Changes are coming in the UK dairy cow profitable lifetime index (£PLI) – the system that provides a ranking of bulls according to genetic merit.

The new PLI will have reduced emphasis on the volume of milk produced but maintaining the same weight of solids from less milk.

Speaking at AFBI Hillsborough this week, Marco Winters, the head of genetics/dairy breeding at DairyCo, said that any increased production is for export and ‘‘we won’t be exporting liquid’’. In this, the UK Genetics Advisory Forum is ahead of the dairy processing sector in its payment incentives for milk components.

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The PLI index will also have increased emphasis on fertility, udder health (reduced susceptibility to mastitis) and functional type (feet, legs and udders). It will maintain the importance of longevity and include the cost of maintenance and calving ease (direct and maternal) as desirable traits.

Winters said that the revamped index will be launched in August. It will re-rank bulls, with some poor fertility bulls dropping out of the high positions, but it won’t be a massive change.

Maintenance cost

Winters pointed out that cow maintenance cost is increasing and said that this has been directly correlated to the bull selection over the past 20 years. This had built-in inefficiency due to increasing size and angularity of animals. “Extreme animals don’t last long in our production systems – they have poor longevity. So, it is desirable to breed for smaller animals,” he argued.

Using a series of graphs to show trends since 1995, Winters indicated the power of genetics to ‘‘design the cow’’. He stressed that £PLI is no longer just a production index and said that the emphasis on volume production prior to 2000 had been pretty disastrous in terms of profitability.

Spring calving

The new PLI will be followed by a separate spring-calving index (£SCI). Winters said this is to take account of a dairy industry that is polarising into separate systems of milk production that require different genetics.

He stressed that the SCI was only for specialist spring-calving herds and not for herds that are block calving at other times of year.

The SCI will focus on milk quality rather than high volume (production efficiency with high components), a high emphasis on fertility and much bigger emphasis on the cost of maintenance (up from 9% to 16% of the overall index).

It will also select strongly on longevity and will value the cost associated with calving difficulties, while protecting udder health and functional type.