There are big differences between the management of herds that produce most of their milk over the winter and those that do so over the summer. For one thing, winter-milking herdowners are paid a premium price for their milk – reflecting the higher costs of production with winter milking.

Secondly, winter milking herds are fed a largely conserved forage diet, usually consisting of grass silage but it can include maize and wholecrop wheat. This is fed in addition to concentrate feed – usually at higher rates than their spring-calving counterparts.

With such big differences in production, it stands to reason that the genetic makeup of winter milking herds should be different to spring-calving cows. It would certainly make for an interesting article if this was true, but it’s not.

The very things that manufacturing milk herds want is what winter milk herds want also – that is a high EBI.

The highest-EBI cows produced 586kg of milk solids per cow and delivered an average milk price of 32.4c/l and daily milk value of €6.66/cow

Teagasc’s Joe Patton looked at the effects of EBI on performance across 900 cows in eight high-output winter milk herds in the southern part of the Lakeland region. The cows were split into quartiles based on their EBI. The highest-EBI 25% of cows had an EBI of €137 while the lowest-EBI 25% had an EBI of -€9.

The highest-EBI cows produced 586kg of milk solids per cow and delivered an average milk price of 32.4c/l and daily milk value of €6.66/cow. The lowest-EBI cows produced 536kg of milk solids per cow and delivered an average milk price of 29.5c/l and daily milk value of €6.14/cow. The higher-EBI cows had better fertility and produced higher-value (fat and protein) milk.

Study

A different study of 3,360 cows across 22 liquid milk herds showed that herds with a high-fertility sub-index within the EBI had a higher chance of reaching fourth lactation (64% of high-fertility sub-index versus 29% of low-fertility sub-index). This study also found that the higher-EBI cows got to fourth lactation faster than the low-EBI cows, getting there on average 296 days earlier than the low-EBI cows.

What does all of this mean for winter and liquid milk herds? Breeding cows with good fertility and milk solids is as important for winter milk herds as it is for manufacturing herds.

Good fertility increases days at milk and reduces the replacement rate. Good solids increase the milk price farmers receive. Both of these factors are major contributors to profit.

In the main, winter and liquid milk herds need to up their game when it comes to selecting bulls based on EBI.

There appears to be a reluctance among many winter milk farmers to fully embrace EBI

Speaking at a winter milk event in 2019, Teagasc’s Richard O’Brien said the average EBI of winter milk herds in the Glanbia region is €58. That’s almost half of the national average for all herds.

There appears to be a reluctance among many winter milk farmers to fully embrace EBI. In many cases, these are legacy issues and go back to the time that EBI was introduced. At that time pedigree herds, many of whom were in winter/liquid milk production, felt that they were going to lose out as the industry moved away from pedigree to more commercial bulls, some of whom do not have a full pedigree status.

There is no reason why pedigree status and type traits cannot be maintained while still choosing high-EBI bulls

Other issues relate to type traits, with some feeling that high-EBI bulls are not good enough on type. While these are all very real issues, particularly for herds that have been breeding cow families for generations, the time will come when a decision needs to be made about the direction of breeding on liquid and winter milk herds. There is no reason why pedigree status and type traits cannot be maintained while still choosing high-EBI bulls.

Secondly, there is no reason why a portion of cows in the herd cannot still be bred for traits other than profit and the majority bred for profit. The suggestion here is that certain cow families can continue to be bred for type traits and brought to shows and so on, but that the majority of cows in the herd will be bred based on commercial decisions.

Winter and liquid milk herds are under threat; breeding the most profitable cow available is necessary for the system to be successful. This can be achieved by continuing with daughter proven or pedigree-registered bulls, if desired, provided they are high-EBI.