Variability in the nutritive value of wheat is established particularly with young poultry and pigs. However, underlying causes have yet to be established unequivocally. Numerous reports attempting to relate variability to varieties have not proved convincing due to interactions with environmental factors. Furthermore reliance on name alone is not appropriate in attempting to differentiate between varieties as it would give no indication of genetic relationships. One promising approach, is the use of near-isogenic lines, which differ in only one key characteristic whose nutritional significance can thus be examined. This was the basis for establishing the negative effects of the IBIR rye translocation and hard endosperm texture, together with interactions, with poultry (Short et al., 2000). Crucially it was confirmed that investigating the IBIR translocation should not proceed without knowledge of endosperm texture, a requirement overlooked by Lewis et al. (1999). The current programme sought to examine the IBIR translocation and endosperm texture in terms of performance of piglets from 15kg fed diets based on identical formulations but containing wheats of known background; presence of xylanase was the second variable.