Relationships between Performance, Intake, Diet Nutritive Quality and Fecal Nutritive Quality of Cattle on Mountain Range

Abstract

Correlations were developed between average daily gain (ADG), forage organic matter intake (INT), fistula sample in vitro organic matter digestibility (DID), fistula sample nitrogen (DN), fecal sample in vitro digestibility (FID), and fecal sample nitrogen (FN) of cattle on forest and grassland range in northeastern Oregon. FN and FID were more closely associated with ADG and INT than DN or DID. Linear regression equations were developed between fistula and fecal samples for both N (r2=.83) and ID (r2=.71). The inclusion of FN as an independent variable with FID improved the equation for predicting fistula sample ID (R2=.83). Forage intake could not be well predicted from either FN or FID in either simple or multiple regression equations. The closer relationship between fecal sample nutritive quality and ADG compared to fistula sample nutritive quality and ADG is attributed to greater sampling precision for fecal nutritive quality. Fecal N and ID appear to be closely associate with DN and DID when grasses comprise most of the ruminant diet but this relationship may not hold when the diet is dominated by forbs and shrubs. Nutritive evaluation of feces shows potential for monitoring trends in ruminant diet quality and performance but much more research is needed before these procedures can be applied.