Alzao, who reached the 100 mark by number of stakes winners last year, has been pensioned from stallion duty at Coolmore Stud in Ireland because of the infirmities of old age, according to the Racing Post.A 26-year-old Northern Dancer grandson, Alzao registered his 100th stakes winner at Keeneland in the spring when the English filly Angara won the Bewitch Stakes (gr. IIIT). Angara later won the Beverly D. Stakes (gr. IT) at Arlington Park.Alzao (Lyphard--Lady Rebecca, by Sir Ivor) sired such other top runners as Alborado, Alcando, Albanova, Alpride, Shahtoush, Winona, Matiya, Pass the Peace, and Alcazar, who won last year's Prix Royal-Oak (Fr-I).Alzao, whose stakes-winning total has remained at 100, stood at Liam Cashman's Rathbarry Stud in Ireland before heading to Coolmore. He also shuttled to Australia. Alzao will reside at Coolmore satellite Castlehyde Stud in Ireland.