摘要 : Data on 798 records of 235 Tharparkar dairy cows in Haryana, India, over a 15-year period (1986-2000) were analysed to determine the effect of period (P1 1986-1990, P2 1991-1995 and P3 1996-2000) and season (S1 winter November-Feb... 展开 Data on 798 records of 235 Tharparkar dairy cows in Haryana, India, over a 15-year period (1986-2000) were analysed to determine the effect of period (P1 1986-1990, P2 1991-1995 and P3 1996-2000) and season (S1 winter November-February, S2 summer March-June and S3 hot humid season July-October) on peak milk yield. It was shown that peak yield was highest in P1, with no significant differences between P2 and P3. Peak yield was significantly higher in S1 compared to S3, with no significant differences between S2 and S3 and between S1 and S2. Peak yield for the 3rd, 4th, 5th, 6th and 7th lactation was significantly different from the 1st, 2nd, 8th and 9th lactation. These results show that peak yield differs between year and season. 收起