The apparent ileal digestibility and the apparent total tract digestibility by growing pigs of energy and carbohydrates in hybrid rye, wheat, barley, corn, and sorghum are different

An experiment was conducted to determine the apparent ileal digestibility (AID) and the apparent total tract digestibility (ATTD) of energy, starch, and total dietary fiber (TDF) in 2 varieties of hybrid rye and compare these values with values obtained for barley, wheat, corn, and sorghum. It was hypothesized that there are no differences in AID and ATTD of energy and nutrients among hybrid rye, barley, wheat, and sorghum. Twenty-four ileal cannulated barrows (initial body weight = 28.1 ± 3.0 kg) were randomly allotted to a 2-period experimental design with 6 diets and 4 replicate pigs in each period for a total of 8 replicate pigs per diet. Diets consisted of 97% of each grain, and each pig received a different diet in each period. The initial 5 d of each period were considered adaptation, whereas urine and fecal materials were collected from the feed provided from d 6 to 10, and ileal digesta were collected on d 12 and 13 of each period. Results indicated that the metabolizable energy on a dry matter (DM) basis was greater (P < 0.05) in corn and wheat (3,732 and 3,641 kcal/kg DM), and least (P < 0.05) in barley (3,342 kcal/kg DM), whereas the 2 hybrid ryes contained 3,499 and 3,459 kcal/kg DM, respectively. The metabolizable energy values in hybrid rye were not different from values determined for barley and sorghum (3,573 kcal/kg DM). In all grains, the AID of starch was greater than 90%, and the ATTD of starch was nearly 100%. Barley contained more TDF than the other cereal grains, and the 2 hybrid ryes had concentrations of soluble dietary fiber that were close to the concentration in barley, but greater than in wheat, corn, and sorghum. The AID of TDF was less than 35% for all cereal grains, but the ATTD of TDF was greater (P < 0.05) in the 2 hybrid ryes (68 and 70%) than in the other ingredients (56 to 58%). In conclusion, feeding hybrid rye to pigs resulted in reduced pre-cecal absorption of energy compared with wheat, corn, and sorghum, but because hindgut fermentation of fiber was greater in hybrid rye than in other cereal grains, the content of metabolizable energy in hybrid rye was not different from barley and sorghum, but less than in corn and wheat.

Keywords: cereal grains; energy digestibility; fiber; hybrid rye; pigs; starch.