A Study On Nutritional Modulation Of Milk Fat Synthesis In Dairy Animal

The present study is consisted of three parts. The first part is aimed to build animal model on goat. The second part is to study the ingredients fermentating coefficients of the feedstuff, to build a way of calculating the production amount of VFAs through ingredients content and fermentating coefficients. In the third part, the effects of different molar ratio VFAs in the rumen and some blood indexes on the milk fat rate were studied.Part1: Animal model: The goats were fitted with permanent ruminal fistulaes and carotid fistulaes. But after surgery, all goats occured thrombus and died. The results indicated that the goats were not fitted with carotid fistulaes. Animal mode2: The goats were fitted with permanent ruminal fistulaes, which raised carotid artery. We could pierce into the raised artery to obtain blood sample.Part 2: Through detected production amount of VFA in the final incubation fluid and the content of five kinds of ingredient in those ten types feedstuff, respectively, the ingredients fermenting coefficients for producing acetate, propionate and butyrate from cellulose, hemicellulose, protein, starch and soluble carbohydrate were obtained. We could find a way to calculate the production of VFA through fermenting coefficients and ingredients in the feedstuffs.The results were: The ingredients fermenting coefficients for producing acetate,propionate and butyrate from cellulose, hemicellulose, protein, starch and soluble carbohydrate were 8.0, 0.9, 0.8; 6.0, 3.3, 1.4; 2.8, 1.0, 0.5; 18.3, 3.3, 0.8; 5.2, 2.0, 0.9mmol/g, respectively. We used the fermenting coefficients and ingredients in the feedstuffs to calculate the production of VFA, and compared the veracious date with the forecast date of nine feedstuffs. The results showed that the predicted way is doable.Part 3: Three Shaneng goats fitted with permanent ruminal fistulae and carotid fistulae were used in 3×4 Latin square design. The infused level of VFA was the equivalent of an additional 30% of ME requirement at maintenance. The experimentation was to study the effect of different molar ratio VFAs infused into the rumen on the milk fat rate, the rumen fermentation and some blood indexes.1. The study showed that the mammary absorption rates of VFA were different. The ranges of mammary absorption rate of acetate,propionate and butyrate respectively were 67.09-74.34%, 40.40-60.19%, 37.15-43.69%.2. While the molar ratio of acetate: propionate in rumen is 3.29, the milk fat rate would increase to the max. Milk fat rate(%)was positively linear correlation to the molar ratio of acetate:propionate in the rumen fluid,the regression equation wasY= -7454X2 +4.1186X +0.0979 r=0.9293 X: molar ratio of acetate:propionate Y: milk fat rate(%)3. The study showed that a relationship existed between milk fat rate and absorption of VF. The following equation was:Y= 0.1488X – 5.3396 r=0.9114 X: mammary absorption rate of acetate(%)Y: milk fat rate(%)Y=0.08739X1+0.02415X2+0.01536X3-2.909 r=0.964 X1: mammary absorption rate of acetate;X2: mammary absorption rate of ropionate; X3: mammary absorption rate of butyrate; Y: milk fat rate(%)4. The study showed that the molar ratio of acetate: propionate in rumen affected the milk fat rate. If the ratio was exorbitant, the gluconeogenesis would be decreased. If the molar ratio of acetate: propionate was less, the insulin would reduce nutrient matter of galactophore. All these could depress milk fat rate.