New Method to Eliminate Ovine Progressive Pneumonia in Sheep Flocks in North Dakota

View the project final report

• 2013 annual report

Commodities

• Animals: sheep

Practices

• Animal Production: livestock breeding
• Pest Management: eradication, genetic resistance

DESCRIPTION

This grant will serve fifteen seed-stock and commercial sheep producers who are members of the North Dakota Lamb and Wool Producers Association (NDLWPA) and are contributing member/buyers of rams at NDLWPA sponsored ram sales.  I, Rick Schmidt, am will serve as the lead project manager and my duties for this grant will be three fold.  First, I own and operate a sheep farm that produces seed-stock genetics for commercial sheep producers, show lambs for 4-H youth, and market lambs.  Secondly, I am the secretary for the NDLWPA.  Finally, I serve as the Oliver County Agricultural Extension Agent.  For the purpose of this grant, I am the representative of the NDLWPA.  However, I will also serve the grant as an NDSU Extension Agent.  The association and I will work closely with Reid Redden, the North Dakota State University Extension Sheep Specialist. Reid and I will conduct the collection of the samples and be in charge of the educational efforts.  Upon advertisement of this grant proposal, we have been contacted by fifteen sheep farms that have volunteered to participate.  Their information is below.

• Benz Family: ~50 head of registered Rambouillet sheep in Beulah ND
• Kuss Family: ~300 head of Dorset and Polypay sheep. Woodworth ND Lagein Family: ~100 head of fine and medium wool sheep. Rock Lake ND
• Lillehaugen Family: ~150 head of purebred Katahdin sheep. Brockett ND
• Pearson Family: ~100 head of registered Rambouillet & Suffolk sheep. Hettinger ND
• NDSU Sheep Unit: ~300 head of registered and commercial sheep. Fargo ND
• Schauer Family: ~50 head of purebred Polypay sheep in Hettinger ND.
• Schmaldtz Family: ~150 head flock of commercial Katahdin sheep. New Rockford, ND.
• Schmidt Family: ~70 head flock of purebred Suffolk sheep. Center ND
• Scheetz Family: ~100 head of Columbia & Rambouillet sheep. Center ND
• Sears Family: ~50 head flock of commercial sheep. Wheatland ND
• Severance Family: ~300 head flock of commercial range sheep. Dickey ND
• Stanley Family: ~25 head flock of registered Dorset sheep. Bismarck ND
• Swenson Family: ~ 150 head of commercial range & farm flock sheep. Walcott ND
• Warner Family: ~75 head flock of registered Rambouillet sheep. Baldwin ND

PROBLEM/SOLUTION

Problem:  It is estimated that 25% of the entire sheep industry is infected with the virus that causes Ovine Progressive Pneumonia (OPP).  Incidence of the disease within an infected flock can vary from 10 to 100%.  The OPP virus can cause: severe and progressive weight loss, labored breathing or pneumonia, paralysis, swollen joints associated with lameness, and palpably hard, unproductive udders.  However, many infected sheep never show clinical signs of disease and they serve as carriers in a flock.  This disease causes major losses that include lower production, higher replacement rate, and greater health management costs.  Traditionally, transmission of the virus occurs from ewe to lamb in the colostrum; however, recent reports show strong indication that transmission can occur later in life, especially, if the sheep are managed in close proximity to one another.  This is common in North Dakota during winter months.  Past recommendations to control the disease were to artificially rear all lambs from infected dams and manage the flock in two groups, infected and non-infected.  This technique is not completely effective and is too labor intensive for most flocks.

Solution:  Recent research from the USDA-ARS Meat Animal Research Center in Clay Center NE has identified genetic markers for animals that are resistant to the virus.  Preliminary has shown resistant genetics are 3 times less likely to become infected.  This technology needs to be verified on many different breeds from many different flocks.  Fortunately, the sheep industry has already been exposed to this type of technology, since it has almost eradicated Scrapie through genetic selection.  If this genetic technology holds true to all sheep, OPP eradication is realistic and could have huge impacts on the sheep industry.  More importantly, it would provide a useful tool for the individual sheep farmer to improve flock health, productivity, and sustainability. 

