Test 2 ANSC 333
what parts of the hypothalamus does the female have - ANS-Surge and Tonic center
what parts of the hypothalamus does the male have? - ANS-only the tonic center
Developing of the hypothalamus in females - ANS--happens during fetal life
-ovaries make estradiol that enters circulation and are chaperoned by alpha-fetoprotein
(aFP) to the blood-brain barrier
-complex bounces off the barrier and triggers the tonic and surge center to develop
Developing the hypothalamus in males - ANS--happens during fetal life
-testes make testosterone that isn't chaperoned and enters the blood
-passes the blood brain barrier and is converted into estradiol by aromatase
-estradiol prevents surge center from developing
Secretions in males - ANS--measured by LH because GnRH is hard to measure as it
taken out of circulation as it binds in the anterior pituitary gland from the hypothalamus
(LH is easier to trace as it has to go from the brain to the gonads)
-peak of GnRH right before peak of LH
-LH acts on leydig cells to make testosterone
-pulses every 4 to 6 hours from puberty to death
secretions in females - ANS--predominant period of low amplitude and frequency and
giant surges of GnRH causing LH
-surges happen every 21 days (cattle) because of estrus (dominant follicle increases
estrogen, increases GnRH so the surge center is activated and increases LH)
secretions before and after puberty - ANS--before puberty, low amplitude and irregular
GnRH
-after puberty, regular pulses of GnRH and surges when in estrus
-in the field, measure levels of progesterone in corpus luteum
factors that contribute to the age an individual reaches puberty - ANS--genetics
-environment
-short term nutrition
-long term nutrition
-photo period
, genetics and puberty - ANS--in cows, bos torus--> small frame dairy cattle (Jersey)
obtain puberty faster than small frame meat breeds (Angus) and Angus obtain faster
than large sire breeds (Limousin, Charolais)
-more masculine= later puberty
-bos indcus obtain puberty 4 to 6 months later than bos torus
-larger sire scrotal circumference= daughters with earlier puberty ages
Acute Nutrition and Puberty - ANS--least observable in production
-measured in hours
-tested with rats that have already achieved puberty and given 2DG (2-dexoglucose)
that prevents the body from receiving glucose
-causes body to temporarily shut down GnRH and LH production
-monogastrics more affected by this because ruminant prevents the body from feeling
lack of resources
Long term nutrition and Puberty - ANS--measured in months
-associate with weight and composition (fat as its an energy reserve)
-for cattle, we say a female is at puberty weight when she reaches 60% of her total body
weight (pregnant before then it permanently affects the heifers overall body weight)
-for heifers we want them calving by 24 months, bred by 15 months
-controlled by Kisspeptin hormones
When do we breed first time heifers? - ANS--early in the season so they have more time
to recover on the backside so they can join the mature cow herd and efficiently be bred
When do we get the earliest puberty age in regards to long term nutritional rates? -
ANS-When we feed high quality feed and supplements, but this isn't always
economically reasonable
Kisspeptin neurons - ANS-act like air traffic control center and takes signals from
glucose, neuropeptide y neurons, fatty acids neurons, Leptide (adipocytes, fat long
term) and pheromones
behavior and social environment and puberty - ANS--as you increase the number of
gilts in the pin puberty is 28 weeks
-decrease number of gilts puberty is 32 weeks
-add a boar in the pin or next to the pin puberty is 24 weeks (contact doesn't change
anything)
-pheromones enter the air and go into the Vomernasal passage causing females to
reach puberty early
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