In situ degradability of forages cut at different stages of growth

The in situ degradability of barley, oats (harvested at heading, milk stage and early maturity) and vetch (flowering, pod formation and early maturity) was determined using three mature rumen fistulate Damascus goats. In a second trial the degradability of barley forage cut at different stages and regrowth was determined in four rumen fistulate mature Chios ewes. The CP content and 'D' values decreased with advancing maturity (trial 1). Vetch had greater CP content than that of cereals. The difference between barley and oats was significant for DM but not for CP degradability. DM and CP effective degradabilities were decreased with advancing stage of harvesting (trials 1 and 2). There was significant increase (P < 0.001) in CP degradability with increasing CP content of forages. Finally, CP degradability was highly correlated (R(2) = 0.81) with DM degradability. It is concluded that there is a shift in CP degradability with stage of maturity, and this should be taken into consideration when formulating ruminant animal diets for meeting their requirements for rumen degradable and undegradable protein.