Effects of monensin feeding during development on female rats and their offspring

Monensin, a growth-promoting agent and coccidiostat used in veterinary medi cine, was studied in terms of its effects on the development of female rats and their offspring when added to the diet. Young female rats received 100 or 300 ppm monensin mixed with powdered chow diet until adulthood, when th ey were mated and their offspring were evaluated for physical and neurobeha vioural development. The data showed that 1) exposure to the higher monensi n concentration reduced female body weight; no deaths occurred after exposu re to the two monensin concentrations; 2) the offspring of the experimental group receiving 300 ppm monensin presented a weight reduction from 10 to 2 1 days of lactation; 3) incisor eruption was delayed only in females after exposure to the 100 ppm concentration. We conclude that exposure to monensi n during development induces toxicity in female rats and has a notable adve rse effect on growth with some limited effects on selective milestones of p hysical and functional development of the offspring during the postnatal pe riod. (C) 1999 Elsevier Science Inc. Ail rights reserved.