LA THERIO - Dairy Cattle Flashcards
What is the main parameter used to measure reproductive efficiency in dairy heifers, and what should be the goal?
- Age at calving (24 months)
- Size at first calving (1200 lb)
- Adequate interval between calving
What is the normal estrous cycle length in cattle?
21 days
What is the normal duration of estrus in dairy cattle?
7-9 hours
?
What is a freemartin heifer, and why are they sterile?
Female born co-twin with a male
Exposed to AMH and testosterone
Causes abnormal development of tubular genetalia
Sterile due to infantile reproductive tract
What is the gold standard for diagnosis of freemartinism?
CYTOGENETICS: PCR to detect Y Ag
most are chimera: XX/XY
What does “white heifer disease” describe?
recessive sex-linked gene of white hair coat
breeds: belgian blue, shorthorn
segmental aplasia of the paramesonephric ducts
normal ovaries
variable degrees of persistent hymen (shorthorn)
Variable degrees of segmental aplasia of the cervix
mycometra
What abnormalities of the reproductive tract are associated with freemartinism?
- abnormal tubular genitalia (paramesonephric duct) and ovaries
- short vagina; uterine horn and cervix are undeveloped
- aplastic ovaries
- male accessory glands may be present (seminal vesicles)
- external genitalia might be normal
What abnormalities of the reproductive tracts are associated with white heifer disease?
segmental aplasia of the paramesonephric ducts:
- normal ovaries
- variable degrees of persistent hymen (mostly shorthorn)
- variable degrees of segmental aplasia of the cervix
- mucometra
When would a placenta be considered retained in a cow?
> 12 hours postpartum
Name some of the most important factors involved in increased incidence of retained placenta.
Abortion
Twinning
C-section
Previous retention
Stillbirth
Veto to my
Age
Dystocia
Selenium/Vitamin E deficiency
What treatments are contraindicated or not effective for management of retained placenta?
NO manual removal!!
NO PGF2a - not effective
Abx only when indicated (septic metritis)
Oxytocin used in early pp; not effective for primary RFM
List three main risk factors for uterine infection in the dairy cow.
Retained placenta
Stillbirth
Twinning
Dystocia
Primiparous
What are the main effects of negative energy balance on reproduction?
happens during transition period: 3 wks before & after parturition
Dystocia
Abortion
Ketosis and fat cow syndrome
Hypocalcemia
Toxic mastitis
Septic metritis
Displaced abomasum
Down cow syndrome
lipid mobilization → increased lvls of NEFAs, ketones: BNB, acetone, etc → decreased immunity: leukopenia, decreased INFy and IgM synthesis → reduced phagocytosis
increased concentrate in the ration → rum acidosis → inflam cytokines + acute phase proteins → increased risk of metritis, mastitis, laminitis, displaced abomasum
Define cystic ovarian disease.
follicle is > 25 mm for more than 10 days in absence of CL→ anestrus
Incidence: 10 -30%
50% resolve on their own
Describe the types of ovarian cysts in the cow.
Follicular - thin walled
Luteal - thick walled; may produce progesterone
How can ovarian follicular cysts be treated?
GnRH or hCG + PGF2a
What are the symptoms of pyometra in cattle, and how would you treat?
Pyometra in cattle does not cause systemic effects.
Clinical signs - vaginal discharge, anestrus
Treat with PGF2a to help with uterine contractions so they can deal with it on their own.
Pyometra is characterized by the accumulation of purulent or mucopurulent exudate in the uterus. In cows, it is invariably accompanied by the persistence of an active corpus luteum and interruption of the estrous cycle. In affected mares, the cervix is often fibrotic, inelastic, affected with transluminal adhesions, or otherwise impaired. Mares may continue to cycle regularly, or the cycle may be interrupted. Discharge from the genital tract may be absent or intermittent and corresponding to periods of estrus. In general, affected animals do not exhibit any systemic signs of illness, but affected mares may be in poor condition. In both cows and mares, pyometra must be distinguished carefully from pregnancy before beginning treatment.
TX: In cows, the treatment of choice for pyometra is the administration of PGF2-alpha or its analogs at normal luteolytic doses. Expulsion of exudate and bacterial clearance of the uterus follows in ~80% of treated cases. Although the first-service conception rate after treatment may be low, most cows may be expected to conceive within three or four inseminations. The treatment may need to be repeated in ~20% of cows. No intrauterine treatment is recommended in conjunction with the prostaglandin.
How would you calculate a pregnancy rate in the herd?
Preg rate = measurement of repro efficiency = #of pregnant cows / # of all cows that should have gotten pregnant in that time (21 day cycle).
In other words, Conception Rate x Heat Detection Rate
How would you terminate pregnancy in a cow between days 30 and 60?
PGF2a or analogues first 150 days of pregnancy – THE GO TO!
Dexamethasone + PGF2a last trimester
How does heat stress affect fertility in the dairy cow?
Decreases oocyte quality (possibly early loss) and conception rate
Temp > 26C / 78 -79 F → increased rectal temp and RR →
→ decreased oocyte activity
→ increased granulosa cells degeneration and decreased steroidogenesis
→ decreased progesterone production
→ reduced embryo quality
→ effect can last over several cycles
What is the transition period, and what are its implications in dairy cattle reproduction?
3 wks before parturition, 3 wks after : NEGATIVE ENERGY BALANCE + high risk for hypocalcemia
How does high milk production affect estrus and pregnancy in the dairy cow?
estrus: increased liver metabolism → increased biodigration of steroids (estrogen) –> poor heat detection
high milk production causes an increase demand for energy which is difficult to achieve with just eating. This will cause a negative energy balance leading to hypoglycemia and lipidosis that will have an affect on the ovaries causing anestrus and cysts
What methods can be used for early pregnancy diagnosis in the cow (day 28 to day 30)?
28 days: transrectal US
28 - 30 days: PSPB (pregnancy specific protein B)
32 -35 days: transrectal palpation
What is the most common parasitic disease involved in dairy cattle abortions in the western United States?
Etiological agents
Clinical manifestation
Neospora Caninum.
infection: ingestion of oocysts + development of tachyzoites in placenta + amniotic fluid
vertical transmission
bradyzoites in CNS
Cows: no CS, no retained placenta
Placentitis
Fetus: autolyzed w/ no gross lesions (mummified)
Neospora caninum: definitive host is canids, infected by ingestion.
No clinical signs in the cow, but will cause reabsorption or mummification between 4-7 months of pregnancy.
In fetuses look for foci of cellular infiltrates in the brain, non suppurative endocarditis, myocarditis and myositis and portal hepatitis.
