Where to now for dairy breeding

Over recent years, the main focus in the dairy cow scene has shifted from being strongly focused on genetics to focusing largely on breeding management.

The key topics for discussion among farmers and advisers now are genotyping, sexed semen, selecting cows for beef, synchronisation programmes and, to a lesser extent, automated heat detection systems.

This shift in focus has come about largely as a result of the desire to sort out the calf problem, where too many dairy-bred calves were born with too low beef values making them undesirable to calf buyers.

While undoubtedly important, farmers cannot pursue the goal of improving the beef characteristics of their non-dairy replacement calves at the expense of breeding top-quality replacement heifers. In other words, they need to maximise long-term genetic gain.

These two things are not in conflict with each other as, thankfully, sexed semen is now widely available.

However, picking the right dairy bulls is as important if not more important than ever and cannot be given any less attention than before.

Traits

In my view, all of the dairy bulls used on Irish farms should be high-EBI, but just selecting for EBI alone is not good enough. Farmers need to delve into the bulls and pick bulls with the most desirable traits within the top EBI bulls.

When it comes to milk traits of bulls, the percentage of fat and protein are more important than kilos of fat and protein, in my view. This is because it is easier to breed a bull with higher kilos because this is largely driven by milk volume, which is highly heritable.

However, this extra volume is delivered at a big cost on farms and, in my view, is not adequately reflected in the A+B-C economic formula used to calculate the value of traits within the EBI.

Furthermore, the economic cost of breeding higher-yielding cows is now greater due to the introduction of banding within the Nitrates Action Programme.

I get a shiver down my spine when I hear farmers or advisers say they pick bulls with +30kg of solids because it doesn’t tell me where those extra solids are coming from.

Ultimately, it is everyone’s desire to produce more milk solids per cow, but this has to be done in an efficient manner. There is more than enough milk volume in the vast majority of Irish herds even if the predicted transmitting ability (PTA) for milk kilos is zero.

Generally speaking, bulls that have high PTAs for fat and protein percentage will have a lower PTA for milk volume.

Importantly, farmers should always be looking to use bulls that are going to improve their herd in this important trait. I have seen it happen where farmers have used a team of bulls with a combined lower PTA for fat and protein than their herd average because they have focused on kilos of solids rather than percentages.

The result will be that the crop of heifers from those bulls will end up bringing down the fat and protein percentage of the milk being sent to the co-op.

The herd average PTA for milk volume and for both kilos and percentages of fat and protein is on the front page of the EBI report.

Fertility

The ICBF says that the fertility figures within the EBI continue to be over-estimated due to the influence of genomics.

To overcome this, the methodology around how much genomics is used in calculating a proof is being capped at a lower level than before.

ICBF says that the recent changes will greatly improve the reliability of fertility, especially for the youngest genomic bulls.

Plans to change the way fertility is calculated within the EBI to a calving rate rather than calving interval basis have been shelved for now.

In terms of advising farmers on the targets for fertility within the bull team, the general advice appears to be to go for as high a fertility sub-index as possible. It’s important to note that the base cow still has a calving interval of 400 days and a survival rate from one lactation to the next of 82.5%.

So, a herd that is minus five days for calving interval PTA still has a long way to go for genetic improvement in fertility. The argument is sometimes made that if the herd is already achieving a 365-day calving interval then reducing that further is of no benefit.

However, calving interval is a proxy for good fertility performance.

In block-calving systems the actual calving interval will be determined by mating start date, so I don’t think there are any downsides to continuing to pursue improved fertility even where the herd may already be operating well.

The introduction of the carbon index into the EBI has had a positive impact on reducing the number of bulls in the active bull list that have a very low figure for maintenance in their EBI.

For most farmers, a cow liveweight of around 550kg is close to ideal in terms of balancing size and efficiency

The lower the maintenance sub-index is, the heavier the cow is likely to be. A cow with a maintenance sub-index of €0 will weigh around 640kg on average and each €1 change in maintenance equals a 5kg change in liveweight.

For most farmers, a cow liveweight of around 550kg is close to ideal in terms of balancing size and efficiency.

We know that larger cows tend to be less efficient as they require more energy for maintenance.

Choosing bulls that have a lower value for maintenance compared to the herd average will lead to the herd getting bigger over time and, for most farmers, this is something that should be avoided.

I still believe there is huge untapped potential from crossbreeding. OK, a team of just Jersey or crossbred bulls will struggle to compete with young Holstein Friesian bulls on EBI alone.

But, fertility in most of the young Holstein Friesian bulls is overestimated and the benefit of hybrid vigour, which is not counted in EBI, is mostly towards fertility.

Having said that, many Jersey crossbred herds have switched back to using predominantly Holstein Friesian bulls, but this is a perfect example of crossbreeding in action as such moves will maximise hybrid vigour.

Whether they will move back to Jersey again in the future remains to be seen.

Equally, what impact the inclusion of methane as a measured trait within the EBI will have on bull selection remains to be seen also, with some suggesting that a smaller, more efficient cow in terms of output per kilo of liveweight will be more favoured by a methane trait.

The point here is that crossbreeding as a tool to improve herd performance should not be abandoned.

Sexed semen and high dairy beef index bulls are an essential part of crossbreeding to ensure no hit on calf quality.

There is currently no in-field validation work taking place on EBI, particularly on the fertility side of EBI, which is very slow and difficult to do.

Ten years ago, Teagasc established the Next Generation Herd to validate EBI and genomics.

While the core herd remains, the research focus has changed. All of the other Teagasc research farms are focused on either clover or multispecies research with no current research trial on dairy genetics.

Genomics has turbocharged genetic selection

Obviously, resources have to be prioritised but as we have seen in the past, it’s very easy to go down the wrong road when it comes to dairy breeding.

Genomics has turbocharged genetic selection, which is great if it’s going in the right direction for any given trait but very bad if it’s going in the wrong direction for a trait, so it is something that needs more, not less monitoring.

Just looking at the national figures for EBI is insufficient as EBI will always be high in young cows that are bred from high-EBI bulls. The question is, will these young cows actually survive in the herd and will their good genotype translate into a good phenotype?

New developments such as the National Genotyping Programme are welcome but are resource-heavy.

There has been distraction from controversies within the beef index, which appears to be more concerned about ensuring farmers get paid for schemes than the actual index itself. This is an unnecessary distraction for geneticists.

There have also been some high-level departures from the ICBF and VistaMilk in recent months.

A bit like with cows, there is no problem with seeing people replaced provided they are replaced by brighter intellects.

There are now great opportunities for the next generation of researchers and geneticists to put their stamp on the Irish dairy breeding programme.

Ultimately, it is the responsibility of the board members of ICBF and Teagasc to ensure that scarce resources are deployed in the right areas.

We must keep investing in order to ensure genetic gain in the dairy herd for decades to come.