Pakistan Veterinary Journal (Oct 2005)
PREDICTION OF LACTATION YIELD FROM LAST-RECORD DAY AND AVERAGE DAILY YIELD IN NILI-RAVI BUFFALOES
Abstract
Different adjustment procedures were compared to determine if prediction of lactation milk yield using last record day information could be improved by using information on the average daily milk yield of the recorded lactation. Weekly milk yield records of 993 Nili-Ravi buffaloes for 2704 lactations were used for the study. Comparison of different procedures of lactation milk yield adjustment from partial/incomplete or complete lactations indicated that milk yield predicted from a linear regression equation, or from last test day information, was higher as compared to actual milk yield due to extrapolation to a higher base. Simple linear regression procedure overestimated the yield, especially in the later part of the lactation curve. Most precise adjustments were obtained when last test day and average daily milk yield information were included as predictors. The standard deviation of bias decreased and correlation between actual and predicted lactation milk yield improved with inclusion of average daily milk yield as a predictor along with the last test day milk yield. Last recorded milk yield information along with average daily yield of the recorded lactation period are suggested to be used for standardization of milk yield data in Nili-Ravi buffaloes.
