Efaciency of different algebraic functions to describe lactation curve of milk lactose in Murrah buffaloes

The data on milk lactose percentage of 92 lactations of sixty Murrah buffaloes maintained at Uvestock Production Research (Cattle and Buffaloes) Farm of the Indian Veterinary Research Institute, Izatnagar, from 1986 to 1990 were utilized for the present study. The average lactose percentage during first month of lactation was 4.76 ± 0.03, which increased continuously to attain a peak of 4.90 ± 0.03 during fourth month after calving. Thereafter, it started decreasing slowly and reached a lowest of 4.72 ± 0.04 during tenth month of lactation. The peak value of lactose percentage was significantly (P < 0.05) higher than its values at first and tenth month of lactation. Ave algebraic functions, viz., quadratic, parabolic exponential, inverse polynomial, gamma type and product of two exponential functions were fitted to monthly least-sqares means. The study revealed that parabolic exponential function [V_t = 4.7032 e^{(0.0148t–0.0014t2)}] was the best function closely followed by quadratic function (V_t = 4.7072 + 0.0710 t - 0.0069 t²) to describe the trend of lactose in the milk of buffaloes during a lactation i.e. ascending phase, peak phase and descending phase.