Training farmers to perform artificial insemination in sheep

Training farmers to perform artificial insemination in sheep

Summary

In this two year project, a team of farmers and veterinarians are investigating a farmer-friendly, low cost artificial insemination (AI) technique. Although numerous research studies have been conducted on AI in sheep, the application of AI at the farmer level is limited. Such knowledge would allow large segments of the sheep industry to make genetic progress similar to other livestock industries. AI is currently being used in other livestock species with tremendous success by allowing semen from high quality sires to be disseminated over larger populations of females allowing for faster genetic progress with decreased biosecurity risk.

AI in sheep is inherently more complicated due to difficulty in preserving the ram’s semen and the anatomic complexity of the ewe’s cervix. Team members will be trained on proper collection and handling of semen, as well as vaginal insemination techniques. Conception rates will be monitored over two years.

Semen extenders are used to dilute the semen, allowing it to effectively cover more ewes, as well as provide nutrients for the sperm and protect against chilling, thus extending the viability of the semen. One of the challenges with sheep is that ram semen has proven difficult to extend beyond 24 hours in the past, making shipment of fresh semen for long distances impractical. The team will use recent research and new extenders, to extend the viability of fresh semen beyond 24 hours which would allow more options for use.

Objectives/Performance Targets

In this two year project, our team plans to show that it is feasible to train shepherds to be proficient in performing posterior cervical (vaginal) AI, as well as collecting and handling semen.   Specific objectives for our team members will be to:

1)      Train and to gain experience in posterior cervical AI;

2)      Learn practical techniques for semen collection, evaluation, preparation and storage; and

3)      Use and compare the performance of three different semen extenders.

Each farm (Bielek, Duerr, and Brown) will supply 20 ewes for this project. All the ewes used will be at least two years old, have at least one prior lambing, and be in good health. Ewes will be randomly assigned to one of two farmer inseminators. The inseminations will be performed and the ewes will be maintained on their home farms.

Timed AI will be used to accommodate the schedules of the entire team and since we will be using freshly collected semen. This requires all the ewes to be in estrus at the same time. Estrous synchronization will be achieved through the use of CIDRs, Estrumate and PG600. CIDR is an intra-vaginally placed device that contains a natural progesterone hormone which is released at a controlled rate into the blood stream to extend the ewe’s current cycle. The CIDR will be inserted by the shepherds into 20 ewes per farm. Injections of Estrumate and PG600 will be administered when the CIDR is removed to stimulate ovulation.

A breeding soundness exam (BSE) will be done on each ram used for AI. Any rams identified with questionable or unsatisfactory results will not be used in the project. A semen sample will be collected on rams that successfully pass a physical exam, and examined microscopically to establish sperm volume, concentration, motility and morphology. In addition, on each farm, semen from three of the same rams used for AI will be randomly selected for extender testing.

At approximately 35 days post insemination, Dr. Zimmerly, with team member assistance, will determine conception rates using trans-abdominal ultrasound. A natural service sire will be used for any ewes not pregnant. Records will be maintained of the actual number of lambs born, the number of live lambs at birth and at one week of age, as well as birth weights and vigor scores.

Extenders will be selected based on recent research and advice from our advisors. To assess the percentage of progressively motile sperm cells, morphology and motility evaluations will be performed on collected samples at 12 hour intervals until 20% motility has been reached. The time lapsed comparison of three extender formulas will allow us to identify the best formula for preserving sperm viability for our project.

Accomplishments/Milestones

The group met at the Duerr farm on September 15, 2013 for training on BSE, semen collection and preparation and AI protocol.

On September 29 the team met at the Bieleks. Placement of CIDRs and injection of Estrumate and PG600 had been performed previously as outlined above. The ewes were sorted into desired breeding groups. A BSE was performed on each ram and semen collected using an electroejaculator. Each ram sample was evaluated immediately upon collection for volume, motility, concentration and morphology. These four factors dictated the number of doses available from that sample, using an extension ratio of 1: 3 (raw semen to extender) and an insemination dose volume of 1mL. The ewes designated for each ram were inseminated immediately after the semen evaluation was completed and before collecting another ram. All of the farmer team members were able to inseminate at least one ewe. Two of the farmers, Anne Brown and Jeff Bielek, each inseminated half the ewes. Twenty one ewes total were inseminated.

