Protection of starch in barley against rumen degradation by glutaraldehyde and formaldehyde as assessed by the dacron bag technique

Abstract

Glutaraldehyde (GCHO) and formaldehyde (HCHO) were applied to barley at three application rates (10, 20 or 30 g aldehyde kg −1 protein) by soaking in solutions of appropriate concentrations of GCHO (for 16 h) and HCHO (for 8 or 16 h). Rumen degradability of barley dry matter (DM), starch (S) and total nitrogen (N) was determined in three rumen fistulated cows using the in sacco technique with incubation times of 2, 4, 8, 16 and 24 h. On average treatment of barley with aldehydes reduced rumen degradability of DM, S and total N compared to untreated barley but the effect was almost totally due to reduction in degradation due to HCHO treatments, there being very little protective effect of GCHO at rates of application lower than 30 g kg −1 protein. For DM and S, irrespective of the aldehyde used or the length of aldehyde treatment, the reduction in rumen degradation increased with increasing application rate, the effects being most noticeable at short incubation times. Disappearance of total N was also reduced by increasing rates of application but this was most noticeable at longer incubation periods.