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Chapter 11. Animal Reproduction. Animal Reproduction Overview. Perhaps most important part of animal industry Animals must reproduce efficiently Complicated process Requires systems to work together Occurs sexually. Production of Gametes. Spermatogenesis (sperm) Oogenesis (egg).
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Chapter 11 Animal Reproduction
Animal Reproduction Overview • Perhaps most important part of animal industry • Animals must reproduce efficiently • Complicated process • Requires systems to work together • Occurs sexually
Production of Gametes • Spermatogenesis (sperm) • Oogenesis (egg)
Spermatogenesis • Testes produce sperm • Four-step process • Replication • Chromatids pair (synapsis) • Cell divides, chromosome separate • Cells and chromatids separate
Oogenesis • Ovaries produce egg • Process similar to spermatogenesis • Difference • One egg • Three polar bodies
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’s tract
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
Artificial Insemination Basics • Process • Collect sperm • Deposit in female reproductive tract • Advantages • Use/select superior males at low cost • Greater reliability • Lower disease occurrence
Semen Collection • Animal mounts dummy • Animal ejaculates • Semen collects in ampule • Semen is inspected • Semen is processed via extender • Semen is placed in straws
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
Embryo Transplant Basics • Transplant embryos between females • High-quality females have many offspring • Inferior females carry • Most feasible with cattle
Estrus Synchronization • Transfer embryo from donor to recipient at once • Process • Get donor and recipient in estrus • Donors undergo superovulation • Donors/recipients brought into estrus • Donor bred or artificially inseminated
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
Cloning • Make genetically identical offspring • Process • Multiply one egg • Remove another egg’s nucleus/DNA • Inject second egg from culture • Transfer cell after division
Summary • Beginning to understand animal reproduction • Through understanding can increase efficiency of: • Animal reproduction • Food production