Polyethylene as a Reference Substance for Digestion Studies with Young Ruminants

Abstract

Ground polyethylene (particle size 50 mesh, density 0.916) was mixed into ground diets containing 5% dry matter and used as a reference substance for estimating dry matter digestion in nine 15-wk. old dairy calves. Higher values were obtained for dry matter and polyethylene in segments beyond the reticulo-rumen. The mean recovery from the digestive tract at the time of sacrifice was 201.2 [plus or minus]62.2 and 158.7[plus or minus] 50.7% of the daily dose of polyethylene and dry matter, respectively. The average percent of daily dose of polyethylene recovered in feces during a 5-day total collection period was 100.3 [plus or minus]9.3%. Dry matter digestion coefficients as determined by total collection and polyethylene-dry matter ratios were highly correlated (r = +0.777) with the means of the 2 estimates being similar (66.7 [plus or minus] 3.9 and 66.4 [plus or minus] 4.7, respectively). It is suggested that polyethylene would serve as a valid reference substance for estimating digestion coefficients for any nutrient in the feces and for those nutrients associated with dry matter in movement and distribution in other parts of the digestive tract.