Chromium oxide technique for intake estimates of chopped elephantgrass (Pennisetum purpureum Schum.) using lactating cows

Dry matter intake (DMI) of nine Holstein x Zebu lactating fistulated cows was measured through difference of offered and refuse feed weight and estimated with aid of the chromium oxide (Cr2O3) for the fecal production (FO) and indigestible of the grass. The experiment was in a three Latin Squares design (30) and treatments constituted the supply of elephantgrass with 30, 45 and 60 days of growth. The in vitro dry matter digestibility (IVDMD) was determined in the samples of the elephantgrass and estimated directly from the measured intake and the fecal production (PF) obtained with the Cr2O3. Fecal production was also calculated (FPc) from the values of the intake (direct method) and IVDMD, as well as it was estimated by the administrated marker /excreted marker relation. Significant differences were observed among DMI obtained in the three elephantgrass growing ages by the two appraised methods. The average DMI obtained by the direct method were 8.00; 10.00 and 11.02 kg/cow/day, respectively, for the grass with 30, 45 and 60 days of growth. DMI esteemed with aid of the Cr2O3 were of 9.00; 11.10 and 12.00 kg/cow/day for the same treatments. The DMI estimates using the Cr2O3 was overestimated in 9.25% in relation to the results obtained by the direct method.