The effects of the addition of various enzyme mixtures on the fermentation of perennial ryegrass silage and on its nutritional value for milk production in dairy cows

Abstract

Two enzyme preparations containing cellulase/hemicellulase (E and FS) were investigated as silage additives. The preparations were similar in cellulase activity (58 U ml −1 and 61 U ml −1, respectively), but FS had almost twice the level of xylanase activity (218 U ml −1 and 517 U ml −1, respectively). Four silages were made from a uniform sward of perennial ryegrass cut when the content of digestible organic matter in the dry matter (DOMD) was around 600 g kg −1. The additive treatments were: no additive (control); E at 0.31 t −1; FS at 0.31 t −1 and at 0.61 t −1 (2 FS). All silages were well preserved. DOMD values determined in sheep were 609 g kg −1, 588 g kg −1, 624 g kg −1 and 635 g kg −1, respectively; compared with the control, E decreased ( P < 0.05) and both FS treatments increased ( P < 0.05) DOMD. The silages were offered ad libitum with 4.5 or 9.0 kg day −1 of concentrates to 16 cows in a series of 2 × 2 Latin squares with 3 week periods. Both FS treatments increased ( P < 0.05) silage intake at both levels of concentrate. Compared with the control, Treatment 2FS increased ( P < 0.05) the yield of milk and milk protein at the lower level of concentrate. There were no differences between treatments in milk production at the higher level of concentrate.