Resumen

SILVA, Edilane Aparecida da et al. Effects of crude protein levels on microbial efficiency and in situ degradability in steers fed Tifton 85 bermudagrass hay supplemented with different protein sources. R. Bras. Zootec. [online]. 2007, vol.36, n.1, pp. 225-236. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982007000100027.

Eight crossbred steers fitted with ruminal and duodenal cannulas were randomly assigned to two replicated 4 x 4 Latin squares to evaluate the effects of crude protein (CP) levels on microbial protein synthesis efficiency and in situ degradability of nutrients. Animals received a control diet containing Tifton 85 bermudagrass hay or the control diet supplemented with urea, soybean meal or corn gluten meal-60. Ruminal pH and concentration of ruminal ammonia (NH₃-N) were determined in the ruminal fluid at 0 (pre-feeding), 2, 4, 6 and 8 hours after feeding. Indigestible acid detergent fiber was used as the internal marker for measuring duodenal flow of nutrients while total purines were used as the direct microbial marker to measure microbial protein synthesis and microbial efficiency. Ruminal pH and NH₃-N were within expected ranges indicating a stable ruminal environment. There were no effects of different dietary CP levels on intakes of DM and N as well as on microbial efficiency and degradability kinetics of DM and NDF. It can be concluded that different CP levels had no effect on microbial protein synthesis and efficiency and kinetics of ruminal degradability.

Palabras llave : corn gluten meal 60; pH; ruminal ammonia; purines; soybean meal; urea.