© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 11 Animal Reproduction

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Animal Reproduction Overview Perhaps most important part of animal industry Animals must reproduce efficiently –Complicated process –Requires systems to work together –Occurs sexually

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Production of Gametes Spermatogenesis (sperm) Oogenesis (egg)

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Spermatogenesis Testes produce sperm Four-step process –Replication –Chromatids pair (synapsis) –Cell divides, chromosome separate –Cells and chromatids separate

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Oogenesis Ovaries produce egg Process similar to spermatogenesis Difference –One egg –Three polar bodies

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Male Reproductive System

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Female Reproductive System

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Artificial Insemination Basics Process –Collect sperm –Deposit in female reproductive tract Advantages –Use/select superior males at low cost –Greater reliability –Lower disease occurrence

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Semen Collection Animal mounts dummy Animal ejaculates Semen collects in ampule Semen is inspected Semen is processed via extender Semen is placed in straws

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Embryo Transplant Basics Transplant embryos between females High-quality females have many offspring Inferior females carry Most feasible with cattle

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 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

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Cloning Make genetically identical offspring Process –Multiply one egg –Remove another egg’s nucleus/DNA –Inject second egg from culture –Transfer cell after division

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary Beginning to understand animal reproduction Through understanding can increase efficiency of: –Animal reproduction –Food production