Effect of maceration on nitrogen fractions in hay and silage

An intensive mechanical conditioning treatment, referred to as maceration, was applied at mowing to alfalfa or timothy in order to enhance drying rate , reduce wilting time and possibly reduce respiration losses and proteolysi s; In 1995, a laboratory trial was conducted using two levels of force (175 0 and 3500 Newton) and five levels of conditioning: a control (no condition ing), one passage, three passages, five passages and seven passages through two steel knurled rolls. All forages were dried in a controlled environmen t at 30 degrees C and conserved as hay. The level of force did not affect t he chemical composition of the forages obtained. However the nitrogen (N) f ractions were affected by the level of maceration. As the level of conditio ning increased, the soluble N fractions (A and B1) of both forages decrease d (P < 0.001). Meanwhile, the slowly degradable N fraction (B3) increased l inearly (P < 0.001) in timothy and quadratically (P < 0.003) in alfalfa. Th e fraction of unavailable N (fraction C) also increased linearly (P < 0.01) with intensity of maceration. In 1996, alfalfa was conditioned in the fiel d at four intensity levels: a control (rubber roll-conditioning), one passa ge, two passages, and three passages through a full-size mower-macerator wi th three knurled rolls. The alfalfa dried under poor climatic conditions wi th alternating rain and sunshine and was conserved as silage at 30% dry mat ter (DM) after a 40-h wilt or as hay after a 90-h wilt. Neutral detergent f ibre (NDF), acid detergent fibre (ADF), and ash contents increased linearly (P < 0.001) with the level of maceration; the increase was greater in hay than in silage. The non protein nitrogen (fraction A) decreased (P < 0.001) while fraction B3 and unavailable N (fraction C) increased (P < 0.001) wit h level of maceration. The results suggest that maceration decreases the ex tent of proteolysis during conservation and preserves a higher proportion o f the slowly degradable N (escape nitrogen).