Studies of marginal zinc deprivation in rhesus monkeys: infant behavior.

Rhesus monkey infants were marginally deprived of zinc (4 ppm diet) from conception and were compared to controls (100 ppm diet) during the first year of life in development of reflexes and motor patterns, mother-infant interaction, delayed response performance, discrimination learning and reversal, and open field behavior. Deficits in amount and variety of behavior were recorded in deprived infants; spontaneous locomotor activity was 50% below control levels in males at 1 mo of age; spontaneous activity was 7-10% lower in both males and females at 3 mo of age; response latencies were 50% lower than controls at 7-9 mo; failure to reach discrimination reversal criterion was seen in 71% of deprived infants as compared to 10% of controls at 10 mo of age; and abnormally low levels of climbing and exploration were seen in two of six deprived infants at 12 mo of age. No abnormalities in the rate of behavioral development or in emotional adaptability were observed. These and other results suggest that syndromes of lethargy, apathy, and hypoactivity are characteristic of behavioral effects of marginal zinc deprivation in primates.