1. Animal Reproduction Animal Science II

2. 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

3. 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.

4. Methods of Reproduction Natural Artificial Insemination (AI) Embryo Transfer Cloning using Nuclear Transfer

5. 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

6. Artificial Insemination Bovine Reproductive Tract Diagram

7. Artificial Insemination Sow Reproductive Tract Diagram

8. Artificial Insemination

11. 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

12. Artificial Insemination

13. Disadvantages –Requires a trained inseminator –Requires more time and herd supervision

14. 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

15. Embryo Transfer Advantage –Genes of the female (dam) can be passed on faster than natural breeding

16. Cloning Using Nuclear Transfer Procedures –Flush (same as embryo transfer) –Filter –Remove genetic materials from recipient oocytes –Nuclei is removed through microsurgery

17. 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

18. Cloning Advantages –Increase herd uniformity –Increase herd quality –Produce genetically identical animals

19. Parturition Process Increased estrogen causes uterus muscles to contract Water bag appears and breaks The second water bag appears with the fetus

20. 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

21. Parturition Process Several hours later the placenta and other membranes (afterbirth) are expelled –A retained placenta is deadly