REPRODUCTION & GENETICS Hormones http://www.youtube.com/watch?v=np0wfu_mgzo
Objectives 2 Define what hormones are; Compare and contrast the male and female hormones; Explain what each hormone in the mail reproductive system does; Describe what the hypothalamus gland secretes; Describe what the pituitary gland secretes;
Objectives 3 Write which hormones are specific to females; Identify the difference between estrous and estrus; Outline the estrous cycle for a cow; and Explain what happens during estrus.
Hormones 4 Chemicals secreted by an animal that affect other parts of the organism.
Hormones in Male Reproduction 5 Gonadotropic Releasing Hormone (GnRH) hormone that stimulates the gonads Follicle Stimulating Hormone (FSH) Causes production of sperm cells
Hormones in Male Reproduction 6 Luteinizing Hormone (LH) Causes endocrine cells in the testes to produce the male hormone Testosterone Testosterone Steroid hormone responsible for the growth and development of secondary sex characteristics in a male such as growth and maintenance of male sex organs and the production of sperm
Hormones are Secreted from 7 Glands Hypothalamus Area of the brain directly above the pituitary that produces one of the hormones which control reproduction GnRH Pituitary gland situated beneath and stimulated by the hyphalamus releases FSH and LH which serve such functions as stimulating production of sperm & testosterone in males
Female Hormones 8 GnRH stimulates the gonads Acts as a light switch turning FSH and LH on and off Released by? Follicle Stimulating Hormone (FSH) Signals the follicle on the ovary to begin production of an egg Released by? Luteinizing Hormone (LH) causes follicles to undergo changes which lead to egg release Released by?
Female Hormones 9 Estrogen As the follicle grows larger, it begins to secrete more and more estrogen. Affects the nervous system causing restlessness, the desire to mount other animals. Causes the signs of heat and it causes the female to accept service from the male. (Released by the follicle) Progesterone yellow body secretes this hormone Hormone that maintains pregnancy Prepares the uterus for pregnancy and prevents the heat cycle
Estrous vs Estrus 10 Estrous series of events occurring in the ovaries and other female reproductive organs Average cow heat estrous cycle 21 days Estrus Portion of the female reproductive cycle when cows and heifers are sexually active, receptive and fertile. Cattle estrus lasts about 18 hours
The Estrous Cycle 11 Day 1: Estrus Day the heifer is sexually receptive to the male and fertilization of the egg may occur Estrogen production is high at this point Day 2-6: Developing Corpus Luteum replaces the follicle, secretes progesterone and some estrogen, and prepares the uterus for pregnancy and prevents heat
The Estrous Cycle 12 Day 7-16: Developed Corpus Lueteum Will stay in this stage if pregnant, secreting progesterone and some estrogen to prevent heat and maintain pregnancy
The Estrous Cycle 13 Day 17-21: Regressing CL Stage CL regresses size and produces less progesterone Follicle begins to grow and mature releasing more estrogen Growth of follicle happens due to the Anterior pituitary producing FSH and LH (Follicular Phase)
Estrus (Day 1) 14 Period of time the cow will accept service Ovulation actually occurs after this period of time. Ovulation actual release of the mature egg from the follicle. occurs about 10 to 14 hours after the end of heat.
Estrus (Day 1) 15 A sharp increase in Luteinizing Hormone causes the follicle to rupture and the egg to release It also stimulates the corpus luteum to develop from the ruptured follicle so progesterone can be produced to help maintain pregnancy, if it occurs. Actual fertilization does not occur until after heat; however the male was accepted during heat.
16 ABS Global Inc. A.I. Management Manual
17 ABS Global Inc. A.I. Management Manual