Changes in body condition of high-yielding dairy cows

Objective of the research was to investigate the level, structure and variability of realized differences between average values of body condition scores in high-yielding cows during most critical phases of production cycle. Realized differences were used as criterion for assessment of changes occuring in the cows? energy status through the level of increase or decrease of body condition. Realized average values of body condition scores, for individual and all body regions, within all studied phases of production cycle, deviated statistically very significantly (p?0,01) from target values. Differences between average values of body condition scores according to phases of production cycle, for individual and all body regions, were statistically very significant (p?0,01). Optimum body condition in dry period was realized by 48,76% cows, at calving 53,61%, in the lactation peak 24,41% and in mid lactation 21,12%. Average value of body condition scores at calving was higher by 0,18 (-0,01 to 0,72) units compared to beginning of dry period, whereas at the lactation peak it was by -1,26 (-2,75 to - 0,41) units lower compared to calving, and in mid lactation compared to lactation peak it was higher by 0,18 (-0,94 to 0,85) units. Within the distribution of achieved differences in body condition scores in the time from the beginning of dry period to calving in 346 cows or 96,11% of total number of animals (n=360) increase of body condition score was realized ranging from ? 0,25 units. Distribution of differences in body condition scores between calving and lactation peak showed that 243 cows or 71,48% of total 340 cows realized loss of body condition score of >1,00 units. Within distribution of differences in body condition scores between the lactation peak and mid lactation, 261 cows or 81,06% of total number of scored animals (n=322) increased the body condition score in value of ? 0,25 units. Study showed that, except in the dry period, changes of the body condition during other phases of production cycle weren?t within the limits of optimum values. Realized results clearly showed the possibility of incidence of various production disorders, health issues and reproduction problems. Consequences are reflected also on longevity, life production and genetic progress. Realzied differences in average values of body condition scoreswere important basis for anticipation of potential problems. In that regard, there are significant reserves in improvement of efficiency of management of body energy reserves in high yielding cows.