Puberty Flashcards

1
Q

Puberty

A

Ability to accomplish reproduction successfully. “Process” of acquiring reproductive competence.

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2
Q

Criteria/definitions for puberty in the female

A

Age at first ovulation (silent ovulation), age at first estrus, or age at which the female can support pregnancy without deleterious effects.

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3
Q

Which of the criteria/definitions for puberty in the female is most applicable practically?

A

Age at which the female can support pregnancy without deleterious effects

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4
Q

criteria/definitions for puberty in the male:

A

Age when behavioral traits are expressed
Age at first ejaculation
Age when sperm first appear in the ejaculate
Age when sperm appear in the urine
Age when the ejaculate contains a threshold number of sperm

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5
Q

What is the most valid criterion/definition for puberty in the male?

A

Age when the ejaculate contains a threshold number of sperm.

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6
Q

Average age of puberty in the female bovine:

A

11 months

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7
Q

Range of puberty age in the female bovine:

A

9-24 months

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8
Q

Average age of puberty in the male bovine:

A

11 months

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9
Q

Age range of puberty in the male bovine:

A

7-18 months

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10
Q

Average age of human male puberty:

A

13 years

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11
Q

Average age of human female puberty:

A

12 years

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12
Q

Is puberty sexual maturity?

A

No. Just because it can happen does not mean it should.

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13
Q

What is the fundamental requirement for the onset of puberty?

A

Secretion of GnRH at appropriate frequency and quantities to stimulate gonadotropin release form the AP

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14
Q

What does the secretion of GnRH at appropriate frequency and quantity, causing release of gonadotropins from the AP result in?

A

Promotion of gametogenesis, steroidogenesis, and development of reproductive tissues.

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15
Q

What are hormone levels like prior to puberty?

A

Low frequency and amplitude of GnRH, low LH and FSH in both males and females

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16
Q

LH pulse frequency and amplitude in the months leading up to puberty in heifers:

A

Increases months before puberty. It takes about 2 months before the pulse frequency is high enough to achieve puberty. Eventually get GnRH/LH surge

17
Q

Onset of puberty in males and females:

A

Decreased hypothalamic sensitivity to negative feedback to testosterone/estrogen.

18
Q

Puberty is associated with:

A

changes in feedback sensitivity of hypothalamus to estradiol.

19
Q

The first LH surges after puberty are:

A

not always associated with estrus

20
Q

What sensitizes the hypothalamus to estradiol to get behavioral estrus?

A

Progesterone

21
Q

What happens after the first LH surge?

A

“Silent” ovulation

22
Q

When does the first estrus begin, “silent” ovulation or first real ovulation?

A

First real ovulation

23
Q

When does sensitization to hypothalamus estradiol occur?

A

When progesterone increases after “silent” ovulation

24
Q

Changing features in peripuberal bulls:

A

Body conformation, increased aggressiveness and sexual desire, rapid growth of the penis and testicles, and separation of the penis from prepuce so extension is possible.

25
Q

Testes size =

A

sperm production

26
Q

Factors affecting age at puberty:

A

Genetics, metabolic/nutritional status, environment (seasonal breeders), and social cues (group housing)

27
Q

Example of genetics influencing age at puberty:

A

Breed
Holstein female age (months): 8.5, male age: 9
Brahman female age (months): 19, male age: 17

28
Q

Threshold of body size before puberty can be achieved means:

A

certain degree of “fatness” required for females

29
Q

How does availability of energy change with growth?

A

In growing animals: food goes to growth, very little body fate, no excess energy
In animals close to maturity: excess energy, glucose, fatty acids, fat deposition

30
Q

In seasonal breeders, _____________ influences age of puberty.

A

month of birth

31
Q

Age of puberty in spring born ewe lambs:

32
Q

Age of puberty in fall born ewe lambs:

33
Q

Group housing in males (effects on puberty onset):

A

Large groups: normal onset
Smaller groups: delayed onset

34
Q

Male exposure effect on puberty onset:

A

accelerated

35
Q

Detrimental factors affecting puberty age:

A

Any factor that slows growth rate and reduces mature size of animal
Ex) nutritional stress, heat stress, poor sanitation, poor health

36
Q

Minimizing age at puberty for males is _____ advantageous for females.

37
Q

How is minimizing age at puberty in males more advantageous?

A

Reduces reproductive “down time” and reduces generation interval

38
Q

Physiological demands of pregnancy/parturition/lactation limit:

A

benefits of hastening puberty in females