A lot of winter herds will be nearly finished calving, grass will soon disappear out of diets and thoughts will turn to the winter feed requirements for these cows. Concentrate feed is the largest variable cost for winter milk farms.

While average cost is around 6.0 to 6.5c/l, there is considerable variation around the average (4.5 to >12c/l). It is important not to lose focus on the economics around feeding the main herd.

When it comes to diet formulation, Table 1 outlines what the typical autumn-calving cow requires at differing daily milk output levels.

Dry matter intakes (DMI) of 20-22.5kg are required to meet nutrient demand. Quality forage (75% DMD) is essential – target at least 60% of DMI as forage (13 to 14kg per day), with the balance as concentrate.

Energy is the first limiting nutrient for milk, as diet UFL per kg is constrained by the need for fibre in the diet. Meet the target UFL per kg with high-quality silage and high-energy concentrates. Ensure you provide enough total PDI (protein) for target production.

To maximize efficiency of energy and protein utilisation for milk production, it is important to match the PDI and UFL ratio of the diet. For example, a diet with 0.94UFL per kg should have 94-97g PDI. A total diet NDF (fibre) target of 30-36% will maintain rumen health and avoid acidosis, with 24% to 28% of this coming from forage.

Silage DMD and intake achieved dictate the overall diet NDF. However, excess NDF (>40%) from poor forage sources or straw reduces DMI and milk yield. Use quality digestible fibre sources if forage intake/quality is limited. Guide meal feeding rates, along with good-quality silage, are included in the table. (Forage analysis should be the basis of all diet formulation. Only analysis completed by a Forage Analysis Assurance (FAA)-approved lab should be used.)

The standard winter milk diet for the Teagasc Johnstown Castle herd (Table 2) comprises a grass/maize silage forage mix, a high protein concentrate blend fed in the forage and a high-energy concentrate fed in parlour.

Target silage DMD is 75%. Maize silage is included at 4.5kg DM, or 500kg DM per cow annually. This also offsets the annual forage shortfall due to milking platform stocking rate of 2.9 cows per ha. In recent years, total crude protein content has been reduced from 17.5% to 15.5%, with no loss of milk yield or solids content, by balancing the diet for UFL and PDI ratios. Last year, the winter group milked 30kg at 4.48 fat and 3.48 protein, or 2.4kg MS in December and January.

Farmers should check the milk yield distribution for their own herd, using winter milk recording data, before setting out their feeding strategy for the coming winter. An analysis of milk recording data for a high-yielding herd (8,000kg) with 40% of the herd calving in the autumn, showed the average milk yield in January and February was 27kg/day. This high-yielding herd had 9% of cows producing over 35kg/day.

The total milk output from the highest yielders accounted for 14% of the total output, while the marginal milk produced (milk produced >35kg by these cows) equates to just 1.2% of daily output. Therefore, 86% of daily milk output comes from the standard base cow within the herd.

The strategy for providing the best economic return should be to ensure the basis of the diet is formulated to a herd level and not that of the best cows, based on the herd’s own performance. Individual high yielders can be managed as a sub group thereafter. To control feed costs during winter, concentrate fed per kg milk should be 0.24—0.28kg. This is only possible with high-quality silage.