Aim: This research aimed to discover the chemical composition, as well as the content of the degradable and undegradable protein of the ruminant feed commonly used as cattle feed by Indonesian farmers.

Materials and Methods: In this study, Pennisetum purpureum, Leucaena leucocephala, Indigofera zollingeriana, Gliricidia sepium, cassava, maize, palm kernel cake, and rice bran were used as feed. Chemical composition was determined by proximate and Van Soest analyses performed in triplicate. Dry matter and organic matter digestibility, as well as the rumen degradable proteins (RDP) and rumen undegradable proteins (RUP) contents, were determined in vitro using the Tilley and Terry method.

Results: The results showed that more proteins can be obtained from legumes than from grass or concentrates. The highest protein amount was obtained from I. zollingerian (31.22%), while the lowest protein amount was obtained from cassava (3.59%). Dry matter digestibility ranged from 18.53% (rice bran) to 49.21% (G. sepium). Organic matter digestibility ranged from 35.71% (cassava) to 59.57% (I. zollingerian). Rice bran had the highest RDP from concentrate (73.26%), whereas I. zollingerian had the highest RDP from forage (74.72%). The highest RUP from concentrate was obtained from palm kernel cake (61.01%), and the highest RUP from forage was obtained from L. leucocephala (49.23%).

Conclusion: The preparation of ruminant livestock rations must be based on RDP and RUP to meet the needs of both the rumen microbes and host animals. Information regarding the RDP and RUP of feeds is still limited, making this study useful in the preparation of ruminant livestock rations based on RDP and RUP ratios.

Keywords: chemical compositions, rumen degradable proteins, rumen undegradable proteins, ruminant, tropical feedstuff.