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Research Shows Dairy Cows Can Be Fussy Eaters

Friday, 12 October 2001


New research has shown that dairy cows are fussy about eating spring pasture that has high potassium content. Therefore farmers need to apply fertiliser carefully during spring months as it is common for the lush, rapidly growing grass to have a potassium content greater than the 3% required for maximum pasture growth.

Dr Hilton Furness, Technical Director of Fert Research says; “The research showed that if the only available pasture is high in potassium, reproduction efficiency and milk production can be adversely affected. This means the farmer will lose out financially, however by monitoring soil potassium levels through regular soil testing farmers could save money. If soil levels are too high then fertiliser potassium applications need to be reduced or stopped until soil potassium levels decline.”

The recent study, funded by Fert Research, and carried out by AgResearch, found that bite rate was greatly reduced when cows grazed on spring pasture containing potassium of more than 3.7%. The trials were conducted on four commercial Taranaki dairy farms where different levels of potassium were applied to pasture in September last year. The number of bites taken by cows in October and November were recorded, with a significant decrease in grazing times as the potassium levels increased for the October grazing.

One factor that impacts on soil and pasture potassium levels is the spraying of farm dairy effluent onto paddocks. Cow urine is naturally rich in potassium, which makes farm dairy effluent rich in potassium. It is unlikely that these effluent paddocks will require fertiliser K, so soil and pasture testing as well as nutrient budgeting should be used to monitor and adjust inputs to this area.

The research will be repeated again in Taranaki this year to confirm the first year’s interim findings and is also being extended to enable researchers to look at four Northland farms.

The researchers were J Morton, C Roach and A Roberts of AgResearch.

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