Social housing and pregnancy outcome in captive pigtailed macaques

We present a retrospective analysis of 30 years of breeding records from a colony of pigtailed macaques at the University of Washington's Regional Pri mate Research Center, specifically examining the effects on pregnancy outco me of sire presence, presence of other pregnant females, group stability, o verall group size, and dam age and parity. Data on 2,040 pregnancies (1,890 live births) of socially housed pigtailed macaques (Macaca nemestrina) wer e obtained from the Washington Regional Primate Research Center's animal co lony records from 1967 to 1996. Our results suggest that the presence of th e sire and other pregnant females, fewer moves, and lower parity increases the probability of a viable birth. In viable and nonviable births, gestatio n length was positively related to contact with the sire and other pregnant females, number of moves, and dam age. Once the effect of gestational age was taken into account, birthweight increased with increasing parity and de creased with dam age. Clinical treatment of the dam decreased as sire prese nce and group size increased and number of moves decreased. The length of t reatment was dependent on the number of moves experienced by the dam, with more moves associated with longer treatments. Sire presence was the single most important factor in nearly all measures of reproductive outcome. Am. J . Primatol. 47:153-163, 1999. (C) 1999 Wiley-Liss, Inc.