Good clamp management can improve daily milk output by 3 litres a cow and with this level of yield increase at stake it is essential that silage production via the clamp method is maximised through best practice and high quality film products. As with baled silage the expulsion of as much air as possible from the crop is crucial to the quality of the ensiled crop. To achieve this, the grass (or other crop) should be rolled repeatedly until it reaches a point where it is firm enough to walk upon. At this point the sheeting of the clamp can begin.
Clamps should be covered with high quality silage sheeting. Advances in polymer technology and sheeting manufacturing processes have enabled the development of exceptional high strength sheets like those found in the Visqueen range. These stronger clamp sheets provide the strength and puncture resistance necessary to cope with the tough farm working environment. When sheeting down special attention should be given to the top and sides of the clamp to ensure that air is prevented from entering. If air does get in, the crop will not ensile properly and the resultant silage will be of poor nutritional quality.
In recent years, farmers have started to apply an additional, thinner, more flexible, low permeability film to the clamp in order to reduce wastage. These new generation clamp sheets sit directly beneath the traditional silage sheet. Specially designed to closely follow and cling to the clamp surface these 'underlay' sheets prevent pockets of trapped air forming to significantly reduce aerobic spoilage on the top and shoulders. Because they provide an effective air seal and create the right anaerobic conditions, they also facilitate a faster, more effecient fermentation process to deliver enhanced silage quality. Such sheets are especially beneficial when ensiling moist feeds like brewers' grains and crimped maize which are not only higher value crops, but are also more susceptible to wastage.
Once the sheeting has been applied it will need to be secured to hold it in place and to maintain the airtight finish. Traditionally used tyres were applied to the top of the clamp to weight it down but increasingly farmers are using heavy duty covers designed to keep the silage sheeting in contact with the surface of the clamp.