Effect of two types of feeding on productivity of cows and composition of the milk

Svabe, A.K.; Zaborova, E.V.

Izv. Timirjazev. Sel'skohoz. Akad, 2, 163-177


Accession: 014027581

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Some published work on the effect of diet on milk composition is reviewed. The experiment was on cows of the high-yielding herd of the experimental farm of the Timirjazev Academy, where feeding practice was such that cows giving 20 to 25 kg milk received 6 to 8 kg concentrates daily. Two groups of 8 cows received the standard ration for a preliminary period of 21 days. During an experimental period of 48 days one group received an increased amount of concentrates and less hay, silage and potatoes than before, while the other group had the concentrates reduced and received an addition of dried grains. For the last 18 days of the experimental period 3 cows of each group received a supplement of 1 kg molasses per head daily. In the first part of the experimental period cows on both rations showed about the same decline of milk yield with the progress of lactation. There was no change of protein or fat content of milk in cows given the high concentrate intake, but reducing the concentrate intake led to a significant fall of milk fat content, on average from 3.75 to 3.49%, and a small fall of protein content. When molasses was added to the diet the milk of cows of both groups showed a small fall of fat content, of the order of 0.13 percentage unit. The high-concentrate ration caused an increase of Hb values and red cell counts but the low-concentrate ration had little effect. Molasses did not affect Hb values but caused some increase of red cell counts. The high-concentrate ration caused a fall of alkali reserve which was compensated by extra carbohydrate as molasses. Reduced glutathione rose by about 10% on high- and fell by about 5% on lowconcentrate feeding. Oxidised glutathione fell by 10% and rose by 13%, respectively. Acetone body metabolism remained normal throughout, as did blood sugar and pyruvic acid. The different amounts of concentrates did not affect serum total protein, but addition of molasses to the diet caused a small fall in each group. In contrast, serum albumin fell by 19% in the high-concentrate group but remained almost unchanged in the other. No difference was found in behaviour of serum lipids but unsaturated fatty acids fell on transfer of cows to the low-concentrate ration. D. Duncan.