Hematological and serum biochemical effects of nursing on the mother in cynomolgus monkeys (Macaca fascicularis)]

The effects of nursing on maternal hematological and serum biochemical values were analyzed in cynomolgus monkeys reared in indoor cages at Tsukuba Primate Center. In our breeding system, infants are usually separated from their mothers at the age of 121 to 180 days. Mother monkeys of such infants were studied hematologically and biochemically (Group B), as were mother monkeys who happened to have nursed their infants past 181 days after parturition (Group A). During the period with their infants, mother monkeys in the latter group showed lower white blood cell counts (WBC) and higher red blood cell counts (RBC), hematocrit values (Ht) and blood urea nitrogen concentrations (BUN) than the mother monkeys who had been separated from their infants. Also, serum calcium concentrations (Ca) were decreased with prolonged nursing periods, indicating that lactation by the mother monkey probably continues even for a period from 181 days to about one year after parturition if she nurses her infant. Lactation during this period may accelerate hematogenesis and protein metabolism in the mother monkey.