for cattle, horses, and sheep, what is the effect of gender on growth?
male > castrated male > female
consider the effects of diet on growth of a fetus. use versus cattle to discuss homeorhesis.
underfed pregnant cows: no effect on fetus growth
underfed pregnant ewes: decreased fetal growth, ewes have lower homeorhesis priority for pregnancy/fetal growth
consider dairy cattle from birth to first parturition, describe, with attention to age and units, the growth. also after first parturition describe the calving interval and lengths associated with pregnancy and lactation.
wean: 1.5 months
puberty: 9-12 months
conception: 15 months
first parturition: 24 months
non pregnant: 82 days
pregnant: 283 days
lactation: 305 days
dry period: 60 days
calving interval goal one per year
consider horses, from birth to first parturition, describe, with attention to age and units, the growth. also after first parturition describe the calving interval and lengths associated with pregnancy and lactation.
wean: 3-4 months
puberty: 18 months
conception: 36 months
first foal: 47-48 months
conception at second foal estrus: 30 days post parturition
pregnant: 335 days
lactation: 2-4 months
dry period: 8-10 months
foaling interval one per year
describe spermatogenesis in males.
1: proliferation- of stem cell pool MITOSIS
2: Differentiation- meiosis I= DNA replication normal DNA but haploid chromosome number. meiosis II= no DNA replication DNA reduced 50% in new cells. Metamorphosis= spermiogenesis shape change from cuboidal to teardrop
what is the first cell that does not have a complete set of chromosomes?
describe the effect of heat on fertility in males
this leads to infertility due to sensitivity of meiotic steps to heat, infertility can occur immediatly or several weeks after hyperthermia of testes. (duration can vary widely)
describe spermatogenic wave
different stages of the spermatogenic cycle distributed along length of a seminiferous tubule
what is the significance of spermatogenic waves?
allows for continual production of spermatozoa
describe the path of sperm out of the testes.
start in seminiferous tubules, to rete testis, to ductus efferens, to capa epidiymis, to corpus epidiymis, to cauda epididymus, to vas deferens.
what is the effect of ACTIVIN on spermatogenesis
it is mitogenic and increases DNA synthesis
what is the effect of INHIBIN βA on spermatogenesis?
decreased DNA synthesis
what is the effect of TGF-β1on spermatogenesis?
increased DNA synthesis
what event must take place in the environment of the female vagina that allows for a sperm cell to fertilize an oocyte.
define sexual differentiation using no more than 10 words
process that creates sexual phenotype
define freemartin using no more than 10 words
phenotypically masculinizing a genotypic female co-twin
schedules for artificial insemination 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.
timing of ovulation
fertile life of oocyte
time required for capacitation and transport of spermatazoa
fertile life and adequate number of spermatazoa
what issue is the most important for scheduling of AI? EXPLAIN.
fertile life of oocyte, it is the shortest interval
time of ovulation, if not calculated correctly, can miss it with AI too late and capacitation takes too long= no fertilization.
what is the weakness of the am pm rule in AI for farm animals?
am pm rule only works properly given that detection of estrus is accurate. if detect estrus too late with am pm rule AI will be too late to fertilize the oocyte before it becomes in-viable
what is the fertilization area within the reproduction tract?
defend or refute, the two major reproductive goals of beef cattle and dairy cattle are different. EXPLAIN.
REFUTE. the two major goals are identicle, age at first parturition ~ 2yrs of age and calving interval ~ 365 days long
use narrative and numbers to state the two major reproductive goals in horse females
first parturition at ~4 yrs of age
successive foaling at 12 months
use narrative and numbers to state the two major reproductive goals in swine females
first parturition at ~12 months of age
successive farrowing at 150 days
defend or refute. Estradiol exerts a direct and indirect regulatory effect on function and life span of a corpus luteum in most mammalian livestock females. EXLPAIN
direct effect- decrease activity of 3-β hydroxysteroid dehydrogenase so less pregnenelone. decrease progesterone.
indirect- increase prostoglandin F2α from endometrium which decreases progesterone
define functional genomics
method to screen activity of entire genome--active vs. not
as a researcher why might you choose to use functional genomics as a tool?
investigate interactions among genes per physiological group
what is a knock out?
eliminate activity/expression of a gene
what is a common objective for using "knock-outs"?
to determine all effects of specific gene
during an estrous cycle, when does diapedesis occur?
including cause describe/define diapedesis.
leaky capillary due to decreased estradiol
define recruitment of follicles. what factor(s) regulate recruitment.
primordial follicles change to primary follicles. species and age determine when this will happen
describe a dominant follicle
largest, most granulosa cells, highest estradiol production
including numbers and time, describe A non-ovulatory follicular wave in mares.
overall duration~~ 7-10 days
~~20 follicles become primary, 1 becomes dominant; 19 atretic.
consider diestrus in a non-pregnant species of livestock that is not a mare. what ovarian structures are present and prominent?
dominant follicle- intermittent
name and describe the strategies for MROP in horses.
name and describe the strategies for MROP in sheep
name and describe the strategies for MROP in swine
anti-luteolytic and luteotropic
name and describe the strategies for MROP in cattle
what is a repartitioning agent in use for swine
what is a repartitioning agent in use for cattle
describe features of a beef cow that will almost certainly experience prolonged postpartum an-ovulation. use cryptic descriptive phrases, not complete sentences.
calf suckles aggressively
low NE in diet postpartum
describe foal heat
estrus and ovulation 7-10 days after parturition
why do cattle and swine not experience an equal version of foal heat?
suckling delays estrus/ovulation
name three major events (not lactation or welfare) prepartum that must occur for successive parturition, include key regulatory hormone for each.
decreased inhibin to myometrium-decreased progesterone