Is increasing ewe prolificacy the key to increasing Canterbury dry land farm profitability? Research using linear programming as a modelling tool

Abstract

The sheep industry contributed $3.47 billion in export earnings for New Zealand in 2007. Canterbury produced 22.6% of the lambs born in the 2007/08 season, making it a significant region for lamb production. Increasing ewe prolificacy (EP) has been a trend over the last 24 years to aid the industry’s productivity to maintain economic sustainability. Previous research suggested that increasing ewe prolificacy could result in lower overall profitability to farms. However, none had related it specifically to Canterbury conditions.

This research involved the development of a Linear Program to relate ewe prolificacy to net profits and biological efficiency of a typical Canterbury dry land sheep and beef farm. Profits and biological efficiency were maximised at 190% and 208% EP respectively. Thereafter, profits and efficiencies reduced with increasing EP. Ewe prolificacy was the main driver of profitability when EP was between 129-190%. Survival rates of triplet and quadruplet lambs became more influential as EP increased, and allowed the biological efficiency to continue to increase (above 208% EP) when they were increased to that of twin lambs. The stated optimal ewe prolificacy levels related specifically to Canterbury dry land conditions and ‘average’ lamb performance in terms of survival and live weight gains. Further research and technology could help to improve these performance measures to increase the optimal ewe prolificacy.

Limitations and advantages of the Linear Program model as a farmer / consultant decision making tool were also discussed.