In situ ruminal degradability of dry matter, organic matter and crude protein of some concentrated supplements used in the feeding of bovines

Abstract

Holstein steers, with permanent ruminal cannula, 650 kg of liveweight, maintained on pasture, and receiving mineral mixture "ad libtum" were used. The present study had the objective of evaluating the "in situ" ruminal degradation of the dry matter (DM), crude protein (CP) and organic matter (OM) of 12 concentrated feed: whole sunflower seed (WSF), partially degreased sunflower (DSF), sunflower meal (SFM), sunflower pie pressed one time (T 1x), sunflower pie pressed two time (T 2x), for extracting of the oil, whole soybean seed (WS), partially degreased soybean (DS), soybean meal (SM), whole cottonseed (WC), cottonseed meal (CM), degreased corn germ (CG) and a commercial concentrate with 36% of CP (CC). The feed were grounded in a mill equipped with a screen with sieves of 2 mm of diameter. Samples 5 g of DM from each one of the mentioned feed were incubated in nylon bags with pores of 50 micras of diameter, measuring 14 x 7 cm, for the times of 12; 20; and 33 h of ruminal fermentation. The effective degradability (ED) of CP, for a passage rate of 5%/h varied from 62.08 to 95.93% for commercial concentrate and sunflower pie pressed two time for OM varied from 48.17 to 85.28% for soybean meal and whole cottonseed. The CC and CG presented the smallest ED of CP, however only the CC have larger protein escapes to be digested in the intestines, because CG presents little PB in its constitution.