Review: Converting nutritional knowledge into feeding practices: a case study comparing different protein feeding...

Area of Science:

• Animal Nutrition
• Dairy Science
• Ruminant Metabolism

Background:

• Optimizing milk nitrogen efficiency is crucial for sustainable dairy production.
• Accurate prediction of milk protein yield (MPY) is essential for effective ration formulation.
• Current feeding systems vary in their ability to predict MPY under different nutritional conditions.

Purpose of the Study:

• To compare the predictive accuracy of five different feeding systems for milk protein yield (MPY).
• To identify key factors influencing the accuracy of MPY predictions in dairy cattle.
• To provide recommendations for improving existing and developing new animal feeding systems.

Main Methods:

• Comparative analysis of five major dairy cattle feeding systems: Cornell Net Carbohydrate and Protein System (CNCPS), Dutch systems (1991, 2007), Institut National de la Recherche Agronomique (INRA), National Research Council (NRC), and NorFor.
• Evaluation of MPY prediction accuracy against observed data in two experimental studies with manipulated protein and energy supply.
• Assessment of prediction bias, specifically slope bias, associated with different system methodologies.

Main Results:

• Feeding systems incorporating a variable efficiency of protein utilization, considering both protein and energy supply, demonstrated superior MPY prediction accuracy.
• Systems relying on a fixed efficiency of protein utilization exhibited the highest slope bias, indicating systematic over- or under-prediction.
• The inclusion of energy supply in the protein utilization efficiency calculation was identified as a critical factor for accurate MPY prediction.

Conclusions:

• Future development of dairy cattle feeding systems should prioritize variable protein utilization efficiency linked to energy supply for improved MPY prediction.
• Refining existing systems and creating new ones requires this integrated approach to protein and energy evaluation.
• The concept of variable efficiency may also need to be extended to essential amino acid predictions for further optimization.