Fitting Milk Curve and its Compounds for Khuzestani Buffaloes using Five Different Functions

In order to investigate the milk and its components curve of Khuzestani buffaloes a total of 9061 data of test-day milk, fat and protein yield of the first lactation period buffaloes collected during 1993-2013 were used. The buffaloes having less than 4 test-day records were removed. The lactation days was considered from the 5th to 210th days of lactation. Five different functions of Wood, Wilmink, Parabolic, Mixed Logarithmic and Reverse Polynomial were tested for fitting the lactation curve of buffaloes using the NLIN procedure of SAS 9.1 software. Comparing the studied functions, the Wood function was the best predictor of the lactation curve. The most suitable models for the fat and protein percentage, fat and protein content were Parabolic and Inverse Polynomial with the same results, Parabolic, Parabolic and Inverse Polynomial with Wood functions, respectively. Based on the suitable models, the expected daily milk yield, fat percentage, fat and protein content and protein percentage at the beginning of lactation (the 5th day of lactation) were 6.10 kg with a peak yield of 8.46 kg on the 89th day of lactation, 5.51% with a peak of 6.35% on the 210th day of lactation, 427.75 g with a peak of 513.73 g on the 153th day of lactation, 4.20% with a peak of 4.23% on the 210th day of lactation, 317.70 g with a peak of 344.43 g on the 82th day of lactation, respectively. The results showed that Khuzestani buffaloes have the same production as other breeds in the world in terms of milk production and peak yield or close to them. Considering the rural breeding situation of buffaloes in Khuzestan province, it is expected that improvement of environmental conditions such as nutrition and management provide the condition for incidence of the maximum genetic ability of the buffaloes.