ø Compare at least 2 sires Compare apples to apples: Ø Same age Ø Similar management Ø Similar dam age, litter size, etc. v Calculate average FEC of all lambs from each sire v Choose sire with lowest average progeny FEC

Selecting Parasite Resistant Replacement Animals v Be sure there is a challenge Ø v Compare adequate numbers Ø v Group average FEC of 1000 epg or higher 15 -25 animals Compare apples to apples: Ø Ø Ø Same age Similar management Similar dam age, litter size, etc. v Choose lambs from sire with lowest average progeny FEC if more than 1 sire v Choose animals with lowest FECs in group Ø At least 2 FECs at different dates increases accuracy

Replacement Animal Selection

SARE Project Conclusions: Dr. Notter’s Comments v Selection favoring low FEC will be effective in increasing parasite resistance in Katahdin flocks. Heritability estimate = 0. 52. v Age at measurement likely less important than level of infection at time of data collection. v Selection on FAMACHA scores on older lambs effective, but likely to produce considerably slower changes than direct FEC measurement and selection. v A combination of recording FAMACHA scores to monitor levels of parasite infection and recording FEC as selection tool may be optimal strategy to improve genetic resistance to internal parasites.

Avoid Single Trait Selection: We select for both low FEC and high productivity

Resources v Southern Consortium for Small Ruminant Parasite Control Ø v Maryland Small Ruminant Page Ø v http: //www. sheepandgoat. com ATTRA (Appropriate Technology Transfer for Rural Areas) Ø v http: //www. scsrpc. org http: //attra. org Katahdin Hair Sheep International Ø http: // khsi. org