to conduct, assist, and foster research, investigation, and experimentation to develop and determine methods of slaughter and the handling of livestock in connection with slaughter which are practicable with reference to the speed and scope of slaughtering operations and humane with reference to other existing methods and then current scientific knowledge; and

on or before March 1, 1959, and at such times thereafter as he deems advisable, to designate methods of slaughter and of handling in connection with slaughter which, with respect to each species of livestock, conform to the policy stated in this chapter. If he deems it more effective, the Secretary may make any such designation by designating methods which are not in conformity with such policy. Designations by the Secretary subsequent to March 1, 1959, shall become effective 180 days after their publication in the Federal Register.