RESULTS AND DISCUSSION
One of the most common models in fitting the
observed daily milk yields is Wood`s lactation curve
(1967). The disadvantages of the Wood`s function arise
from the use of power function tb
, to describe the growth
phase of lactation (Friggens et al., 1999). At calving time
when t = 0, milk production is 0 and the function predicts
0 yield. This major criticism of the Wood`s function was
dismissed by Tozer and Huffaker (1999) by following
explanation: when a cow calves the colostrum produced
has no economic value and the cow does not enter in the
milk-producing herd immediately after calving.
Therefore, fixing production at zero at calving is not a
significant problem when determining an appropriate
function to use in management research. This model
provides good flexibility in fitting the estimated curve to
the measured values and does not require a large number
of measurements, which cannot be obtained in regular
milk recording. It has been concluded that the incomplete
gamma function and its variants proved powerful in terms
of fitting observed daily milk yields (Grossman and
Koops, 2003; Val-Arreola et al., 2004; Silvestre et al.,