4.5. Food consumption, excretion, and assimilation efficiency

Birds fed natural food ate more than control birds during the feeding trial excluding the first week in work III (Table 5), but there was no difference between groups in work V (Fig. 1a). Tannin had no effect on the amount of food eaten (V, Fig. 1a).

In work III the diet groups differed in the amount of produced excreta during the feeding trial, although the results were not unambiguous (Table 5). The amount of food was calculated based on fresh weight, and MEC based on the dry weight of food. Based on the dry weight of the food, the test group consumed less food than the control group (III, Table 5), depending on the high water content of the shoots of barley (III, Table 1). The change in diet decreased the GE, ME and MEC, and increased the EE in the test group (III, Table 5).

The nitrogen content of intestinal excreta was higher in natural than in control or tannin groups, but in caecal excreta the control group showed the highest nitrogen content (V, Figs. 3a, 4a). The tannin content of both intestinal and caecal excreta was highest in the tannin group (V, Figs. 3b, 4b).