EXPERIMENT WITH COWS ON SILAGE

Press, Volume CVIII, Issue 31588, 27 January 1968, Page 9

EXPERIMENT WITH COWS ON SILAGE

Feeding experiments at Ruakura agricultural research centre have demonstrated that, contrary to expectations, cows produce better on stack silage than on vacuum silage. This was reported to the agriculture, forestry and horticulture section of the congress of the Australian and New Zealand Association for the Advancement of Science this week by Mr R. J. Lancaster, of the Ruakura agricultural research centre.

“Considerable research has been directed toward controlling silage fermentation to produce a fodder of the desired characteristics,’’’' he said. “How \ desirable are these, characteristics to the ruminant? Some information on this question had been obtained in feeding-milking trials conducted at Ruakura. The trials were conducted in each of_two years on stack, vacuum and bunker type silages made out of dairy-type ryegrass-white clover herbage. “Three groups, each of 10 milking cows, were fed these silages to appetite as their sole diet over a period of nine weeks. The animals were grazed on spring pasture until one week after peak milk production, when they were changed during a further week from grass to silage. “The results of these trials may be summarised as follows: “(1) In both years about 10 per cent more dry matter was consumed from stack than from other treatments. “(2) In the first year differences in milk production were negligible, but in the second stack gave the highest, milk production. “(3) Stack consistently gave the highest butterfat per cent; vacuum the lowest. “(4) Butterfat production was highest from stack in both years.

“(5) Negligible differences in solids-not-fat production were recorded for each year. “This is a clear demonstration by the cow of the superiority of stack silages assessed as inferior by laboratory tests. This is the reverse of what we expected . . . But why should we have expected this? Are our views based on experimental evidence or is this another example of tradition governing our thinking? “The search of the enormous literature on silage feeding has revealed no good evidence on the effect of silage fermentation quality on animal production. This is surprising 'in view of the considerable interest in controlling the silage fermentation to produce certain qualities. “The data from the present feeding experiments indicate that the factor limiting production was feed intake. The limiting effect of silage intake is well known. In the search for appetite depressants in silage, numerous fermentation products have been shown to have some depressing effect, but no clear picture has yet emerged. “A hypothesis little examined so far is that appetite is reduced by the acid nature or by the buffer capacity of silage. Such a hypothesis would be in difficulties if the view was correct that the lower the silage pH the higher the intake, but would be supported by our observations.”