The use of tannins as silage additives: effects on silage composition and mobile bag disappearance of dry matter and protein

The effects on silage composition of ensiling perennial ryegrass (PRG) with three commercial tannins (mimosa, myrabolam and quebracho tannins) were as sessed (Experiment 1), The effects on silage composition and mobile bag dis appearance of DM, nitrogen and true protein of the addition of these tannin s or a combination of tannin plus formic acid, formaldehyde alone, formic a cid alone, or a combination of formaldehyde and formic acid (Experiment 2) were also studied. In Experiment I, the PRG was a third cut with a mean ove n-dry DM content of 200 g/kg. All silages were prepared on a small laborato ry scale (500 g), with the additives added in 20 mi aliquots/kg herbage fre sh weight. The tannins were added at the rate of 5 or 50 g/kg herbage DM an d in Experiment 1, samples were examined after 7 or 32 days of ensiling, In Experiment 2, a Ist cut PRG with a mean oven-dry Did content of 188 g/kg w as used and the samples were taken on days 7, 14 and 49. In Experiment 1, t reatment with tannins reduced the soluble nitrogen (SN) and ammonia content of the silages. In Experiment 2, the tannins used also reduced silage SN d uring ensiling, and were able to reduce degradation of silage nitrogen and true proteins in the numen. Of the tannins used, quebracho tannin was also able to reduce SN and rumen degradation better than mimosa tannin, However, the tannins were not as good as formaldehyde at protecting silage proteins both during ensiling and in the rumen. neither were they better than formi c acid in enhancing silage quality. For both the tannins and formaldehyde, formic acid addition further reduced the SN content as a result of the comb ined effect of rapid acidification and protein binding. (C) 1999 Elsevier S cience B.V. All rights reserved.