Reproduction 2015 Flashcards
Name the structure that holds the uterus and ovaries in their proper position.
Broad ligament
Name the site where semen is deposited during natural service and during AI.
Natural - vagina
AI - in uterus
What are the two main functions of the ovaries?
Production of eggs
Secretes hormones essential for reproduction
What percentage of the cow’s ova were present at birth?
100%
The process of releasing an ovum from the follicle on the ovary is known by what term?
ovulation
After release from the follicle, how many hours will the ovum be fertile?
6-12 hours
What is the name of the temporary gland that forms on the ovary after the ovum is released?
Corpus luteum, or yellow body
Which reproductive hormone is produced in the hypothalamus of both cows and bulls?
Gonadotropin releasing hormone (GnRH)
GnRH causes the release of which two reproductive hormones?
LH and FSH
The follicle stimulating hormone stimulates the growth of what?
Ovarian follicles
Which reproductive hormone produced by the ovarian follicles causes estrus and peaks at the onset of standing heat?
estrogen
Which reproductive hormone is produced by the corpus luteum?
progesterone
What function does progesterone have in cows?
Necessary to maintain pregnancy by inhibiting release of GnRH
What function does prostaglandin have in the female reproductive cycle?
Restarts the estrous cycle by destroying the corpus luteum
Which reproductive hormone helps deliver the calf by stimulating muscular contractions of the uterus?
Oxytocin
Which reproductive hormone helps deliver the calf, by causing the tissue in the birth canal to relax?
Relaxin
What is the purpose of the female reproductive hormone prolactin?
Stimulate the udder to grow and start producing milk.
What is the normal range in length of the estrous cycle?
18-24 days
What is the average number of days between estrous cycles?
21 days
How many phases of the estrous cycle are there?
2 phases
Name and describe the two phases of the estrous cycle.
Follicular - active follicles are present
Luteal - corpus luteum is dominant ovarian structure
How many stages of the estrous cycle are there?
4
Name and describe the four stages of the estrous cycle.
Estrus - heat period
Metestrus - transition
Diestrus - corpus luteum present
Proestrus - prior to estrus
Name the term used to describe follicular development.
Follicular wave
Name the five phases of a follicular wave.
Recruitment, selection, growth, dominance, regression
Approximately how many follicular waves occur during an estrous cycle in cattle?
2-3 follicular waves
The period of heat in dairy cattle is known as what?
estrus
What is the duration of standing heat, and what is the average length?
Standing heat lasts 2-12 hours, with an average of 7 hours
What is the most common reason a cow does not come back into heat?
Pregnancy
What percentage of pregnant cows exhibit signs of estrus?
3-5%
Describe the levels of milk progesterone during estrus?
Progesterone levels are low
Identify the condition when the physical signs of heat are difficult to detect.
Silent heat
What term is used to describe the failure to have an estrous cycle?
Anestrus
Name five signs of estrus in dairy cattle.
Restlessness, bellowing, following and smelling another cow, mounting another cow, standing to be mounted, clear mucus discharge from vulva, vulva becomes red and swollen
What is the most reliable sign of estrus?
Standing to be mounted
Name five estrous synchronization programs.
CIDR, Ovsynch, Pre-Synch, Co-Synch, Heat-Synch
Name five heat detection aids used on dairy farms.
Heat expectancy charts, tail chalk, pedometers, accelerometers, pressure sensors, detector animals, electronic heat detection systems
Freezing semen from a bull and thawing it later to fertilize ova, is known as what process?
artificial insemination
Name 5 advantages of using artificial insemination over natural selection.
safety, genetic improvement, better disease control, better record keeping, easier to prove bulls, less expensive than keeping a bull
Approximately how long after the onset of standing heat, should a cow be artificially inseminated?
5-15 hours
The thin cylinder used to preserve frozen semen is known by what term?
A French straw
Name the element and its state used to freeze and store frozen semen.
liquid nitrogen
What is the temperature of liquid nitrogen?
-320º
Frozen semen should be thawed using what temperature of water and for how long?
90-95º for a minimum of 40 seconds
Why is it necessary to use the proper temperature of water for the appropriate time?
using the correct time and temperature of water will maximize the number of motile sperm
The process of joining an ovum and a sperm is known by what term?
fertilization
Where does fertilization take place?
oviduct
What is a zygote?
fertilized ovum
Where does the fetus grow and develop?
uterus
The process of removing a fertilized ovum from a donor cow and transferring it to another cow or heifer is known by what term?
embryo transfer
About how many days after breeding, are embryo transfers conducted?
7-8 days after breeding
What is name given to a cow or heifer that receives a fertilized ovum from a donor cow?
recipient
What hormone is given to the cow in the process of superovulation?
follicle stimulating hormone
Why is a cow given FSH during super ovulation?
to increase the number of ova produced by the cow
Name the process which uses ultrasonography to view the ovary while removing oocytes through the vagina using a needle.
transvaginal aspiration
Conception rate is defined as the percent of what?
percent of breedings that result in a preganancy
Name three factors that affect a dairy herd’s connection rate.
heat detection accuracy, cow fertility, bull fertility, technician competency
Name five reasons that a herd doesn’t become pregnant when bred by artificial insemination.
failure to ovulate, fertilization failure, hormone imbalance, poor quality semen, failure to inseminate, improper insemination technique, heat detection errors
The term pregnancy rate is a percentage that represents what?
percent of cows that become pregnant out of those eligible to become pregnant in a given period of time
What is the usual length of time over which the pregnancy rate of a herd is determined?
