RANKING LACTATION CURVE FUNCTIONS, OF

Abstract

: Ranking analysis was carried out on fourteen mathematical functions that have been used in the literature to describe the lactation curve. A total of 20831 test day records of milk yield were obtained biweekly during the period 1996-1999 on two dairy farms of AL MARIE Company in the central region of Kingdom of Saudi Arabia. Ranking criteria included Adjusted R2 , Durbin Watson (OW) and Residual Standard Deviation (RSD). Lactation curve function showed a diversity in ranking for each of five lactation, two season of calving, two milking levels and -three classes of Days in milk (300, 405 and 450 days) .