4 – Reproductive Management

Question 1

What is the importance of reproductive management in a dairy operation?

Answer 1

• Calving required for lactation
• Genetic improvement through shorter generation intervals
• Consistent calving distribution
  o Required for constant milk supply
  o More animals close to peak
• Calves provide
  o Replacement heifers
  o Breeding bulls

Question 2

What do we need to do? (ideal, lactation, gestation)

Answer 2

• 1 calf/year
• Negative energy balance: 0-60d of lactation
• 305d left to get them pregnant
• 280d gestation
• **25d left to get them pregnant

Question 3

Holstein pregnancy rates

Answer 3

• Higher in 1900s, but produced less milk
• 1999-2000: pregnancy rates were incorporated into genetic index
  o *increase in pregnancy rates over last 20 years

Question 4

What are the components of a reproduction program?

Answer 4

• Assessing readiness of breeding
  o Post-partum exam?
  o Cost-benefit analysis
• Heat detection +/- technology
• Timed AI protocols
  o Mange CL function, follicle development, ovulation
• Breed the cow
  o AI or bull breeding

Question 5

What is ideal for heat detection?

Answer 5

• Breeding take place 12h following observed standing estrus
• Takes time to detect heat (should do at least 2-4hrs/day but difficult)
• *aim for >50% heat detection rate

Question 6

What are some aids for heat detection?

Answer 6

• Pedometers
  o When in estrus=walk around more (unless lame)
• K-mar detectors
  o Put on tail head: when an animal rides her=turns red
  o Need to put them on correctly
• (teaser bulls)

Question 7

Why do some herds use estrus synchronization? (ex. use of estrotect patches after same synch treatment in dairy cows + heifers and beef cows)

Answer 7

• Beef cows: showed strong estrus behaviour
• Dairy cows: bad at showing estrus behaviour
  o *why did timed AI

Question 8

Cycle length change over 50 years (1/2 herd no-genetic changes, ½ herd genetic improvements)

Answer 8

• Control: half had 21d cycle
• Now more at 21 or 28d cycles

Question 9

What are the principles of AI protocols?

Answer 9

• Control CL function
• Control follicle development
• Control ovulation

Question 10

Insemination rate:

Answer 10

• % cows inseminated of those eligible to be inseminated during a single estrus cycle

Question 11

What is your benchmark for insemination rate?

Answer 11

• 44%

Question 12

Conception rate

Answer 12

• % inseminated cows that become pregnant during a single estrus cycle

Question 13

What is your benchmark for conception rate?

Answer 13

• 42%

Question 14

Pregnancy rate

Answer 14

• % all cows that become pregnant during a single estrus cycle

Question 15

What is the benchmark for pregnancy rate?

Answer 15

• 17%

Question 16

Insemination rate does NOT equal heat detection rate

Answer 16

• Cow eligible for insemination > insemination > preg check
• If cow seen in standing estrus 21 days after insemination=producer will rebreed
• If cow gets pregnant=2 inseminations, 1 pregnancy, insemination rate=50%
• BUT heat detection rate=100%

Question 17

Bull breeding

Answer 17

• No need for estrus detection
• No breeding date available
• Disease spread
• Increased housing and facility expense: 25% of dairy animal injuries caused by bulls
• Risk to humans
• Separate bull pens? ONLY where AI is not permitted (Ex. Hutterite colonies)

Question 18

AI breeding

Answer 18

• Maximize genetic improvement potential
• Need to detect estrus
• Skilled staff needed
• Genetic concentration in a herd
  o Effective population size in 10M cows in NA=50
• Sexed semen
  o >90% accuracy (flow cytometry)
  o Animals with most genetic merit can produce heifers

Question 19

What are some other strategies for ‘breeding’?

Answer 19

• AI first then bull breeding
• Embryo transfer
• Genomics

Question 20

AI first then bull breeding

Answer 20

• Allows for genetic improvement
• Animals not responding to AI may respond
• Require big enough herd for 2 groups (>350 cows)
• Increased housing and facility expense
• Danger of bull loose in pen

Question 21

Embryo transfer

Answer 21

• High genetic merit cow undergoes superovulation and AI
• Multiple embryos recovered by uterine lavage 6-8 days after insemination
• Implanted in recipient cows

Question 22

Genomics

Answer 22

• 54,000 relevant single nucleotide polymorphisms (SNPs) in bovine genome
• Most commercial test look at most important 6000 SNPs
• ID genetic merit in all ages

Question 23

What is the importance of pregnancy diagnosis?

Answer 23

• ID non-pregnant animals most important
  o Return to breeding program ASAP

Question 24

What are some early and accurate ways to diagnose pregnancy?

Answer 24

• Palpation/ultrasound at 30-32 days following insemination
• *errors: rare but they do happen

Question 25

What are some other technology for pregnancy diagnosis?

Answer 25

• Blood assays
• Milk assays
• Se and Sp =0.98
  o Can test at 23d following insemination

Question 26

Dairy producers buying their own ultrasound units

Answer 26

• They are allowed to do it on their own animals
• *to get on the farm our herd health skills are important!