Evaluation of Semen Extenders for the Preservation and Shipment of Chilled Ram Semen

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2017: $7,089.00
Projected End Date: 01/30/2019
Grant Recipient: Promised Land & Livestock Co.
Region: North Central
State: Ohio
Project Coordinator:
Donald Brown
Promised Land & Livestock Co.


  • Animals: sheep


  • Animal Production: animal protection and health, livestock breeding
  • Education and Training: farmer to farmer
  • Sustainable Communities: analysis of personal/family life


    The focus of this project is to obtain a series of ram semen samples collected by artificial vagina on a phantom ewe. These samples will be evaluated in 3 commercial semen extenders, then chilled and re-evaluated at 24 hour increments. The purpose is to identify effective ram semen handling methods and optimal chilled extension media, to make chilled shipped semen an available resource to small sheep ranchers.

    The primary resulting issue discovered in the first year of this project, 2017,was difficulty in convincing the rams to mount the phantom and ejaculate into an artificial vagina (AV). Numerous re-configurations of AV, phantom and venue were attempted, without reliable ram performance attained.

    After consultation with other researchers and sheep producers, further protocol adjustments are planned for year two of this project.

    The results of these adjustments were as follows. Regardless of the availability of appropriately cycling (hot) ewes, we were not successful in convincing the rams to mount the phantom. We were, however, consistently successful at collecting the 2 adult rams by hand-held artificial vagina over a jump ewe, in the breeding chute. The 8-month old ram refused collection at this time. The collected semen was maintained at 100 degrees F in a warmed cooler for transport to the warm room, and placed in an incubator also maintained at 100 F. Volume of ejaculate was recorded, gross progressive motility was determined via microscopic examination, and morphology examined, with defects recorded. Concentration was measured via Quick Check-Canine Semen Management System device (see photo evidence). Samples from each ram were divided and extended to a 4:1 ratio of extender to raw semen, totaling a 1mL dose, then placed in a foam buffer tube, inside a Canine Express Chilled shipping container, to await 24, 48 and 72 hour progressive motility evaluations. Three commercial extenders were chosen from data discovered during the previous project # FNC13-901 and year 1 of this current project. These were INRA-96 Stallion semen extender from IMV Technologies, BotuSemen equine semen extender from Botu Pharma, USA, and Next Generation Universal Formula semen extender with amikacin and K-Penn antibiotic additives, from Exodus Breeders corporation. By collecting 2 rams over 5 cycles, we evaluated 10 samples in each of the 3 study extenders.

    CIDR insertion protocol
    Preparing semen concentration analysis
    Loading Quick Check concentration analysis machine.
    Three semen samples before extending, showing visual evidence of clean catch and varying opacity due to concentration differences.

    Project objectives:

    Since the original objective of this project was to evaluate ram semen, it was essential to first identify a reliable method for collection of clean catch semen samples.

    The second year proposal was adjusted to include further modifications to the phantom, and utilized three ewes for rotating forced estrous to ensure the availability of "hot" ewes at required collection times. The phantom was further modified by inserting the AV into the phantom, eliminating the distraction of a handler between the ram and phantom.

    In year two of this project, 2018, further adjustments refined the phantom. The body was angled to drop the hind end by 15 degrees to more accurately simulate a mounted ewe, the rear supports were shortened so the ram would not stumble on them, and a smooth-edged funnel was secured in the opening for the AV, to guide the penis into the AV.

    Three vet approved ewes had CIDR's inserted vaginally with removal and PG-600 shots utilized per protocol to ensure effective tease ewe availability which should entice rams to mount phantom and ejaculate reliably into AV.  [Editor's Note: CIDR stands for Controlled Internal Drug Release -- an intravaginal progesterone insert used to synchronize estrus.] 

     Cycling ewes were assured by choosing 4 proven calm, fertile ewes whose cycles were manipulated through the use of intravaginal CIDR devices and PG-600 injections. By rotating these ewes through cycles every two weeks, we were assured two receptive ewes available as teasers for every 14-day collection cycle. On day 1, CIDR's were inserted in 2 ewes using clean technique per protocol. On day 13, the CIDR's were removed and 2mL PG-600 administered IM. At the same time, CIDR's were cleanly inserted in the other 2 ewes, in preparation for the next cycle collection. This rotation was effective at maintaining "hot" ewes on each collection date. Since the rams were occasionally picky about which ewe they wanted, we always had two prepared to choose from. 

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.