Tall fescue endophyte: effect on congenital development and pup growth in mice.

This study was designed to assess effects of a diet containing endophyte (Acremonium coenophialum)-infected tall fescue seed on litter growth and development in mice. Twenty pairs of mature CD-1 mice were allocated to dietary treatments containing 50% (wt/wt) rodent chow plus either 50% endophyte-infected tall fescue seed or seed that was not infected. At parturition, six pups of approximately equal BW and sex ratio were selected from each litter and fostered to each of the dams for suckling, resulting in four suckling groups. Pups born to dams fed the infected diet weighed less at birth and experienced developmental delays in BW gain and in eye opening (16.7 vs. 13.7 d) regardless of the foster dam's diet. Pups born of dams fed the diet that was not infected attained the greatest growth rates and weaning weights; those suckling dams fed the diet that was not infected demonstrated the largest gains. Pups born of and suckled by dams fed the infected diet demonstrated greatly reduced growth rates and weaning weights compared with the other groups. Results suggest that the congenital effect on pups born of dams fed an infected diet was significant in lowering the growth rate of the pups during suckling. The dam's ability to provide nourishment to the pups also was lowered when fed this diet. When these two factors were combined, the differences were greater than for either factor separately.