Why genetics is important for improving dairy cow fertility – Farmers Weekly

Dairy cow reproduction is central to herd income, driving milk yield, cutting interventions and improving cow life.

Evidence supporting the role of genetics in improving fertility accumulates every year, and new data from the AHDB now strengthens this link (see graph below).

Since the introduction of the female fertility index (FI) in 2005, fertility genetics have shown significant improvement in the nation’s dairy herd.

This is also reflected in the actual performance, or phenotype, and the genetic prediction of the reproductive index (also shown in the graph).

See also: Leeds leads latest bulls with 914 PLI

But today’s improvement follows years of decline when producers had no idea of ​​the bull’s ability to reproduce the female’s offspring and mostly opted for milk production.

This had the effect of not only ignoring the cow’s fertility, but selecting against it.

This was driven by the negative correlation between milk production and fertility, which was known at the time, but difficult to correct.

However, today’s computing power and gene expression systems have turned this situation on its head.

And with the development of comprehensive indices, such as the probable lifetime index (PLI), which includes the element of fertility alongside other traits, it has become easier for producers to include fertility in their genetic selection criteria.

These indicators have made it possible to ensure that the genetic selection made today does not have unexpected results in the balance between desirable and undesirable traits, as was the case in the past.

Marco Winters, head of animal husbandry at the AHDB, says producers should be congratulated for implementing the change.

Cut during spawning

“Their efforts have effectively reduced the gestation period from nearly 425 days in the mid-2000s to about 395 days today,” he says.

This advance, in fact, was predicted in a previous genetic study about five years ago.

Meanwhile the AHDB estimates, based on genetics, that the average UK reproductive age will reach 390 days by 2024.

“With this forecast still on target, it is possible to confidently predict further improvements to come,” he said.

“This improvement will be slow, as we have taken the low-hanging fruit, but we expect to continue to reduce the breeding season by about one day per year for the next five years.”

This puts the national dairy herd on target for a calving period of 385 days by 2029.

“This will bring us back to the prosperity levels of the mid-1990s,” Marco continues. “But surprisingly, this has been achieved at the same time as milk yields have increased dramatically.”

A legacy of prosperity

This achievement shows the power of genetics as a force for improvement. And it proves that it is worth choosing with low inheritance characteristics.

“Fertility is about 3% heritable [or 0.03]which is considered low,” he says.

“However, genetics is the level at which a trait is considered to be passed down from generation to generation, and female fertility is greatly influenced by environmental factors – from nutrition and housing to reproductive timing and sperm production.”

The genetic indexing process is effective in filtering out this external “noise”, and identifying cows with natural breeding.

“If we can measure the calving capacity of cows, it is clear that we can have a significant impact on animal performance,” he said.

Strongly encouraging every farmer to consider FI, Marco says it should be a key part of all dairy production plans.

“We want cows that will calve and we want them to last a long time, and this index will help us achieve these goals.

But breeding is also good for income, welfare and the environment and for this reason, it is included in all our main indices including HealthyCow, EnviroCow and PLI, as well as seasonal breeding indices.

“Of course, improved management can have an immediate impact on dairy cattle productivity, but the improvements made through husbandry will be sustainable over the long term, and accumulate over generations,” he said.

As with all symptoms, it is important to consider both genetics and management, and remember that having better genetics will make management easier.

Essex dairy crosses the calving index at 40 days

Farm Facts: Battle Hall Farm, Essex

• 429 ha
• Curtismill’s pedigree Holsteins, fully preserved
• Breeding throughout the year
• Milking three times a day
• Average yield 13,500 liters at 4% fat and 3.28% protein
• Milk sold to Muller

Rory, Robert and John Torrance © Jack Hill/the Times

Essex farmer and NMR/RABDF Gold Cup winner John Torrance quickly took to the AHDB fertility index when it was introduced in 2005 and has been using it as a breeding tool ever since.

He says the index has transformed the performance of his 700 cows, which have improved their fertility continuously for about 15 years, with greater productivity.

The fertility rate today is 40 days shorter than it used to be, dropping from 420 to 380 days.

He says: “We have made great strides since we started using health indicators, and especially Oman bloodlines have changed health and fertility.”

He has full confidence in the data and selecting high breeding bulls within the Holstein breed, adding: “The data doesn’t lie – before we had it, we were selecting bulls very quickly.”

Acknowledging the importance of monitoring activities, he says they play an important role, working in harmony with genes.

Together, they have allowed the herd’s voluntary waiting period to be extended to 55 days, as John is more confident than ever about getting his cows into calf.

The pregnancy rate shows the success of the policy and is currently running at an average of 29.5%.