Forage degradability data from pooled forage samples were compared to those obtained from field samples using an in situ technique. Four fistulated sheep were employed as part of a Split Plot design within a 4×2 factorial (four times of incubation as plots and two forages as subplots) over a 4×4 Latin Square. The field site sample technique led to more realistic confidence limits for all parameters when modelling forage degradation and suggested the possibility of working with a single fistulated ruminant. Such a technique meets animal welfare requirements, saves experimental work and may stimulate the use of the in situ technique with simpler designs.