[Evaluation of the indicators of protein, carbohydrate and mineral metabolism in the blood of cows fed supplementary high-energy food].

Abstract

Cows of the white-black breed from the Sudeten piedmont were divided into two groups: control and experimental. Both groups were fed the same basic fodder, e.g. pasture, green forage of clover and maize, and hay; afterwards they were fed grass silage, hay and beets. Maize forage, containing little fibrin, lot of starch and soluble carbohydrates, was substituted by grass silage with little starch and soluble carbohydrates, but rich in cellulose and hemicelluloses. So, energetic value of the food was different. The chosen chemical indices were estimated during the change of fodder from pasture to winter silage and hay. Cows from the control group were fed additionally, one month before calving, 1 kg of the protein food (bruised barley) without urea, whereas cows from the experimental group were fed additionally with bruised barley, in the amount of 1.5-3 kg, when giving less than 4000 l of milk, and 2.5-4 kg, when giving over 4000 l of milk. The amount of food increased by 0.5 kg every week beginning with smallest dose. This additional feeding had positive influence on the milk production, especially in the 2nd and 3rd month after calving (2.3 kg during 4 months after calving), and improved the effectivity of fertilization after the first insemination. The chemical composition of the milk has not been changed significantly; the total protein and its fraction, levels of urea, Ca, Fe and Mg in the blood plasma have not been changed. Only the level of ketones in blood decreased a little. During the transition period, green forage feeding caused the increase of the glucose level in blood to 60 mg% (50 mg% in winter). Additional energetic feeding of cows before calving improved productivity indices and did not change the internal body balance (homeostasis).