Final Report for LNE00-138
Three of the major problems facing the sheep industry today include (1) low wool prices, (2) increasing resistance by the major internal parasite in sheep, Haemonchus contortus, to all forms of chemical control, and (3) the challenge of the prion disease in sheep, scrapie. This project addressed all three problems.
The Katahdin Hair sheep breed was selected because it does not produce wool and currently the return to most sheep producers from wool is less than the cost to shear and manage for wool production while the price of lamb meat has continued to rise. A technique to test for genetic resistance to infection by the major internal parasite was developed and selected cross breeding was used to produce Katahdin sheep with improved natural resistance. An unexpected spin off was the development of a technique by workers in South Africa that made testing by farmers for infection by this parasite much easier and we have become one of the few in the United States to train producers via workshops on how to use the procedure.
In cooperation with Dr. Katherine O’Rourke, Washington State University, we used genetic testing techniques to breed and select Katahdins with greater resistance to scrapie. This valuable approach offers the opportunity along with the USDA Scrapie Eradication Program to rid the sheep industry of this disease.
The project also used selected breeding to provide the genetic base for production a more acceptable lamb carcass. Cross breeding was used to improve carcass characteristics including size of the carcass and the amount of leg and loin muscling.
The project has also provided the opportunity to investigate the biological mechanism of how animals are more resistant to Haemonchus contortus. Nine Bowdoin College students have completed research on various aspects with two publishing Honors thesis. A University of Maine student is currently examining the genetic and immunological difference in parasite resistant and non-resistant sheep from the project.
The project through support of LNE-03-178 will continue through December 2005 and at that time the breeding stock developed as part of the project will be distributed to qualified applicants in the Northeast. The Katahdin Hair Sheep breed has grown in popularity in the last few years and is now the third largest sheep registry in the United States. The producers who receive the Katahdin breeding stock will have excellent opportunity for not only producing high quality meat lambs but also the opportunity to benefit from the unique genetic features of these animals from the project and benefit from sale of breeding stock.
The Katahdin Hair Sheep Upgrade Project was designed to provide the genetic base for more profitable production of lamb using sustainable agricultural techniques. The end product provided an improved hair sheep that is resistant to internal parasites, requires less management and input costs than traditional sheep production while producing a carcass size with less fat that meets today's lamb market need.
This project not only provided the sheep genetic base to Northeast farmers for producing lamb meat but also the opportunity to add significant income from the sale of breeding stock both nationally and internationally. Two of the major problems facing the sheep industry include low wool prices and increasing resistance to all forms of chemical control of internal parasites.
This project addressed both problems. The project upgraded the Katahdin hair sheep, a breed developed in the Northeast in the 1950’s. We used the genetics of Suffolk, Gulf Coast Native, Dorper, Dorset, Florida native and East Fresian breeds of sheep, to produce a larger more acceptable carcass. Our goal is to produce a sheep that will not require shearing, docking, extensive foot care and have natural resistance to internal parasites. The upgraded sheep was selected to produce lambs using environmentally friendly rotational grazing systems.
Three performance targets included: (1) By the use of hands-on farm field days, written articles, slide and video presentations, provide 1,000 current and new sheep farmers with information about the potential of using improved Katahdin sheep as a farm enterprise. Informed farmers will learn the advantages of rotational grazing, the use of production records, the importance of the scrapie certification program and the features of a proactive health program.
(2) Through a defined crossbreeding plan and using a detailed selection process, upgrade the Katahdin sheep to be parasite resistant and produce lambs that have a more market acceptable carcass weight.
(3) The initial project was extended by support of SARE project LNE-03-178. A the end of the project in 2005, approximately 10 farms will be provided with a group of upgraded Katahdin ewes at the end of the project to produce and sell meat lambs and breeding stock.
Over 1,000 current sheep farmers and those considering sheep received information about hair sheep, rotational grazing, use of production records, the scrapie certification program, natural parasite resistance and selection and proactive sheep health programs:
Through a defined breeding program and using a detailed selection process, the Katahdin hair sheep was upgraded to produce a larger, more market acceptable lamb carcass weight and have increased resistance to internal parasites. By the end of the project, approximately 60 breeding ewes will be produced.
Selected farms in the northeast will receive a group of upgraded breeding animals for production of lamb meat and breeding stock. This group will also commit to participation in formation of a group breeding and marketing program. Farmers will be selected by application.
