Studies On The Rumen Digestion Character And Feeding Effect Of High Producing Dairy Cow With Alfalfa Hay Based Diet

In order to establish alfalfa based dairy industry production system in China, studies on the rumen degradation characteristics and fermentation characteristics of alfalfa hay, corn silage, concentrate, DDGS, diet 1(alfalfa hay addition is 3kg,16.4%CP, 5.2%RUP of DM, control diet), diet 2(alfalfa hay addition is 6kg, 17.9%CP, 6.8%RUP of DM), and diet 3(alfalfa hay addition is 9kg, 19.4%CP, 8.2%RUP of DM), application of RDP-RUP system in feeding high producing dairy cow with alfalfa hay based diet, technical and economic analysis of feeding high producing dairy cow with alfalfa hay based diet, feasibility of establishing alfalfa based dairy industry production system in china were conducted with nylon bag techinique, in vitro method, and feeding trial during May 2001 to December 2002. Effective degradability of alfalfa hay in DM, CP, OM are higher than that of corn silage, whereas in NDF is little lower than corn silage, but both alfalfa hay and corn silage are better than Chinese wildrye and corn stalk. Alfalfa hay have more RDP and less RUP, DDGS have more RUP and less RDP, ideal ratio of RDP to RUP in diet of high producing dairy cow can be attained when using alfalfa with DDGS. Nylon bag technique is an effective method to measure the degradation characteristics of diet. Associate effect of diet exists in effective degradability of DM, CP, NDF, OM and balance of energy to nitrogen, positive effect exists in DM and NDF, which also exists in CP, OM and balance of energy to nitrogen of diet 1, but negative effect exists in diet 2 or diet 3. DM degradability measured by nylon bag technique is highly correlated with that measured by in vitro method(P<0.01). So, in vitro method can be used as routine method to determine DM degradability of forage. In 24-h time point, the contents of NH3-N and TVFA are higher than that of corn silage, which mainly attribute to the contents of CP and OM and their degradation rate. The acetate ratio of alfalfa hay is higher than that of corn silage, while propionate ratio and butyrate ratio are lower than the latter. In 24-h time point, associate effect exists in DM degradability, NH3-N content, TVFA content, the content and ratio of acetate, propionate,and butyrate, pH value. Positive associate effect is observed in NH3-N content, while negative associate effect exists in TVFA content. The associate effects of DM degradability, the content and ratio of acetate, propionate,and butyrate, pH value are irregular, but greatest positive associate effect always exists in diet 2 or diet 3. Increasing DDGS addition as RUP supplement in alfalfa hay based diet can significantly improve milk yield(29.06,31.35,33.55kg/d for diet 1, diet 2, and diet 3) , DMI, milk fat yield, and milk protein yield, while milk fat percentage, milk protein percentage, lactose, and SNF content were unchanged. Higher RUP diet elevated PUN in our study, but had no negative effect on pregnancy rate. 19.4% CP and 8.2% RUP(RDP:RUP=57.7:42.3) may be appropriate and safe for milk production and reproduction in early and middle lactation of Chinese high producing dairy cow. With equal NDF in diet, the replacement of corn silage by alfalfa hay had no influence on milk fat percentage, but significantly decrease the SCC in milk. Profit improves as the RUP concentration in the diet increases, which mainly caused by the addition of DDGS. Greatest added profit(7.9yuan RMB/d) is obtained in diet 3. DDGS is an excellent, cheap and safe RUP supplement compared with other RUP source, which should be widely used in alfalfa hay based diet for high yielding dairy cow in China. The ideal price of alfalfa hay in Beijing area varies from 850 to 1133.3 yuan RMB/t. In this range, alfalfa hay can be effectively used within about 9 kg upper limit in the diet of Chinese dairy cow, while need not concern the elevation of diet cost. Aalfalfa hay processing factory can get profit about 100yuan RMB/t. In 2000, total number of dairy cow in China is 4,887,000. In order to meet their requirement for alfalfa hay, to enhance the milk yield per cow and to improve the profit of dairy farm, 1,067,000 hm2 of plowland should be used to produce about 8,000,000 tons of alfalfa hay. It is feasible to establish alfalfa based dairy production system in China.