COMPLETE MASS CORRECTIONS OF ORDER ALPHA(S)(2)M(B)(2) M(Z)(2) TO THE AXIAL Z-BOSON DECAY-RATE IN THE LARGE TOP-MASS LIMIT/

We analytically compute the QCD mass corrections of order alpha(s)2m(b )2/M(Z)2 to the decay rate of the Z-boson coming from anomalous ''doub le triangle'' diagrams which comprise single gamma5 matrices inside bo th of two closed fermion triangles. Coupled with our previous results, the present calculation determines the complete next to leading alpha (s)2 corrections to the leading power suppressed term of order m(b)2/M (Z)2 in the axial part of the decay rate of the Z-boson. Numerically, the anomalous diagrams lead to a further decrease of the (already quit e small) corrections.