Reaching Puberty Flashcards
What is puberty?
Period where the animal acquire reproductive competence
Why do producers want the animal to reach puberty as soon as possible?
They want to minimize the cost of production
Average age of puberty in the following species
Alpaca
Male: 2
Female 1
Average age of puberty in the following species
Bovine
Male 11 months
Female 11 months
Average age of puberty in the following species
Camel
Male: 3-5yrs
Female: 3 yrs
Average age of puberty in the following species
Canine
Male 9 months
Female 12 months
Average age of puberty in the following species
Equine
Male 14 months
Female 18months
Average age of puberty in the following species
Feline
Male 9 months
Female 8 months
Average age of puberty in the following species
Llama
Male 2-3 yrs
Female 6-12 months
Average age of puberty in the following species
Ovine
Male and Femal 7 months
Average age of puberty in the following species
Porcine
Male 7 months
Female 6 months
What for things influence puberty?
Hormones
Genetic
Nutritional conditions
Environmental Conditions
Two Centeres in brain that influence puberty
Surge Center: Release a boost of GnRH
Tonic Center: Release Small amount of GnRH
What is GnRH?
Small decapeptide that causes the release of gonadotrophins FSH and LH from anterior lobe of the pituitary
Explain the influence of estradiol or testosterone on the surge center
Female fetal ovaries produce Estradiol which binds with a protein called - AlphaFP, this complex can not pass the BBB. Therefore surge center develops
Male Fetal testis produce testosterone, AlphaFP does not bind to Testosterone. Testosterone passes through BBB into brain and is converted to Estradiol by Aromatase. Surge center does not develop due to presence of estradiol
What occurs with increased amounts of GnRH?
Increased amount of gonadotrophin hormones
What occurs in females that does not occur in males with regards to release of LH
Surge of LH occurs in females because they have a surge center
Why do we want low levels of GnRH prepuberty?
GnRH triggers for estrus cycle to begin. We dont want ovaries to enter estrus cycle
With regards to estradiol, what occurs in the brain at puberty?
Negative sensitivity to estradiol is reduced and a higher release of GnRH is observed
Explain the experiment used to show the importance of internal energy
Add deoxyglucose which ends glycolysis thus resulting in a lack of energy. By doing this we see a decrease of LH production. This is because we need energy to produce GnRH which is required to release LH
General discription of the effect of nutrition on puberty
Over feeding can cause an early onset of puberty
Underfeeding can delay puberty
What is the influence of season on puberty?
Length of Light triggers or halts onset of puberty
Spring birth results in a shorter prepuberty phase
Two types of environmental influence
Seasonal
Visual and Olfactive
Explain influence of visual and olfactive cues
- Decrease number of females in a pin increase prepubertal period
- Introduce male no physical contact shorten prepubertal period
- Introduce male with physical contact, shorten prepubertal period, however, not more so than no physcial contact
When does the first discharge of LH appear in a bull?
Around 4 weeks and the next ones are at irregular interval (25hrs)
What occurs to the discharge of LH in bull at 8 weeks?
Interval shorten from 25 hrs to 6hrs
What is the role of FSH in prepuberty?
Insures that leydig cells do not multipy
What affect does LH have on FSH
Causes reduction of FSH - Leydig can multiply and produce testosterone
