Effect of Aerobic Deterioration on Feeding Value of Low-moisture and High-moisture Grass Silages

Abstract

In an attempt to clarify the effect of aerobic deterioration on the feeding value of silage, digestion, nitrogen balance and palatability studies were conducted, using wether sheep. The sheep were fed low-moisture (L-) and high-moisture (H-) silages which were made from the same source of forage and were at different stages of aerobic deterioration, having been stacked in a room after being removed from silos for 0 (L-0, H-0 silage: control), 4 (L-4, H-4 silage) and 7 days (L-7, H-7 silage). The results obtained are summarized as follows. 1) Changes in silage temperature during the aerobic exposure period varied with the site in silage stack, but, in total, the temperature rise was greater for I-silage than for H-silage. 2) The aerobic deterioration resulted in decreased WSC and lactic acid contents and increased ADF, NDF and lignin contents of L- and H-silages. 3) There was no significant difference (P>0.05) between silages stacked for 4 days and control Silages in the digestibilities of all chemical composition. However, the digestibilities of crude protein, NFE and energy were significantly (P<0.01, P<0.01) lower for L-7 silage than for L-0 silage. The digestibility of crude protein was lower (P<0.05), but that of NDF was higher (P<0.05) for H-7 silage than for H-0 silage. 4) With respect to the DCP and TDN contents, the silages stacked for 4 days were approximately equal to the control silages, but the silages stacked for 7 days were 2-3% lower than the control silages. 5) The losses of nutrients from silages increased with proceeding aerobic deterioration: L-silage lost 3.5% DM, 6.5% DCP, 5.4% TDN and 10.0% DE, and comparable values for Hsilage were 3.2, 5.6, 4.8 and 6.3% during the 7-day aerobic exposure period. 6) There was no marked difference in the nitrogen retention between the sheep fed the deteriorated silages and control silages. 7) Ammonia and total VFA concentration in the rumen of the sheep fed H-silage tended to be somewhat lower with aerobic deterioration. 8) In a palatability study using the cafeteria method, the amount of silage consumed by the sheep decreased as aerobic deterioration proceeded, showing a great difference (P<0.01) even between the silages stacked for 4 days and control silages.