Remember the fertility sub-index when assessing EBIs

Mary Kinston

With mating approaching the 12 week mark on many farms, the bulls should now have been removed from the cows.

Breeding on is only worthwhile where a farmer has had a very poor breeding season or where there are strict management plans to offload late calvers.

Any cow bred now will calve around May 1, giving her no time to heal and prepare for AI.

If a good cow comes bulling once the bulls are removed, avoid the temptation to give her a straw. Remind yourself that she can no longer be defined as "a good cow" because she will not calve when required. Having removed the bulls it's now time to book in your scanning for the end of August or early September so that you can accurately date the cows' pregnancies.

During July I've been in the midst of finishing my KT (Knowledge Transfer) group's farm improvement plans.

The scheme closes on May 31 next year for its third and final year. All animal health plans also need to be submitted ahead of that date by your vet, so make sure your compliant with this if you're involved in the KT scheme.

One element of the FIP focuses on breeding. Here we assess the performance of the milking herd between the 2017 and 2018 season in calving rate and EBI gains, along with a few other measures.

When making recommendations to farmers I can't help but reflect on Donagh Berry's talk given at the Moorepark open day in July. Donagh stressed the importance of the continued EBI gains associated with gains in fertility.

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He stated that while significant gains in fertility had been made, that there were still further gains yet to be realised.

He suggested that a farmer should focus on achieving a fertility sub-index of plus €100. Having reviewed the EBI gains of my five KT discussion groups between 2017 and 2018 I was shocked by the over-riding trends.

First calvers

It became apparent that between 2017 and 2018, the average gain in herd EBI was around €30, but only €4 to €7 was associated with a fertility sub-index gain against the approximately €20 gain seen in milk sub-index.

In comparison, gains between 2016 and 2017 were smaller and much more balanced between milk and fertility.

When considering the herd's EBI, these gains must be associated with the 2018 first calvers, which were generally born in 2016 from AI decisions made in 2015 breeding season.

This four-year time difference highlights the time it takes to make breed changes.

Obviously 2015 was our first year of deregulation from quotas when farmers had a glimpse of being able to maximise the productivity of their herd and increase gross income through milk sales.

This may have prompted farmers to pick bulls with higher milk sub-index values, but I'm surprised how generic this trend is irrespective of herd differences or AI company used.

One can't help but question whether it was significantly influenced by the AI bulls on offer or possibly the difference in the heritability of traits or the reviewed EBI values.

There are many questions here to which I do not have the answers.

But as farmers we must review gains in EBI and the need to consciously select for significant gains in fertility as well as milk. A herd's fertility will drive profitability as it determines days in milk. In addition, it also significantly affects the required replacement rate and stock sales because of increases in cow longevity within the herd.

And while the 2019 breeding decisions have been made and implemented, one last point to note is that where a farm is struggling with fertility, Donagh Berry stressed that there was clear evidence of additional gains from cross-breeding with Jersey especially in the average herd.

Therefore, we can't write Jersey AI off, even in light of all the concerns about Jersey calves we've heard this year.

Indo Farming


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