A two-generation reproduction study to assess the effects of cows' milk on reproductive development in male and female rats.
OBJECTIVE
To examine whether the considerable quantities of increased female sex hormone levels found in modern milk as a result of modern dairy farming practices are safe for human consumption.


METHODS
Males and females of the P generation were maintained on a diet containing milk for 10 weeks before mating. Exposure to milk was continued up to the end of weaning of the F2b offspring.


METHODS
Two-generation reproduction study.


METHODS
Male and female Wistar Galas rats.


METHODS
P- and F1-generation rats were mated.


METHODS
Fertility, fecundity, and morphology and function of reproductive organs.


RESULTS
Although milk had growth-promoting effects in both parents and offspring, it caused no impairments in fertility, fecundity, or reproductive organ development in either generation. However, a whole litter from a dam of the P generation was born dead, three litters in total had a pup with skeletal abnormalities, and the AGD of F2a female pups was reduced. These events occurred only in the milk-treated rats. It is unknown whether these issues had any relevance to milk or only happened by chance.


CONCLUSIONS
Further study is required to determine whether milk from pregnant cows is completely free from adverse effects on reproductive health.
Department of Environmental Health, Medical University of Yamanashi, Japan.
Davaasambuu
D
Ganmaa
Li-Qiang
LQ
Qin
Pei-Yu
PY
Wang
Hideo
H
Tezuka
Shoji
S
Teramoto
Akio
A
Sato
D001003:Anal Canal / Q000002:abnormalities; D000818:Animals; D001842:Bone and Bones / Q000002:abnormalities; D002417:Cattle; D015988:Cohort Effect; D000013:Congenital Abnormalities / Q000453:epidemiology; D004326:Drinking / Q000502:physiology*; D004967:Estrogens / Q000032:analysis; D005260:Female; D005298:Fertility / Q000502:physiology; D005835:Genitalia / Q000254:growth & development; D005836:Genitalia, Female / Q000002:abnormalities; D015994:Incidence; D008297:Male; D008892:Milk / Q000737:chemistry; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D011374:Progesterone / Q000032:analysis; D051381:Rats; D012098:Reproduction / Q000502:physiology*
D004967:Estrogens; D011374:Progesterone