Effect of Phase Feeding Protein on Cattle Performance and Nitrogen Mass Balance in Open Feedlots

Two experiments using calves fed 176 days from November to May (WINTER) and yearlings fed 117 days from May to September (SUMMER) were conducted to compare conventional CP levels to phase-fed diets balanced for degradable intake protein and undegradable intake protein on performance and N volatilization. Phase fed diets were formulated to balance degradable intake protein and metabolizable protein. Phase feeding resulted in greater ADG and better F:G in WINTER and similar performance in SUMMER than traditional feeding methods. Nitrogen excretion was significantly reduced in both WINTER and SUMMER which translated into significantly less N volatilization without impacting N removed in manure