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BREEDING SYSTEMS Free-Ranging Breeding The following shows the locations of certain free-ranging colonies: Macaca mulatta-Cayo Santiago, near Puerto Rico. Further information may be obtained from Laboratory of Perinatal Physiology National Institute of Neurological Diseases and Blindness San Juan, Puerto Rico 00753 M. fuscata-Oregon Regional Primate Research Center, Beaverton, Oregon 97005 Baboons-Sukhumi Primate Center. Further information may be obtained from Institute of Experimental Pathology and Therapy Academy of Medical Sciences Sukhumi, Georgia, U.S.S.R. ChimpanzeesâHolloman Air Force Base, New Mexico. Further informa- tion may be obtained from 6571st Aeromedical Research Laboratory Aerospace Medical Division Holloman Air Force Base, New Mexico 88330 Breeding success under free-ranging conditions depends largely on the so- cial organization of the species involved. Other factors to be considered follow. 38
39 Adequate food and water are necessary. Time must be allowed for establishment of a social order in the group. Although the animals may copulate within one or two days, early concep- tion is not likely. This system requires little labor. This system provides maximum opportunity for exercise of animals and for normal social development of infants. Clinical observation and collection of specimens for laboratory examina- tion are difficult. Colony Caging Colony caging has been successful with most Old World monkeys in routine laboratory use, including Macaca mulatta, M. nemestrina, M. arctoides, and M. fascicularis. A proved sire is placed in a colony-type cage with 3 to 12 fe- males. Females are left in the cage until they are pregnant, whereupon they are placed in separate cages for delivery. The advantages of this system: Labor is saved by having fewer cages to clean and fewer groups of ani- mals to feed and water. The need for daily examination for mating or estrus is eliminated. The disadvantages: Conception date is difficult to establish. Reintroduction of females into the home cage after parturition often precipitates fighting, which is repeated until the social order is re-established. Caged Breeding In this system of breeding, females are caged individually or in small groups apart from the male. They are generally moved into the male's cage during each estrual period until they become pregnant. The system has several advantages: It permits individual breeding records to be maintained on the females and the offspring. It facilitates clinical laboratory examination and observation of the ani- mals in general. It identifies the nonbreeders, who can be eliminated from the breeding group.
40 Permanently Paired Mating This system has the advantages listed for caged breeding (above) but is extremely expensive to maintain for the larger species because of the num- ber of males required. BREEDING IN RELATION TO CERTAIN SPECIES Tree Shrews Tree shrews are best caged in male-female pairs. This practice prevents the fighting that often occurs between members of the same sex. Copulation has been observed throughout the year in captive tree shrews. Some estrus cycle and birth data, however, suggest the existence of seasonal breeding in Tupaia. A basic 10- to 12-day estrus cycle, with the period of sexual receptivity lasting 2 to 4 hours, is reported in one species. The gestation period is believed to be 6 to 7 weeks. Generally, one, two, or three babies are born. Two is the common num- ber in most species. In captivity, infant tree shrews often are abandoned by the mother shortly after birth. Occasionally they are eaten by the mother or by other adults in the cage. Lorisidae The species of Lorisidae that have been carefully studied seem to be seasonal breeders. With the possible exception of several of the smaller Galago species, the Lorisidae are fairly solitary. Caging of male-female pairs is generally success- ful, but caging of groups is generally unsuccessful. It seems likely from periodic fluctuations of body weight and testicle size that the male is as great a factor in breeding seasonality as the female. The vulva of the Lorisidae is imperforate from birth until puberty. There- after it opens at regular, seasonally specific intervals for estrus. Galago spp. that do not conceive during the first seasonal estrus usually cycle at approximately 30-day intervals for several months or until concep- tion occurs. The gestation period for G. crassicaudatus panganiensis is 132 Â± 5 days, and for G. senegalensis braccatus, 139 Â± 5 days. The infants are well developed and fully haired at birth. It is advisable to isolate females for parturition and during early stages
