
mammary growth in rats treated with somatotropin during
pregnancy and/or lactation
groups of rats received daily
injections of 2 mg somatotropin (sth) from
either day 3-19 of pregnancy or day 1-13
of lactation.  another group of rats received
graded increments (0.5-3.0 mg) of sth
every 6 days during both pregnancy and
lactation.  other groups of rats served as
pregnancy and lactation controls.  mammary
gland deoxyribonucleic acid (dna) content
was determined in all rats and milk yield
was determined in all rats carried to day
14 postpartum.  significant increases in mam-
mary dna occurred in all rats treated with
sth irrespective of dose or schedule of in-
jections when compared to gestation controls.
a significant elevation in mammary dna
above the lactation control level was also
evident in rats receiving the hormone and
carried to day 14 of lactation.  milk yield
of rats treated with graded increments of
sth was significantly greater than that of
control lactators but milk yield of rats re-
ceiving a constant daily dose of the hormone
did not differ from that of controls.
