11:067:327 Lecture Notes - Lecture 10: Alpha-Fetoprotein, Thelarche, Pulse Generator
25 Apr 2016
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Document Summary
Age at 1st estrus (heat) displays behavioral signs of sexual receptivity. Age at 1st ovulation difficult to detect. Expression of behaviors mounting and erection occur early. Full development of nerves, muscles and accessory glands. Sperm in the ejaculate collect ejaculates, analyse. Sperm appear in urine sperm lost in urine during sexual rest. Threshold number of sperm achieved in the ejaculate. Energy for sperm production and copulation is minimal. Metabolic status and onset of puberty is less critical. Season of birth (fall, 10-12 months vs spring, 5-6 months) Photoperiod (long, 17 day estrus interval vs short days, 66 day) In ewe, doe, sow, and cow male presence enhance puberty onset. Useful management tool to improve animal production. Volatile signal remove olfactory bulb stops cycling. Requires hypothalamic gnrh pulses increased frequency and amps. Influenced by genetics, energy metabolism, body size, external and social modulators. Gnrh neurons must be capable of pulsatile release of gnrh. Body size/composition fatness for reproductive cycling.
