Effects of chop length of silage on chewing time, feed consumption and milk production

摘要

Grass silage of high quality is a natural prerequisite for modern European dairy production. Physical structure of silage is important for animal performance as well as for animal welfare. Allowing a longer cutting length of the silage decreases the energy used for harvesting the silage. This must, however, not be at the expense of feed intake or milk production. Grass silage of high nutritional quality (11.5 MJ ME kg~(-1) DM; 157 g CP g kg~(-1) DM; -400 g kg~(-1) DM) was harvested with two differenttypes of self-loading wagons giving different physical structures. A mechanical separation showed relatively small differences in half weight length (34 or 25 mm) but the upper quartile differed more (57 vs. 39 mm). Image analyses for the same silage showed mean lengths of 57 and 35 mm. The silage was fed to dairy cows of different parity and stages of lactation. Pattern of consumption and chewing time was measured using IGER animal behaviour recorders. The most obvious difference between the two silages was longer chewing time per kg DM silage for the longer silage (51 vs. 43 minutes). However, the average daily silage consumption did not differ significantly between treatments (13.6 vs. 13.9 kg DM cow~(-1)) and neither did the total feed intake (24.0 vs. 24.4 kg DM). Overall daily milk production (kg ECM cow~(-1)) was similar for the treatments (31.5 vs. 30.8). The conclusion from the present experiment is that, given high quality silage, differences in physical structure within the limits of the experiment do not restrict feed intake and milk production.