Studies on the amount and composition of digesta flowing through the duodenum of dairy cows. 1. Rate of flow of digesta measured direct and estimated indirect by the indicator dilution technique.

Abstract

1. Feed intake and the output of faeces, urine and milk were recorded for 8 to 10 days on 2 Friesian cows, with duodenal re-entrant cannulae, receiving hay and concentrates or fresh-mown herbage at the early or mature growth stage. One cow was also given 50 g calcined magnesite daily. During and in the 5 days preceding the collection periods 100 g polyethylene glycol (PEG) and 5.25 g Cr2O3 were given twice daily into the rumen. The digesta were measured and sampled from the re-entrant cannulae for 120 h in the middle of each balance period. All of the administered PEG and Cr2O3 were recovered from the duodenal digesta and faeces. The PEG content of duodenal digesta reached a peak 3 to 4 h after administration, but no diurnal pattern was observed for Cr2O3. The contents of PEG, Cr2O3, DM, Ca and Mg in spot samples of duodenal digesta taken at 2-h intervals agreed well with proportional samples collected during the same hours. (Abstract retrieved from CAB Abstracts by CABI’s permission)