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Animal Reproduction

Estrus Cycle. Time of day when a female will accept a male for breedingLength21 day cycleCow- 16-18 hoursSow- 2 daysBest indicator is when the animal stand to be mounted. Ovulation. Release of the egg from the ovaryNumber of young born is an indicator of eggs releasedSows: 10 to 15Cow: OneS

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Animal Reproduction

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    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

    7. Artificial Insemination

    8. Artificial Insemination

    9. Artificial Insemination

    10. Artificial Insemination

    11. 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

    12. Artificial Insemination

    13. Artificial Insemination 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

    22. Animal Genetics Genotype kinds of gene pairs the animal has

    23. Dominant Genes Genes in a pair that hides or dominates the effect of the other gene in the pair Indicated by upper-case letters P=polled

    24. Recessive Genes Genes that are hidden or covered by the dominant gene in the pair Indicated by lower-case letters p = horned

    25. Homozygous Homozygous gene pair carries two genes for the same trait PP = polled and polled.

    26. Heterozygous Heterozygous gene pairs carries two different genes that affect a trait Pp = polled, horned

    27. Sex Determination Half the sperm carries an X chromosome and one half carries a Y chromosome All the ova carry an X chromosome Male offspring in mammals XY Females XX In poultry the chromosome configuration is opposite of mammals

    28. Sex-Linked Characteristics Some traits are carried on only the X chromosome and some on only the Y chromosome Traits on the Y chromosome are transmitted only from fathers to sons Certain genes are expressed in only one sex although they are carried by both sexes milk production egg laying rooster tail feathers Sex-linked traits are often recessive and are covered by dominant genes

    30. Incomplete Dominance Takes place when one gene does not completely hide the effect of other gene The offspring has a mixture of the two traits Roan color is a mixture of red and white

    31. Linkage The tendency for certain traits to appear in groups in the offspring because the genes for those traits are located near each other on the chromosome and stay together to pass traits in groups

    32. Crossover Chromosomes cross over one another and split to form new chromosomes with different combinations of genes

    33. Crossover

    34. Mutation A new trait appears Did NOT exist in the genetics of either parent

    35. Punnett Square Used to predict the results of crossing animals Male gametes are shown across the top Female gametes are shown down the left side

    36. Punnett Square P= Polled p= horned Example: Two polled cattle that are homozygous for the polled trait

    37. Punnett Square N= Normal size n= Dwarfism Example: Normal size in cattle is dominant to dwarfism

    38. Punnett Square N= Normal size n= Dwarfism Example: What if both parents are carriers for a trait or disorder?

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