Cattle fertility Flashcards
What is the ‘interference level’?
where action needs to be taken
How long is a cow’s gestation?
283 days (beef longer0
What is ‘VWP’?
Voluntary waiting period = the time you leave a cow between calving and you serving her the first time.
UK mean = 42-45 days
What is the calving to first service interval on average?
mean = 65 days
What is the average ‘calving-conception’ length? Interfernce?
mean = 85 days Interference = >95 dyas
When does uterine involution occur?
Between calving and day 42
How long is a cow’s cycle?
21 days
Why might a cow’s first cycle post-partum be delayed?
metritis poor BCS RFM (i.e. > 24 hours) dystocia poor nutrition mastitis fatty liver
What is the target calving interval (CI)?
365 days
What is the difference between the calving index and the calving interval?
CALVING INTERVAL = relates to an individual cow, time between two calvings
CALVING INDEX = the herd average/mean of the calving indexes
What is the a.) target b.) interference level of conception rate at the first service?
Target = 60% Interference = <55%
What is the a.) target b.) interference level of conception rate for all services?
Target = 55% Interference = <50%
At what point should you interfere with the calving index?
When >380 days (target = 365 days)
What should be the target and interference earliest service date?
Target = 50 days Interference = <42 days
When should you interfere with the calving-first service interval?
When it is > 75 days (target = 65 days)
What is the VWP affected by?
postpartum problems
return of ovarian cyclicity
oestrous detection
Why is the timing of the 1st service critical?
Too soon after calving –> lower pregnancy rates
Too late after calving –> prolongs calving interval
What happens if you insemminate 30, 40, 50 or 60 days after calving?
30 days - conception rate is 30%
40 days - conception rate is 40%
50 days - conception rate is 50%
60 days - conception rate is 60%
approximately! this is a rule of thumb
How is timing of first service measured? 2
Mean interval between calving and first service over time
OR
First service submission rate
What are the problems of assessing timing of first service based on mean interval between calving and first service?
cows that aren’t served are missed
large spread not seen (early and late cows cancel out)
unusual VWP
Define ‘first service submission rate’
= the proportion of cows served within 3 weeks of the earliest allowed start date (i.e the VWP). Ideally = 100% (i.e. between day 50 and day 74 post-partum)
What is the general quality of oestrous detection on farms?
generally poor!
What is an inter-oestrous interval?
the time between oestrous/showing heat, usually 21 days
How long does oestrous last?
18 hours but can be considerably shorter (some cows only show standing heat for 20 minutes!)
What are causes of cyclic irregularity in ruminants?
erroneous heat detection endometritis intrauterine therapy COD heat stress leptospirosis IBR BVDV Campylobacteriosis Trichmoniasis Embryo death after maternal recognition
How can the accuracy of oestrous detection be asssessed?
Milk sample at time of AI - test of progesterone level (should be low at oestrous since CL is lysed - alternative reason for low P4 is that the cow is acyclic)
What is a ‘Q sum’ or ‘Cu sum’?
A way of displaying every insemmination in date order and then indicating whether or not the cow has become pregnant.
What should the 120 day in-calf rate be?
> 64%
What should the 210 day snot in calf rate be?
<7% (i.e. the problem group of cows as this is the late lactation stage for the cow)
What should broadly happen on a routine fertility visit?
Be regular
Examine animals
Examine records
Advise
What is VLD?
vulval discharge
What are ways of describing irregular inter-oestrous intervals?
ONO - ostrous not observed
NSB - not seen bulling
NVO - no visible oestrous
What should you consider/remember when examining animals on a routine fertility visit?
PROBLEM ANIMALS: RFM, metritis, VLD Post or pre calving checks? Irregular inter-oestrous intervals (ONO, NSB, NVO) PDing Pregnancy and odd events
