Cattle Reproduction Flashcards
What is all livestock production based on?
Maximizing the reproductive ability of animals
Why is it important to understand the reproductive cycles of different animals?
It increases the frequency of offspring production
How many calves does a dairy cow need to produce to keep lactating?
1 calf
What are the requirements for successful pregnancy production?
-Selection of superior animals for breeding
-Successful breeding
-Successful contraception
-Successful implantation
-Successful gestation
-Successful parturition
What is the estrous cycle?
The reproductive cycle that females enter after puberty continues throughout most of their life
What is the estrous cycle controlled by?
Hormones from the ovary and brain
What are the 4 stages of the estrous cycle?
-Proestrus
-Estrus
-Metestrus
-Diestrus
What are the types of estrous cycles?
-Polyestrus
-Seasonally polyestrous
-Monoestrous
What is estrus?
-AKA heat
-Time when a female is receptive to the male and will allow breeding
What do we need to detect that is crucial for successful breeding?
When the female is in heat
When should a heifer reach puberty/get their first estrous cycle?
1 year of age but can range anywhere from 4-24 months. Should be 30-40% of their mature weight when it comes.
How lomg does the estrous cycle last in cows?
21 days
Once a heifer has her first heat, she will go into heat every…
21 days`
When will a heifer not go into heat?
When they are pregnant or have a certain disease
How long does estrus last?
12-18 hours and ends with ovulation
What is ovulation?
The release of an egg from the ovary due to a surge in the luteinizing hormone from the brain
What is the optimum time to breed a cow for increased conception?
At the later part of estrus/as close as possible to ovulation
The optimum fertility of the ova is…
6-12 hours after ovulation
What is the maximum duration of fertilizing ability with sperm in the cow reproductive tract?
1.5 to 2 days
What are the 2 ways to breed cattle?
-Natural Service
-Artificial Insemination (AI)
What is natural service?
-When a farm keeps bulls on the property to breed cows when they are in heat
-Generally stay in the pen or pasture
-Most farms don’t have many bulls on site
-More popular with beef cattle
What are the advantages of natural service?
-High pregnancy rates
-No special skills are required by the farmer
What are the disadvantages of natural service?
-Increased cost for bull maintenance
-Risk of disease transmission and injury
-Bull libido is a factor
What is artificial insemination?
-Semen is deposited into the uterus of the cow by a farmer or by a breeding service
-Preferred route by over 50% of dairies
When should artificial insemination be done?
Within 4-16 hours of observed estrus
What are the advantages of AI?
-Increased genetic field: selection of semen from multiple bulls
-Safer for the cow: decreased risk of disease transmission
-More accurate dry off state
-Lower cost
What are the disadvantages of AI?
-More labor-intensive
-Decreased pregnancy rates
How are bulls selected for AI?
-Young bulls are selected based on pedigree
-Receive a breeding soundness exam to determine the overall health of the bull and his semen
What does a breeding soundness exam look for?
-Free of genetic defects
-Shape and mobility of sperm
The bull is a bred to a limited…
Number of cows
All of the bull’s daughter’s are…
Evaluated
Bull semen can also be sold by…
Mixing it with an extender and freezing it in individual straws
What is extender?
A fluid that contains nutrients to keep sperm alive and healthy
What are some of the signs that a cow is in heat?
-Increased activity
-Increased vocalization
-Vulva swelling, reddening, mucus discharge
-Mounting other cows
-Decreased feed intake
-Decreased milk yeild
What is the #1 sign that a cow is in heat?
She is standing to be mounted
How can you tell a cow has standed to be mounted?
-Rubbed tailhead
-Dirty flank
What is the best way to observe if a cow is in heat and why is it risky?
-Observe the herd for 30 mins. at least 2x a day
-Time consuming
-Risk of missing a cow when she is in estrus and susceptible to breeding
What skill is necessary to have to be effective at getting cows bred both artificially and naturally?
To detect when a cow is in heat
What is a heat detection aid?
Tools that help reveal when a cow is standing to be mounted or is standing in heat
What are some heat detection aids?
-Breeding indicator
-Tail marker
-Electronic mounting markers
-Pedometers (increased activity)
What is estrus synchronization?
-Manipulating the cow’s estrus cycle to make cows come in heat together over a short period of time for insemination
-Can be used to bring a large group of cows into heat at the same time
What is timed breeding?
-Both the onset of estrous and ovulation are induced
-Allows for insemination at a specific time without heat detection
What is the synchronization protocol?
-Utilization of hormones to control the timing of heat and ovulation
What are the benefits of the synchronization protocol?
