Changes in body condition of high-yielding dairy cows

Abstract

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 occurring 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. Realized differences in average values of body condition scores were 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.

Realizovane prosečne vrednosti ocena telesne kondicije krava, za pojedinačne i sve telesne regije, u okviru svih ispitivanih faza proizvodnog ciklusa, statistički vrlo značajno (p≤0,01) su odstupale od ciljnih vrednosti. Razlike između prosečnih vrednosti ocena telesne kondicije po fazama proizvodnog ciklusa, u okviru svake pojedinačne i svih telesnih regija, bile su statistički vrlo značajne (p≤0,01). Optimalnu telesnu kondiciju na zasušenju ostvarilo je 48,76% krava, na teljenju 53,61%, u vrhu laktacije 24,41% i na sredini laktacije 21,12%. Prosečna vrednost ocena telesne kondicije krava kod teljenja bila je veća za 0,18 (-0,01 do 0,72) jedinica u odnosu na početak zasušenja. Srednja vrednost ocena telesne kondicije krava na vrhu laktacije bila je za -1,26 (-2,75 do -0,41) jedinica manja u odnosu na teljenje. Prosečna vrednost ocena na sredini u odnosu na vrh laktacije bila je povećana za 0,18 (-0,94 do 0,85) jedinica. Kod svih utvrđenih prosečnih razlika u ocenama telesne kondicije između svih ispitivanih faza proizvodnog ciklusa bila je prisutna visoka varijabilnost. U okviru distribucije ostvarenih razlika ocena telesne kondicije u periodu između početka zasušenja i teljenja kod 346 krave ili 96,11% od ukupnog broja grla (n=360) ostvareno je povećanje telesne kondicije u intervalu ≤ 0,25 jedinica. Raspodela razlika ocena telesne kondicije između teljenja i vrha laktacije kod ukupno 340 krava pokazala je da su 243 krave ili 71,48% ostvarile gubitak telesne kondicije u iznosu >1,00 jedinice. U okviru raspodele razlika u ocenama telesne kondicije između vrha i sredine laktacije 261 krava ili 81,06% od ukupnog broja ocenjenih grla (n=322) povećale su telesnu kondiciju u vrednosti ≤ 0,25 jedinica.