Female reproduction characteristics in a large-scale breeding colony of cynomolgus monkeys (Macaca fascicularis).

We studied two mating systems for a large-scale breeding colony of cynomolgus monkeys: (i) a 3-day timed system that keeps one female and one male together in a cage for 3 days beginning 11 days after menstruation, and (ii) a 7-day timed system beginning 9 days after menstruation. Regardless of the mating system used, we propose a practical definition of an infertile female as one that does not become pregnant in up to six pairings. If we eliminate these animals from the breeding colony, the pregnancy rates would be 3.6 times higher. Eliminating infertile females from a breeding colony is important in order to save labor, time and cost and to maintain a healthy breeding colony.

Simian betaretrovirus infection in a colony of cynomolgus monkeys (Macaca fascicularis).

Of the 419 laboratory-bred cynomolgus macaques (Macaca fascicularis) in a breeding colony at our institution, 397 (95%) exhibited antibodies or viral RNA (or both) specific for simian betaretrovirus (SRV) in plasma. Pregnant monkeys (n= 95) and their offspring were tested to evaluate maternal-infant infection with SRV. At parturition, the first group of pregnant monkeys (n = 76) was antibody-positive but RNA-negative, the second group (n = 14 monkeys) was positive for both antibody and RNA, and the last group (n = 5) was antibody-negative but RNA-positive. None of the offspring delivered from the 76 antibody-positive/RNA-negative mothers exhibited viremia at birth. Eight of the offspring (including two newborns delivered by caesarian section) from the 14 dually positive mothers exhibited SRV viremia, whereas the remaining 6 newborns from this group were not viremic. All of the offspring (including 2 newborns delivered by caesarian section) of the 5 antibody-negative/RNA-positive mothers exhibited viremia at birth. One neonatal monkey delivered by CS and two naturally delivered monkeys that were viremic at birth remained viremic at 1 to 6 mo of age and lacked SRV antibodies at weaning. Family analysis of 2 viremic mothers revealed that all 7 of their offspring exhibited SRV viremia, 6 of which were also antibody-negative. The present study demonstrates the occurrence of transplacental infection of SRV in viremic dams and infection of SRV in utero to induce immune tolerance in infant monkeys.