Abstract:
Formaldehyde-treated silage, formic acid-treated silage, formaldehyde-formic acid-treated silage, untreated silage, and lucerne hay were made from a lucerne sward and offered to Merino wethers. The formaldehyde was applied at a rate of 0.9 % of the weight of the dry matter and formic acid at 0.5 % of the fresh weight of the lucerne. Formaldehyde-treated silage and formaldehyde-formic acid-treated silage had significantly lower concentrations of ammonia nitrogen and total and individual organic acids than untreated silage. Formic acid-treated silage had a similar degree of fermentation to untreated silage, but more acetic acid and less lactic acid were produced than in untreated silage. However, when formic acid was applied in combination with formaldehyde, the ensiling fermentation was inhibited more than when formaldehyde was applied alone. There was some apparent protection of protein by the formaldehyde treatment. Treatment with formic acid significantly increased the in vivo digestibility of both nitrogen and dry matter, but did not increase ad libitum intake or wool growth by sheep offered this silage. Compared to untreated silage, treatment with formaldehyde significantly reduced the in vivo digestibility of nitrogen, produced a non-significant increase in intake, and significantly increased wool growth. The treatment of lucerne with both formaldehyde and formic acid significantly increased in vivo digestibility of dry matter, ad libitum intake, and wool growth compared with untreated silage. The treatment of lucerne with a mixture of formaldehyde (0.9% of the dry matter) and formic acid (0.5% of the fresh weight) was a suitable method of controlling the ensiling fermentation in order to increase the ad libitum intake of lucerne silage by sheep and their subsequent wool production. However, the intake and wool production of sheep offered such silage was still significantly less than that of sheep offered lucerne hay.