Ms Eimear Mulhern, daughter of former Taoiseach Mr Charles Haughey, said she had no direct involvement in the sale of a foal to Mr Mahmoud Fustok in 1985.
The tribunal is investigating the receipt of £50,000 by Mr Haughey in 1985 which he has said was for the sale of a foal or yearling by Abbeville Stud.
Ms Mulhern, who has run Abbeville Stud since 1979, said that although she was aware of the sale at the time, she had no direct involvement and never knew the price paid. The money was not passed on to her or the stud farm business by her father.
Responding to Mr John Coughlan SC, for the tribunal, Ms Mulhern said the financial and breeding records from the period were no longer available. She said the stud farm moved to Meadow Court, in the Curragh, Co Kildare, in 1989, the year after her marriage.
Ms Mulhern said she first met Mr Mahmoud Fustok when he was introduced to her at a bloodstock sales by Dr John O'Connell. She said she met him subsequently on a number of occasions, including a bloodstock sales in Lexington, Kentucky, in the United States.
She had no knowledge of how the foal or yearling bought by Mr Fustok was selected and had no memory of its being removed from the stud farm. She knew nothing about any cheque issued to pay it. The animals were not given names as the purchaser usually wanted to name the horse.
Ms Mulhern said she was aware her father tried to convince Mr Fustok to set some of his bloodstock operation in the State and that Mr Fustok subsequently made the purchase from the stud "as a gesture of good faith".
Ms Mulhern said the books for the stud farm would have recorded the nominated fee for the pregnancy which led to the foal. She had been advised by the farm's accountants, Deloitte & Touche, that it was possible to properly record in the accounts the fact that no profit or income had been produced from the foal.
She said that given the fact the stud farm operated from property owned by her father in those years and that he paid ESB and water rates bills, she felt he had a right to sell one of the farm's foals in this way.
Mr Coughlan asked if Mr Haughey "was the real boss", to which Ms Mulhern responded that he was her father.
