By Tim King
Shepherds and University Extension personnel at Virginia Tech are working together to increase parasite resistance and growth in sheep raised in predominantly forage based production systems. To that end, a forage based ram test, conducted at Virginia Tech’s Southwest Agricultural Research and Extension Center near Glade Springs, has been conducted annually since 2012.
The test aims to provide a standardized post-weaning performance evaluation for parasite resistance and growth that will provide records useful to the breeding programs for shepherds that consign rams to the test. Following the test there’s an auction of rams that have successfully completed the 70-day trial. There’s also an educational component: A field day that accompanies the sale each year.
“The usual program consists of general production content like parasite management, nutrition, forages and hay production, feeding strategies, and management techniques,” Lee Wright says. Wright is the Superintendent at Glade Springs. “We’ll then typically insert any research topics of interest we may be working on. This year, one of our graduate students presented two years of data from the terminal sire project taking place here at the Center.”
This year’s educational component also included a presentation by local veterinarian Chris Fletcher. Fletcher is the co-owner, with his wife Mandy, of a Katahdin flock of around 90 ewes. They farm near Abingdon, Virginia.
“He’s been utilizing rams purchased from the test to upgrade from a commercial to a registered flock and has also begun entering his data into NSIP,” Wright noted. “His presentation allowed for a unique perspective on how someone fairly new to sheep production has utilized rams from our test to make genetic improvements in their flock.”
The Fletchers have been pleased with the tested rams that they have purchased at the Virginia Tech post-test sale. This year they purchased one of the auction’s top lambs from Hound River Farm in Hahira Georgia.
“We have used the rams to improve our flock by adding growth to our lambs and really trying to live by what we preach as far as de-worming,” Chris Fletcher said. “We have started only de-worming if we have to. We use FAMACHA scoring to decide if and when to de-worm. In my presentation, I worked out the numbers comparing de-worming lambs and purchasing resistance genetics. You would be saving around $3,000.00 on a one-hundred ewe flock by not having to de-worm and through decreased death loss. I can buy nice genetics for $3,000.00.”
Jay Greenstone, of Silver Maple Farm near Rose Hill Virginia, also raises Katahdins. He’s developing a flock of ewes that are parasite resistant and that lamb three times in two years. He consigned ram lambs to the test in 2016 as well as in prior years. Two of his 2016 lambs completed the test and were sold at the sale. He’s pleased with the prices he received at the auction.
“One of our rams at the sale sold for $1,000 and another brought $1,900,” he said. “But the real pleasure with the test is seeing how they put the parasite larvae in those lambs and then seeing how their egg count goes up and then drops. It shows how resistant they are and how they can fight off those parasites.”
Providing lambs a dose of parasite larvae is central to the test. But first they have three weeks to settle in at Glade Springs.
“We keep all the lambs on dry lot for the first three weeks as a way to quarantine and acclimate them to the feed supplement,” Lee Wright said. “We also want to make sure we have successfully reduced the parasite burdens they have brought with them from their home farms.”
After the three-week acclimatization period, the test starts with each lamb receiving an oral dose of 5,000 third stage Haemonchus contortus (Barber Pole worm) larvae.
“We’ve found that resistance to the Barber Pole worm is a highly heritable trait from the sire,” Wright said. “So one of our primary goals in the test is to identify rams with genetics to help improve parasite resistance in their offspring. Rams need to be on pasture in a natural setting to consistently consume these worm larvae in order for us to collect the data and track the rams’ performance and immune response to the adult worms in their system throughout the course of the test period.”
Farmland in western Virginia is hilly and not conducive to raising row crops. Livestock operations utilizing mainly grass are very common in the area, according to Wright. So, to match the farming systems of the area, the parasite inoculated rams are put into paddocks of mainly fescue grass. They also receive supplemental concentrate feed at a rate of three percent of their body weight daily. Wright says this concentrate ration is around half the amount consumed by rams in another Virginia Tech ram test that is an ad lib grain based test.
“That forces rams to consume pasture for the remainder of their daily intake requirements,” he said. “It also assures rams continue to be exposed to a parasite challenge so we can monitor resistance levels. This approach allows us to find rams that will excel in a forage based system while under the stress of parasites.
“The pellet concentrate provides adequate protein and energy requirements, and also has a mineral supplement added in, so rams are receiving the necessary baseline for nutritional requirements. We don’t expect to see the higher average daily gains that are observed in an all-grain test, but the sheep do get what they need to grow.
“Some of these rams have gained right around half a pound per day while at the same time dealing with a significant worm load. Our best performers tend to shed those higher worm loads on their own, maintain lower fecal egg counts, gain weight, and never require de-worming for the duration of the test period,” Wright said.
Wright, and his staff measure body weight, fecal egg counts (FEC), and FAMACHA scores at the beginning of the test period and at regular fourteen day intervals throughout the test. Rams requiring de-worming during the test are disqualified from the test and sale and marketed for slaughter.
“Poor performers simply can’t deal with the worm challenge and require at least one de-worming during the test and they typically gain less than the average,” Wright said.
At the end of the test, rams are de-wormed and scanned via ultrasound to estimate carcass merit and body composition. Rams that passed the test then must pass a breeding soundness exam to further qualify for the sale.
After the rams are tested, de-wormed, scanned and checked for soundness, they’re auctioned. At the September 23, 2016, auction thirty-two Katahdin ram lambs and one Dorper ram lamb were put on the sale and sold. They came from flocks in Virginia, West Virginia, Tennessee, Ohio, North Carolina, Missouri, Kentucky, and Georgia and they sold for an average of $1,015.00.
“Over the years, we’ve sold test rams to all of Virginia’s surrounding states, and as far away as Texas, Wisconsin, Missouri, and Florida. Word has spread about our program and seems to be catching the attention of many producers looking to incorporate parasite resistance into their flocks,” Wright said. “The high selling ram this year went for $2,800 and belonged to Roxanne Newton of Hound River Farm in Hahira, Georgia,” Lee Wright said.
Chris and Mandy Fletcher purchased the second top selling ram for $2,600.00. That was also a Hound River ram. That ram had an average daily gain of .24 pounds during the test. It also had a mean FEC of 73, a weaning weight EBV of +2.3, and a post weaning EBV of 4.3, placing it in the top ten percentile for the Katahdin breed. The top selling ram was similar but with slightly better test growth, according to Roxanne Newton.
“Both of these rams were structurally sound and a great example of the rams on test as well as great performers in terms of growth and parasite resistance,” Lee Wright said.
All the rams sold at the 2016 sale were hair sheep.
“Since hair sheep have become so popular in our area, much of the research we have done at our Center has focused on Katahdins,” Wright said. “The test was somewhat designed as a follow-up to previous research we have done as well as a way to support local producers in identifying quality breeding rams. Once word got out of what we were doing, local interest expanded to regional interest and beyond much faster than we ever anticipated.”
Although most animals in the test have been Katahdins, Wright says shepherds are welcome to consign other breeds to the test and sale. Suffolks, Dorsets, Dorpers, and Polypays have been in the test in previous years, he said.
“It’s proving a great way to learn about the parasite resistance in your flock at home, as well as to identify potential breeding rams for incorporating parasite resistance into anyone’s breeding program.”
To learn more about the test at Glade Spring, shepherds can e-mail Wright at firstname.lastname@example.org.
Costs for lambs that complete the 70- day test run about $100 per head and are deducted from the sale price, according to Wright.
Originally published in the January/February 2017 issue of sheep!.