21 days
The pregnancy rate is the combined effect of what two other rates?
heat detection rate and conception rate
How often is the pregnancy rate calculated and why?
it is calculated every 21 days, because that is the average length of the dairy cow’s estrous cycle
For which types of herds can the pregnancy rate be calculated?
Iy can be calculated for AI herds, bull bred herds, or a combination of both
Through which structure does the fetus receives all of its nutrients?
placenta
Name the two structures which attach the placenta to the uterus.
maternal caruncles and fetal cotyledons
What is the condition called when the fetal membranes remain attached to the maternal caruncles for greater than 24 hours?
retained placenta
During which season is the rate of retained placenta the highest?
summer
What is gestation and when does it begin and end?
the period of pregnancy, it begins at fertilization and ends at birth
What is the average length of gestation?
276 to 292 days
Name 5 factors that can affect the length of gestation.
age of the cow, breed of the cow, sex of the calf, number of calves carried, season of the year
Which breed of dairy cattle has the longest gestation period?
Brown Swiss
Name the technical term for the act of giving birth.
partuition
Name the hormone released by a pregnant cow, which is triggered by her calf’s response to stress.
cortisol
Why is the hormone relaxin released by the cow, just prior to calving?
the hormone relaxin enables the cervix to soften and stretch, in preparation for expelling the calf
Give 5 signs a cow is near calving.
udder full, vulva enlarged, mucus discharge, relaxation of ligaments at tail head, restlessness
What is the normal birth position of a calf?
front feet first with its head between the legs
What is the main function of a bull’s testes?
to produce sperm and to produce the male sex hormones
Cryptorchidism is what condition?
when one or both testes fail to descend from the abdomen into the scrotum
The condition of cryptorchidism may affect what?
fertility
The epididymus is the structure in the bull which stores what?
mature sperm
Approximately how long does sperm live after being deposited in the cow’s reproductive tract?
24-30 hours
Approximately how long does it take for the sperm to become capacitated?
6 hours
Name the primary sugar found in sperm.
fructose
What acid is produced by sperm during metabolism?
lactic acid
Name the two male reproductive hormones which stimulate sperm production.
FSH and LH
Name the male reproductive hormone which is responsible for the male sex drive.
testosterone
In reproductive terms, what do the letters VWP mean?
voluntary waiting period
How long is the most common Voluntary Waiting Period?
60 days
Define the term voluntary waiting period.
the time period after calving when the dairy producer chooses not to breed a cow
“Days to first service” is a term which describes what time period?
the days from calving until first breeding date
The period of time from one calving until the next calving, is known by what term?
calving interval
Name 4 factors which can affect the calving interval.
voluntary waiting period, heat detection, conception rate reproductive culling
The acronym SCR stands for what?
sire conception rate
The evaluation of artificial insemination service-sire fertility is known by what term?
sire conception rate
Name 5 uses for ultrasound in a reproductive management program.
pregnancy determination, determine embryonic losses, determine if twins are being carried, monitor cystic ovaries, determine sex of embryo
What is the number one reason for culling in U.S. dairy herds?
reproductive failure
What is involution?
the process where the uterus returns to normal size after calving
Approximately how many days does it take for a cow’s reproductive tract to return to normal?
30 - 45 days
What is the term used to describe an infection of the uterus?
metritis
Endometritis is an inflammation of what?
uterine lining
During what season of the year, is the incidence of endometritis the greatest?
summer
Sterility describes an animal that cannot do what?
cannot reproduce
The premature expulsion of a fetus is known by what term?
abortion
Name 5 dieseases that cause abortions in dairy cattle.
brucellosis, chlamydia, IBR, leptospirosis, listeriosis, neospora, trichomoniasis, vibriosis
Approximately 12-14% of problem breeders are found to have what reproductive problem?
cystic ovaries
Approximately what percentage of dairy cows will develop cystic ovaries over their lifetime?
10-40%
What are the three types of cystic ovaries?
follicular cysts, luteal cysts, cystic corpus lutea
Thin-walled, non-ovulating ovarian cysts, which secretes variable amounts of estrogen, are known as what type of cyst?
follicular cysts
Thick-walled ovarian cysts which secrete low levels of progesterone, are known as what type of cyst?
luteal cysts
Which type of ovarian cyst is most like normal corpora lutea?
cystic corpus lutea
Name 3 disadvantages to twinning in dairy cattle.
reduced milk production during lactation, calving difficulties are more frequent, abortion rates are higher, twins are often weak at birth, potential for a freemartin heifer
What is a freemartin?
a sterile heifer born twin to a bull
What percentage of heifers born twin to a bull are sterile?
90%
Why is it important to feed appropriate amounts of grain and silage?
To ensure maximum growth potential of the calf, without excessive weight gain
Why is it important to transition your animal to a diet similar to what it will have at a show?
so the animal does not go off feed and to prevent stomach problems
Why is it important to constantly monitor your animals body condition?
to adjust their diet as needed to prevent excess fat, or ensure proper growth
Why is dehorning of calves an encouraged management practice in the dairy industry?
for the safety of the animal, other animals and people
