Dairy Cattle Reproduction

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Lab tomorrow
Farm Bureau Pavilion classroom
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Reproduction in Dairy Cows
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The Reproductive Cycle

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1st breeding anytime after VWP
Later breedings
Conception
Voluntary waiting period
Cycle from one calving until the next calving
Calving
Gestation
The Reproductive Cycle
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Voluntary Waiting Period (VWP)

• Determined by herd owner
• Fixed period following calving before attempting
  to breed cow
• Often the same for all cows in the herd although
  some have a longer VWP for 1st lactation animals
• Usually between 40 and 70 days

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Dairy cattle reproductive cycle
Voluntary waiting period
Breed after this date
Calves
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Days to first service
Number of days between calving and when the
animal is bred for the first time Calculated on
a herd basis not for an individual
animal Animal may or may not conceive to this
breeding/service
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Dairy reproductive terms linear display

Days to 1st service
Bred for 1st time
Calves
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Days Open
Number of days between calving and
conception Calculated on a herd basis not for
an individual animal
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Days open Days to first service - linear display
Days open
Days to 1st service
Bred for 1st time and conceives
Calves
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Days open Days to first service - linear display
Days open
Days to 1st service
Bred again and conceives
Bred for 1st time
Calves
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Dairy reproductive terms linear display
Days open
Days to 1st service
Bred again (3rd service) and conceives
Bred again - 2nd service
Bred for 1st time - 1st service
Calves
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Gestation period
Number of days that a cow is pregnant Number of
days from conception to birth of the
fetus Average gestation 279 days there are
breed differences
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Calving Interval
Period from one calving until the next Measured
in months Calculated on a herd basis not for an
individual animal
Days open Gestation period Calving interval
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Dairy reproductive terms linear display
Calving interval
Calves again
Calves
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Measuring Reproductive Efficiency
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Measures of Reproductive Efficiency

• Days to first service
• Days open
• Calving interval
• Services per conception
• Conception rate
• Heat detection rate
• Pregnancy rate

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Services per conception

• Calculated on a herd basis not for an
  individual animal
• Inverse of conception rate

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Conception Rate

• Calculated on a herd basis not for an
  individual animal
• Inverse of services per conception

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Heat detection rate

• Also known as service rate
• Percentage of eligible cows detected in heat
  during a 21-day period

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Pregnancy Rate

• Calculated in two ways
• Takes into account FERTILITY and TIME

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The Estrus Cycle
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Estrous Cycle

• Period of time from first signs of sexual
  receptivity (estrus) to start of next estrus
• Averages 21 days in length (18-24 days normal)

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Ovarian Cycles
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Reproductive Hormones

• Estrogen (estradiol)- responsible for sexual
  behavior and changes in the estrous cycle
• Leutinizing hormone (LH)- causes ovulation and
  maintains corpus luteum
• Follicle stimulating hormone (FSH)- promotes
  follicular development
• Progesterone- maintains pregnancy

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Estrus

• Commonly known as heat
• Period of time when the female is sexually
  receptive and ovulation is about to occur

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Timing

• Standing heat 8-30 hrs (21 hrs average)
• Ovulation occurs 10-14 hrs after estrus ends
• Breed 12 hrs after last visual sign of standing
  heat

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A trend to note

• Cycle lengths are getting longer over time
• BST
• Cows milking more
• Better management

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Estrus Detection
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Primary sign of estrus

• Cow stands to be mounted

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Visually Detecting Estrus

• Cows must INTERACT
• Cows must be OBSERVED
• Average mounting time is 7 sec (range 2-15 sec)
• Visual observation should be at least twice/day
  for 30 minutes
• Easy to miss should be only job at that time

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Mounting Activity vs. of Cows in Heat
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Distribution of Mountings by Time
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Secondary signs of estrus

• Hair on tail head ruffled and matted
• Clear and viscous mucous discharge
• Very nervous and excitable
• Red and swollen vulva
• Mounting other cows
• More active, restless
• Bawling/bellowing

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Estrus Detection Aids

• Records
• Rump Indicators
• Electronic Aids
• Teaser Animals

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Records

• Increases chance of predicting estrus
• Paper records/calender
• 21 day barn wall charts
• Breeding wheels
• Palm pilots

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Rump Indicators

• Chalk and paint marks
• cheap and easy
• must be monitored closely!
• not always reliable

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Rump Indicators

• Heat detection patches
• Help detect mountings
• Come off easily
• Dont tell when cow was mounted
• Ex Kamar detectors (1.00 ea.)

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Electronic Aids

• Vaginal probe - measures electric conductivity in
  the uterus
• Electronic nose- measures pheromones
• Pedometers- measures activity
• Must know what is normal for your cows

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Electronic Aids

• Heat-Watch
• Computerized system involving patches and a
  transmitter,
• Gives exact time animal was mounted, duration of
  mount, etc.
• Patches can come off, not always reliable
• Relatively expensive

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Detector or teaser animals

• Surgically altered bulls (vasectomized or gomer
  bulls)
• Testosterone treated cows, free martin heifers
  and steers
• Drawbacks
• Must feed an additional animal
• Cost of surgery/ drugs
• Can be dangerous to workers

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Controlled Breeding Programs

• Synchronization of ovulation
• Timed breeding programs
• Ov-sync, pre-sync, targeted breeding, CIDRs

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Artificial Insemination Getting Cows Bred
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When to breed

• AM/PM rule
• Cows showing estrus in morning should be
  inseminated the same day
• Cows showing estrus in evening should be
  inseminated the morning of the next day

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Artificial Insemination

• Increase genetic diversity
• Decrease risk of disease transmission
• Dont have to keep a bull
• Dangerous and expensive
• Breed the best to the best

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Questions???