Monitoring Fertility Flashcards
What are the 3 most important measures of fertility?
Calving interval
Calving index
Calving to conception
How can you monitor whether cows are getting served in a dairy herd?
Submission rate =
no. animals served / no. animals eligible for service in a 3 week cycle
- 1st service submission rate
- All services submission rate
How can you monitor how long it took to conceive in a dairy herd?
Calving interval - individual cows that calved in the last year
= too historic
Calving to conception interval
- produces a predicted calving index
Pregnancy rate =
Number pregnant / number eligible to be served in a 3 week interval
What is the pregnancy rate?
Number pregnant / number eligible to be served in a 3 week interval l
Or submission rate % x conception rate
What is the submission rate?
No. Cows served / no. Cows eligible for service in a 3w period
What is the conception rate?
No. Pregnant cows / total no. inseminations
Name some common intervals used to assess fertility.
Calving to... 1st observed heat 1st service Conception Calving
Name some rates used to monitor fertility.
Submission rate
Oestrus detection rate
Pregnancy rate
Service rate
How is the productivity of a beef herd assessed?
Calving spread = most sensitive measure of a cows performance
When is a beef animal sent for slaughter?
18-24m at 600-800kg
Usually sent at 18m
What is a store animal?
A beef calf, whose growth is deliberately restricted overwinter to 0.8 kg/day. Compensatory growth occurs when the calf is put out on the Spring grass
Why should a beef farmer aim for a low calving spread?
To ensure calves have the longest time to grow before all calves are sent to slaughter at the same time
To reduce disease spread by pathogen multiplier effect - more uniform age group will not get so much disease
To reduce culling rates - cows have more time to recover between pregnancies therefore culling rates reduce
What length calving spread should you aim for?
9-12 weeks
What other fertility targets should be set in a beef herd?
1 calf per cow per year
65% of cows calve down in the 1st month of the calving period
Barren rate 3-5%
Conception rate - 60-80%
What is the effect of the conception rate on the calving spread?
The better the conception rate, the tighter the calving spread
What is an important factor that reduces the conception rate in rebreeding beef cows?
Presence of the calf
When should you serve a beef cow to maximise conception rate?
Early summer - when she is on a rising plane of nutrition
How long should you allow for sexual rest on cattle before you serve them again? (VWP)
6-8 weeks
How many calves will a beef cow produce in her lifetime if she maintains a tight calving spread?
7-9
How long should the bull be left in with beefs cows for?
9 weeks and no longer
Accept that some cows will not get pregnant to maintain the calving spread
What BCS should you be aiming for in a beef herd?
Autumn calvers - 3 at calving
Spring calvers - 2.5 at calving
How can you feed cows to manipulate beef cow condition?
Supplementary feeding at mating - Autumn calvers only
Continue 6 weeks after mating period to ensure implantation
Early weaning in heifers - allows them to keep on 0.5-1 BCS
How much food should you provide a heifer?
Maintenance + 10% for growth
How should you manage heifers at service to minimise the risk of dystocia?
60% mature body weight at service - 360-380kg
Easy calving bull
2yo at calving
6 week service period
This means heifers get 3 weeks longer to recover
Wean heifers one month early to allow for her to finish growing
How can a farmer achieve a tight calving spread?
Cull late calvers and replace with heifers
Split the herd in to autumn and Spring calvers and manage well
What estimated breeding values are desirable in a beef bull?
Birth weight - negative
200 day weight - positive
400 day weight - positive
