ASSESSMENT USING SHEEP OF THE NUTRITIVE-VALUE OF LIQUID POTATO FEED AND PARTIALLY FRIED POTATO-CHIPS (FRENCH FRIES)

Three experiments were carried out in which the nutritive value of co- products of the potato processing industry was assessed, In experiment 1, apparent digestibilities in sheep of organic matter were 0.78 and 0.81 for liquid potato feed (LPF) and partially fried potato chips (Fr ench fries), respectively, and for energy, 0.76 and 0.81, Digestible a nd metabolisable energy (MJ kg(-1) dry matter (DM)) values were 13.4 a nd 11.5 for LPF and 17.6 and 16.4 for chips. In experiment 2, the effe cts of LPF or chips (500 g kg(-1) diet DM) on rumen metabolism were me asured in sheep fed hay as forage in comparison with barley, Feeding L PF increased rumen ammonia concentrations, propionate molar proportion s and the extent of hay degradation in polyester bags compared with ba rley, whereas feeding chips reduced rumen ammonia concentrations, incr eased propionate molar proportions and decreased the extent but not ra te of hay degradation. In experiment 3, chips were fed to sheep with g rass silage at the maintenance level of feeding in four different rati os ranging from 150 to 600 g chip DM kg(-1) diet DM. Diet DM digestibi lity did not differ between treatments. As the proportion of chips fed increased, the numbers of protozoa in the rumen decreased and molar p roportions of butyrate increased. The extent of silage degradation in the rumen, measured using either the polyester bag or gas production t echnique, was depressed as the proportion of chip DM fed increased. Th e extent of depression was most marked when more than 300 g chip DM kg (-1) total diet DM was fed. In all experiments, both co-products were consumed readily.