The effect of silage chop length on the voluntary intake and rumination behaviour of sheep

Two experiments were conducted with sheep to investigate the effect of silage chop length on voluntary intake and eating and ruminating behaviour. The silages, made from Italian rye-grass, either received no additive or formic acid at a rate of 4 g kg^?1 and were chopped to lengths of 5.3 cm (long), 1.8 cm (short) before ensiling or 1.8 cm (long/short) before feeding. The addition of the additive and short chopping improved the fermentation characteristics of the silage. Voluntary intake of silage dry matter and organic matter was higher with the short than with the long silage. Differences in silage digestibilities and cellulolytic activity did not explain the increase in silage intake. Sheep on the long silage had a lower rate of intake and a shorter ruminating time than on short silage, and thus the effective breakdown of the silage in the rumen was delayed, i.e. an increased latency time. Pseudo-rumination was significantly higher on the long than on the short silage.