Farmlet testing of the DairyNZ Conservation Demo

Abstract

The DairyNZ Modelling Group has developed a model called the Conservation Demo to assist in identifying and conserving surplus pasture on dairy farms. The hypothesis was that a computer algorithm would be able to make decisions concerning timing and amount of conservation similar to an experienced pasture manager. Weekly grazing decisions on DairyNZ farmlets, with stocking rates of 2.6 to 3.5 cows/ ha, were made by a team of research staff over three years. The model was run for each farmlet to compare its recommendations with the conservation decisions made by the research team. In spring on all farmlets and in summer on the higher stocked farmlets, the model was more conservative than the team in recommending paddocks to be closed in all seasons. In summer 2011/12 the recommendations from the model were more variable week-to-week (paddocks being closed one week and not the next), and on the lower stocked farmlet the model was more aggressive than the team. The Conservation Demo is a useful tool for identifying surplus pasture if the output is moderated by the farm manager, and the use of a feed wedge in conjunction with the model would improve the decisions. However the model requires pasture covers for each paddock, ideally at least weekly, and currently <20% of dairy farmers collect these data on a regular basis.