1. Jeremy Bryant NZ Animal Evaluation Ltd Manager
How fertility is dealt with by the NZ dairy industry - genetics and environment
Jeremy Bryant
NZ Animal Evaluation Ltd Manager

2. Introduction Fertility came in focus in the late 90’s
NZ was less impacted
Need cows that calve every 365 days

3. Reproductive performance in NZ
6-week in-calf rate
Non-pregnancy (‘empty’) rate
Xu & Burton, 2003 Fertility Monitor Report 10 20 30 50 40 60 70 90 80
100 % 5 17 57 68 78
Overall
Lower quartile
Upper quartile
(36 – 90%)
(1 - 32%)
Seasonal calving is underpinned by seasonal breeding. The ultimate performance indicator for seasonal breeding are the rate with which the herd gets pregnant during a defined and limited period of weeks.
Two overall measures are the 6-week in-calf rate and the non-pregnancy rate (which we call ‘empty rate’).
On average, the farmer can manage reproduction so that 68% of cows get pregnant during the first 6 weeks of the seasonal breeding program. But there is substantial variance around this, with the mean of the top-quartile herds achieving 78%.
At the end of the seasonal mating period ( weeks), those cows which failed to get pregnant average 10%, but again there is substantial variance among herds. Cows that fail to get pregnant are generally culled, which is a great waste to the farmer and the industry as a whole.

4. Reasons for culling in NZ
≈ 50% on repro. 4% 6% 9%
45%
16%
16%
Herd replacement rate ≈ 20% p.a.
In fact, if we look at the reasons for which cows are culled in NZ, nearly half of it is dues to cows failing to get pregnant during the week seasonal breeding period. It’s certainly half when you add ‘due lates’ and abortions as other reasons for culling.
Average replacment rates in NZ are 20%. Farmers would much prefer to have these heifers replacing poor producers or cows with a history of mastiits or lameness.
Xu & Burton, 2003 Fertility Monitor Report

6. National Breeding Objective
“animals whose progeny will be the most efficient converters of feed into farmer profit”
Breeding Worth (BW) =
$ net farm income/5 tonne of DM

7. Genetics in NZ Multi-trait model – since 2006
Presented for mating - Parity 1-3
Calving rate within 42 days of calving start (CR42) - Parity 2, 3, 4
270 day milk volume yield (Parity 1)
BCS (Parity 1)
Low heritability but lots of genetic variation
New Model (potentially 2017)
Gestation length of animal itself
Use heifer calving information

8. Genetic Trends

9. Fertility BV Validation. It works !
Avg. Fert. Herd
Low Fert. Herd
High Fert. Herd
Every +1 Fertility BV = day mean calving date (MCD)
-0.17d
+1.19%
-0.83d
+1.31%
-0.81d
+1.10%
-0.17d
+1.40%
-1.15d
+1.59%
-1.16d
+1.49%
-0.19d
+0.84%
-0.52d
+0.90%
+0.66%
2 yr old
Every +1 Fertility BV = 1.19% increase in cows presented for mating in 21 days (PM21)
Fertility BV is more important in low than high fertility herds
3 yr old
4 yr old

10. It works ! Fertility Validation
Avg. Fert. Herd
Low Fert. Herd
High Fert. Herd
Every +1 Fertility BV = day mean calving date (MCD)
-0.17d
+1.19%
-0.83d
+1.31%
-0.81d
+1.10%
-0.17d
+1.40%
-1.15d
+1.59%
-1.16d
+1.49%
-0.19d
+0.84%
-0.52d
+0.90%
+0.66%
2 yr old
Every +1 Fertility BV = 1.19% increase in cows presented for mating in 21 days (PM21)
Fertility BV is more important in low than high fertility herds
3 yr old
4 yr old

11. Fertility Research Herd
Purpose build for extremes in genetic fertility, but balanced for other key traits
Currently have month-old heifers
Focussing on underlying reasons for fertility divergence as well as markers for increasing the rate of genetic gain in fertility
This work is funded by:
Ministry of Business, Innovation and Employment
New Zealand dairy farmers through DairyNZ Inc.

13. InCalf (NZ) 2008

14. Fertility fundamentals
Rear calves and heifers well
reach target weights
First mating
bull power, start mating earlier for heifers, calving ease bulls
First calving
BCS of 5.5 at calving
2nd mating
pre-mating heats, treat anoestrus, focus on heat detection
Pregnancy
Prepare cows so they reach BCS of 5 at second calving

15. Fertility Focus Report
Answers 3 key questions:
Where is the herd now?
What improvements are realistically achievable for the herd?
What areas for improvement should I be focusing on?

16. Conclusions
Gains can be made by improving environment/management and genetics
Genetics works
National breeding indices include a strong focus on fertility
Secondary selection possible
Fertility fundamentals
Significant gains can be made by focusing on some key principles

17. 6-week in-calf rate trend
78%
NZ Dairy Statistics