KEY
Note Taking Guide
Topic # 3106
Sheep Artificial Insemination
Created by: Tracey Hoffman
Source: http://www.agednet.com/subs/la140.htm
NEED FOR AI IN SHEEP INDUSTRY
Why?
·
Semen from outstanding sires can be extended and used to inseminate more
ewes that a ram could naturally service
·
Disease spread is minimal
·
Easier to send frozen semen long distances than transport live animals
Difficulties
·
Ewes do not show obvious signs of heat
·
Rectum of ewe is too small for an inseminator to insert a gloved arm to
manually guide the insemination rod through the cervix
ESTRUS SYNCHRONIZATION
·
Hormonal therapies
·
Ewes should ovulate at similar times
·
Progesterone impregnated vaginal suppositories & removed at day 10
·
Progesterone serves to suppress heat
·
At day 8 ewes are injected with prostaglandin to stimulate cycling
immediately after suppository removal
· Ewes should be ready to imseminate 50 – 54 hours after suppository removal,
which is 4 – 8 hours before ovulation
METHODS OF AI
· Semen must be deposited in uterus
· Cervix of ewe is difficult to penetrate
· Three techniques:
1. Vaginal insemination
· Simplest method
· Deposit semen in vagina as close to cervical opening as posible
· 50% conception rate with fresh semen
1. Transcervical artificial insemination (TAI)
· Technicians attempt to navigate the cervical rings via the vagina
· Some scopes have a bent tip to help navigate the twists and turns of the
vagina
· Semen is deposited in uterus
· 40 – 50% for ewes successfully penetrated
· Semen can be dilluted ½ or 1/3
1. Laparoscopic artificial insemination
· Semen is surgically deposited directly in uterine horns, bypassing the
vagina and cervix completely
· Ewes are sedated and two small incisions are made in the abdomen
· A lighted laparoscope is placed in one hole to view the organs
· A probe in the other incision allows insemiantor to manipulate organs
to find uterus
· When uterus is located, probe is replaced with insemination syringe
· Semen is deposited into the uterine horn
· The procedure is repeated for the other uterine horn
· Procedure takes about 5 minutes to perform
· 65 – 80% conception rate
· Fresh or frozen semen can be used
·
Semen can be diluted to 1/6 the concentration
http://www.hawksmountainranch.com/laproscopyai9-12-00web.jpg