Lucerne can be used for flushing

Press, 27 February 1981, Page 15

Lucerne can be used for flushing

It has become pretty much accepted by farmers that it. is dangerous to flush ewes on lucerne prior to mating because of the depressing effect that this may have on the subsequent lambing percentage.

However, it seems that to attribute this undesirable effect to all lucerne is unfair. Dr M. W. Dunbier and Dr R. B. Wynn-Williams, scientists at ’the Crop Research Division of the Department of Scientific and Industrial Research at Lincoln, said this week that it was incorrect to say that in all situations it was dangerous to flush ewes on lucerne.

In a dry season like this one it can be perfectly satisfactory to flush ewes on young, fresh lucerne regrowth if another alternative feed like grass is not available.

It will certainly be a lot better than not flushing them at all. It seems that the young, fresh regrowth almost invariably contains none of the oestrogenic compounds that have a harmful effect on the fertility of the ewe.

The higher levels of these compounds are associated with lucerne infected with leaf-spotting fungi and aphids and these conditions

are favoured by wet weather. high humidity, heavy dews and use of spray irrigation. But because of the dry conditions this season lucerne is generally free of disease and lucerne that has been only been cutor grazed about four weeks previously is likely to be doubly safe for as it gets older and more mature the lower leaves at least become diseased. This season Dr Dunbier and Dr Wynn-Williams said that farmers could be in three positions and in two of these the answers were quite clear. Where a farmer had other alternative feed for flushing as well as healthy or diseased lucerne he should use the alternative to lucerne for flushing.

In the second case like many fanners this season he could have little or no grass but it was on the cards he had relatively disease-free lucerne and in that case it would be desirable to flush on lucerne rather than not flush at all.

Work at the Ruakura agricultural research centre had shown that where the same liveweight gain was made on healthy lucerne. — free of spotting by fungi and in the absence of aphids —- as on grass, the lambing perform-

ance was comparable with that obtained on grass. However, no clear answer or advice could be given if the farmer had only diseased lucerne — it was not known then whether the effect of flushing on diseased lucerne would be more harmful than not flushing at all and lifting liveweight. ■ , ‘ -

Ideally the scientists say that where flushing feed is expected to be short and the farmer.; has a considerable area of lucerne, then around the end of January he could consider cleaning up areas of his lucerne in sequence, either by cutting or heavy grazing, so that he will have a reserve of lucerne regrowth ahead of his ewes in the vital flushing and mating period. Fortunately .under extremely dry conditions when lucerne is most needed in the late summer or autumn it is most likely to be safe to feed, and conversely it is most likely to be oestrogenic in a wet autumn when alternative feed should be readily available.

Fungicides may be used to control the leaf spotting organisms in lucerne and to keep levels of oestrogenic compounds down, but it is not thought that this is an economic or practicable proposition.