A randomized block experiment was carried out. Two dairy farms that the large scale dairy farm and the park-style dairy cooperative were selected.A total of 80 dairy cows with similar age,body weight,parity,milk production and lactation stage were selected from each farm and then divided into 2 groups,40 Holstein cows in each group.The experiment groups were used to evaluate the effect of supplementation of rumen-bypass amino acid（Lys） on milk production,and milk components. 25 g rumen-protected lysine（RPLys） was added for individual dairy cow in experiment groups.The results showed that comparing with the control group,the milk yield of the experimental groups was increased significant （P﹤0.05）. The milk protein and milk fat percentage were tended to increase（P 0.05）.Other milk components content also increased slightly（P 0.05）.The net income of experiment group was higher than that of control group. The increased net income for experiment group were 1.80 yuan/d,0.52 yuan/d for the large scale dairy farm and the park-style dairy cooperative respectively.

The objective of this experiment was to investigate the effect of increasing dietary NFC/NDF on populations of B. fibrisolvens,S. bovis and M. elsdenii in the rumen of dairy goats under the condition of induced subacute rumen acidosis （SARA）.Six lactating Guanzhong dairy goats fitted with permanent rumen fistulae were used in a self-contrast experiment design.This experiment consisted of four experimental periods,with ten days in each period.Goats were fed 4 diets with different NFC/NDF （1.02,1.24,1.63 and 2.58,respectively）.The induction of SARA was conducted by gradually increasing dietary NFC/NDF.Realtime PCR was used to detect the populations of B. fibrisolvens,S. bovis and M.elsdenii.The results showed as follows：① The number of B. fibrisolvens and M. elsdenii was both increased with the increasing of dietary NFC/NDF,and when NFC/NDF reached the level of 2.58,the number of M. elsdenii was significantly increased （P0.01）,whereas the number of B. fibrisolvens was significantly decreased （P0.01）.② The number of S. bovis was significantly decreased with the increasing of dietary NFC/NDF （P0.05）,however,during the occurrence of SARA,the number of S. bovis returned to the same level of experimental period Ⅰ.The results indicated that there was no difference in the number of S. bovis at the induced stage of SARA,however,the number of B. fibrisolvens was markedly decreased,whereas the number of M. elsdenii, which is a kind of aciduric bacteria, was significantly increased.

This experiment was conducted to investigate the effects of different dietary NFC/NDF ratios on ruminal microorganisms and pH in dairy goats under the condition of subacute ruminal acidosis（SARA）.In this self-contrast experiment Guanzhong lactating dairy goats fitted with permanent rumen cannula were selected.The experiment was composed of 4 periods with 10 d in each period.The goats were fed diets with different NFC/NDF ratios,which were 1.02（period Ⅰ）,1.24（period Ⅱ）,1.63（period Ⅲ） and 2.58（period Ⅳ）,respectively.Meanwhile,subacute rumen acidosis（SARA） was induced by gradually increasing the content of concentrate.The results showed as follows： the ruminal pH decreased significantly with the increasing of dietary NFC/NDF rations（P0.05）,and the decreasing scale increased;the number of amylolytic bacteria increased significantly with the gradually increasing dietary NFC/NDF ratios（P0.01）,the number of ruminal total bacterial,Lactobaillus and Fusobacterium necrophorum increased significantly when the ratio was 1.63（P0.05）,and the number of Megasphera elsdenii and Selenomonas ruminantium increased significantly when the ratio was 2.58（P0.05）;the number of total ciliates was the lowest in period Ⅳ,but the populations of Strepococcus bovis did not change obviously（P0.05）.The results indicated that when the NFC/NDF ratio was 1.63,the majority of rumen bacteria which related to the degradation of carbohydrates increased obviously,especially during SARA period,but the population of total ciliates decreased to the lowest level.

A batch culture technique was used to determine the effects of different doses of Compositae Ordos Wormwood extract （COE） on biohydrogenation of fatty acids,concentration of CLA and trans-11C18：1 in culture medium. The dosage of COE was 0（control）,3,30,300 and 3 000 mg/L mixed culture fluid ,respectively. The sampling time was 2,6 and 24 h, respectively.All COE treatments were tested in triplicate at each sampling time.The results showed that COE treatments tended to reduce C18 polyunsaturated fatty acids biohydrogenation,whereas the concentration of trans-11C18：1 and cis-9,trans-11 CLA in culture medium tended to increase.

The effects of different cryopreservation methods of Holstein cow mammary epithelial cells on its viability were studied. Primary bovine mammary epithelial cells were passing five generations and adjusting the cell density to 1×106 cells/mL,and then being cryopreserved by 6 different methods.The viability of cells including mortality,adhering dish rate,apoptosis rate was measured after being recovered.The results showed that the death rate of cell being cryopreserved by treatments 2,3,5 was significantly different from treatment 1（P0.01）.Whereas no significant difference was found among treatments 1,4 and 6（P 0.05）.There was significantly different for death rate of cryopreserved cell between treatment 2 and 6（P0.01）.Adhering rate of cryopreserved cell from treatment 4 was significantly higher than treatment 2,5 and 6（P0.01）.Cell growth state of treatment 1 and 4 were better than others. The results indicated that the treatment 4 was the best cryopreservation method in this study.