Parasite Testing - The procedures for producing animals with the desired genetics were standard animal breeding techniques. To determine level of parasite infection three techniques were used including the McMaster technique for fecal parasite egg counting, blood packed cell volume and a new technique, the FAMACHA procedure.
The FAMACHA procedure depends on the concept that as blood sucking parasites such Haemonchus contortus increase in numbers in the infected animal the concentration of red blood cells in the blood decreases. As red blood cell numbers decrease the color in the blood vessels in the mucus membranes becomes pale. Researchers in South Africa have developed a color chart that relates color in the mucus membranes in the lower part of the eye to red blood cell count. The workers created a five color chart that can be used to estimate color and thus red blood cell concentration. This procedure became available in 2003 and we were some of the first in the country to receive training in using the technique. We have tested the procedure by comparing results with blood samples and fecal egg counts and found the procedure to be very accurate, easy to use and a very valuable procedure. We are now certified to train others and have conducted several workshops for farmers.
Parasite Resistance - Currently there is no genetic test for determining which animals might carry natural resistance to Haemonchus contortus infection. We created an applied test to gauge the level of natural protection and used this approach to select breeding stock.
The procedure included taking a “test pasture” area at the Buxton, Maine project location and bringing animals (non-project animals) to the site that were infected with the parasite. We pastured these animals on the “test pasture” for two weeks allowing the infected animals to deposit parasite eggs with their fecal material on the pasture. After the two weeks the infected animals were removed from the site. When the parasite eggs hatch and move up the grass blades, they are available for any grazing animal to eat and thus provide an “infective challenge.”
Our procedure was then to put animals we wanted to test on the pasture and measure level of infection over a 4 week period using the three procedures described above. As a result, we were able to determine which animals became infected and which did not and use this information to select breeding stock. It should be mentioned that resistance is not all-or-nothing. There were animals that repeated tested to be totally resistant and a majority that demonstrated varying levels of natural resistance.
Resistance to Scrapie - Dr. Kathryn O’Rourke, USDA, Washington State University, along with others has discovered that sheep with specific genotypes are resistant (if not fully protected) from the prion disease, scrapie, if specific sequences are located at the genetic site that code for the prion protein. Specifically sequences located at codons 171 and 136 have been associated with protection against getting this prion disease. In our work we collected blood samples containing white blood cells which were a source of the animals DNA, and working with Dr. O’Rourke had the samples tested by a commercial laboratory, GeneCheck, Inc. We used this information to select breeding stock that was resistant to scrapie.
Breeding Program - The major objectives of this work were to breed for natural resistance to the round worm, Haemonchus contortus; resistance to scrapie; hair instead of wool coats; increased muscling; and larger frame size while still maintaining the excellent maternal traits of the Katahdin. Standard breeding and selection techniques were used to accomplish these objectives.
In the first year a group of 34 Katahdin breeding ewes were obtained from some of the top breeders in the United States including breeders in Maine, Kansas, New Jersey and Florida. These ewes were bred to one of two heavy muscled Dorper/Katahdin rams and offspring were selected that were heavy muscled, fast growers, and either a twin or triplet.
Also in the first year a group of medium framed, heavy muscled Suffolk ewes all tested to carry the genetics for scrapie resistance were obtained and bred to one of two Florida Native rams that had come from the University of Florida research flock where no treatment for parasite infection had been used in over 20 years. These rams were parasite free on testing and therefore presumed to have at least some natural resistance to parasite infection. Off spring were selected for muscling, growth rate, resistance to scrapie and at least some resistance to parasite infection.
In Year Two, selected off spring from each of the crosses described above were bred to each other. The goal being to produce Katahdin-crossed sheep that had a larger, more muscled frame and resistance to scrapie and parasite infection.
Also in year Two the Suffolk ewes were bred to Gulf Coast Native rams obtained from Mississippi and Louisiana that tested to be parasite resistant. As in year One, the offspring were selected for growth, muscling, scrapie resistance and parasite resistance. We also obtained two purebred Katahdins from a flock in West Virginia that tested to be parasite resistant. We bred some of the F1 and F2 ewes to these rams as well as exposing these rams to some of the original Katahdin ewes. This was done to try and produce a pure Katahdin ram that was parasite resistant and could be used to introduce Katahdin genetics back into the offspring produced in the project.
