Moderate zinc-iron deprivation influences behavior but not growth in adolescent rhesus monkeys

Primate species demonstrate a prolonged period of development before reproductive maturity that includes distinctive periods of rapid growth in the late fetal, late infancy and early adolescent stages. Rhesus monkeys resemble humans in this discontinuous pattern of growth and also in its relationship to brain development. Studies of zinc deprivation in rhesus monkeys have suggested an important relationship among growth rate, nutrient status and behavioral performance in infancy as well as adolescence. Recently, moderate combined zinc and iron deprivation (intake 0.2 mg Zn and 0.8 mg Fe/d, compared with control intake of 2.9 mg Zn and 1.7 mg Fe/d) during the adolescent growth spurt (29-32 mo. of age) of female rhesus monkeys (n = 8/group) was shown to influence behavior without affecting growth. Behavioral assessments included the Continuous Performance Test, the Delayed Nonmatch to Sample Test and activity (measured with an actimeter). The behavioral syndrome was characterized by reduced activity, reduced participation in behavioral testing and slower response. These changes could be reversed or prevented to some extent by altering the diet to include tablets of powdered beef (adding approximately 1.7 mg Zn and 0.7 mg Fe to daily intake). The study suggests that behavior may be sensitive to the quality of the diet available during the period of rapid adolescent growth and development.