Experiences with evaluating two farming systems in a split herd comparison on a commercial Waikato dairy farm

Abstract

An on-farm demonstration of the effects of a higher stocking rate (expressed as cows per hectare), supported by purchased maize silage, was conducted on a commercial Waikato dairy farm that was split into two farmlets. Milk from each farmlet was collected into separate vats. This paper reports on two seasons of comparison between: 1. A 57-ha farmlet with 185 Friesian cows stocked at 3.25 cows per ha, representing the farm's previous management (Control -LS) and; 2. A 51-ha farmlet with 185 Friesian cows stocked at 3.6 cows per ha, supported by the purchase of 430 kg DM per cow of maize silage (Treatment -HS) The comparison aimed to demonstrate that higher stocking rates, supported by purchased maize silage, would increase total pasture utilisation and increase profit per hectare. Milksolids production for the HS farmlet was 105 and 99 kg per ha higher than LS in years one and two with Economic Farm Surplus per ha increasing by $113-$375 per ha (depending on payout). The comparison highlighted the difficulty of determining stocking rate on a cows-per-ha basis for a farm with unknown pasture production. In effect, the comparison was between two herds stocked at a similar level relative to total feed supply, with both herds being limited by total feed supply. This study also demonstrated practical management issues involved for farmers who are adding purchased feed into their systems. Being a commercial dairy farm meant this split herd demonstration could not be subjected to strict scientific protocols, as the commercial objectives of the farmers had to be met. The limitations and advantages of this type of on-farm demonstration are discussed. Keywords: economic farm surplus, maize silage, milksolids production per ha, on-farm demonstration, split-herd comparison, stocking rate