A comparison of particulate markers for the estimation of digesta flow from the abomasum of sheep offered chopped oaten hay

Abstract

Five sheep with simple cannulae in the rumen and abomasum were given a diet of chopped oaten hay at 95-98% of ad libitum intake from continuously moving belts. Flows of digesta from the abomasum were estimated by a double marker method by reference to 51Cr-EDTA as the fluid marker, and either 103Ru-P, lignin, or acid insoluble ash (AIA) as the particulate marker. Estimates were also made by reference to lignin as a single marker. Estimates of the weight of digesta leaving the abomasum daily were unaffected by the choice of particulate marker when used with 51Cr-EDTA, but were 25% lower when lignin was used alone. The estimated flows of dry matter and acid detergent fibre (ADF) were dependent upon the choice of markers. Compared with estimates of ADF flow given by 51Cr-EDTA and lignin, estimates given by AIA were lower (-24.6%) and those given by 103Ru-P were higher (+26.2%). Lignin alone gave estimates 1.6% higher. Observations on the distribution of 103Ru-P in digesta dry matter indicated a markedly higher concentration on fine than on large particles. It is concluded that lignin may be preferable to 103Ru-P as a particulate marker when certain coarsely chopped roughages are given to sheep, and when samples of digesta from the abomasum are obtained through a simple cannula.