An analysis of milking recording data has shown that there is money to be made from increasing butterfat and protein levels in James and Owen Martin’s high-output Holstein herd.

The 160-cow herd is currently averaging 9,706 litres at 3.88% butterfat and 3.24% protein, which equates to a milk solids yield of 712kg.

When ranked on milk solids yield, the top 25% of first-lactation cows average 690kg from an average volume of 8,257 litres. It compares to the bottom 25% on 658kg coming from 9,107 litres.

The Martins farm in Dromintee, Co Armagh, and, under the milk pricing system in Northern Ireland, they are paid on a per litre basis, with bonuses available for butterfat and protein.

As Table 1 shows, even though cows in the top 25% produce almost 1,000 litres less, they still bring in £12 more per cow than the bottom 25% of the herd. This is because bonuses for milk components outweigh lower milk volume payments.

With the Martins operating a feed to yield system based on litres, the cows in the top 25% will also have lower concentrate costs than the bottom 25% group.

At the herd’s current feed rate of 0.38kg/litre, the top 25% of cows will consume 323kg less meal, which equates to a saving of almost £90/cow under current feed prices.

Milking regime

With average yields approaching 10,000 litres, Owen and James feel that there is not much room left to increase milk output under twice-a-day milking.

“To really push yields on, we would have to start milking three times a day and that is something that we do not want to do. The next thing we want to do is increase butterfat and protein levels because it will increase the value of our milk with little or no extra cost,” James said.

The Martins are now focused on using Holstein sires that have high predicted transmitting ability (PTA) for butterfat and protein.

Table 1 shows that cows with high PTAs for milk components at Garaba Holsteins are already producing the goods in terms of actual milk solids in the bulk tank, and therefore milk quality bonuses. The aim is to replicate this across the entire herd.

The Martins select sires using the UK-based Profitable Lifetime Index (PLI) system. The herd has an overall PLI of £92, PTA for milk is 121kg and PTA for butterfat and protein is 0.05% and 0.01% respectively.

Speaking on a Dairylink webinar on breeding strategy, James made clear that although he wants to lift milk components, he also wants to hold milk yields in volume terms.

So, what emphasis should he put on PTA for milk volume when selecting sires going forward?

James initially suggested only using bulls with a milk PTA of at least 500kg, but after discussing this with Dairylink adviser Aidan Cushnahan and Joe Patton from Teagasc, it was decided that this was not necessary.

PTA example

Aidan gave an example of using a bull with a PTA for milk of 200kg on a cow with the Martin herd’s average milk PTA of 121 kg. They will produce a heifer with a breeding value of 321kg.

“This means the heifer still has the genetic potential to produce 321kg of milk more than the average heifer in the UK. She will be able to transmit half of that to the next generation, which gives her a milk PTA of 160kg,” Aidan explained.

It shows that using sires with lower (or even negative) breeding indexes for milk yields has a much smaller impact than commonly thought on the genetic potential of progeny to produce litres, especially when the herd already has a high PTA for milk.

A key point raised by Joe during the webinar was that putting a requirement for high milk PTA can exclude a lot of bulls that could improve other traits, such as milk components or fertility.

He pointed out that the factor limiting milk yields in a lot of dairy herds is not genetic potential but is often the likes of fertility, herd health or milking frequency.

This was seen in a previous analysis of herd performance at Garaba Holsteins which found there was no longer a correlation between milk PTA and actual milk yield (see www.ifj.ie/dairylink).

Producing solids

This analysis also showed that cows on the Martin farm with higher breeding indexes for protein and butterfat are delivering in terms of actual milk components.

“If you breed for butterfat and protein, you will get butterfat and protein. If you breed for milk volume, you might not necessarily get milk volume,” Joe said.

Having too many minimum requirements for different traits when picking bulls often shortens the list of potential sires down to the point that there are very few to choose from.

When selecting sires, Joe advises against setting strict criteria for traits that are not likely to have an impact on the actual performance of heifers.

“If it’s not the main limiting factor to the trait, it shouldn’t be top of sire selection criteria,” he said.