BETH Howells, NWF Technical Development Co-ordinator looks at optimising supplementary feeding at grass during periods of wet weather.

To determine a cow’s intake requirement of grass, we make assumptions and estimates, considering the quality and quantity of the grass, and the behaviour and capability of the cow.With weather fluctuations giving us periods of drought and high levels of rain, grass management and intakes are extremely difficult to predict; intervening with supplementary feed is essential to mitigate any drop in performance.

The average grass dry matter for July is 18 percent and with a target intake of grass at 12kg DM, cows are required to eat 67kg of grass. When grass DM decreases by just six percent (DM 12 percent), the intake required of fresh grass increases by 33kg to a total of 100kg, to meet intakes of 12kg DMI. If required intakes are not met, as expected, production losses will occur. Understanding grass DM, and the likeliness of cows achieving their target intakes through grazing, is not the only key to knowing when to offer supplementary feed, but also to optimize it. For each one percent drop in DM, a cow would need to eat an extra 5Kg fresh weight of grass to meet the same DM. Farms should have a plan B as to when they should provide some supplementary feed. An example could be that when DM drops below 17 percent, supplementary feeding, in the, in the form of conserved forage, blends or compound, should be done.The fundamental barrier is time, the lower the grass DM is, the less likely the cow will be able to achieve their target intakes at grazing, giving the opportunity to optimise resources whether that is grass, conserved forage, blends or compound.

For information on managing herd nutrition and performance contact NWF Agriculture on 0800 756 2787.

NWF Agriculture started life in 1871 as a farmer-owned trading company and now forms part of the AIM market quoted NWF Group plc.