RELATIONSHIPS BETWEEN TECHNICAL, ECONOMIC AND ENVIRONMENTAL RESULTS ON DAIRY FARMS - AN EXPLANATORY STUDY

Path analysis was used to model multivariate relationships between mil k yield, reproductive parameters, replacement, milk contents, farm cha racteristics, net returns and N-surplus. Data from an economic informa tion system and DHIA-data were available from 478 farms. Two models we re constructed: one to analyze the gross margin per 100 kg of milk, an d one to analyze N-surplus per ha. The first model showed that on the level of individual farms milk yield per cow in 305 days influenced re productive parameters, the replacement rate and gross margin per 100 k g of milk. Besides milk yield, gross margin is highly dependent of quo ta per ha, concentrates per cow per year, percentage of protein in the milk and amount of silage bought per ha. Number of inseminations per pregnancy, births per cow per year, young stock per ha and the replace ment rate had a small, but significant influence on the gross margin. In the second model N-surplus per ha was found to be highly dependent upon milk quota per ha and the amount of concentrates per cow per year . Weaker, but still significant relationships were found with replacem ent rate, young stock per ha and milk yield per cow. (C) 1997 Elsevier Science B.V.