In year Three, some of the ewes were bred to a heavy muscled Dorset ram in an attempt to increase muscling and frame size in the project sheep. We obtained from Florida some Friesian ewes bred to a Katahdin ram. We had found that animals from this farm had exhibited a high natural resistance to parasites, and we wanted to add some Friesian genetics to our project sheep since this breed are excellent milk producers and could produce offspring that have increased milk production. Obviously, good milk producers would result in better lamb growth during the lactating period and would be a desirable trait in lambs bred to reproduce.
In year Four, we had three breeding groups. Two of the crossbred groups were bred to ¾ Katahdin rams produced within the project that were both parasite resistant, scrapie resistant, heavy muscled, either a twin or triplet, and indexed for rapid growth rates. We continued to select offspring that from these crosses based on these criterions.
For year Five, (the extended year supported by LNE-03-178) we again used the best rams in terms of muscling, growth parasite resistance and scrapie resistance produced within the project to breed our ewe group. We also bred some of our original ewe group to a purebred Katahdin ram with the idea that the best rams from this breeding would be useful to the producers who will receive the breeding animals from this project in the summer of 2005.
From the very first breeding to the last, we have been pleased and somewhat surprised at the high genetic heritability seen with breeding for resistance to parasite infection. This result is even more important now than when the project began since more and more sheep producers are finding that the chemical control of Haemonchus contortus is becoming less and less effective. Interest in and about the project has grown and we have been invited to areas outside of the Northeast to share our work including a presentation in Georgia, two in Florida and one in Mexico.
Over 1,000 sheep producers have learned about the project through the following:
- field days at the project site
- articles published in the Shepherd magazine
- talks at 16 different locations
- displays at fairs using posters and handouts
- presentations at the 2003 Katahdin Hair Sheep International, Inc annual meeting and workshops which we hosted in Maine
By the end of year Two, we had produced 14 breeding animals that tested to be resistant to infection by the parasite. By the end of the project in the summer of 2005 we expect to have over 60 animals that have tested to be resistant.
At the end of Year Four, we had a lambing percentage of 200% live animals at weaning, that had an average weight gain of 0.60 pounds per day on grass with some grain supplement. We have been able to demonstrate that it is possible to increase the level of parasite resistance and establish more clearly that selected breeding programs can be used as a powerful tool in controlling round worm infection.
One of the major breakthroughs that occurred during the second year of the study was learning about the FAMACHA technique (see methods section) for measuring level of parasite infection. Other techniques require special expensive equipment and a great deal of time. This technique developed in South Africa requires no microscopes or special equipment and virtually anyone with good eyesight can be trained to be skilled in the technique. (Color blindness does not appear to be a factor in using this visual scale.)
We early on recognized the importance of this technique and Professor Settlemire went to Florida to become trained in the use of the procedure. Currently he is the only individual trained in the Northeast to train farmers and others in the use of the procedure. It has not only made the work for this project much more efficient but over 100 farmers, extension agents and research workers have been trained as part of this project on how to use the procedure.
In the final phase of the project, the distribution of breeding stock to farmers who make application has been delayed until summer 2005 as a result of obtaining additional support via LNE 03-178.
This project has shown that selective breeding practices can be a powerful and useful tool in the control of parasite infection and is one of the few if not the only project exploring the use of genetics to provide at least a partial answer to the number one problem facing the sheep industry in the world.
A very important approach that proved successful was the search we conducted to find breeding stock naturally resistant to infection by this round worm. We hypothesized that we would be more likely to find genetically resistant sheep in environments where sheep were exposed to high levels of parasite infection but where little intervention or treatment took place. This parasite is passed sheep to sheep by grazing sheep in areas where infected sheep have left fecal matter containing parasite eggs. These eggs hatch and the larvae move up the grass blades where they are consumed by grazing sheep. The parasite then infects the digestive tract of the new host. We speculated that areas where this problem would be most serious would be in the continuously warm Southeast regions of the United States. In states such as Arkansas, Florida, Louisiana, Mississippi, Georgia, and Alabama, it is possible for the grazing season to extend the entire year allowing for continuous re-infection to occur. We looked for flocks that had not had any parasite treatment programs which then allowed natural selection against parasitic infection to take place within the flock. We found and purchased breeding stock from three flocks located in Mississippi and Louisiana including two Gulf Coast Native and one Florida Native flock that appeared to be naturally parasite resistant. None of these sheep had any treatment for parasites in over 20 years. Using the procedure described in “methods” we tested these animals for resistance to parasites and nearly all showed very high resistance to infection. When we used these sheep in crossbreeding programs with the hair sheep, we were pleased to obtain offspring with increased resistance to the parasite.
