University of Arkansas, Fayetteville Division of Agriculture


acid-detergent insoluble ash


Digestibility markers are used to determine total digestibility without collecting total feces, which reduces time and labor and allows greater numbers of animal observations to be obtained. The goal was to determine if the digestibility marker acid detergent insoluble ash (ADIA) was fully recovered, and based on that information, determine the accuracy of total digestion predictions using ADIA. Different proportions of sericea lespedeza hay and alfalfa silage were offered to 16 gestating Dorper ewe lambs (Ovis aries) (41.8 ± 4.61 kg body weight) to determine digestibility. Total feed intake and fecal excretion were measured during 2 experimental periods consisting of a 14-d adaptation period followed by 5-d of total fecal collection. Accuracy of ADIA recovery and its use to predict digestibility were analyzed using PROC MIXED of SAS. Recovery of ADIA averaged -0.16 g/d across treatments and was not different (P = 0.97) among treatments. Digestibility was underestimated by 6.2 g/kg, or 0.62 percentage units and treatment differences were not detected (P = 0.92). Neither of these measurements were different (P > 0.51) from zero. Therefore, ADIA was proven to be a reliable internal marker to replace total fecal output for sheep offered forage-based diets with mixtures of diverse forages. Due to the recovery rate and total digestibility calculated, ADIA is a realistic and reliable procedure to determine total digestibility when total fecal collections are not feasible.