Assisted Reproductive Technologies Flashcards

1
Q

What are the main assisted reproductive technologies?

A
  • Artifical insemination
  • Semen sorting
  • Multiple ovulation & embryo transfer
  • IV production of embryos
  • Cloning
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2
Q

Name 4 ways hormones can be manipulated to control reproductive cycles

A
  • Breeding season extension
  • Oestrus synchronisation
  • Multiple ovulation
  • Hormonal treatments of infertility
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3
Q

How is oestrus synchronisation carried out?

A
  • Injections of progesterone - inhibit oestrus by preventing release of GnRH, LH & FSH & ovulation
  • Treatment must be long enough to allow CL to regress to obtain synchronisation
  • Oestrus & ovulation are prevented until treatment is withdrawn
  • Once withdrawn, the pulsed release of GnRH leads to LH/FSH release & oestrus in 2-6 days
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4
Q

What have progesterone injections been replaced with?

A

Synthetic progestins in the form of implants or topical applications

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5
Q

Give 4 management advantages to synchronising oestrus cycles

A
  • Numbers of females can be brought into oestrus at the same time so can be ‘batched’
  • Allows scheduling of handling tasks
  • Reduces time spent on oestrus detection
  • In some species, this allows the breeder to shift the breeding process (planning parturition so offspring ready form market at most profitable time)
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6
Q

Give 4 problems that can arise when synchronising oestrus in cattle

A
  • Conception rates are about 15% below normal (can be improved by combining progestin and
    oestrogen)
  • Treatment of undetected already pregnant animals can cause abortion
  • Animals must be cycling and not in the post-partum anoestrus phase
  • Heifers must be checked to ensure they have reached puberty
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7
Q

What can testosterone replacement therapy be used to treat?

A
  • Hypogonadism
  • Androgen deficiency
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8
Q

What is a negative result of testosterone replacement therapy?

A

Exogenous testosterone adversely spermatogenesis

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9
Q

How can injections with human chorionic gonadotropin aid in fertility?

A
  • HCG stimulates leydig cell production of testosterone so helps to maintain or increase intratesticular level of testosterone
  • In non ovulating females, can stimulate follicular development in ovaries, leading to ovulation
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10
Q

Give an example of a selective oestrogen receptor modulator

A
  • Clomiphene
  • Induces ovulation by inhibiting oestrogen receptors in hypothalamus, blocking negative feedback of oestrogen on gonadatropin release
  • Hypothalamus perceives low levels of LH/FSH so trigger pituitary to produce more
  • Can also be used on males to stimulate testosterone production
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11
Q

What is artificial insemination?

A
  • Allows fertilisation with semen from specific individuals or strains from anywhere without transporting animals
  • Can also be used in conservation of breeding programs
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12
Q

How is artificial insemination carried out?

A
  • Semen collected from male
  • Frozen in plastic tubes (straws)
  • Mixed with solution containing glycerol or other cryoprotectants
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13
Q

Give 4 advantages of artificial insemination

A
  1. Allows insemination of a large number of females from a single mate
  2. Allows control of paternity of offspring
  3. Overcomes physical breeding difficulties in some species
  4. Avoids injury to valuable animals during natural mating
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14
Q

What is intrauterine insemination?

A
  • Effectively AI
  • Inserts semen sample into uterus just before ovulation
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15
Q

What is the goal with sexed semen?

A
  • To produce a calf of a specific sex
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