Monitoring Fertility

Question 1

What are the 3 most important measures of fertility?

Answer 1

Calving interval
Calving index
Calving to conception

Question 2

How can you monitor whether cows are getting served in a dairy herd?

Answer 2

Submission rate =
no. animals served / no. animals eligible for service in a 3 week cycle

• 1st service submission rate
• All services submission rate

Question 3

How can you monitor how long it took to conceive in a dairy herd?

Answer 3

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

Question 4

What is the pregnancy rate?

Answer 4

Number pregnant / number eligible to be served in a 3 week interval l

Or submission rate % x conception rate

Question 5

What is the submission rate?

Answer 5

No. Cows served / no. Cows eligible for service in a 3w period

Question 6

What is the conception rate?

Answer 6

No. Pregnant cows / total no. inseminations

Question 7

Name some common intervals used to assess fertility.

Answer 7

Calving to...
1st observed heat
1st service
Conception
Calving

Question 8

Name some rates used to monitor fertility.

Answer 8

Submission rate
Oestrus detection rate
Pregnancy rate
Service rate

Question 9

How is the productivity of a beef herd assessed?

Answer 9

Calving spread = most sensitive measure of a cows performance

Question 10

When is a beef animal sent for slaughter?

Answer 10

18-24m at 600-800kg

Usually sent at 18m

Question 11

What is a store animal?

Answer 11

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

Question 12

Why should a beef farmer aim for a low calving spread?

Answer 12

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

Question 13

What length calving spread should you aim for?

Answer 13

9-12 weeks

Question 14

What other fertility targets should be set in a beef herd?

Answer 14

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%

Question 15

What is the effect of the conception rate on the calving spread?

Answer 15

The better the conception rate, the tighter the calving spread

Question 16

What is an important factor that reduces the conception rate in rebreeding beef cows?

Answer 16

Presence of the calf

Question 17

When should you serve a beef cow to maximise conception rate?

Answer 17

Early summer - when she is on a rising plane of nutrition

Question 18

How long should you allow for sexual rest on cattle before you serve them again? (VWP)

Answer 18

6-8 weeks

Question 19

How many calves will a beef cow produce in her lifetime if she maintains a tight calving spread?

Answer 19

7-9

Question 20

How long should the bull be left in with beefs cows for?

Answer 20

9 weeks and no longer

Accept that some cows will not get pregnant to maintain the calving spread

Question 21

What BCS should you be aiming for in a beef herd?

Answer 21

Autumn calvers - 3 at calving

Spring calvers - 2.5 at calving

Question 22

How can you feed cows to manipulate beef cow condition?

Answer 22

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

Question 23

How much food should you provide a heifer?

Answer 23

Maintenance + 10% for growth

Question 24

How should you manage heifers at service to minimise the risk of dystocia?

Answer 24

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

Question 25

How can a farmer achieve a tight calving spread?

Answer 25

Cull late calvers and replace with heifers

Split the herd in to autumn and Spring calvers and manage well

Question 26

What estimated breeding values are desirable in a beef bull?

Answer 26

Birth weight - negative
200 day weight - positive
400 day weight - positive