Feeding protein supplements is advantageous because of a positive response in milk production. Rapeseed meal has given better production responses on a protein basis than soybean meal, but its supply is not sufficient to meet the requirements of dairy production. Red clover is one alternative to reduce the requirement of protein supplements in dairy cow diets. Efficiency of N utilization in the rumen is high with red clover due to polyphenoloxidase (PPO) that promotes complexing of plant proteins with mono or di-phenolic substrates present in the plant itself. It has been suggested that imbalanced uptake of amino acids in the small intestine may limit the conversion of dietary N into milk N in cows fed red clover containing diets. Understanding the limitations of red clover it could be possible to select and breed varieties with optimal level of PPO that optimize both ruminal degradability and intestinal digestibility for maximizing the supply of amino acids for milk synthesis.