Report on SIDE project: pasture analysis to investigate the spring milk production dip

Abstract

The objective of this project was a more detailed investigation of the rapid decline in milksolids production experienced at LUDF during late October and November in the 2003/04, 2004/05 and 2005/06 seasons. Analysis of a sample of production curves from dairy farms across New Zealand failed to identify consistent patterns of ‘Spring milk dip’. While some farms in each region showed a dip in milk production during the period of interest it was not as large as that observed on the LUDF and was not repeatable across years. 2006 was an atypical year at LUDF, with a wet Winter and cold Spring resulting in high sugar levels, high DM% and low protein content in the early pasture. There was no evidence of differences in pasture composition between cultivars growing at LUDF (Bealey or Tabu). A ‘Spring Dip’ in MS production was not observed at LUDF during late October/November 2006. This allowed us to make comparisons of pasture covers and composition with previous ‘Spring Dips’, notably the large dip in 2005. The LUDF ‘Spring Dip’ appears to result from lower pasture covers in the period soon after peak milk yield and is not related to pasture composition. It may be more of a feature of herds that adopt extremely low grazing residuals and so are more likely to run into low covers at this time, though national database information did not allow us to verify this assertion (see above). Further studies of this aspect are justified. The project reinforces the importance of maintaining pasture monitoring during this busy (mating) period. Further work should focus on ensuring a reliable indication of pasture covers during this critical phase of lactation.