The digestibility trials are important in the development and evaluation of animal feed. They are carned out through the total collection method (TC) or by the use of indicator methods (IM), where the indicators can be classified as external (added to the feed), or internal (already present in the feed). In the present work, the comparison of both methods was made, aiming the search for simpler and safer methods for the determination of the digestibility of commercial cat feed. We tested the TC and IM using, for the latter, the crudefibre (CF) and the acid-detergent fibre (ADF) as internal indicators. We used 4 young adult cats (2 males and 2 females) held in individual metabolism cages for 30 days (24 for adaptation and 6 for total collection of faeces) and fed ad libitum with a commercial dry extruded cat feed. The results for the TC, CF and ADF were, respectively, 74.0, 71.4 and 75.0% for dry matter, 77.0, 74.8 and 77.9% for organic matter, 79.2, 77.2 and 80.0% for crude protein, 81.7, 80.4 and 82.8% for ether extract and 78.8, 76.6 and 79.6% for nitrogen-free extract. The statistical analysis did not show significant diffèrences between the methods (p > 0.2). It was recovered 96.1% of the ADF and 104.3% of the CF, and these figures could be considered statistically equivalents by the t test (p > 0.49). The internal markers method presents some practical advantages when compared to the total collection method. However, further studies are required in order to check the efficiency of the tested markers, using diets with different amounts and sources of CF and ADF.
domestic cat; digestibility; internal markers; crude fibre; acid-detergent fibre; feeds