41 of infant development. Infants are often left alone in the nest box and are thus very vulnerable to attack. Galago infants gain about 80 percent of their birth weight per week during the first 12 weeks of life. Sexual maturity is generally reached be- tween the ninth and the twelfth month. New World Monkeys Good reproduction is achieved when breeding pairs of marmosets are housed in cages 18 in. wide, 18 in. deep, and 24 in. high. Successful breeding of squirrel monkeys has been achieved with pairs, with groups containing one male and five females, and with groups contain- ing multiple males and females. Mothers with babies usually do well when left in the cage in which breeding took place. Little information is available on the breeding of other New World mon- keys in a laboratory situation. Old World Monkeys Most of the successful breeding of Old World monkeys has been with macaques, especially M. mulatta. Cercocebus spp. have not been successfully bred in the laboratory en- vironment. However, modest success has been achieved with Cercopithecus mitis and C. aethiops by following, in general, macaque breeding practices. Female macaques become sexually mature at 3 to 4 years of age; males, at 4 to 5 years. Signs of the menstrual cycle vary among Old World monkeys in routine laboratory use. For example,M. mulatta shows bleeding primarily; C. niger displays prominent perineal tumescence with little bleeding; M. nemestrina shows both bleeding and tumescence. With Cercopithecus spp. the bleeding is scanty. A successful timed-pregnancy breeding program for macaques requires day-to-day records of the menstrual history of each female. Females can be trained to present their perineum for daily examination to determine the onset of menses. Limiting breeding-troop size to 10-12 females and 1 male permits the observer to keep the daily records without which timing of pregnancies is impossible. Groups of more than 12 females cannot be adequately observed. Radiography also can be used in estimating the gestational age of a preg-
42 nancy in which the conception age is unknown, and is a fairly reliable tool in the hands of an experienced radiologist. The first day of menstrual bleeding is designated as day 1 of the cycle. Peak days for ovulation are days 11 through 14. It is generally believed that mating from noon of the 11th day until noon of the 12th day is most likely to result in conception. The female is placed in the male's cage the morning of day 11 and remains with the male 24 to 48 hours. Belligerent animals should not be placed together, as this results in fight- ing and poor conception rates. Animals should not be placed together when there would be immediate competition for food. Maintenance of a male room eliminates most of the social competition and thus fosters a higher conception rate. It is generally recommended that there be 1 male for every 20 to 25 females. The female monkey usually "menstruates" once following conception. This is referred to as placental or implantation bleeding. It lasts longer (15 to 20 days) than the menstrual cycle (3 to 5 days) and is brighter in color than menstrual bleeding. Observation of this bleeding permits tenta- tive diagnosis of pregnancy by the 17th to 25th day; rectal palpation at the 30th to 35th day is needed to confirm the diagnosis. One must keep in mind the possibility that placental bleeding may result from an intrauterine hem- orrhage after an early abortion. The usual gestation period forM mulatta is 163 to 165 days. However, it may be as long as 180 days, and infants born as early as 147 days after conception have been known to survive. After 180 days, life is in jeopardy and the infant should be delivered by Caesarean section. M. fascicularis follows the same gestational pattern as M. mulatta; M. nemestrina averages 173 Â± 3 days. Limited experience with C. aethiops shows the period to be 135 to 160 days. Baboons Baboons reproduce readily in captivity after adapting to the new environ- ment. Ovulation and conception seldom occur until after the mature female has been in her new surroundings 6 to 8 months. The baboon has a menstrual cycle of approximately 35 days' duration. The optimum time for mating is the 17th day-or 2-4 days before the onset of detumescence. The gestation period is 164 to 186 days. Breeding animals may be caged in groups or in pairs. When a gang cage is used, a ratio of 1 male to 10 to 12 females is recommended.
43 Chimpanzees Chimpanzees reproduce readily in captivity provided they are adapted to their new environment and have been raised with sufficient social stimula- tion to permit ready acceptance of a member of the opposite sex. When one considers that most of the apes are imported as infants and raised in some form of isolation, it is understandable why their reproduc- tion rate is rather low. Observers differ as to the proper male-female ratio, but they agree that a male and a female should "be acquainted" before they are paired. If male and female are customarily apart, pairing is more likely to be effective if they are brought together while the female is in substantial perineal swell- ing and is receptive to the male's advances. Female chimpanzees are at breeding age when they are 9 to 10 years old; males, when they are a year or so older. The menstrual cycle is about 35 days and the gestation period between 245 and 256 days.