Chromic oxide and acid‐insoluble ash as markers in digestibility studies with growing pigs and sows

Summary The results of three experiments, focused on the determination of endogenous ileal flow ( EIF ) of amino acids ( AA ) and nitrogen (N) (Exp. 1), apparent ileal digestibility ( AID ) of AA and N (Exp. 2), and apparent total tract digestibility ( ATTD ) of dry matter ( DM ), organic matter ( OM ), N, calcium (Ca) and phosphorus (P) (Exps. 2 and 3), were used to compare chromic oxide (Cr 2 O 3 ) and acid‐insoluble ash ( AIA ) as digestibility markers. In Exps. 1 and 2, a total of six gilts fitted with T‐cannula in terminal ileum, and in Exp. 3, a total of 24 pregnant sows were used. In Exps. 1 and 2, the pigs were assigned into four dietary treatments according to 4 × 6 crossover design (Exp. 1; diets with 0%, 4%, 8% and 12% of casein; Exp. 2 basal diet with different levels of phytase). In Exp. 3, the sows were assigned to four dietary treatments (basal diet with different levels of phytase) of six sows. In Exps. 1 and 2 ileal digesta and in Exps. 2 and 3 faeces were collected for the determination of EIF , AID and ATTD . Differences in EIF of AA determined by Cr 2 O 3 and AIA ranged (p ˃ 0.05) from −4.62 to 4.54%. The lowest EIF was for methionine and the greatest one for proline, determined by both markers. Apparent ileal digestibility determined by Cr 2 O 3 was slightly greater (p ˃ 0.05) in comparison with AIA . Differences ranged from 1.88% (Arg) to 7.08% (Gly). The greatest AID was for arginine and the lowest one for glycine, determined by both Cr 2 O 3 and AIA . Similarly for ATTD of DM , OM , N, Ca and P, there were no differences in digestibility determined by Cr 2 O 3 and AIA . Both, Cr 2 O 3 and AIA , are suitable and comparable markers for digestibility studies in pigs.