[Use of mestranol as an anabolic substance in fattening bulls].

In 5 experiments 137 fattening bulls received between 0 and 20 mg Mestranol per animal and day. In one experiment a dose of 10 mg/day reduced consumption. The cause of this effect could not be found. In three experiments Mestranol increased weight gain by 4-13%. Feed expenditure was significantly decreased in only one experiment, in which 5-10 mg were given (average of all experiments: 4%). In dependence on the amount of Mestranol the weight of skin, horn and testicles decreased, when only 5-10 mg were given, however, protein retention increased whereas fat retention decreased. When 20 mg Mestranol are given per animal and day, the anabolic effect is missing although the NEFcattle-expenditure per kJ retention including maintenance decreases. This is due to a higher fat retention, which is causally inexplicable. The ergotropic effect of Mestranol depends on its dosage and possibly the nutrients in the ration.