Farm Ireland
Independent.ie

Friday 15 December 2017

A balanced diet for Winter milk

Joe Patton

Milk quota concerns and the move to pricing based on milk solids mean that a moderate milk volume with good fat and protein percentages is an ideal that many farmers are aiming for this autumn.

It should provide scope for feed savings but how do you achieve this without your cows getting too thin? The aim should be to reduce body condition score losses to less than 0.5 units before breeding.

Despite the huge range of diets and costs at farm level, there are some basic principles which should be followed to improve cow performance while leaving a decent margin:

•Target 0.90 UFL/kg in the total diet for higher yielding herds. Energy is first limiting for milk production. Ingredients should be valued on a UFL basis (the standard unit of energy). Cheaper ingredients may seem good value but are often more expensive per unit of energy.

•Start on 2kg of meal and increase by 1kg every second day after that. Milk energy output rises faster than feed energy intake in early lactation, resulting in a negative energy balance (NEB). A more severe NEB is associated with reduced fertility. Much has been written about preventing this by achieving high intakes very quickly after calving. In practice, this often leads to digestive and metabolic problems, making situations worse. It is important to point out that some degree of NEB is inevitable. Focus instead on achieving a slow and steady increase in daily feed intake. High quality forage fed ad-lib is critical.

Rumen

•Limit added fat to 2pc and aim for 20-25pc starch plus sugar in the total diet. The type of energy fed is also important. Fat is energy-rich but can affect rumen function. For high milk solids yield, there should be adequate starch but if you overdo it, acidosis becomes a risk. Divide starch in concentrates between maize and barley/wheat.

•Aim for a body condition score (BCS) of 3-3.25 at calving. The importance of correct BCS at calving cannot be overstated. Excess BCS is a major cause of milk fever, ketosis etc. For autumn calving cows, dry cow intakes at grass must be strictly controlled.

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•At least 75pc of dietary fibre should come from forage. Adequate fibre is important to maintain rumen pH. Excess fibre will dilute energy and reduce intake, so the aim should be to meet the minimum requirements for rumen health.

•Crude protein (CP) is not a good measure of diet quality as it only measures nitrogen content. Dairy cows can take protein directly from the diet (bypass protein) or from protein manufactured by rumen microbes. This requires both fermentable energy and nitrogen, which need to be balanced to have good feed efficiency.

The PDI system can be used to balance the diet for energy and nitrogen. Target PDI is around 100-105g/kg. Using this method, the cow can be fully fed for protein at 16pc CP or less.

An example diet is shown in the table (above). Energy and protein content are closely matched to support 27 litres and 28 litres respectively. The PDIN-PDIE protein content is also balanced. Using this formulation method, there is potential for reducing crude protein from the standard 17-18pc in early lactation. Curtailing crude protein to around 15pc is likely to be beneficial in that it should reduce the cost of purchased concentrates, produce a flat lactation curve and reduce body condition loss.

This method is being used for the Teagasc winter milk herd in Johnstown Castle.

Indo Farming