EFFECT OF AVOTAN ON PRODUCTION OF MILK AN D UTILIZATION OF NUTRIENTS IN DAIRY-COWS

The aim of the experiment was to investigate the influence of feeding additive substance AVOTAN (the effective component of which is AVOPARC IN - antibiotic of glycopeptic type) on utilization of feeds, producti on and composition of milk. Tle group feeding trial was performed with three groups of dairy cows in two periods, each lasting 42 days, with various levels of nutrition. Ten dairy cows were observed in each gro up. The dairy cows in experimental groups were given AVOTAN in mixture with barley meal in the dose of 1 g and 1.5 g per head and day in the group P1 and P2, respectively. All cows were fed the same basic feedi ng ration in each period. The production feed mixture was fed individu ally according to production of milk. The live weight of cows was dete rmined at the beginning and at the end of the trial. The total amount of milked milk was observed daily. The individual milk production test ing was done together with milk sampling once a week. We observed the production and composition of milk, consumption of feeds and nutrients , the live weight of cows in the experiments. The conclusions can be d rawn from the results of experiments as follows: The effect of the fee ding additive substance AVOTAN in the feeding rations of dairy cows on the production of milk and utilization of nutrients is conditioned by the level of nutrition and it can manifest itself only with normative , full-value nutrition of dairy cows which corresponds to the level of production and maintenance. With this condition fulfilled the level o f effect was proportionate to the level of the daily dose of Avotan wi th the two levels we observed. With the normative level of energy in f eed rations we noticed the increase of production of milk with the dos e of 1 g Avotan by 5.4 %, or 4.9 % FCM (P less-than-or-equal-to 0.05), and with the dose 1.5 g by 11.94 % or 11.80 % FCM (P less-than-or-equ al-to 0.01), it represents a difference ranging from 0.64 kg to 1.54 k g milk. The addition of Avotan had no influence on production of milk with the feeding ration deficit in energy (approx. - 10 %). We did not observe significant differences in the content of individual milk com ponents between the groups. The average day intake of dry matter and n utrients was not significantly affected by Avotan. The consumption of nutrients per production of 1 kg FCM decreased by 5.84 - 8.33 % with t he dose 1 g, or by 9.71 - 13.59 % with the Avotan dose 1.5 g.