Interpretive Summary: Impact of supplementing different sources of non-protein nitrogen on ruminal fermentation, nutrient digestibility, and microbial protein synthesis in beef cattle consuming a corn silage-based diet
By: Juan de J Vargas, Federico Tarnonsky, Araceli Maderal, Federico Podversich, Ignacio Fernández-Marenchino, Wilmer Cuervo, Vanesa Ramirez, Sabina Novo, Andrés Fernández-Lehmann, Martín Ruiz-Moreno, Tessa M Schulmeister, Isabel Ruiz-Ascacibar, Ignacio R Ipharraguerre, Nicolás DiLorenzo
Ruminants can use non-protein nitrogen (NPN) due to the symbiotic relationship with rumen microbes; however, there is limited information on supplementing different NPN mixtures on ruminal fermentation and microbial protein synthesis. Twelve American Aberdeen steers were used in a replicated and balanced 3 × 3 Latin square design with 3 periods of 35 d each. Urea (U), urea-biuret (UB), and urea-biuret-nitrate (UBN) mixtures were supplemented in an isonitrogenous corn silage-based diet. Intake, digestibility, blood, ruminal fluid, and omasal samples were collected, and digesta flow and microbial protein synthesis were estimated. Steers supplemented with UB tended to consume more dry matter (DM) than those supplemented with UBN. However, animals supplemented with UBN tended to digest more acid detergent fiber. Steers supplemented with U and UB showed greater DM flow throughout the omasum than UBN. Microbial protein synthesis, microbial efficiency, and the concentration of total volatile fatty acids were not different among NPN supplements. Steers supplemented with UBN showed lower concentrations of NH3-N than those with U and UB. In conclusion, novel NPN mixtures have the potential to modify the intake of DM and ruminal fermentation without affecting microbial protein synthesis when compared with U.
Read the full article in the Journal of Animal Science.