Plan: We intend to collect 50 samples from 15 different flocks in North Dakota.  Flocks are of varying size and represent many different breeds.  A blood sample will be collected from each animal to determine the animals’ OPP haplotype for resistance and to conduct a serological test to identify if the animal has antibodies to the virus.  Results for individual animals will be held confidential and only the flock owner will get access to the individual animal information.  However, overall results of the genetic test to predict animals’ resistance to the virus will be presented by breed.  Not only will this information help the participating individuals but they will serve as educators.  The best method to control this disease is to educate sheep producers on how to select for animals that have resistant genetics.  These techniques will be promoted at: seminars, extension flyers, educational articles, social media, and webinars.

TIMELINE

2013

• Collect samples from sheep producers and submit samples to GeneSeek Laboraties in Lincoln NE
• Present results to participating flocks and complete summary of results
• Present results to NDLWPA annual convention

2014

• Present finding in poster format, educational bulletins, and popular press articles
• Host seminars at both NDLWPA sponsored ram sales (Jamestown and Hettinger Ram Sales)
• Host a webinar and publicize the archive for sheep producers to view at their disposal

PREVIOUS RESEARCH

Recent research from USDA-ARS-MARC designed a genome-­wide association study to test whether or not sheep have genetic variation that protects against OPPV infection. The study became possible with development of the OvineSNP50 BeadChip in 2009 by the International Sheep Genomics Consortium (ISGC). Using this approach they discovered a gene (TMEM154) that affects susceptibility to OPPV infection1. There were three major variants (called haplotypes 1, 2 and 3) of the TMEM154 gene. In more than 8000 sheep tested, 97% had some combination of these three haplotypes.  Haplotypes 2 and 3 were strongly associated with OPPV infection and considered to be OPPV infection. Studies are underway at USMARC to determine whether or not haplotypes 2 and 3 are expressed in an additive or dominant manner compared to haplotype 1. In contrast to ewes with one copy of haplotype 2 or 3, those with two copies of haplotype 1 were many times less likely to be infected. These findings were quickly confirmed with the help of other USDA scientists at the Animal Disease Research Unit in Pullman, WA, and those at the U.S. Sheep Experiment Station in Dubois, ID. They suggest that one genetic strategy to reduce OPPV is to reduce the overall frequency of TMEM154 haplotypes 2 and 3.  They also observed six additional TMEM154 haplotypes that occur at low frequencies, yet may also confer low susceptibility like haplotype 1. For example, it appears that haplotype 4 encodes a non-­functional protein and may confer OPPV resistance. Because the scientific and production information on 4,4 knockouts are very limited, additional research is needed to determine the effects of haplotype 4 before any recommendations can be made to use this haplotype to lower OPPV infection. Currently, the effects of TMEM154 variants on OPPV infection rates are being studied at USMARC under conditions of natural challenge to provide selection guidelines for industry use. Although these findings are promising, OPPV is a highly adaptable virus and it is not known if selection for TMEM154 haplotype 1 will reduce the incidence of OPPV infection in all flocks. To that end, research is being conducted at USMARC to determine if some OPPV strains have adapted to infect sheep with TMEM154 haplotype 1. Other sheep genes are also being evaluated as possible gateways for OPPV infection in the presence of specific TMEM154 haplotypes. Additionally, adverse production conditions like high animal density, indoor housing with poor ventilation, and moist climates, may enhance virus transmission and overcome sheep genetic resistance.

OUTREACH

Educational Outreach:

Educational materials will be developed for the following publications (The North Dakota Sheep Industry Newsletter, Ag Communications Press Release, Extension Bulletin and Display Poster). Educational presentations will be given at the NDLWPA annual convention (early December 2013), online via a webinar hosted by NDSU Extension (Spring 2014), at the Jamestown Ram and Ewe Sale (early August 2014), and at the Hettinger Ram Sale (September 2014).  The educational article developed for press release and the link to the extension bulletin will be posted on the NDLWPA Facebook page.

EVALUATION

After each oral presentation, an evaluation will be collect to assess the participants’ interest in the technology and how they feel it can impact their farm sustainability goals.

In the fall of 2014, a survey will be sent to the original participating flocks to assess their value in this technology.  The survey will contain the following questions.

1. Has their knowledge of OPP testing to select for resistant genetics improved?
2. Has their ability to educate fellow sheep producers improved?
3. Do they feel that OPP testing will improve their flock health and productivity?
4. Has OPP testing improved their ram and/or ewe sales?