Projection of partial lactation records and calculation of 305-day yields in the Republic of Ireland

Abstract

Standard lactation curves for 2160 contemporary groups were derived for projecting records in progress and short lactations to 305-day yields in the republic of Ireland. Projection was based on the deviation of the last test day and previous lactation 305-day yields from the corresponding expected yields from the standard lactation curves. Calving season and age influenced the shape of the standard curves while level of production mostly affected the scale. Correlation between yields projected from lactations 51days or more in lenght with realised yields were over 0.9 but accuracy increase with lenght of the record in progress. ___________________________________________________________________________