Whenever, in any action brought upon a bond given in accordance with the provisions of section 52-308, the defendant sets up in his answer, or claims, that the interest of the principal in the bond in the property attached in the action in which the bond was given was, at the time of the giving of the bond, of less value than the amount ordered by the process in the action to be attached, the burden of proving the actual value of the interest shall be upon the defendant.