Study On The Effect Of Dietary Manipulation On The Concentration Of Conjugated Linoleic Acids Of Milk Fat In Lactating Cows

This paper studied on the effects of rapeseed, Sunflower seed, benne seed which are rich of oleic acid,linoleic acid, linolenic acid and their oil on increasing of proportion of conjugated linoleic acids in milk fat, and on mechanism of increasing of amounts of conjugated linoleic acids (CLA)in milk fat by the experiment in vitro ,the experiment of digestion and metabolism, and the experiment of feeding .Part 1 The experiment in vitroIn vitro experiment, we studied on the effects of diet with different levels of fat after that was adding three oil seeds on rumen fermentation in vitro, on degradation of dry matter of substructure and NDF. The purpose of this experiment was selection the proper amount of fat additive in animal experiment. Three oil seeds were rapeseed, sunflower seed and benne seed. After adding each oil seeds in diet, the level of fat in diet was up to 5%, 6.5%, 8% respectively. The result showed that the effect of the diet adding rapeseed of different levels of fat on pH of fermentation liquid, the number of ciliate, the concentrate of NH3-N, the concentrate of BCP, and the concentrate of TVFA was not significant, but the difference of the degradation of dry matter of substructure and NDF in each fat level, adding rapeseed was significant, and the groups of dietary fat level were 5% and 6.5% had not significant effect on the degradation of dry matter of substructure and NDF(P<0.05), but they were higher than the group of dietary fat level was 8%(P>0.05). And the effect of the diet adding Sunflower seed and benne seed of different levels of fat on the parameter of rumen fermentation, and the degradation of dry matter of substructure and NDF was not significant, but the groups of dietary fat level 6.5% was highest. Anaylizing all of the data ,we concluded that when the ration of fat was 6.5% in diet,either could increasing CLA in milk, or had no effect on normal rumen fermentation.In this time,the ration of seed in diet is 8%~10%.Part 2 The experiment of digestion and metabolismExp1.Three fistulated Holstein cows in the midlactation (body weight and age were similar, 15 kg/d milk yield ) were used in a 3 x 3 Latin square design, in order to research the effects of diet (dietary fat level were approaching 6.5%)adding different oil seeds on rumen metabolism, furthermore offering basic data for the research of diet adding different oil seeds increasing amount of CLA in milk. The result showed that the...