Lactation curve of Beetal goats in Pakistan

Abstract. This study was accomplished with the objective to determine parameters of lactation curves in Beetal goats using Wood’s model. Therefore, milk yield data on 127 Beetal goats maintained at five different government farms were recorded from post-kidding to drying off of does. Wood model parameters were estimated using non-linear regression and individual curves were fitted. The characteristics/parameters of lactation curve were computed. The mean initial yield »a«, rate of increase »b« and rate of decline »c« parameters in Wood’s model for Beetal were 1,214.97, 0.3690 and 0.1196, respectively with R² value of 98.2 %. The value of percent squared bias (PSB) and the persistency were 0.13 and 60.2%, respectively with mean square error value of 38.45. Flock effect was a significant (P<0.01) source of variation for all the lactation curve parameters, PSB and persistency. Parity did not affect significantly any of the parameters. Type of birth significantly influenced parameter »a«, Time to reach peak (TPY) and lactation milk yield (LMY). Sex of kid also did not affect significantly any of the parameters. Age of doe was significant for parameters »a«, »b«, »c«. Quadratic effect of age was non-significant for all parameters and characteristics. Lactation length significantly affected parameter »a«, »b« and LMY.