SECTION 1. Paragraph one hundred and sixty-nine of the Act of Congress entitled "An Act to raise revenue for the Philippine Islands and for other purposes," approved August fifth, nineteen hundred and nine, is hereby amended to read as follows:
"169. Bovine animals;
"(a) Bulls, cows, oxen, each, three dollars. On and after the first day of January, nineteen hundred and thirty-one, each head, four dollars; on and after the first day of January, nineteen hundred and thirty-three, each head, five dollars; on and after the first day of January, nineteen hundred and thirty-five, each head, six dollars; and on and after the first day of January, nineteen hundred and thirty-seven, the duty herein imposed shall be seven dollars per head.
"(b) Suckling calves, each, two dollars."