The use of cobalt ethylenediamine tetraacetic acid as a soluble marker in the determination of rumen outflow rate in sheep

Abstract

Rumen outflow rate in sheep was studied using cobalt ethylenediamine tetraacetic acid as soluble rumen marker in three rumen fistulated sheep of an average body weight of 9.6±0.07kg. Single dose time sequence spot sampling technique was adopted at various time intervals of 2, 4, 6, 8, & 24 h. The ruminal concentrations of cobalt ethylenediamine tetraacetic acid after each post-dosing spot sampling time was determined by a graphical comparison of spectrophotometric absorbance of known concentrations of cobalt ethylenediamine tetraacetic acid and the absorbance of equal volume of ruminal fluid collected from each sheep at given time intervals post-dosing with marker. Depletion of marker with time from the rumen reflected the liquid turnover in the rumen. The ruminal volume of marker distribution was estimated as 1.5499±0.0198L. Using the exponential equation for determining the fractional turnover rate, the average fractional turnover rate was 0.09624±0.0017/h or 9.624%. The rumen half- life of the marker was 7.204±0.12h. The average outflow rate was 0.149±0.002L/h. The data obtained will help in regulating feeding time of intensively reared sheep towards achieving high voluntary intake of dry matter and effective rumen degradability of ruminant feed fractions, which are influenced by rumen outflow rate.Keywords: cobalt ethylenediamine tetraacetic acid, rumen, outflow rate, sheepNigerian Veterinary Journal Vol. 26(1) 2005: 18-24