The most suitable winter milk structure to fulfill liquid milk contracts is to have two compact calving blocks lasting between 10 and 12 weeks.

The first of these should be in early February and the second in early October, according to James Dunne, a Teagasc dairy specialist, based in Ballyhaise, Co. Cavan.

In a recent report, he outlined the importance of matching calving rates to match liquid milk contracts. The report figures are based off of a 100-cow herd, receiving an average milk price of 35c/L.

The report looks at three production brackets of liquid milk contracts:

  • <25%;
  • 50%;
  • ≥70%.

<25%

A liquid milk contract of <25% for a 100-cow herd requires 15% of cows calving in the autumn. James outlined that at this level of production, the viability of this operation has to be questioned.

Liquid bonus revenue should be calculated against additional costs that occurred to determine the viability of this production system, with an estimated extra feed cost of €200/cow.

50%

A 50% liquid milk contract requires 30-35% of the cows calving in autumn. October-calving cows have similar feed costs to summer-calving cows but will produce approximately 50-60% more milk output over the winter period.

This maximises milk revenue over feed cost and ensures contract volumes for each month are met. This, in turn, reduces the overall cost to supply the fixed contract.

≥70%

For ≥70% liquid contract, this will require 55% of cows to calve in the autumn. Calving should start in mid-September, with late calvers being kept to a minimum.

With this pattern, August and early-September milk supplies may fall below required daily levels on the farm; but the benefits of block calving to the farm should be recognised in this situation.

James highlighted that the practice of carrying stale cows over from spring to autumn is negligible.

The calving pattern must not become a consequence of poor fertility.

Allowing cows that don’t go in-calf to transition into autumn production can lead to more animals with extended lactation length and a negative fertility cycle that is hard to break.