Apparent digestibility in meat-type guinea pigs as determined by total collection or by internal marker

Six adult male meat-type guinea pigs were subjected to three subsequent digestibility trials with 100% alfalfa, 50% alfalfa and 50% sugar cane and 50% alfalfa and 50% concentrate. For each animal in each period, feed intakes were recorded and all faeces were collected and stored at -20°C until analysis. Feeds and faeces were analysed for dry matter, crude ash, crude protein, ether-extract, crude fibre and acid-insoluble ash. Coefficients of apparent digestibility were calculated according to both the total collection method and the marker method with acid-insoluble ash as internal marker. The present study suggests that acid-insoluble ash is not valid as an internal marker when looking at differences between individuals, but might be useful to demonstrate differences between diets, albeit with lack of accuracy for estimating the absolute digestibility coefficients obtained through the total collection method. Sugar cane was slightly less digestible than alfalfa in meat-type guinea-pigs.