Feeding value of wilted silages made using formic acid, formaldehyde and propionic acid

The nutritive value of four silages was compared using eight rumenfistulated wethers. Wilted ryegrass was ensiled without additive (A); with formic acid (13·9 kg/t dry matter) (B); with formic acid (10·3 kg/t dry matter) plus formalin (formaldehyde at 4·8 kg/t dry matter) (C); with formic acid (4·9 kg/t dry matter) plus formalin (formaldehyde at 2·3 kg/t dry matter) plus propionic acid (5·6 kg/t dry matter) (D). Dry-matter intakes were 13·8, 15·1, 14·3 and 14·3 g/kg live weight for A, B, C and D respectively. Digestibilities of organic matter and dry matter were not affected by the additives. Digestibility of nitrogen and peak ruminal ammonia concentration were significantly (P<0·05) reduced by the addition of formaldehyde. The effect on rumen fermentation characteristics, of chemically restricting in-silo fermentation, is illustrated. Differences in the rumen volatile fatty acids and in the efficiency of utilization of the energy for growth, fattening and lactation are discussed.