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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 (French fries), respectively, and for energy, 0.76 and 0.81. Digestible and metabolisable energy (MJ kg −1 dry matter (DM)) values were 13.4 and 11.5 for LPF and 17.6 and 16.4 for chips. In experiment 2, the effects of LPF or chips (500 g kg −1 diet DM) on rumen metabolism were measured in sheep fed hay as forage in comparison with barley. Feeding LPF increased rumen ammonia concentrations, propionate molar proportions and the extent of hay degradation in polyester bags compared with barley, whereas feeding chips reduced rumen ammonia concentrations, increased propionate molar proportions and decreased the extent but not rate of hay degradation. In experiment 3, chips were fed to sheep with grass silage at the maintenance level of feeding in four different ratios ranging from 150 to 600 g chip DM kg −1 diet DM. Diet DM digestibility did not differ between treatments. As the proportion of chips fed increased, the numbers of protozoa in the rumen decreased and molar proportions of butyrate increased. The extent of silage degradation in the rumen, measured using either the polyester bag or gas production technique, was depressed as the proportion of chip DM fed increased. The 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. |
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