THE EFFECT OF 2 HEAT-TREATMENTS (STEAM FLAKING AND EXTRUSION) ON THE DIGESTION OF PISUM-SATIVUM IN THE STOMACHS OF HEIFERS

Six Friesian heifers weighing 546 kg body weight and fitted with permanent ruminal and duodenal cannulae were used in a cross-over design to study the effect of steam flaking and extrusion of peas (Pisum sativum) on ruminal fermentation, and starch, nitrogen and amino acid flow to the duodenum. Ground (GP), steam-flaked (SFP) and extruded peas (EXP) were fed in diets composed of 39% peas, 32% dried sugar beet pulp and 25% wheat straw supplemented with vitamins and minerals. Chromic oxide, polyethylene glycol and diaminopimelic acid were used as particulate, liquid and bacterial markers, respectively. Steam flaking did not significantly affect any of the parameters studied in vivo. Extrusion of pea decreased N solubility and gelatinized starch without a negative effect on N pepsin solubility and lysine bioavailability. The total volatile fatty acid concentration was higher for EXP than for GP (98.5 and 87.3 mM l-1; P<0.05) and ruminal ammonia was lower (9.8 vs. 15.5 mg per 100 ml; P<0.001). The duodenal flow of starch was not significantly affected by processing. Extrusion was associated with higher feed N (81 vs. 68 g day-1; P>0.05), bacterial N (104 vs. 68 g day-1; P<0.01), non-ammonia N (185 vs. 136 g day-1; P<0.001) and flow of all amino acids to the duodenum (P<0.01). © 1990.