Milk yield composition and cholesterol level in dairy cows fed rations supplemented with zinc and fatty acid calcium salts
2002
Brzoska, F. (Research Institute of Animal Production, Balice (Poland). Dept. of Feed Sciences) | Kowalczyk, J. (Polish Academy of Sciences, Jablonna (Poland). The Kielanowski Inst. of Animal Physiology and Nutrition)
Feeding dairy cows a diet with the addition of calcium fatty acid salts, produced from a mixture of rape seed and fish oils, does not increase milk yield or cholesterol level but significantly elevates the level of unsaturated fatty acids, acidity and renneting time. It also slightly decreases the milk protein and fats contents. Zinc at levels ranging from 39 to 59 mg/kg of the diet for dairy cows does not affect milk yield, cholesterol or other metabolite levels in blood plasma or milk. Cows fed diets with higher levels of zinc efficiently absorb theis element, increasing its concentration in blood plasma but not in milk, suggesting the existence of a mechanizm blocking its transport into the milk
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