RESUMO
In 3337 dairy cows, urine was examined for ketone bodies by help of Bililabstix during the first and second phase of lactation and in the eighth to the ninth and a half month of pregnancy; at the same time needed supply of energetic nutrients in 175 summer and 308 winter feed rations was calculated. Intensity and frequency of ketonuria in lactating cows fed winter rations is significantly higher than in those fed green feeds; it decreases significantly with a phase of lactation and with milk production. On the contrary, cows in late pregnancy have higher intensity and frequency of ketonuria (32.9%) when fed green feeds than when fed winter rations (30.7%). In winter feed rations energy input was significantly lower, percentage of deficient feed rations at a relatively broader caloric-protein ratio was higher than in summer season. The highest deficits of energy and digestible nitrogen compounds were observed in cows in the first phase of lactation. Discussion concerns the causes and mechanisms of different ketonuria in groups of dairy cows in relation to deficit of energetic nutrients, caloric-protein ratio, to the level of glycaemia, non-esterified fatty acids in plasma, triglycerides of plasma and to the state of liver function.
