FITTING OF GOMPERTZ CURVE FOR GROWTH OF SHEEP IN SARAWAK, MALAYSIA

Abstract

An experiment was conducted using randomized complete block design to study the growth of crossbred sheep at two locations in Sarawalg Malaysia. The two sites were one in Samarahan and the other in Bau, which held 348 and 73 sheep respectively. Data on birth weight and subsequent body weights were collected every 28 days to 364 days of age. The scattered plot of body weight of sheep against time exhibited approximately a sigmoid shape. A Gompertz model was fitted on happenstance body weight data using SAS package (PROCNLIN) on mainframe computer at MARDI, Serdang. Ad hoc starting values of the model
parameters helped the Levenburg-Marquardt iterative algorithm to globally converge to stationary points in 12 and 7 iterations for model parameter estimations of body weight at Samarahan and Bau experimental sites respectively. The fitted models were diagnosed using nonlinear model adequacy measures. On examination of the residual scatter plots, the Gompertz curve exhibited apt function to describe sheep body weight. The relative growtlr rates (RGR) at
Samarahan and Bau were 0.0983 and 0.0962 kg kg" month'l respectively.