[The effect of testosterone administered in the neonatal period on the growth of piglets].

The body weight, metabolic parameters and adrenocortical activity were followed in 38 piglets administered intramuscularly testosterone propionate at the dose of 4 mg . kg-1 one day after birth. In the treated gilts the body weight gains were increasing from the very beginning and at the age of 42 days their weight was on the average by 590 g higher than that of the control animals from the same litter. No differences in the concentration of the total protein, glucose, nonesterified fatty acids and blood serum cholesterol were observed during 14 days after weaning. Just a lower increase in the urea level than in the control animals suggests a possibility of the positive impact on protein metabolism. The differences in parameters of adrenocortical activity were neither significant nor explicit. In piglets of both sexes with the birth weight under 1 kg the neonatal testosterone application did not affect the number of the reared animals, however, it increased the growth rate. At the age of 42 days the treated piglets weighed 8.48 +/- 1.96 kg, on the average by 790 g more than the control animals. A discussion is presented on the importance of testosterone for the development of piglets and on the potential mechanisms of the neonatal androgenization in comparison with the findings known from the masculinization of the neural development of female rats. The administration of testosterone to new-born piglets with the weight below the average should be verified as a biotechnical method enabling a more successful rearing.