AI
“Doing artificially what comes naturally”
- Collecting semen from males and depositing it into reproductive tract of females in estrus
- The use of AI has doubled milk production by dairy cows in about 40 years because the use
of superior sires that could not possibly naturally mate as many cows as can be AI’d
Advantages of using AI:
- Greater use of superior sires
- Can be stored semen after sire’s death
- No problem with “fussy” males or females
- Less danger of males to humans
- Don’t have to maintain a sire
- Reduces spread of reproductive diseases
- Can evaluate a sire more quickly
- Crop of offspring are more uniform ($$)
Disadvantages of using AI:
- Inbreeding can increase because so many offspring have the same sire
- AI training is necessary
- Genetic defects can be spread “far and wide”
- More labor than letting male “do his thing” – must detect females in heat
- Fads and fancies increase too quickly
Semen collection techniques:
Can use-
- Artificial vagina with a water jacket
o Train male to a dummy, use a female in heat, or use a castrate
- Mechanical manipulation
o Gloved hand
- Electrical stimulation
o Mainly for checking seen of young males before using them
Microscopic evaluation of semen:
- Concentration of sperm
o More is better
- Motility
o More is better
o What percent of sperm cells are moving forward
- Morphology
Extension (dilution) and freezing of semen:
- Nutrients, buffer, antibacterial agents, glycerol
- Diluents
o Egg yolk citrate
o Milk
o Fruit and vegetable juices
o Addition of glycerol before freezing (antibiotics)
- Number of inseminations/ejaculate from a normal male
o Cattle; 300-400
o Sheep; 20-30
o Goats; 20-30
o Hogs; 10-20
o Horses; about 10
*the more ejaculate does not mean more sperm*
Packing semen:
- Straws
o Contains fertile sperm capable of reproducing
- Ampules
- Pellets
- Freeze dried (experimental but possible)
o Doesn’t require refrigeration during storage
Storage of semen:
- Refrigerated at 4-5*C (39-40*F)
o Stallion; 1 day
o Bull; 3 days
o Boar; (18-20*C) 5-7 days
▪ Boar and stallion semen does not freeze well
- Frozen liquid nitrogen
o -196*C (-320*F)
o Semen can be stores for >50 years if properly done
o Must be thawed before insemination
Thawing of semen and insemination:
- Thaw for 10-30 seconds at 35-37*C (95-98*F) or in ice water for several minutes
- Inseminate
o Preferred technique for species?
o Restrain of female – as little as needed
o Site of deposition of semen
▪ Cow – uterine body at tip of cervix (into uterus)
▪ Sow – cervix
▪ Mare – cervix
▪ Ewe – cervix
Estrous synchronization:
- Can have the majority of females in “heat” at one time for AI
- Prostaglandins (produced by cow and cause corpus lutenum to recede and stop producing
progesterone) and progestins are used for estrus synchronization
- Can detect estrus when they are naturally in heat
o But have to constantly monitor cow if showing signs of heat
- Not all cows have a CL
- CIDR
o Controlled Intervaginal Drug Release
▪ A device that releases progesterone (15 days – depending on protocol)
▪ Should synchronize females
o Progesterone
- Lutalyse
o Prostaglandin F2alpha
- MGA
o Melengesterol Acetate
o Progesterone can be fed
▪ Consistent and has to be eaten
▪ Fed to a pen of heifers to prevent from being in heat
- Regumate
o Oral progesterone
▪ Used for horses
Heat Detection:
- Note actions
o Some show more signs than others
- Estrus behavior
o Restless and vocalizing
o More active
- personal observations
- Use marker animals
o grease on brisket, collar, chin ball marker, heat-mount patches (kamar)
▪ Kamar patch releases dye in the patch when pressure is applied during
mounting by another animal
o Winking of vulva, exposing clitoris (one sign of estrus in mares)
o Sow in heat stands still and assumes the mating stance when pressure is applied to
her back as a boar would when mounting
- Use teaser animals
o altered males, “Gomer” bulls or vasectomized males
- Use computer pedometer
o measurement of walking or mounting
Time of insemination:
- Cows; 12-18 hours after beginning of estrus
- Ewes; 15 hours after beginning of estrus
- Sows; 30 hours after beginning of estrus
- Mare; days 3, 5, 7 of estrus
How efficient is artificial insemination:
- Average values
o 95% of females in heat x 90% fertility x 95% fertility of sperm x 90% efficiency of
inseminator
o .95 x .90 x .95 x .90 = .73 (73% of females become pregnant)
o Usually use a “clean-up” sire
Embryo Transfer:
- Using superovulation to produce multiple ova, fertilizing them, and flushing them from the
donor of female
- Embryos then can be transferred to recipient females that are in the same stage in their
estrous cycle as the donor female
Benefits:
- Extends the productivity of superior females:
o Extends productive life of a fertile female that is unable to carry young
o More rapid proof of female’s worth
o Shorter generation interval
o Get around some import restrictions
Problems:
- Expensive
- Response to superovulation is variable
- Can cause an outstanding female to become fertile
- Females that are low in fertility can be propagated because of superovulation
Procedures:
- Have donor and recipient females in the same stage of their estrous cycles
- Superovulate donor with PMSG or FSH
o Encourage more follicles to contain eggs
- Inseminate the donor
- Flush embryos from uterus
- Examine embryos for abnormalities
- Transfer embryos to recipients
Sexing Semen:
- More expensive option
- 90% effective
Freezing Embryos:
- Can preserve embryos until needed some time in the future
Microsurgical Procedures on embryos:
- In the future, birth defects may be repaired
Induced Parturition:
- Widely used in humans to save babies that otherwise would not live or to lessen danger to
mothers