Summary. Ewes were each mated on four separate occasions, at 3, 9, 15 and 21 h after the start of oestrus and at each time by a different ram. The progeny were assigned to sires by blood typing, supplemented by resemblance between lambs and rams. The paternity of 64 lambs, born to 41 ewes, was established: 2 were conceived at a 3-h mating, 27 at 9 h, 23 at 15 h and 12 at 21 h. The optimum time for a ram to inseminate, when in competition with others, is therefore 9\p=n-\15h after onset of oestrus, and this finding accords with behavioural observations. Ewes tended to lamb during the same half of the day as that when they had come into oestrus.
Carrying out a campaign promise to eliminate burdensome and unnecessary government regulations, President Reagan recently signed Executive Order 12,291 into law.I The Order aims to improve the efficiency and accountability of the informal rulemaking processes of executive agencies. The heart of the Order is its requirement that "major'' 2 rules survive cost-benefit analysis. Section 2, which applies to the extent permitted by law, stipulates that regulatory action may not be undertaken unless, "taking into account affected industries [and] the condition of the national economy," the potential benefits to society outweigh potential costs, and net benefits are at a maximum. 3
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