The technical problems posed by beef-production are linked to the production and growth of young animals and to social restrictions in animal production. In order to increase the productivity of a meat-herd, a certain number of possibilities are provided by zoo- technical research : — The control of the sexual cycles by the blocking of certain functions of the hypophysis : 25 days after treatment, 80 to 85 per cent of the cows treated can be pregnant ; — increase in the fertility of the herd by selection; — increase in the fertility by provoked superovulation : 25 per cent of twinbirths have thus been obtained amongst French Friesan «r Pie Noire » cows ; — control of parturition ; — control of thé social structure of groups of cattle