Ten days later the ewes were put into breeding groups with the same rams they had been bred to using AI. The rams were fitted with marking harnesses. Exactly two weeks following the AI, ten of the ewes were marked by the ram, which suggested a 50% success rate. Thirty five days following the AI, ultrasounds were done on all the ewes. These results also showed a 50% success rate.

The same procedures were followed on the Duerr farm on November 1 and on the Brown farm on November 30 with 20 ewes each, with similar success rates. On the Duerr farm, we found that some rams did not respond to the electroejaculator, so an artificial vagina (AV) with jump ewe collection was attempted. The volume of semen collected using the AV was higher, and only the AV method was used on the Brown farm.  

Semen samples were collected from three rams on each of the three participating farms for extender testing, for a total of nine evaluated samples. As mentioned above, collection procedures began with electro-ejaculation on the first farm, and proceeded to artificial vagina (AV) with jump ewe collection. Three doses were taken from each ram sample and chilled in three different extenders, then evaluated for vitality and motility at 24, 48, and 72hrs. A total of six different extenders were trialed, in order to identify which provided the greatest vitality and longevity. Extenders employed were a home-mixed UHT milk + egg potion, and commercial Next Generation Universal semen extender base in plain, Amikacin + KPenn, and Timentin antibiotic (AB) variations. The protocol of semen handling also progressed throughout the study. Samples were chilled and held in Exodus Equine Express 11 shipping containers.

In view of the poor time-lapse chilled motility results in all samples on the first two farms, regardless of farm, ram, or extender, the handling protocol was altered to address the following issues. Stored semen may be sensitive to the exposure to air in the 10mL tubes, so the third trial stored the semen in 1mL non-spermicidal syringes, with all air carefully expressed. Next, the Equine Express 11 shipping/holding containers are calibrated to chill a fluid volume of 80-100mL. Since all of the ovine samples totaled only 9mLs, the resulting altered chill rate may have caused excess sperm cell death. For this reason, two 40mL ballast syringes of sterile water were included in the chilling container to correct the chill factor. Finally, the coolant packs in the previous two trials were not changed during the 48hr time period, possibly allowing the samples to become too warm, elevating their metabolism and hastening death. For the third trial, the coolant pack was refreshed with a fully chilled pack at each 24hr evaluation period, maintaining the chill within original specifications.

Impacts and Contributions/Outcomes

In Year 1, we partnered with the Ohio Heartland Sheep Improvement Association (two of our team are members of OHSIA) to co-sponsor their annual fall educational workshop on September 28, 2013. The focus of the workshop was breeding and genetics, and three members of our group were speakers: Dr. Duerr, Dr. Zimmerly, and Kathy Bielek. Information presented included biosecurity, breeding soundness exams, the benefits and challenges of AI, genetic selection, and a BSE demonstration.

 Social media is being used to not only raise awareness but also to provide outreach for our project. A blog, web site, and Facebook page has been created entitled ‘Breeding Better Sheep’.   The team felt it important for online project specific posts to lag behind actual events as we digested the information we were learning ourselves.   Therefore, in order to help build an audience in 2013, articles related to sheep were shared with our Facebook Fans two to three times a week.   In the last quarter of 2013, the Facebook page was promoted to various sheep organizations on a local, regional and national level. There are currently 235 fans and each post is reaching an average of 50 people. As we move forward in 2014, project updates can hopefully be shared via blog entries that will automatically post to Facebook along with monthly entries by various guest blogger experts who have been contacted to write articles related to artificial insemination. www.BreedingBetterSheep.com www.facebook.com/BreedingBetterSheep

Two members of this proposal, Don Brown and Dr. Craig Zimmerly, gave a presentation of this work at the 2014 Ohio Ecological Food and Farm Association (OEFFA) annual conference in February, 2014 as part of the NCR-SARE Farmers Forum. A recording of this presentation is available throught NCR-SARE’s YouTube channel at: https://youtu.be/91tKLGoP9ys?list=PLQLK9r1ZBhhGr9RLwfvRvJLEtHJOLdXZz

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