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Chapter 11
Animal Reproduction
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Animal Reproduction Overview
•Perhaps most important part of animalindustry
•Animals must reproduce efficiently
–Complicated process
–Requires systems to work together
–Occurs sexually
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Production of Gametes
•Spermatogenesis (sperm)
•Oogenesis (egg)
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Spermatogenesis
•Testes produce sperm
•Four-step process
–Replication
–Chromatids pair (synapsis)
–Cell divides, chromosome separate
–Cells and chromatids separate
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Oogenesis
•Ovaries produce egg
•Process similar to spermatogenesis
•Difference
–One egg
–Three polar bodies
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Male Reproductive System
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Female Reproductive System
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Mating Process
•Estrus occurs at about ovulation
–Female allows male to mate
–Females may be aggressive
–Males may be belligerent
•Act of mating deposits sperm in female’stract
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Fertilization
•Sperm and egg join in fallopian tube
–Egg secretes attracting chemical
–Many sperm dissolve egg membrane
–One sperm enters
–Fertilization membrane forms
•Processes ensure female stays pregnant
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Artificial Insemination Basics
•Process
–Collect sperm
–Deposit in female reproductive tract
•Advantages
–Use/select superior males at low cost
–Greater reliability
–Lower disease occurrence
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Semen Collection
•Animal mounts dummy
•Animal ejaculates
•Semen collects in ampule
•Semen is inspected
•Semen is processed via extender
•Semen is placed in straws
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Process of Artificial Insemination
•Female comes into estrus
•Semen is thawed immediately prior
•Straw placed in tubelike instrument
•Instrument placed in female tract
•Technician releases semen
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Embryo Transplant Basics
•Transplant embryos between females
•High-quality females have many offspring
•Inferior females carry
•Most feasible with cattle
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Estrus Synchronization
•Transfer embryo from donor to recipient atonce
•Process
–Get donor and recipient in estrus
–Donors undergo superovulation
–Donors/recipients brought into estrus
–Donor bred or artificially inseminated
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Embryo Transfer Process
•Prostaglandin is injected
•Estrus about ~48 hours later
•Fertilization occurs
•Embryos are collected/examined
•Recipient brought into estrus
•Embryo placed in recipient uterus
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Cloning
•Make genetically identical offspring
•Process
–Multiply one egg
–Remove another egg’s nucleus/DNA
–Inject second egg from culture
–Transfer cell after division
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Summary
•Beginning to understand animalreproduction
•Through understanding can increaseefficiency of:
–Animal reproduction
–Food production