-Can improve the efficacy and efficiency of the breeding program
-Reduces variation in calving intervals
-Reduces involuntary culling secondary to difficult breeding
-Concentrate labor for breeding at specific times
What is involuntary culling?
The involuntary segregation of organisms based off of characteristics
What does GnRH stand for?
Gonadotrophin Releasing Hormone
What does GnRH do when injected?
Causes ovulation or resets the cycle for ovulation for synchronization purposes
GnRH is naturally produced by…
The hypothalamus
GnRH is normally used in combination with…
Prostaglandin
What are some commercial products of GnRH?
-Cystorelin
-Fertagyl
Progesterone is produced naturally by…
The ovary between days 5-16 of the estrous cycle
Progesterone prevents…
Heat and ovulation
Progesterone maintains…
Pregnancy
What are some commercial products of progesterone?
-CIDR insert device (controlled by drug release)
-NGA in feed for beef cattle
What is Ovsynch?
A series of injections of GnRH and prostaglandin for synchronization protocol
How is Ovysynch done?
-Day 0: GnRH injection
-Day 7: Prostaglandin injection
-48-56 hours later: 2nd prostaglandin injection
-A.I. 12-18 hrs. after 2nd GnRH
What are additional reproductive options?
-In-vitro fertilization
-Cloning
-Embryo transfer
What is embryo transfer focused on?
Increasing the number of cows produced by valuable cows
What is the ideal donor female for embryo transfer?
-Regular estrus cycle that begins at a young age
-Routinely conceives with no more than 2 inseminations
-Maintains a 14-month or less calving interval
-Calves w/o difficulty
-Free of reproductive abnormalities and disease
-No conformational or known genetic defects
What is the embryo transfer procedure?
-A valuable donor cow undergoes a hormone regimen to be superovulated
-Cow is AI’ed by a valuable sire
-Several days later, the cow’s uterus is flushed and the embryos are collected
-Eggs are examined microscopically to determine which are fertilized
-Embryos are implanted into recipient heifers or frozen in liquid nitrogen and sold
What is superovulation?
Many eggs developing at once
What is the in-vitro fertilization procedure?
-Sexed frozen semen or reversed sorted semen can be used for fertilization
-EMbryos develop in an incubator for 7 days before being placed into a recipient
-Embryos may be frozen
What is the pregnancy rate of in-vitro fertilization?
45-45%
What is in-vitro fertilization focused on?
Producing embryos by collecting eggs directly from the ovaries and fertilizing them in a petri dish
What is cloning?
The production of an identical copy of an individual genetically
How is an animal cloned?
Splitting an animal to produce 2 identical twins
Who is cloning available for?
Commercially available for animal production
What is the average gestation period in a cow?
280 days/ 9 months
How is pregnancy detected in a cow?
-Rectal palpitation at 35 days after breeding
-Transrectal ultrasound 28 days after breeding
What is a herd check?
A transrectal ultrasound that allows for the diagnosis of pregnancy in dairy cows as well as checking overall reproductive health by checking the uterus and ovaries
What does a transrectal ultrasound detect?
-A fetus and its viability
-Determining where a cow is in her estrous cycle
Fetal sexing can be done at…
55-70 days
A transrectal ultrasound gives early detection of…
-Abortion
-Pyometra
-Ovarian abnormalities that prevent pregnancy
-Twins
What is pyometra?
Uterine infection
What is a freemartian?
Where a heifer is born as a twin to a bull, they both have a 90% chance of being sterile
What is freshening?
When a dairy cow gives birth
What are the 3 stages of labor?
-Prep stage
-Expulsion of the fetus
-Expulsion of the placenta
What happens during the prep stage?
-Increased restless behavior (kicking belly, straining, decreased interest in food)
-Cow is moved into a pen by herself (calving pen)
-Cervix begins to dilate, fetus moves into position
-Contractions start
-Ends with the fetus entering the birth canal
What happens during calf expulsion?
-Delivery of calf should take 30-90 mins
What happens when the placenta is expelled?
-May take 6-12 hours in cows
-Cow should be monitored
-After 24 hours, if the placenta has not been expelled then it is considered retained
What is dystocia?
Difficulty calving
Why is dystocia important in cattle parturition?
-Leading cause of calf death during or after birth-
-Can cause trauma or infection in the cow
-Can increase calving intervals
What are the main causes of dystocia?
-Fetal-maternal size mismatch
-Fetal malpresentation
-Dam related issues (uterine torsion)
How is a fetal-maternal size mismatch treated?
C-section
How is a fetal malposition treated?
-Manual repositioning of the fetus
-C-section
How is uterine torsion treated?
-Rolling the cow
-Rolling the uterus
What are the signs of a healthy reproduction?
-A healthy calf entering the production cycle
-A healthy cow entering lactation
