Comparison of apparent and true digestibility of nutrients determined in dairy cows either by the nylon capsule or in vivo method

In this study the values of true digestibility of DM, OM, CP, NDF and starch determined either by the nylon capsule method or conventional in vivo method were compared. Four intact crossbred dairy cows (mean milk yield 21.9 kg/d) were used in two experimental periods. TMR consisted of maize silage, lucerne hay and concentrate. Nylon capsules (external diameter 10 mm) were made of nylon cloth (pore size 42 μm). Capsules were filled with TMR and at the beginning of the in vivo trial they were administered orally as a paper bolus into the cows. The values of true digestibility (after washing loss correction) of DM and OM, as determined by means of the nylon capsule method were lower than those estimated by the in vivo method. The respective differences were –6.9 and –7.3% (P < 0.05). Insignificant differences were found in CP, NDF and starch.