[Safety assessment of milk on reproductive development by reproduction study]

Observe the influence of whole fat milk and high-dose soy isoflavones (SI, 1 g/kg) on reproductive development to assess the safety of milk.

Sixty Spraque-Dawley rats (30 male and 30 female) were randomly separated into milk group, S1 group and control group (10 male and female each) according to body weight and were fed with milk, the diet with 1 g/kg SI and basic diet, respectively. Intervention measures were implemented from 11 weeks before mating to sexual maturity of F1. Parental weight, morphology, reproductive capacity, reproductive organ function, the level of hormones of parental rats and the development status of the first filial generation rats were examined. ANOVA were used to assess differences in groups with SPSS 13.0 statistical software; P < 0.05 were considered statistically significant.

The birth weight of F1 offspring in milk group was significantly increased (P < 0.05). The level of luteinizing hormone (LH) of male rats and progesterone (P) of female rats in milk group were lower than those of control group (P < 0.05). SI group vs control group significantly decreased P and PRL in female rats of the P generation (P < 0.05). And The level of FSH in male rats of the P generation was lower than that of control group (P < 0.05). There was no significant differences on the other indices such as estrous cycle, mating index, fertility index, pregnant index, gestation length, Number of pups, sex ratio, anogenital distance, vaginal opening (VO), preputial separation (PPS) in milk group and SI group, compared with control group.

Milk did not show significant influence on the reproductive development ability in the one-generation reproduction study. Further study is required to determine whether milk have adverse effects on reproductive health for F2-generation.