Vegetable protein (VP) diets, i.e. diets based entirely on plant material, are increasingly used by the poultry industry around the world for a variety of reasons, including cost, ingredient availability and growth of the organic product sector. However, VP diets are difficult to formulate because of potential nutrient imbalances, and VP sources can contain anti-nutritive factors, which necessitates processing and nutrient supplementation. In a series of research trials at the University of New England, the nutritive value of VP diets was assessed, in which soybean and canola meals partially or completely replaced fishmeal or meat meal. Diets containing soybean meal or canola meal as protein sources were slightly inferior to diets containing fishmeal but similar to diets containing meat meal. The digestibility of amino acids and minerals was greater for diets containing animal protein sources, but carcass fat content was also higher in birds fed diets containing fish meal. Leg bone development was superior in chicks on diets containing fish meal. The quality of the VP diets was improved through supplementation with carbohydrase and phytase. In feed selection tests, birds preferred diets containing canola meal to diets containing soybean meal, although productivity on the latter was superior. Birds also consumed more of the diet containing meat meal than the VP diets.

The aim of the present study was to determine the gastro-ileal behaviour of pea protein in humans. For this purpose, twelve healthy volunteers were intubated with an intestinal tube located either in the jejunum (n 5) or in the ileum (n 7). After fasting overnight, they ingested 195 mmol N of [15N]pea. Intestinal samples were collected for 6 h in the jejunum and for 8 h in the ileum. Before meal ingestion the basal liquid flow rate (ml/min) was 2·01 (SD 0·31) in the jejunum and 2·02 (SD 0·33) in the ileum. After meal ingestion the liquid phase of the meal peaked in the 40–60 min period in the jejunum and in the 150–180 min period in the ileum. The jejmo-ileal transit time of the liquid phase of the meal was 102 min. The basal flow rate of endogenous N (mmol N/min) was 0·22 (SD 0·15) in the jejunum and 016 (SD 0·10) in the ileum. The endogenous N flow rate peaked significantly ( P < 0·05) in the jejunum in the 40–60 min period whereas no stimulation of endogenous N could be detected in the ileum after meal ingestion. A significantly increased (P < 0·05) concentration of exogenous N was detected in the jejunum during the 20–3u)lnin period and during the 9–480 min period in the iteum. The overall true gastro-ileal absorption of pea N was 894 (SD 1·1)% with 69 (SD 14)% absorbed between the stomach and the proximal jejunum and 20·4% between the proximal jejunum and the terminal ileum. The percentage of ethanol-insoluble fraction (PN) in the exogenous N at the terminal ileum increased significantly ( P < 0·05) to 75% after 360 min. These results suggest that heat-treated pea protein has a digestibility close to that of animal protein