The digestion by cattle of grass silages made with no additive or with the application of formic acid or formic acid and formaldehyde |
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Authors: | J A ROOKE H A GREIFE D G ARMSTRONG |
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Institution: | Department of Agricultural Biochemistry and Nutrition, University of Newcastle upon Tyne, UK |
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Abstract: | The aim of the experiment was to assess the effect of applying, at commercially recommended rates, formic acid or formic acid/formaldehyde at ensilage upon the subsequent digestion of the silages by cattle. Three wilted grass silages were made from perennial ryegrass ensiled at a DM concentration of 206 g kg?1 after a poor wilting period of 49 h without additive application and with application of 2.5 litres t?1 of formic acid or of 4.5 litres t?1 of a mixture of (gkg?1) 500 formic acid, 200 sulphuric acid and 200 formatin giving an application rate of 15 g formaldehyde kg?1 herbage crude protein (N × 6.25). The silages were fed to cattle equipped with rumen cannulae and duodenal re-entrant cannulae. Results from analyses of silage composition and from the digestion of organic matter and N showed no major differences between silages. The efficiency of rumen microbial N synthesis, the rumen degradability of silage N (determined in vivo or in sacco ) and in vivo digestion of individual amino acids were also unaffected by additive treatment. These results indicate that poor wilting conditions before ensilage restricted the effectiveness of additive treatment; the ineffectiveness of formaldehyde in reducing the rumen degradability of silage N may also have been related to the low rate of formaldehyde application. |
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