Note Taking Guide 2 Key
Breeding Methods
By Walt Iciek
Two Main Types of Breeding
• Artificial Insemination
– Collected semen deposited directly in to females reproductive tract by humans
• Natural Insemination
– Animals breeding the way they would in nature
Function of the male
• Produce large number of live sex cells
• Contribute half the chromosomes
Male Reproductive Organs
• Testicles
– Produce spermatozoa & testosterone
• Scrotum- sack which carries the testicles
– Heat regulator
• Epididymis- tube that connects testes
– Stores sperm
– Sperm matures there
• Vas Deferens
– Tube which connects to epididymis
• Accessory Glands
– Prostate
– Seminal vesicles
– Cowpers glands
– Adds volume and nutrients to semen
Function of the Female
• Contribute half the chromosomes
• Give birth to offspring
• Care for young until weaning
Female Reproduction Organs
• Cervix- “mouth of the womb”
– Opening into uterus
• Uterine Horns
– Two branches of the Uterus
• Fallopian Tubes- uterine horn
– Lined with cilia, aids in egg migration
• Ovaries
– End of fallopian tubes
– Large number of eggs, all stages of development
– Few eggs reach maturity
– If not fertilized, eggs are reabsorbed by the body
“Heat”
• Time when female is receptive to male and is willing to breed
•
Identified by:
– Aggressive behavior
– Swelling of vulva
• Consist of four stages of estrous
Estrous
• Proestrous
– Ovary is about to release an egg
• Estrous
– Female receptivity
• Metestrous- uterus prepares for pregnancy
– Fertilized egg attaches to uterus
• Disestrous- longest period of cycle
– inactive
Natural Breeding
• Advantages
– Less expensive
– Requires no special equipment
•
Limitations
– Slower genetic improvement
– Cost of maintaining sires
– Passing on traits or diseases to offspring
Artificial Insemination
• Definition
– Deposition of sperm in the female by artificial means
– Used commercially in U.S. since 1938
– Most widely used in dairy and beef cattle
Process of A.I.
• Equipment needed
– Liquid nitrogen– used to store semen at –385 degrees Fahrenheit
– Semen straws contain one dose of semen
– Stainless steel insemination straw
• Used to place semen in reproductive tract
– Semen thawing unit
Insemination Process
• Restrain female gently, squeeze chutes most common method
• Prepare semen
• Palpate the rectum and locate the cervix
•
Insemination
– Insert insemination gun into vagina and deposit semen
Eight steps in the procedure
• Thaw frozen semen slowly
• Place plastic glove over hand and arm
• Lubricate plastic glove
• Restrain animal
•
Insert arm into animal’s rectum
• Grasp animals cervix
•
Insert insemination gun into the vagina
• Deposit semen into animal’s cervix
Artificial Insemination- Advantages
• Use of outstanding sires
• Alleviates danger of keeping sires
•
Lessens sire costs
• Helps control diseases
• Creates large families of animals
•
Increases profits
Artificial Insemination- Disadvantages
• Requires trained technicians
• May accentuate poor sires
• Restricts the sire market
• Hard to identify true heats in females
• Timing is crucial