A novel procedure for estimating energy digestibility of feedstuffs fed to pigs

Abstract

The first objective was to develop a novel in vitro degradation procedure using the Daisy^II incubator to predict energy digestibility in different feedstuffs fed to pigs. The second objective was to develop equations to predict in vivo energy digestibility using the in vitro dry matter disappearance (IVDMD) determined using both the conventional and the newly developed procedures. The apparent total tract digestibility (ATTD) of energy in 11 feed ingredients including 3 cereal grains and 8 byproducts and a corn-soybean meal-based diet and 11 diets containing corn, soybean meal, and the 11 ingredients fed to growing pigs were determined in a previous study. First, the IVDMD in the feed ingredient and diet samples were determined using a conventional 3-step in vitro system (IVDMD_Flask). The novel procedure mostly followed those for the conventional in vitro procedure except that the incubation time of step 2 that simulates the digestion in the small intestine was longer (14 vs. 4 h) for the novel procedure (IVDMD_Daisy) compared with the conventional procedure and the novel procedure employed the Daisy^II incubator instead of flasks. Results indicated that the IVDMD_Flask provided a reasonable estimate: ATTD of energy = 1.22 + (0.930 × IVDMD_Flask) with r² = 0.96 and P < 0.001. The IVDMD_Daisy also resulted in a reliable estimate: ATTD of energy = 2.26 + (0.931 × IVDMD_Daisy) with r² = 0.88 and P < 0.001. In conclusion, both the conventional and the novel in vitro procedures can be used to predict energy digestibility of feed ingredients and diets fed to pigs. The Daisy^II incubator allows for the simultaneous measurement of the IVDMD of a large number (up to 36) of feed samples in a jar, which will reduce the needs for multiple flasks and the associated handlings required for the conventional in vitro procedure.