Dark And Yellow Rapeseed Hulls, Soybean Hulls And A Purified Fiber Source: Their Effects On Dry Matter, Energy, Protein And Amino Acid Digestibilities In Cannulated Pigs

Abstract

Hulls from Tower rapeseed (dark colored cultivar), R500 rapeseed (yellow colored cultivar) and soybean were included in semipurified diets for growing pigs at 10%, to investigate the effects of these fiber sources on dry matter, energy and protein digestibilities. Celufil, a purified fiber source, was also included in another diet at a 10% level for comparison. Casein, which was the main protein source, was added at a 15% level in all the diets. Four 40-kg barrows fitted with cannulas at the terminal ileum were used in a digestibility trial with a 4 • 4 Latin square design. The digestibilities of dry matter, protein and amino acids were measured to the ends of both the small and large intestines, while the digestibility of energy was measured only over the entire gastrointestinal tract. The true protein digestibility was also determined at the ileal and fecal levels. The Celufil diet had a higher cellulose content (8.7%) than the other diets (2.8 to 5%). The Tower rapeseed hull diet contained the highest lignin percentage (2.9), while the Celufil diet had the lowest value (.06). The dry matter and energy digestibility values were lowest with the Celufil diet. Highly significant negative correlations between the digestible energy and the dietary crude fiber, neutral detergent fiber, acid detergent fiber and cellulose were respectively shown. Protein and majority of amino acid digestibility values were higher (P<.05) with the Celufil diet than with the hull diets. The dark rapeseed hull diet had the lowest protein digestibility value at the terminal ileum. However, there were no differences (P>.05) in protein digestibility values for the hull diets measured over the total digestive tract. The digestibility values of dry matter, protein and amino acids were lower at the terminal ileum than at the fecal level. The results suggest that cellulose can be included in swine diets up to 9% without a deleterious effect on protein and amino acid digestibilities, although this level will lower dry matter and energy digestibility values. The lignin content of the diets and possibly other undetermined factors appear to have some adverse effects on protein and amino acid digestibilities. (Key Words: Rapeseed Hull, Dietary Fiber, Energy, Protein, Amino Acids, Cannulated Pigs.)