Role of dietary fibre source and meal size on the ileal transit of digesta in growing pigs

The rate of digesta passage can be an important factor affecting digestion and nutrient absorption. A slower passage rate may reduce feed intake probably due to distension of the gastrointestinal tract wall. Dietary fibre may also increase the contractile activity in the gut and accelerate digesta passage. Additionally, have also reported that digesta passage increases with the level of feed intake. It was hypothesized that dietary fibre and meal size may regulate motility and digestive transit time through the gastrointestinal tract. We studied the effect of diets containing either white rice or oats (as low and high fibre sources, respectively), offered at two levels of feeding (41.4 and 82.4 g feed/kg W^0.75•day), on the kinetics of the rate of passage of digesta through the gastrointestinal tract until the ileum (pGIT) in pigs. Eight 45-kg pigs fitted with a T-cannula at the terminal ileum were used following a double Latin square design. The rate of digesta passage, lag time (Tlag) and mean retention time (MRT) through the ileal cannula were measured for 36 h using titanium dioxide (TiO2) and Cr-mordanted fibre as indigestible markers for whole digesta and the fibrous phase of digesta, respectively.

The effects of cereal source and feeding level and their interaction on the pGIT digesta kinetics parameters were analyzed for each marker. As expected, TiO2 had a shorter MRT than Cr-mordanted fibre (7.0 h vs 10.4 h; P < 0.001), indicating that they followed different phases of digesta. Oats resulted in faster rate of digesta passage (P < 0.05) than rice for Cr-mordanted fibre, and in longer Tlag (P < 0.05) and MRT (P = 0.05) for TiO₂. No effect of feeding level or interaction between feeding level and cereal source were observed for any of the markers (P > 0.1).

It is concluded that cereal sources differing in dietary fibre content, independently of feeding levels tested, play an important role on the proximal gastrointestinal tract digesta kinetics in continuously fed pigs.

D Solà-Oriol, D Torrallardona and J Gasa, 2010. Livestock Science, 133: 67-69.