Paraformaldehyde Compared with Formic Acid As a Direct-Cut Silage Preservative

In two experiments, direct-cut grasslegume forage ensiled with planned 2.5% of 90% formic acid and forage ensiled with .5% paraformaldehyde in the dry matter were compared.In the second experiment untreated silage was compared also.In 1971 the two silages were fed ad libitum as the sole ration for 50 days to 30 dairy heifers paired on body weight.In 1972 the three silages were fed in the same way for 91 days to 24 dairy heifers blocked on body weight.Daily gains averaged over the 2 yr were nearly identical on formic and paraformaldehyde silages (812 versus 817 g) and considerably better than on untreated silage (258 g) in the 2nd yr.These gains resulted from comparable intakes (256 versus 263 kcal digestible energy/kg "75), partial feed conversions (8.4 versus 9.1 Mcal digestible energy for growth/kg gain) and energy digestibilities (59.2 versus 58.8%) of formic and paraformaldehyde silages.These data on the untreated silage were 230, 18.9, and 58.8.Formic acid and paraformaldehyde were equivalent in producing gain per metric ton of stored forage (111 versus 114 kg), which was considerably greater than that of untreated silage (41 kg).