Variation in milk yield and milk composition during the entire lactation period in Mithun cows (Bos frontalis)

Abstract

The characteristics of the lactation curves and the effect of lactation stage on yield and composition of milk were investigated in 11 multiparous mithun (Bos frontalis) cows. Average lactation length was found to be 340 ± 2 d. The effect of lactation stage on milk yield (0.87 to 1.46 kg) and the milk content of total solids (TS, 20.94 to 22.62%), fat (7.72 to 10.25%) and urea (36.65 to 43.54 mg/dL) was found to be significant (p<0.05). In contrast, the contents of total protein (6.31 to 6.78%), casein (4.38 to 4.77%), solid-not-fat (SNF, 13.40 to 13.70%), lactose (4.36 to 4.60%), non protein nitrogen (NPN, 0.41 to 0.43%) and ash (0.90 to 0.93%) did not vary among the different stages of lactation. Peak milk yield was recorded on 30 d of lactation and persistency was maintained until 90 d. Milk yield declined significantly (p<0.05) during the late lactation stage with a simultaneous increase (p<0.05) in milk fat, TS and milk urea. The casein and ash contents were found to be the least variable milk constituents. The study revealed that the trend in variation of milk yield and major milk constituents during the entire lactation in mithun was comparable with the other domesticated ruminants. Though mithun produced less amount of milk, but the major milk constituents in mithun milk were found to be much higher than that reported for other domesticated ruminants. The results of the present study indicate that mithun should not be milked after 255 d of lactation as milk yield was less than 40% of peak yield after this period.