The effect of formaldehyde treatment on the chemical composition and nutritive value of silage

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Abstract
Two experiments were conducted in which solutions of formaldehyde (HCHO) were applied to clover-dominant herbage before conservation as high-moisture silage. In Experiment 1 the HCHO application rates were 0, 0.6, 1.1. 2.2, and 4.4% (wjw of the dry matter treated), and 15 kg quantities of the herbage were ensiled in small polythene containers. Rates of HCHO up to 2.2% decreased the content of acetic acid, increased the content of a compound identified as 2,3~butanediol, but had no effect on silage pH (4.74 units). The 4.4% rate decreased the contents of acetic acid and ?..3-butanediol to very low levels and increased the pH to 5.02 units. The two higher rates of HCHO decreased nitrogen (N) breakdown in the silages and reduced ammonia production ill vitro. In Experiment 2, untreated silage and silage treated with HCHO (1.7% wjw of the dry matter) were ensiled in 6000 kg polythene-covered stacks. Formaldehyde treatment decreased the contents of acetic, propionic, n-butyric, and lactic acids, decreased the extent of N breakdown. and increased pH. The treatment decreased the osmotic pressure and conductivity of silage juice by 25 and 19% respectively, 2.3-butanediol comprised 2.40% of the dry matter and was unaffected by HCHO treatment. Untreated silage showed a strong buffering action to both sodium hydroxide and artificial saliva solutions. Formaldehyde treatment before ensiling eliminated this effect. Secondarv fermentation was apparent in a 30 em deep surface layer of HCHO-treated silage, but was not present to any marked extent in untreated silage.