This experiment was conducted to study the effects of different levels of crude protein（CP） and ruminal undegraded protein （RUP） in ration on the rumen fermentation. 18 Holstein dairy cows were selected to study the effects of different levels of CP and RUP on the rumen fermentation parameters. This experiment was a 2×3 factorial arrangement with total 6 dietary combinations, the first factor was CP level （7.5%,9.0% and 10.5%）, and the second factor was RUP level （45% CP and 55% CP）. The ratio of concentration to forage was 3∶7. Pre -trial period was 10 d. The ruminal fluid samples were collected at the time points of 2, 4, 8, 12, and 24 h for 2 d. The results showed as follows： The rumen NH3-N concentration was significantly affected by CP levels of diets, but it had little effect on BCP and VFA contents. The rumen fermentation parameters for 9.0% CP level were slightly better than that of other levels; The high levels of RUP（55% CP）could reduce the pH value and NH3-N content in the rumen, and increase the concentrations of BCP and VFA in the rumen. Under the present experimental conditions, the results indicated that the treatment（9.0% CP） and RUP （55%CP） could slightly improve rumen fermentation.

Introduction Milk favored by consumers because milk contain a large number of nutrients,such as protein,amino acids,fat,lactose,a variety of vitamins,immune activity factors,essential minerals and so on,and the proportion of the nutrients is very reasonable and those nutrients are easy to digest and absorb.So,milk is nearly a perfect food.

Introduction Milk favored by consumers because milk contain a large number of nutrients,such as protein,amino acids,fat,lactose,a variety of vitamins,immune activity factors,essential minerals and trace elements and so on,and the proportion of these nutrients is very reasonable and easy to digest and absorb,so milk is nearly a perfect food.

Introduction Subacute ruminal acidosis（SARA）has become common and important economic and health issues for high-yielding dairy cows.Rumen pH takes a central position in the pathogenesis of SARA.So monitoring of rumen pH is play important role in recognizing,quantifying and subsequently controlling this disorder. The objective of the present

Introduction It has been well established that plant oil or fish oil could enhance cis-9 trans-11CLA content in the ruminant food products.However,it is generally accepted that adding unsaturated fatty acid to ruminant diets may exert negative effects on fiber degradation and rumen microbe populations.For this reason,there is

Six Inner Mongolian semifine-wool wethers（1.5 years old,29-31 kg BW） fitted with a ruminal and a duodenum cannula were used to study the effects of increasing production rate of ruminal acetate and butyrate on their absorption and passage in alimentary tract by simulating continuous feeding and pulse-continuous infusion technology.The sheep were

An in vitro study was conducted to determine the effect of different doses of Composite Artemisia annua extract（CAE） on rumen microbial fermentation.CAE was a crude extract from the stem and leaves of Composite Artemisia annua extracted with ethanol.The doses of CAE supplementation with frozen-dry form were：control（no addition）

Introduction Cis-9,trans-11 CLA has been shown to be potentially health-promoting CLA in many animal models.The C18：1 trans-11 fatty acid（VA） is also desirable as a product flowing from the rumen,because the flow from the rumen of VA play a more important role than CLA in determining CLA concentration in animal tissues.

Based on forage grading index（GI2001）proposed by Prof.LU De-xun in 2001,in this study we selected new parameters and attempted to establish a new forage grading index（GI2008）for cows in 2008.In order to confirm the rationality of GI2008,GI2001 and RFV were used to evaluate four forages quality and the results were compared.The values of GI2001,GI2008 and RFV were calculated according to their formulas,respectively.The results showed that the values of GI2008 for the 4 forages ranked as follows：alfalfa（145.50）corn silage（108.44）chinensis（20.10）corn stalk（12.09）;the values of GI2001 ranked as follows：alfalfa（32.11）corn silage（19.70）chinensis（9.39）corn stalk（3.98）;the values of RFV ranked as follows：alfalfa（109.20）corn silage（100.12）chinensis（91.55）corn stalk（69.93）.The sequences of the quality of four forages were identical by GI2008,GI2001 and RFV methods.GI2008 and GI2001 were superior to RFV,and both of them could be used to evaluate the forage quality scientifically.The regression equation obtained between GI2001 and GI2008 was as follows：Y=5.1669X-12.683（R2=0.946 3,P0.000 1,n=4）.GI2001 is simple and easy to operate,but GI2008 is more scientific than GI2001 when using for research purpose.Thus,GI2008 can more accurately and scientifically evaluate the quality of forages on research in future.

Introduction Forage quality can be defined as the extent to which forage has the potential to produce a desired animal response or level of performance,for example,daily gain or milk production.Due to forage quality is a function of both animal and plant factors.It is difficult and complex to completely evaluate forage quality.Recently,

In the course of silage fermentation,different kinds of Lactobacillus have different capability to produce lactic acid and also produce different bacteriostasis and aromatic materials.In the past few years,some studies showed that lactic acid and other aromatic components are produced during the fermentation of silage with Lactobacillus.These components have great effects on quality of silage.Bacteriocine and other bacteriostasis materials are also produced and they inhibit the growth of harmful microorganisms.The article reviews recent advances in metabolism of Lactobacillus and its effects on quality of silage.