Evaluation of a dynamic in vitro model to simulate the porcine ileal digestion of diets differing in carbohydrate composition

¹ Equipe de Recherche Technologique Conception, Ingénierie et Développement ddicament, Centre de Recherche en Nutrition Humaine, Faculté de Pharmacie, Université d'Auvergne, 28 place H. Dunant, 63001 Clermont-Ferrand, France
² Animal Nutrition, Management and Welfare Research Group, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
³ Departament de Medicina i Cirurgia Animal, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

^* To whom correspondence should be addressed. E-mail: j-philippe.meunier{at}u-clermont1.fr.

	Abstract

The aim of the study was to assess the ability of a dynamic in vitro model to determine the digestibility of OM, CP, and starch as compared to a validated static in vitro method and in vivo ileal digestibility obtained from growing pigs fitted with a T-cannula. Five experimental diets with different carbohydrate types and level were assessed: a standard corn-based diet (ST) or the same diet with coarse ground corn (CC), 8% sugar-beet pulp (BP), 10% wheat bran (WB), or 8% sugar beet pulp and 10% wheat bran (HF). In the in vivo experiment, diets CC and HF reduced (P = 0.015) ileum digestibility of OM when compared to ST diet. The inclusion of sugar-beet pulp reduced (P = 0.049) ileal CP digestibility in the BP diet. This reduction was not statistically significant when sugar beet pulp was combined with the wheat bran in the HF diet. No differences were shown for in vivo starch digestibility among diets. With the static in vitro method, the OM disappearance was greater than the in vivo experiment. In this static method, the BP and HF diets reduced (P = 0.004 and < 0.001, respectively) the disappearance of the OM comparing with the ST diet. The coarse grinding of corn did not alter OM digestibility but decreased (P = 0.005) the starch digestibility. The R² between the in vivo results and static in vitro methods for OM and starch digestibility was 0.99 when CC diet was not considered. The dynamic in vitro model yielded OM and CP digestibility coefficients comparable to those obtained in vivo for the ST and CC diets. However, values were considerably affected by the incorporation of the fibrous ingredients. Diets BP, WB, and HF had decreased (P = 0.009, 0.058, and 0.004, respectively) OM digestibility compared with ST diet. Protein digestibility was also decreased (P < 0.001, P = 0.019 and 0.003, respectively) with the BP, WB, and HF diets than with the ST diet. However, digestibility was decreased to a greater extent in the BP diet than in the WB and HF diets, both containing wheat bran. The R² between the dynamic model and in vivo results for CP digestibility was 0.99 when CC diet was not considered. No differences were detected in starch digestibility among the diets with the dynamic in vitro model. This dynamic in vitro model yielded the ileal digestibility results comparable to those obtained in vivo for CP and OM with a corn-soybean diet, or a diet including coarse corn, but it underestimated digestibility when fibrous ingredients were included in the diet.

Key Words: carbohydrate, digestibility, in vitro model, pig, sugar beet pulp, wheat bran