Reproductive performance of all AB herds

Find out how the reproductive performance of no bull/all AB herds compares to the results from herds that use a combination of AB and natural mating bulls.

Under the current state of heightened biosecurity in New Zealand, there are indications that more farmers will be going all AB/no bull this mating season.  To provide some insights into the reproductive (repro) performance of all AB herds, we’ve pulled together data from the 2014 to 2017 spring matings and looked at the performance of herds that have used all AB/no bulls (all AB) and compared it with herds that used AB + natural mating bulls (AB + Bull)*.

How many all AB herds are there?

The number of herds doing all AB has been increasing over time.  Across the 2014 to 2017 seasons, there were 290 - 417 farmers doing all AB a season.

Performance of All AB herds compared with AB + Bull herds

Combining the four seasons worth of data together we looked at the performance of All AB herds compared with the AB + Bull herds.  The results indicate that the All AB herds tend to have similar/slightly better reproductive performance than the AB + Bull herds.

Average

AB + Bull herds

All AB herds

Difference

Average 6-week-in-calf rate

AB + Bull herds 66.2%

All AB herds 67.7.%

Difference +1.4%

Average Not-in-calf rate

AB + Bull herds 16.6%

All AB herds 17.1%

Difference +0.6%

Average Total Mating Length (days)

AB + Bull herds 76.0

All AB herds 76.4

Difference +0.3

Average Herd 3-week submission rate

AB + Bull herds 79.0%

All AB herds 83.6%

Difference +4.6%

Average First calver 3-week submission rate

AB + Bull herds 80.6%

All AB herds 85.3%

Difference +4.7%

Average Conception rate

AB + Bull herds 52.6%

All AB herds 51.3%

Difference -1.3%

Average AB Mating Length (days)

AB + Bull herds 45.3

All AB herds 76.4

Difference +31.1

Average Number of herds

AB + Bull herds 13996

All AB herds 878

How were the all AB herds performing before going all AB?

In the year before switching to all AB, these herds were higher performing, larger, and already doing around 8 weeks of AB.

What happens to their results when they switch to all AB?

The year that herds switch to all AB, there is a slight drop in reproductive performance, but in the second and third years of being all AB, performance lifts to be similar or better than it was before the switch to all AB.

In addition, we seem to be getting better at switching to all AB.  When we look at the results for the herds that go all AB on an individual season basis (e.g. just looking at herds that went all AB in 2015 vs those who went all AB in 2016), we see that any detrimental impact of switching to all AB has been reducing.

Do farmers who go all AB stay with it?

The results indicate that just over half of the herds that go all AB continue to do all AB for a second season, but only around a third go on to do a third or fourth all AB season.  In light of M. bovis and the drive to be more self-contained, the rate of farmers sticking with all AB may increase.

What happens to the results of the herds that don’t stick with all AB?

The year that the herds changed back to AB + Bull, their 6-week in-calf rate and not-in-calf rates returned to, or were better than, the performance they had before going all AB.

Herds that changed back to AB + Bull tended to have a greater drop in performance in their first year of all AB than those who stayed with it.

Together, these two results highlight the fact that going all AB is not for everyone. 

Summary

The results indicate that in general herds that are all AB have a very similar repro performance to AB + Bull herds, but there is a journey that all AB herds tend go through over a couple seasons when switching to all AB.

In other words, going all AB may not be for everyone, but sticking with all AB can produce similar or slightly better repro performance than AB + Bull herds. 

For more information, check out this National Reproductive Strategy Group article - Biosecurity focus at mating.

*Herds included in the analysis for this article were spring calving seasonal herds that had a Detailed InCalf Fertility Focus Report.  The seasons analysed were the 2014 to 2017 spring matings.  The reproduction measures analysed were generated from data and information entered by herd owners and collected by LIC and DairyNZ.  Accuracy of the results reported here is subject to the accuracy of the data entered.

Want to back up your decision with data?

Read the stats from the 2014 to 2017 seasons, showing the performance of All AB herds compared with AB + Bull herds.

Download the all AB statistics

Want to back up your decision with data?

Read the stats from the 2014 to 2017 seasons, showing the performance of All AB herds compared with AB + Bull herds.

Download the all AB statistics