The accuracy of using the ratio of nitrogen to acid detergent fibre in faeces to partition nitrogen between faeces and urine in total excreta collections from ewes

P. F. White, T. T. Treacher, Adnan Termanini, S. Rihawi. (30/10/2003). The accuracy of using the ratio of nitrogen to acid detergent fibre in faeces to partition nitrogen between faeces and urine in total excreta collections from ewes. Grass and Forage Science, 52 (1), pp. 122-124.

Abstract

A comparison was made of the estimates of the outputs of nitrogen (N) in faeces and urine on Awassi ewes using two methods: (1) conventional collection in digestibility crates, with urine acidified to prevent volatilization (separation method); (2) collection of both faeces and urine together in bags placed over the tail of the ewe and using the ratio between N and acid detergent fibre (ADF) in samples taken from the rectum to partition the total N output between faeces and urine (N:ADF method). The comparison was made on eight ewes in a crossover design using three collection periods of 5 d. There were no significant differences between the methods in the estimates of nitrogen in urine and faeces, although differences between methods in the estimation of total N output were close to being significant. The precision of the estimates was lower with the N:ADF method.