Med. Weter. 69 (4), 231-234, 2013
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| Bodarski R., Kinal S., Orda J., Preś J., Twardoń J., Sierżant K. |
| Fat supplementation of high-yielding dairy cows’ rations: the effect on feed intake as well as fat and protein concentration in milk |
| After the addition of fat in rations for cows, a decrease in dry matter intake (DMI) is frequently observed. Stimulation of cholecystokinin release and an increase of the absorption and oxidation of fatty acids in the liver explain the mechanism of this phenomenon. The addition of fat does not reduce the lipolysis of storage fat. Differences in the hypophagic operation of different fats can be explained on the basis of their physical and chemical characteristics and acceptance by cows. The worst tolerated are calcium soaps of palm oil, whereas other fats are consumed by cows quite willingly. Occasionally fat causes the opposite effect – it increases dry matter intake by cows. This occurs when fat is replaced by cereals. DMI and milk yield in cows decreases when increasing the dose of the percentage of unsaturated long-chain fatty acids. This hypophagic effect is explained by either the lowering fiber degradation in the rumen or metabolic regulation of feed intake: unsaturated fatty acids absorbed and oxidized in the liver gives a feeling of satiety and the effect of metabolic fuel or slows intestinal peristalsis. A decreased amount of fat in milk may induce metabolic factors associated with the mammary gland or increase the amount of trans fatty acids in the metabolism of linoleic acid in the rumen. In certain cases, fat supplementation results in reducing the concentration of protein in milk. It decreases the ratio of blood flow through the cow's udder tissue compared to the amount of milk produced (slower blood flow and a net amount of amino acids per saldo of kilogram of milk secreted is reduced), which results in lower protein content in milk. |
| Key words: dairy cows, kinds of fat addition, calcium soaps, feed intake |