Effects of variety, the 1B/1R translocation and xylanase supplementation on nutritive value of wheat for broilers.

1. Three consecutive studies were done with 12 wheat samples (4 per study), each of different variety (6 containing the 1B/1R rye translocation) to examine the effects of wheat variety, presence of 1B/1R and interactions with xylanase addition (Avizyme 1310). The wheat varieties covered a wide range of in vitro viscosity (6.3 to 19.8 cps). In each study 64 male, Ross broilers were individually caged and given the diets ad libitum from d 7 to 28. Bird performance, viscosity of ileal contents and diet metabolisability (AME) were measured. 2. The diets contained (g/kg): wheat 790, casein 134, dicalcium phosphate 21.4, potassium bicarbonate 10.8, sodium bicarbonate 7.5, soya oil 10, arginine 5, minerals etc. 21.3. 3. Within each study there were large differences in dry matter (DM) intake between varieties but the variety effect was significant (P<0.01) only in study 2. Liveweight gain (LWG) differences mirrored DM intake, being significant (P<0.01) in study 2. Mean gain:food was unaffected by variety in any study. 4. Calculated wheat AME (MJ/kg DM) ranged from 13.4 to 14.4 in study 2 (P<0.05), the values for studies 1 and 3 lying within this range. 5. Across all 3 studies, in vivo viscosity (proximal ileum) ranged from 5.0 to 37.6 in the absence of enzyme and from 3.9 to 12.1 with enzyme addition; in studies 1 and 2 variety differences were significant (P<0.05). 6. Enzyme addition had no effect on DM intake or LWG but gain:food tended to be improved (NS), metabolisability of energy (ME:GE) was increased (P<0.01) by 2.2% and calculated wheat AME by 4% while in vivo viscosity was reduced (P<0.001). 7. There were no significant differences in DM intake, LWG, gain:food, ME:GE or calculated wheat AME concentration associated with the presence of the 1B/1R translocation and no interactions between enzyme and 1B/1R. 8. There were poor relationships between either gain:food or wheat AME concentration and in vitro or in vivo viscosity. There was no significant relationship between AME concentration and either specific weight or thousand grain weight. 9. It was concluded that (a) variety differences tended to be small (b) there was no negative impact of the 1B/1R rye translocation with the diet formulation used (c) in vitro viscosity failed to predict satisfactorily any aspect of performance with the high wheat/low fat diet formulation used.