Identifying changes with age in physiological variables of captive nonhuman primates will aid in the proper treatment and clinical diagnosis of these animals, as well as enhance our understanding of nonhuman primate models for human aging. Information for 33 physiological variables was obtained from the Primate Aging Database, a multi-centered database being developed for clinical and research use. Using multiple regression analyses, we investigated the relationship of age to hematological variables, blood chemistry and body weight in 345 captive rhesus monkeys (age range 7-30 years) from three different primate research facilities. The analyses revealed that 15 of these variables show a significant relationship with chronological age and are altered in older as compared with adult animals. Here we present the first phase of a project that will: a) identify changes with age in physiological variables among adult captive rhesus macaques; and b) characterize normative values for the aging rhesus population.
Common marmosets (Callithrix jacchus) demonstrate significant variation in reproductive output on both a yearly and lifetime basis in comparison to other anthropoid primates. We explore the factors that may be most important in determining reproductive variation in captive common marmosets. Studies have found that maternal age, maternal condition, and dam survivorship are related to reproductive output; however, these reports are not in agreement and are far from conclusive. With the use of a large, multicolony, demographic database pooling data across five marmoset colonies, we examined litter information for 1,649 litters, and reproductive summaries for 400 dams to assess 1) how reproductive output variation (total production, total weaned production) is determined by litter size, interbirth interval (IBI), age at first birth, and dam survival age; 2) the relationship between maternal age and reproductive output variables; and 3) relationship between the reproductive output variables and survival. We used stepwise regression procedures to describe the amount of variation in lifetime reproductive output among dams, and found that mean litter size accounted for 18% of the variance in total production, survival age accounted for 10.6%, age at first birth accounted for 8.8%, and mean IBI accounted for 5%. For total (nonzero) weaned production, survival age accounted for 7.6% of variance, age at first birth accounted for 7.2%, mean IBI accounted for 2%, and mean litter size accounted for 1.6%. We identified significant effects (P<0.05) of maternal age on litter size and IBI length, but no effect of dam age on weaned litter size. Cox proportional hazards regression analyses revealed significant effects (P<0.01) of number of litters, age at first birth, and site on dam survivorship. Dams that produced more litters showed higher survivorship. Age at first birth showed a positive relationship with dam survivorship, i.e., dams that delayed first reproduction had higher survival. Our findings about reproductive variation in marmosets may have practical applications for the management of marmoset breeding colonies.
Temperature selection by five young common garter snakes, Thamnophis sirtalis, was studied using a simple, two-choice thermal mosaic. The animals were housed in an arena (60 × 120 cm) within an environmental room, where they were exposed to a photoperiod of 12 h light: 12 h dark and a general ambient temperature of 20 °C. The arena contained two shelters (20 cm × 20 cm), one at ambient temperature and one heated to 30 °C. On a given day, we determined the snakes' locations in the arena twice an hour for several hours. Observations were made in this manner on most days over a period of 19 weeks. Within 1 h following a late afternoon feeding, use of the hot shelter increased from about 5–20% of observations to above 80%. Occupation of the heated shelter remained at a high level the next day and then decreased, reaching a background of 10–40% by the 3rd day after feeding. The animals displayed a higher background use when maintained on a weekly feeding regime than they did when on a biweekly regime. During a 5-day period preceding ecdysis, occupation of the hot shelter again exceeded 80% of observations; decline to a background of 0–10% began about the day of molt. Runs tests performed on the daily records of individuals indicate that hot-shelter use tended to occur in bouts. There was no suggestion of diurnal variation in thermoregulatory behavior.
With relatively high fertility and short lifespan, marmoset monkeys (Callithrix jacchus) may become useful primate models of prenatal nutritional effects on birth condition and adult disease risk. The present study determined the effects of energy restriction to 75 % of expected ad libitum consumption during mid-(day 66) or late (day 99) gestation on maternal weight, fetal growth and pregnancy outcomes in this species. Mid-restriction reliably induced the loss of pregnancy before term, at 92 d, on average. Of the late-restricted pregnancies, four of seven were normal term length while three were preterm deliveries, at 101, 117 and 132 d. Control females had a mean mid-pregnancy weight gain of 0·67 g/d while mid-restricted females lost 2 0·65 g/d, on average. Control pregnancies averaged a 1·06 g/d gain during late pregnancy, while energy-restricted females lost 20·67 g/d, on average. Restriction-related weight change was highly variable, ranging from þ0·55 to 2 2·56 g/d for mid-restriction pregnancies and from þ0·79 to 2 3·91 g/d for late-restriction pregnancies. For mid-restriction pregnancies, the number of restriction days was best explained by linear weight change and total weight loss while the number of restriction days in late pregnancy was best explained by linear weight change alone. In late-restriction pregnancies, smaller females had higher daily weight losses. Restrictions did not induce litter-size reduction or growth restriction in those infants that were delivered at term but the size of aborted fetuses suggested that at least some pregnancies lost preterm may have involved impaired intra-uterine growth.
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