This work aimed to determine the in situ rumen digestibility of dry matter (DM) and crude protein (CP) using 10 protein sources. Potential degradabilities of DM and CP of soybean meal, cottonseed meal, castorbean meal and palmist coconut meal were high (around 100%), however due to higher fractional degradation rates of soybean meal (10%) and lower for cottonseed meal (4%), castorbean meal (DM:3%, CP:1.2%) and palmist meal (1.7%), the effective degradability (ED) of soybean was significantly higher despite the rates of passage, showing this protein source has the highest ruminal nitrogen availability (from 86% to 63%, as rate of passage increased from 2 to 8%). Gluten meal is a low rumen degradable protein source (ED of CP: 16% for 0.05 passage rate). Among protein sources of animal origin, the highest potential CP degradability was observed for meat and bone meal (75.5%), followed by fish meal I (58.5%), feather and viscera meal (52.3%), and blood meal (36.7%). The highest ED for a passage rate of 5% was observed for meat and bone meal (51%), followed by fish meal I (41%), feather and viscera meal (40%) and blood meal (33%). Fish meal II showed very low rumen degradability with only 22% of CP disappearance at 48 hours of incubation.
bovine; rumen; in situ; digestibility; protein source
