Assessment of fertility Flashcards
How can the number of offspring be used as an assessment of fertility?
- E.g. per 100 dams - casualties, disease, pregnancy loss
- Per year - seasonality
- Born, live births, weaned, sold
Gender
What are the implications if there is dairy cow infertility?
- Less milk per year
- Unnecessary culling = replacement costs
- Fewer calves per year
- Increased semen costs
- Increased labour costs
What are some of the targets within a 365 day calving interval? Be specific with the number of days.
- Voluntary waiting period = 40-42 days
- Calving to 1st service = 65 days
- Calving to conception = 85 days
- Services per conception = 1.6
- Abortion after day 42 < 3-5%
- Number of pregnant cows >96%
How many days would you wait between a first and second service of a cow?
21 days - length of oestrus cycle
Which factors could alter how long the calving interval is?
- Number of services required
- Length of pregnancy can be variable
- Failure to detect oestrus
In monitoring give a definition of primary indices and some examples
= Factors affecting losses
- Calving interval
- Failure to conceive
- Services per conception
- Abortion
- Heifers age at first calving
Give a definition of secondary indices and provide some examples
= directly affect primary indices but can be monitored constantly
- calving to 1st service
- 1st service pregnancy rate
- overall pregnancy rate
- heat detection
- abortions/embryo loss
Why is the timing of first service so important?
Too early - decreased fertility
Too late - increases the calving interval
How can you calculate the 1st service pregnancy rate?
No. of 1st services resulting in pregnancy/total number of 1st services
E.g. 60 cows served once, of which 33 pregnant. 1st Service PR = 55%
How can you calculate the submission rate (heat detection rate)
No. of cows presented for service/ No. of cows eligible for service
In a beef herd, how would you calculate the weaning%
calves weaned/cows to bull
How is performance monitored within a beef herd?
- % pregnant at 21 days
- % pregnant at 63 days
- median calving date
- overall pregnancy rate
- calving rate
- weaning rate
In a ewe what is monitored for optimal reproductive performance?
- Ovulation rates
- Conception rates
- Early embryonic/foetal loss
- Abortion
- Peri-parturient problems
How do you calculate the lambing %?
Number of lambs reared per 100 ewes to ram
How do you calculate the number of productive ewes?
Total number of ewes - (deaths + barren)
