Reproductive Management of Dairy Cows Flashcards
Name a grain we commonly use to feed dairy cows?
barley or corn
fibre in the ration supports milk fat production or glucose precursors?
glucose precursors
What is the importance of reproductive management?
- calving is required for lactation
- impact on genetic improvement through shorter generation intervals
What is important about a consistent calving distribution in dairy herds?
- required for constant supply of milk (quota)
- more animals close to peak milk production
What do calves provide in dairy herds?
- replacement heifers
- breeding bulls
What stats do you need to get a dairy cow pregnant?
- ideally 1 calf/yr
- negative energy balance in days 0-60 of lactation (dont even try to get them pregnant then)
- 305 days left
- ~280 day gestation
- ~ 25 days left to get them pregnant (just over 1 cycle - 21 days)
How do we assess readiness for breeding in a dairy cow?
- post-partum exam
- cost-benefit analysis
- heat detection +/- technology
What do timed artificial insemination (AI) protocols do in dairy herds?
manage CL function, follicle development, ovulation
how do we breed dairy cows?
- AI
- bull breeding
What is ideal heat detection in dairy herds? How long to spend detecting heat?
- breeding should take place 12 h following observed standing estrus
- aim for > 50% HEAT DETECTION RATE
What kind of aids are their for heat detection in dairy herds?
- pedometers
- K-mar detectors/ Estrotect patches
- (teaser bulls)
Why do some dairy herds use estrus synchronization?
modern dairy cows are really bad at showing estrus behaviour & this is why we have started switching to timed AI
What are the principles of timed AI protocols?
- control CL function
- control follicle development
- control ovulation
What is the insemination rate in dairy cows?
% cows inseminated of those eligible to be inseminated during a single estrus cycle
What is the conception rate in dairy cows?
% of inseminated cows that become pregnant during a single estrus cycle
What is the pregnancy rate in dairy cows?
% of all cows that become pregnant during a single estrus cycle
What is the benchmark for insemination rate in dairy cows?
~44%
What is the benchmark for conception rate in dairy cows?
~42%
What is the benchmark for pregnancy rate in dairy cows?
~17%
Why does insemination rate not equal heat detection rate?
- cow eligible for insemination -> insemination -> preg check
- cow seen in standing estrus 21 days after insemination, producer will rebreed
- if cow gets pregnant after 2 inseminations, insemination rate is 50%, but heat detection rate was 100%
What are the pros & cons of bull breeding in dairy herds?
- no need for estrus detection
- no breeding date available
- disease spread
- increased housing & facility expense
- risk to humans & other cows
- potentially separate bull pens
only done if AI not permitted (Hutterite colonies)
What are the pros & cons of AI in dairy herds?
- maximize genetic improvement potential
- need to detect estrus
- skilled staff needed
- genetic concentration in a herd
- sexed semen (animals w/ most genetic merit can produce heifers
What are other strategies than bull breeding or AI in dairy herds?
- AI first then bull breeding
- embryo transfer
- genomics
What is important about AI first then bull breeding in dairy cows?
- allows for genetic improvement
- animals not responding to AI may respond to bull
- require big enough herd for 2 groups (>350 cows)
- increased housing & facility expense
- danger of the bull loose in a pen
What is important about embryo transfer in dairy cows?
- high genetic merit cow undergoes superovulation & AI
- multiple embryos are recovered by uterine lavage 6-8 days after insemination
- implanted in recipient cow
What is important about genomics in dairy cows?
- 54,000 relevant single nucleotide polymorphisms (SNPs) in bovine genome
- most commercial tests look @ most important 6,000 SNPs
- identify genetic merit in all ages
Why is identification of pregnant (open) animals most important in pregnancy diagnosis?
to return them to the breeding program ASAP
pregnancy diagnosis in dairy cows?
- EARLY & ACCURATE
- palpation/ultrasound at 30-32 days following insemination
- errors rare but they do happen
what technology is used for pregnancy diagnosis in dairy cows?
- blood assays
- milk assays
- sensitivity & specificity is 0.98 23 days following insemination
What happens when there is an error and pregnancy is not diagnosed?
open animals will be given prostaglandin which causes pregnant cows to abort
why are herd health skills becoming more & more important in dairy med?
- vets have used their pregnancy diagnosis skills to get onto dairy farms
- as tech gets better & dairy producers are buying their own U/S units & learning, this is how we might get onto farms in the future
