Comparative studies for the determination of precaecal digestibility as a measure for the availability of B-vitamins

The aim of the present investigations was to examine the suitability of two kinds of surgical procedures of ileorectal anastomosis (IRA) for the quant itative determination of the availability of naturally occuring B-vitamins for humans and monogastric animals. For this purpose nine female growing pi gs of the German Landrace breed were fitted with ileorectal-anastomosis in end-to-end (six pigs) and end-to-side performance (three pigs) with preserv ed ileo-caeco-colic valve (EEV or ESV) to determine precaecal digestibility as a measure for availability. Metabolic trials were carried out using the operated animals and the precaecal digestibility of thiamin, riboflavin an d vitamin B6 from wheat, whole-grain bread, boiled potatoes, roast pork and roast beef was measured. In all cases the EEV-procedure resulted in significantly higher digestibili ties. This means that in the ESV-technique a certain reflux of digesta occu rs in the bypassed colon and microbially synthesized B-vitamins are excrete d together with the ileal chyme. Therefore EEV-technique has to be taken fo r measuring precaecal digestibility of B-vitamins. The comparison of determ ining digestibility of B-vitamins of wheat in two different periods post su rgery (4th-9th versus 12th-17th week) gives no age effects, so that this wh ole experimental period can be used. In EEV-animals the precaecal digestibility of thiamin was 87% in wheat, 75% in whole-grain bread, 84% in boiled potatoes, 96% in roasted pork and 79% in roasted beef. The values for riboflavin amounted to 71% in pork and 63% in beet: The precaecal digestibility of vitamin B-6 was determined at 69% i n wheat, 71% in whole-grain bread, 87% in boiled potatoes and 89% in roaste d pork and roasted beef.