In addition, we developed a spin off project using the Gulf Coast Native ewes and rams of this wool producing breed. Since they showed excellent protection against parasite infection, we thought this breed might be of interest to producers interested in marketing spinning fleeces. We contacted a spinning group and 16 of the spinners agreed to evaluate fleeces. Each received approximately a pound to evaluate. The conclusion was that pure Gulf Coast Native sheep do not produce a top quality spinning fleece. It would be necessary to use this parasite resistant animal in a cross breeding program with sheep that produce high quality fiber in order to introduce the parasite resistant genetic.
Another spin off from this project has been a grant from the University of Maine Agriculture Center to (a) support laboratory work on the biology of the parasite resistance in the project sheep and (b) to write a handbook for on-farm monitoring of internal parasites in sheep. This project will be completed by summer, 2005.
The Katahdin Hair Sheep Improvement Project through support of SARE grant LNE 03-178 will continue through December 2005 to allow for more of the genetic work to be completed and the objectives met. At that time it is expected that most of the objectives if not all will have been met.
Our outreach included two successful and well-attended field days. One took place early in the research at which we introduced over 50 participants to the idea hair sheep. Participants learned about the benefits of a hair sheep breed in addition to practical sheep management topics such as rotational grazing, using locally grown concentrates, sheep health, keeping production records and measuring rate of gain. Our team hosted the 2003 Katahdin Hair Sheep International Gathering in October 2003. Approximately 100 people from around the country took part in some aspect of this three-day event. The gathering included workshops on natural parasite resistance, training for the FAMACHA parasite monitoring technique, hair coat evaluation, meat and carcass evaluation, farm tours and more.
Other educational outreach components included colorful displays, power point presentations, presentations at sheep and wool festivals and conferences, and two honors thesis authored by science majors at Bowdoin College in nearby Brunswick, Maine. These and other college students were involved in the project. We interacted with producers from around the region at agricultural trades shows, a sheep & goat marketing summit, sheep & wool festivals, shepherd meetings and other farm gatherings.
Impacts of Results/Outcomes
Impacts of Results / Outcomes
The major impact of this project will be the distribution of the animals obtained from the breeding in this project to farmers. This will occur at the end of the extended project supported by LNE 03-178. Approximately 10 farmers will receive a group of breeding animals with unique genetics. They will be resistant to infection by Haemonchus contortus, the cause of the number one problem in the sheep industry. The sheep producers who will receive the animals will have the opportunity to not only produce high quality meat animals without chemical intervention but also have the opportunity to sell breeding stock. Offspring that are resistant to infection will be in high demand and offer excellent opportunity to have a sheep enterprise that will add significantly to their farm income.
This project appears to demonstrate that within all sheep breeds there is a variable genetic base for resistance to parasite infection. The genetics are more concentrated in the Katahdins, the Florida Natives and Gulf Coast Natives but it is possible to create a breeding program that selects for parasite resistance within other sheep breeds. On-farm testing programs for resistance would be easy to implement and would aid the farmer in selecting breeding stock likely to pass on parasite resistance. In the booklet being prepared as part of the funding from the University of Maine Agricultural Center, we will be outlining the steps a sheep producer would use for his farm. The major contribution to make this possible has been the FAMACHA parasite testing procedure described in methods.
We know that several farmers from around the region have been influenced by our research. Many sheep producers have adopted some of the practices we presented to this point. Examples include farms that have starting raising hair sheep, a sheep specialist who have been certified in FAMACHA monitoring, and requests for information on natural resistance to internal parasites in sheep and goats.
We were granted an additional year of funding for the project with a SARE LNE-03-178 and will have solid numbers to report at the end of 2005 regarding farmer adoption and impacts.
Areas needing additional study
We recommend that further study be initiated in the area of natural resistance to internal parasites in sheep and goats. This issue is important for sheep and goat producers and the sheep industry as a whole.