| The purpose of this thesis is to study the effects of supplementing fresh alfalfa with different quantities and modes on dairy performance, the body metabolism level and the composition of milk fatty acids of dairy cows; also study the influence of fresh alfalfa on the plasma reproductive hormone, luteal quality, rate of estrus, conception, and some behavior of Yellow cattle.Trial I Effects of fresh alfalfa on the dairy performance and the composition of milk fatty acids of dairy cowsThe objectives of the trial were to determine the effects of fresh alfalfa on the dairy performance and the composition of milk fatty acids in dairy cows. According to the principle of similar milk yield, parturition numbers, lactation day and body weight, 15 early-lactation and 15 mid-lactation Holstein cows were chosen and were randomly allocated in-pair to three groups. The dairy cows in group I (control group) were fed basic diet; group II and III were fed fresh alfalfa 2.5kg and 5kg (according to DM) respectively except the basic diet. The results showed that the DMI of dairy cows increases in early and mid-lactation and then decreases with the improvement of fresh alfalfa level in the diet; the lactation stability and the milk yield can be improved; the concentration of TP in the plasma of group II (82.74±4.59g/L) is significantly higher than that of group I (76.38±1.79g/L) (p<0.05), the BUN in the plasma of group III (7.92±0.79mmol/L) is significantly higher than that of group I (6.73±0.73mmol/L) (p<0.05), the CO2cp in plasma of group I (22.68+0.46mmol/L) and groupIII (22.56±0.28mmol/L) are both significantly higher than that of group II (21.74±0.55mmol/L) (p<0.05) for the dairy cows in early-lactation. The BUN in the plasma of group III (7.88±0.73mmol/L) is significantly higher than that of group II (6.56±0.79mmol/L) (p<0.05) and extremely higher than that of group I (5.88±1.07mmol/L) (p<0.01) for the dairy cows in mid-lactation. Fresh alfalfa has...
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