Study On Associative Effects Between Crude Protein And Neutral Detergent Fiber In Dairy Cows

The emergence of Associative Effects Theory makes a huge challenge to the present ruminant feeding standard, because the traditional way that each nutrient factor was added to one group in brief has no longer adapted to the livestock development.The present research was conducted to investigate the associative effects (AE) between different sources of neautral detergent fiber (NDF) and protein by using an in vitro gas production technique in order to explore the theories and the practices of the Associative Effect based on animal test.Experiment 1.A series of mixtures of neautral detergent fiber (NDF)and soyben meal were incubated using in vitro gas production technique.The ratio (NDF/CP) in the mixtures were 3.8,3.4,3.0,2.6,2.2,1.8,respectively.The gas prodution was recorded at 0, 2, 4, 6. 8, 12, 24, 36, 48, 72 and 96h. The pH,NH₃-N and volatile fat acid (VFA)were detemined.When Chinese wildrye mixed with soybean meal at the proportion of 3.4,the positive AE was different significantly (p＜0.05), when alfalfa mixed with soyben meal, at the proportion of 3.0,the positive AE was different significantly (p＜0.05),when corn silage mixed with soyben meal at the proportion of 3.8,the positive AE was different significantly (p＜0.05).The sources of NDF and the interaction of NDF and CP affected the AE significantly.Experiment 2 The Chinese wildrye mixed with soybean meal,rapeseed meal and cotton seed meal were incubated using in vitro gas production technique.The ratio (NDF/CP) in the mixtures were 3.8,3.4,3.0,2.6,2.2＞1.8,respectively.The gas prodution was recorded at 0, 2, 4, 6, 8, 12, 24, 36, 48, 72 and 96h. The pH,NH₃-N and volatile fat acid (VFA)were detemined.Positive AE was observed for all the mixtures at all times of incubation and positive AE was a numeric increasing with ratio of NDF/CP was dereased. When soybean meal mixed with Chinese wildrye,the highest positive AE was pronounced at ratio NDF/CP=2.6; When rapeseed meal mixed with Chinese wildrye, at ratio NDF/CP=2.2 or 2.6,the highest positive AE was pronounced; When cotton seed meal mixed with Chinese wildrye, at ratio NDF/CP=2.2 or 3.0,the highest positive AE was pronounced The sources of CP were no affect the AE significantly.Experiment 3.The objectives were to detemine the effects of four diets with different ratio of NDF with CP (NDF/CP=2.4,2.,3.2,3.4) on milk performance and milk composition of lactating dairy cows.Sixteen Holstein cows in middle lactation were selected and randomly allocated four groups according to their parity,milk yield and days in milk.The results indicated that there was significant effects of diets with different ratio of NDF with CP on milk yield of lactating dairy cows (p＞0.05),When NDF/CP of diets was 3.4,there was a numeric increasing trend for milk fat. When NDF/CP of diets was 2.8,milk protein increased numerically.Experiment 4. The effect of ratios NDF with CP on digestibility in lactating dairy cows was investigated. The digestive test was used when Exp3 was at 6 week.The results indicated that NDF/CP of diets was 3.2,the apparent digestibility of DM,OM,NDF and ADF were significant improved.(p＜0.05). In summary,this experiment researched the characteristices of AE between NDF and CP,the best ratio of NDF/CP was determined,the AE evaluated form animal test was consistent with in vitro gas production...