THE ADDITIVITY OF THE DIGESTIBLE ENERGY AND APPARENT ILEAL DIGESTIBLEAMINO-ACID SUPPLY IN BARLEY, WHEAT AND CANOLA-MEAL OR SOYBEAN-MEAL DIETS FOR GROWING PIGS

Six barrows, average initial body weight 35 kg, were fed six diets acc ording to a 6 x 6 Latin square design. Diets 1 and 2 contained 94% bar ley and wheat, respectively. Diets 3 and 4 were com starch-based and f ormulated to contain 17% crude protein from canola meal and soybean me al, respectively. Diets 5 and 6 were formulated to contain 17% crude p rotein from mixtures of barley-wheat-canola meal and barley-wheat-soyb ean meal, respectively. The pigs were fed twice daily, at 68.00 and 20 .00 h, 900 g each meal. Each experimental period lasted 9 days. Feces were collected for 48 h from 08.00 on day 6 to 08.00 h on day 8. Ileal digesta were collected for a total of 24 h during the time period fro m 08.00 on day 7 to 08.00 h on day 9. Chromic oxide was used as digest ibility marker. The directly determined digestible energy content and apparent ileal amino acid digestilities in diets 5 and 6 were compared with those calculated based on the determinations in the single ingre dients (diets 1, 2, 3, and 4). With the exception of glycine (in the m ixture of barley-wheat-soybean meal), there were no differences (p > 0 .05) between the directly determined and calculated apparent ileal ami no acid digestibilities in the diet mixtures as was the case for the d igestible energy content. These results show that the digestible amino acid and energy supply can be predicted from amino acid and energy di gestibilities determined in single ingredients.