Golubets O. Isomeric fatty acid composition of rumen digesta and milk lipids depending on carbohydrate and lipid composition of diet

The effect of different amounts of fiber, nonstructural carbohydrates and fat in cow's diet on fatty acid profile of lipids of rumen digesta and milk, milk yield and composition were examined. It was established that changing of a part of forage by grain concentrates results in decreasing of amount of odd- and branched-chain fatty acids, which are specific for rumen microflora, and increasing of isomers of unsaturated fatty acids, that depress synthesis of milk fat: trans10-18:1 and trans10,cis12-18:2. The amount of biologically active acids trans11-18:1 and cis9,trans11-18:2 in rumen digesta and milk are decreased. The addition of sodium bicarbonate prevents the negative influence of starch surplus on fatty acids' metabolism. Concentrate-based ration without sodium bicarbonate reduced fat content of milk from 3,74 to 3,04 %. The addition of sodium bicarbonate restored fat content of milk up to a level of control group. Changing of part of grain in cow's ration by sunflowerseed cake promoted increasing in lipids of rumen digesta of amount of cis,trans isomers of linoleic acid, trans isomers of oleic acid and amount of stearic acid. In milk of cows from experimental group mass part of cis9,trans11-18:2 and trans11-18:1 acids was elevated, at the same time amount of trans10-18:1 and trans10,cis12-18:2 didn't variety. Daily milk yield from cows of experimental group was increased on 7% and production of milk protein and fat were increased on 6 and 10 % respectively.