A one-generation reproduction toxicity study in rats treated orally with a novel galacto-oligosaccharide

Galacto-oligosaccharide (GOS) is a naturally occurring prebiotic that beneficially affects the host by selectively stimulating growth and/or activity of one or a limited number of colon bacteria to improve host health. A novel GOS was administered by gavage to male and female Sprague Dawley rats at 0, 500, 1000, and 2000 mg/kg/day for 10 weeks. In males, administration of GOS was initiated prior to mating and continued for 91 days. Females received GOS beginning 2 weeks prior to mating through day 20 of lactation. Parents were observed daily, and body weight (BW) and feed consumption were measured. Vaginal smears, mating behavior, and observation of delivery/lactation were evaluated in parents. Effects on the reproductive function of parents including gonad function, estrous cycle, mating performance, fertility, delivery and lactation, and effects on the growth and development of pups were examined. No deaths occurred, and no general toxicological effects or abnormal reproductive functions were observed in any dose group. Pups were observed at birth and the following measurements were undertaken: BW, external differentiations, sensory functions, and reflex reactions during lactation and just prior to necropsy. No external malformations or differences in the number of pups, in the sex ratio, or BW at birth occurred in any dose group. Growth and development of pups were normal. The No Observed Effect Level for reproductive function of male and female parent animals and for the growth and development of their offspring was at least 2000 mg/kg/day.