4In section 1(2) of the [1967 c. 24.] Slaughter of Poultry Act 1967, for the words "the Slaughter of Animals Act 1958" there shall be substituted the words " the Slaughterhouses Act 1974 " , and in section 1(4) of that Act for the word " 1958 " there shall be substituted the word " 1974 ".