News last update:6 Aug 2012

Course ground lupin seeds digest better

Researchers at the Walloon Agriculture Research Centre in Gembloux, Belgium have conducted an experiment with cannuled Belgian Blue bulls to evaluate processing effects on the digestibility of lupin seeds.

All trial diets contained 320g/kg of lupin seed (Lupinus albus, var. Lublanc) on a dry matter (DM) basis.

Four grinding treatments of raw lupines (RAW) were used to obtain median particle sizes of approximately 0.5, 2.0, 4.2 or 6.0 mm.

One extrusion treatment (EXTR) was also used and consisted of heating to 180°C for 30 seconds.

When inserted into the cannules it showed that pH and ammonia nitrogen (NH3–N) concentration kinetics in the rumen liquid differed between RAW and EXTR, the latter induced larger variation in these parameters after the meal.

Clear effect of grinding
Clear effects of the grinding level on rumen fermentation parameters were observed at several sampling times for RAW.

The grinding level had also clear effects on the intestinal digestibility of DM, organic matter (OM) and N, reaching a maximum with treatment 4.2 mm.

Max 4.2 mm particles
The final outcome of the trial suggests that lupin seed should be coarsely ground or flattened to obtain a mean particle size between 2.0 and 4.2 mm for cattle feed, but that an insufficient grinding level (6.0 mm) induced a higher degradability of lupin protein, probably due to more intense rumination.

Under the experimental conditions, extrusion did not sufficiently improve the nutritional value of the seed to be economically viable.

These results show that feeding standards should consider the influence of the grinding level of legume seeds in order to assess their nutritional value accurately.

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