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Animal Reproduction. Animal Science II. Estrus Cycle. Time of day when a female will accept a male for breeding Length 21 day cycle Cow- 16-18 hours Sow- 2 days Best indicator is when the animal stand to be mounted. Ovulation. Release of the egg from the ovary
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Animal Reproduction Animal Science II
Estrus Cycle • Time of day when a female will accept a male for breeding • Length • 21 day cycle • Cow- 16-18 hours • Sow- 2 days • Best indicator is when the animal stand to be mounted
Ovulation • Release of the egg from the ovary • Number of young born is an indicator of eggs released • Sows: 10 to 15 • Cow: One • Split eggs produce identical twins, triplets, etc.
Methods of Reproduction • Natural • Artificial Insemination (AI) • Embryo Transfer • Cloning using Nuclear Transfer
Artificial Insemination • Steps • Insert hand into the rectum and grasp cervix • Insert insemination rod • Deposit bull semen from the middle of the cervix to just into the uterus
Artificial Insemination Bovine Reproductive Tract Diagram
Artificial Insemination Sow Reproductive Tract Diagram
Artificial Insemination • Advantages • Wider variety of superior bulls used • Increase number of cows that can be bread to a superior bull • Reduces disease • Don’t have to keep a bull on the farm
Artificial Insemination • Disadvantages • Requires a trained inseminator • Requires more time and herd supervision
Embryo Transfer • Procedures • Superovulate donor • AI • Flush embryos (catheter) • Isolate and classify embryos • Store in liquid nitrogen • Transfer to recipient • Diagnose pregnancy 1 to 3 months later
Embryo Transfer • Advantage • Genes of the female (dam) can be passed on faster than natural breeding
Cloning • Using Nuclear Transfer • Procedures • Flush (same as embryo transfer) • Filter • Remove genetic materials from recipient oocytes • Nuclei is removed through microsurgery
Cloning • Procedures (continued) • The nuclei are separated and each one is transferred to an unfertilized egg cell that has had its nucleus removed • Plugs are placed in sheep for 5 to 6 days (develops to the 32 to 64 cell stage) • Embryos are placed in surrogate, frozen or used to clone more animals
Cloning • Advantages • Increase herd uniformity • Increase herd quality • Produce genetically identical animals
Parturition Process • Increased estrogen causes uterus muscles to contract • Water bag appears and breaks • The second water bag appears with the fetus
Parturition Process • Normal Presentation • Front feet first • Nose • Head and shoulders • Hips • Rear legs • Rear feet last • Any presentation not in order could cause death of the baby and/or mother
Parturition Process • Several hours later the placenta and other membranes (afterbirth) are expelled • A retained placenta is deadly