4 – Reproductive Management Flashcards
(26 cards)
What is the importance of reproductive management in a dairy operation?
- 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
What do we need to do? (ideal, lactation, gestation)
- 1 calf/year
- Negative energy balance: 0-60d of lactation
- 305d left to get them pregnant
- 280d gestation
- **25d left to get them pregnant
Holstein pregnancy rates
- 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
What are the components of a reproduction program?
- 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
What is ideal for heat detection?
- 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
What are some aids for heat detection?
- 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)
Why do some herds use estrus synchronization? (ex. use of estrotect patches after same synch treatment in dairy cows + heifers and beef cows)
- Beef cows: showed strong estrus behaviour
- Dairy cows: bad at showing estrus behaviour
o *why did timed AI
Cycle length change over 50 years (1/2 herd no-genetic changes, ½ herd genetic improvements)
- Control: half had 21d cycle
- Now more at 21 or 28d cycles
What are the principles of AI protocols?
- Control CL function
- Control follicle development
- Control ovulation
Insemination rate:
- % cows inseminated of those eligible to be inseminated during a single estrus cycle
What is your benchmark for insemination rate?
- 44%
Conception rate
- % inseminated cows that become pregnant during a single estrus cycle
What is your benchmark for conception rate?
- 42%
Pregnancy rate
- % all cows that become pregnant during a single estrus cycle
What is the benchmark for pregnancy rate?
- 17%
Insemination rate does NOT equal heat detection rate
- 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%
Bull breeding
- 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)
AI breeding
- 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
What are some other strategies for ‘breeding’?
- AI first then bull breeding
- Embryo transfer
- Genomics
AI first then bull breeding
- 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
Embryo transfer
- High genetic merit cow undergoes superovulation and AI
- Multiple embryos recovered by uterine lavage 6-8 days after insemination
- Implanted in recipient cows
Genomics
- 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
What is the importance of pregnancy diagnosis?
- ID non-pregnant animals most important
o Return to breeding program ASAP
What are some early and accurate ways to diagnose pregnancy?
- Palpation/ultrasound at 30-32 days following insemination
- *errors: rare but they do happen
