Effects of feeding raw or extruded linseed on the ruminal ecosystem of sheep

Polyunsaturated fatty acids affect bacterial and protozoal population, inducing important modifications in rumen metabolism. The aim of this study was to investigate the effect of linseed extrusion on in situ ruminal degradability and microbial number and distribution. Six ruminally fistulated sheep were divided in 3 groups and fed one of the following diets according to a replicated Latin square design: (a) control, based on mixed hay and maize grains; (b) as in (a) plus 130 g of grounded raw linseed; (c) as in (b) except that the linseed was extruded. Extrusion decreased linseed dry matter and fat degradabilities. There was a marked reduction of total protozoal population in sheep fed supplemented diets. No effects were observed between groups on bacterial concentration, hay dry matter and NDF in situ degradabilities.