The effect of mechanical treatment of silage on intake and production of sheep

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Abstract
Over a period of 3 years, silages subjected to various mechanical treatments by the use of conventional silage harvesters were offered ad libitum to pregnant ewes and to castrated male lambs and the effects on intake and productivity were measured. The intake of silage made from grass harvested with a precision-chop harvester was substantially greater than the intake of silage made with other types of harvester (especially, a flail harvester), causing a lower degree of comminution.Mean daily silage dry-matter intake of ewes was 0·99 kg and 1·28 kg in mid-pregnancy, and 0·85 kg and 1·10 kg in late pregnancy with flail-harvested and precision-chop silages respectively. Silage was supplemented with various levels of concentrate in late pregnancy and an increasing level of concentrates did not reduce silage intake. In early lactation, when 800 g concentrate was given daily, ewes consumed 1·00 kg flail-harvested silage and 1·39 kg precision-chop silage. Compared with flail-harvested silage, precision-chop silage increased ewe body weight immediately post lambing by 5·1 kg, lamb birth weight by 0·27 kg and lamb growth rate by 58 g/day. Increases in intake of precision-chop silages by hoggets were on average greater, though more variable, than by ewes and were reflected in increased carcass weight.The reason for the increased intake of the finely-chopped silage was examined. It would appear that the major factor is the physical size of particle involved though there was some evidence that improved fermentation resulting from finer chopping may have been partly responsible for increased intake.