This study sought to quantify effects of undernutrition on behaviors a
nd to relate these to gonadotropin and prolactin concentrations in the
lactating dam. Dams were studied in a 2 X 3 factorial design with lit
ter size and food intake as the two factors. Behavioral data were coll
ected from each dam and her litter on day 9, day 14, and day 19 of lac
tation, and maternal blood samples collected. Plasma was analyzed for
luteinizing hormone, follicle stimulating hormone and prolactin. On da
y 15 of lactation, percent time nursing, number of pups actively nursi
ng, total number of pups nursing and dam location acted as mediating f
actors of the effect of diet group on plasma luteinizing hormone conce
ntration. No such relationships were seen for plasma follicle stimulat
ing hormone, and only nest condition score appeared to be a mediator f
or plasma prolactin concentration. In conclusion, this analysis sugges
ts that food restriction indirectly influences plasma concentration of
luteinizing hormone, but not follicle stimulating hormone, by changin
g maternal and pup behaviors. The relationship among diet, behavior an
d circulating prolactin was less clear.