Optimizing nitrogen use efficiency in ruminant feeding

The effects of protein level and source in cattle diets on rumen microbial N turnover and N partitioning

The German protein evaluation system uses rumen nitrogen balance (RNB) as an indicator for adequate nitrogen (N) supply to rumen microbes. However, only rough and highly variable estimates of the microbial protein synthesis efficiency are available. The synchronization of nutrients, provision of dietary N and energy, simultaneously in proportions required by rumen microbes, is expected to optimize both, digestibility of the diet and efficiency of microbial protein synthesis.

Therefore, the general objectives of this research work include:

• to understand the effects of the interactions between RNB and the carbohydrates (CHO) or N sources on rumen fermentation patterns, efficiency of microbial protein synthesis, composition of microbial biomass, and the N partitioning in vitro and in vivo
• to analyze the effects of synchronizing CHO and N supply to rumen microbes at low rumen-degradable N availability.