Modeling lactation curve of Saudi camels using the linear and non-linear forms of the incomplete Gamma function

• Lactation curve was described by the linear and the non-linear forms of the incomplete Gamma function.
• In addition to the lactation curve parameters, several characteristics were also estimated, including time to reach peak production, peak production, persistency.
• The linear form of the incomplete Gamma function was more appropriate for describing lactation curve of camel milk yield than its non-linear counterpart.

The objectives of this study were to describe lactation curve of Saudi camels using the linear and non-linear forms of the incomplete Gamma function, to estimate lactation curve characteristics and to determine the appropriate form describing lactation curve. Records of weekly milk yield representing 9 parities were collected from 56 she-camels. Data were collected over the period 2007–2013. The results revealed that averages of total milk yield, lactation length and daily milk yield of the nine parities, ranged between 967.3 and 3107.21 kg, between 273 and 416 days and between 2.96 and 7.40 kg/day, respectively. Initial milk yield (a) estimated by the linear and non-linear forms of the nine parities ranged between 0.194 and 1.775 and between 0.155 and 1.818, respectively. The increasing rate (b) ranged between 0.754 and 1.414 and between 0.750 and 1.533, while the decreasing rate (c) ranged between −0.054 and −0.020 and between −0.059 and −0.036, respectively. Days to attain peak production, peak production and persistency, as well as persistency percentage were also estimated. It is concluded that the linear form of the incomplete Gamma function is more appropriate for describing lactation curve of camel milk yield than its non-linear counterpart.