A comparison of parameters of the passage of nylon capsules and digesta calculated from faecal excretion data obtained in lactating cows

Abstract

ABSTRACT:The aim of the study was to compare parameters of passage of nylon capsules and digesta represented by Cr-labelled maize silage through the digestive tract of dairy cows. The capsules were made of nylon cloth (42 µm pore size, 10 mm outside diameter) and applied orally. The evaluation was carried out in dairy cows with milk yield of 19.0 kg/day. The diet (17.6 kg DM/day) consisted of maize silage, lucerne hay and concentrate. Total mean retention time (TMRT), delay time (τ), summarised compartmental mean retention time (CMRTS), and mean individual compartmental retention times (CMRT1 and CMRT2) were calculated. TMRT, τ, CMRTS, CMRT1 and CMRT2 values of nylon capsules and Cr-labelled silage were 36.2 and 45.4 h (P < 0.01), 16.2 and 8.3 h (P < 0.01), 20.1 and 37.2 h (P < 0.01), 7.8 and 8.5 h, 12.2 and 28.7 h (P < 0.05), respectively. The calculated mean retention time of nylon capsules in the reticulo-rumen (CMRTS) was shorter and in the intestines (τ) was longer than that of digesta. For this reason the estimation of digestibility using the nylon capsule method can be questionable.