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Defend or Refute. based on the principle for sexual differentiation in mammals, it is possible to feminize a male. EXPLAIN
REFUTE. all embryos female unless masculinized. Y chromosome dominant. cannot feminize a male.
Define sexual differentiation. Use no more than 10 words.
process that creates sexual phenotype.
Define a Freemartin. Use no more than 10 words.
masculinize genotypic female co-twin
Start at conception and in sequence describe four key events and the cause for sexual differentiation in a stallion.
- Gonad-genital ridge-> Testes HY anitgen
- Tubular- wolffran ducts-> Vas deferens AMH
- Ext. genitalia-scrotum, penis DHT
- CNS-masculinize LHRH nuclei E2->T
schedules for artificial insemination(AI) are based on fundamental biological issues. Excluding seasonality and type of ovulator, describe four fundamental issues that determine schedule for AI in virtually all mammals.
- 1) timing ovulation
- 2) fertile life of oocyte
- 3) time required for capacitation and transport of spermatozoa
- 4) fertile life of adequate number of spermatozoa
select one of the issues from above 2a and defend as the most important to determine the schedule for artificial insemination.
- fertile life of oocyte-- shortest interval
- OR time of ovulation
what is the weakness of how the AM-PM Rule is applied/used to time AI in cattle?
failure to detect onset/start of estrus so AI is too late in many animals
Within the reproductive tract of female mammals, what is the location of fertilization?
Define puberty in female swine. No more than 10 words
first spontaneous ovulation.
A group of females have challenges with health and growth. Use a common theory for puberty to describe and explain the likely timing for occurrence of puberty in these females.
with health or growth limitations, accumulation of fat will be limiting. thus older when achieve threshold for fat to allow puberty.
Defend or Refute. the two major reproductive goals for beef cattle are different form the major reproductive goals for dairy cattle. EXPLAIN
- Refute. the two major goals are indentical-->
- age at 1st parturition and calving interval
Use narrative and numbers to state specifically two major goals for reproduction in horse and swine female.
- 1) Horse female: a. 1st parturition at 4 yrs
- b. successive foaling at 12 mo
- 2) Swine female: a. 1st partur at 11-12 mo
- b. successive farrowing at 150 days
Defend or Refute. Estradiol exerts a direct and indirect regulatory effect on the function and life span of a corpus luteum in most mammalian livestock females. EXPLAIN.
- direct- decrease activity of 3BHSD
- indirect- increase PGF2 from endometrium.
Defend or Refute. after ovulation, the ovulated follicle has no further functional significance and is reabsorbed.
REfute. granulosa and theca differentiate into luteal cells and become corpus luteum
from 2 to 18 days postestrus in a nonpregnant ewe, describe inventory of luteal cells in a corpus luteum and the association with function of that corpus luteum.
- small--> decrease as days progress
- large--> increase as days progress
During an estrus cycle, when does diapedsis occur?
including cause, describe/define diapedesis.
leaky capillaries due to decrease estradiol.
define follicular recruitment. what factors regulate recrutiment.
primordial follicle--> primary
Describe a dominant ovarian follicle.
largest, most granulosa, highest estradiol
Including numbers and time, describe a non-ovulatory follicular wave in mares.
- overall duration 7 to 10 days
- _ 20 follicles become primary
Define postpartum anovulation in beef cows.
interval>21 days with no ovluation
Describe features of a beef cow that almost certainly will experience very prolonged postpartum anovulation.
- -uterine infection
- -low NE in diet prepartum
Define "foal heat"
estrus and ovulation 7 to 10 days postpartum
Beef cows do not experience "calf heat" and sows do not experience "piglet heat" EXPLAIN
suckling delays estrus/ovulation
Exclude lactogenesis, start of lactation, and welfare of neonate and dam. Name 3 major prepartum changes or events that must occur for successful parturition.
1) ⇣ inhibition to myometrium--⇣P4
2) ⇡expulsive forces--⇡PGF2
3) soften cervix--relaxin
Defend or Refute. During parturition, myometrium is a target for oxytocin.
- Refute.Oxytocin binds to endometrium
- does not cause contractions
Provide the duration of gestation for horse, swine, sheep. Include units for time. Classify species according to need for corpus luteum during gestation. Indicate % of gestation that CL required.
- 1)Horses: 330days % 50/175d 15/53%
- 2)Swine: 114d % 114d 100%
- 3)Sheep: 145d % 55 33%