The feeding of untreated or treated cereal straw and grass silage in combination to growing cattle

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Grass silage is a major constituent of the diet of ruminants but a reduction in voluntary feed intake has been observed by many workers (e.g. Osboum 1967, Taylor 1967) when compared with hay feeding. This reduction in feed intake is often accompenied by decreased production (e.g. live weight gain). The exact reasons for this reduction have not yet been confirmed but the low pH of silage is considered to be one of the many reasons because it prevents the animal eating large amounts of silage with problems. If animals are also getting concentrate with the silage, the situation may become worse as the animal has to face an enormous task of buffering so that blood pH can be maintained. Animals can produce saliva to buffer the low pH of silage and the acids produced by rumen fermentation. Thus feeds which stimulate saliva production such as straw, can help the animal (Webster 1988). Although straw is not highly digestible, due to lignification, after treatment with NaOH its digestibility can be improved and it could have a role in buffering acidic silage and the acid produced in the rumen, as well as stimulating saliva production. For this purpose a study was planned to investigate the use of straw (treated or untreated) in the diets of growing beef animals.