Effects of different stocking rates with dairy cows on herbage quality and milk production in organic farming

Summary

In order to identify the optimum stocking rate for grazing dairy cows in organic farming, grazing experiments were conducted from 2004 to 2006. Cows of one herd were divided into two groups during vegetation periods. The paddocks of the rotational pasture were split in a way that the low stocking rate group (SRL) had 15% more pasture area than the high stocking rate group (SRH). Post grazing sward height for SRH, was decisive for the simultaneous change of the sub-paddocks. Annual stocking rates for SRH were 2.0, 2.3 and 2.3 cows per hectare (ha). In the offered herbage mass for SRL significant lower ash-, CP-, APDE- and APDN values as well as higher NDF values were detected. Sugar- and NEL values were unaffected. No significant differences were found for milk production per cow, but milk production per ha was significantly higher for SRH. Apart from two exceptions (lactose 2005 and urea 2006), no significant differences were identified for milk composition. The attribution of more pasture area without topping leads to a lower pasture quality. Increasing the stocking rate, within limits, slightly reduces the milk yield per cow, but clearly improves the utilization of grown herbage.