The usage of chlorophyll for evaluation of dry matter intake and nutrients digestibility in a pasture

Abstract

Two experiments involving 8 adult ewes were carried out. In experiment No. 1 the sheep were fed  exclusively on the pasture, whereas in the second experiment  the green forage was supplied to sheep individually in feeding racks, to compare the roughage intake values to the results obtained using markers-based evaluation. In the studies, the double indicator method was applied, using the following markers: internal – chlorophyll and external – chromium oxide (Cr₂O₃). To evaluate potential changes of chlorophyll concentration in the samples, it was established three times: directly after sample collection, in the sample chilled to 0–4 centigrade  and in the frozen sample. The average amount of dry matter consumed by all the sheep, established by weighing  did not differ significantly from the amount assessed on the basis of chlorophyll A. The differences between  the dry matter consumption related to 1 kg of BW^0,75 in the experiments No. 1 and No. 2 resulted from the experimental animals weight gain during the studies. The sensitivity of chlorophyll A as a marker helpful for nutrients digestibility  trials was also satisfactory. It stems from directional changes of digestibility coefficients, related to changes in the chemical composition of examined pasture roughage.