<strong><em>By Jennifer Ireland, Animal Management Supervisor
and Terry Webb,  Former Curator of Mammals*
North Carolina Zoological Park, Asheboro, NC
*currently Collections Manager at WCS/Prospect Park Zoo</em></strong>

<strong></strong>

<strong>Abstract:</strong>

On 2 August 2010 a primiparous chimpanzee at the North Carolina Zoo gave birth to a healthy infant.  Maternal competence was questionable as improper positioning of the infant prevented nursing.  On Days 1 and 2 of the infant’s life, the mother was anesthetized and the infant was allowed to nurse.  On Days 3 through 5 zoo keepers were able to periodically bottle feed through caging without the mother interfering.  On Day 6 the decision was made to remove the infant for hand-rearing as bottle feeding through the cage front became unreliable and required considerable cooperation from the mother.

The infant chimpanzee was put on a scheduled feeding regime consisting of human infant formula.   Consumption, fecal output, and daily weights were recorded.  Adjustments to the amount and type of formula offered were made based on consumption, fecal output, weight, behavior, and social and behavioral milestones.

Traditionally, hand-reared chimpanzee infants are introduced to adults between six and 18 months of age.  With the permission of the Chimpanzee Species Survival Plan (SSP®) of the American Association of Zoos and Aquariums (AZA), plans were made for introduction at approximately four months.   Physical development and mobility of the infant were the two factors that determined if the infant was ready.   Traditional methods for food introduction and feeding schedules were accelerated.

<strong>Introduction</strong>

Chimpanzees have frequently been hand-reared (i.e. reared by humans) in research facilities and/or zoological institutions, though the frequency of hand-rearing has greatly reduced over the past 50 years due to improved husbandry practices (Porton and Niebruegge, 2006).   Historically, hand-rearing has occurred for various reasons including: maternal incompetence, medical concerns, aggression towards the infant by the mother or conspecifics, death of the mother, rearing so that the animal was tractable for shows, educational presentations, or research, and the popularity of nursery exhibits with the public.

In AZA, accredited zoos’ female chimpanzees are given every opportunity to raise their offspring.  Only in the cases of maternal incompetence, aggression, or significant health issues are infants pulled for hand-rearing.   If total neglect or abuse is not present, institutions are encouraged to allow the mother and infant to stay together for 72 hours prior to making the decision to hand-rear (AZA Ape TAG, 2010).  Infants can survive these 72 hours without nursing (Rogers and Davenport, 1970).  Maternal care is learned and can improve with practice, so this time allows the mother and infant time to develop proficiencies.

Research has shown that even chimpanzees hand-reared in socially and environmentally complex nursery settings show higher levels of abnormal behaviors (Maki, Fritz, and England, 1993; Bloomsmith and Haberstroh, 1995) and a greater chance of developing non-breeding behaviors or maternal incompetence as adults (King and Mellen, 1994).  In order to encourage the development of a normal behavioral repertoire, chimpanzees that cannot be mother-reared should be peer-reared and/or integrated with conspecifics at an early age.  The SSP® Care Manual for Chimpanzees suggests that socialization back to the mother should occur within six months or to a surrogate by 18 months (AZA Ape TAG, 2010).

In developing a hand-rearing plan for chimpanzee infants it is therefore necessary to take both behavioral and nutritional factors into account.  When the North Carolina Zoo was recently faced with the task of hand-rearing a chimpanzee infant we carefully considered the need to socialize the infant with conspecifics.  The high degree of similarity between humans and chimpanzees allows for the relatively straight forward adaptation of human infant diets to the raising of chimpanzees.  However, given the need to integrate the infant with adult chimpanzees at an early age, we accelerated some of the traditional timelines for diet presentation in order to prepare the young chimp for reintroductions to the troop.

<strong>Hand-rearing Nutrition Overview</strong>

Chimpanzees are humans’ closest, living relative, with similarities in physiology as well as growth and development.  As a result nutritional and feeding recommendations for humans can be adapted to chimpanzees with relative ease.  In fact, prior to 2003 it was recommended that the human recommended daily allowance (RDA) tables be consulted when approximating chimpanzee nutritional requirements (Fulk, Loomis, and Garland, 1992). Currently, the specific nutrient requirements for chimpanzees are defined and are available in the book Nutrient Requirements of Nonhuman Primates (National Research Council, 2003)

In 1985, Fritz, Ebert, and Carland outlined the nutritional management of hand-reared chimpanzees at the Primate Foundation of Arizona in Tempe, AZ. This information is used as the basis for current recommendations for the feeding of infant chimpanzees that are being hand-reared (Porton, 1992).   These recommendations provide suggestions on the frequency of feeding, volume, supplements, when to introduce solids, and weaning, which closely match dietary recommendations for human infants.

<strong>Hand-rearing and Dietary Practices at the North Carolina Zoological Park</strong>

On 2 August 2010 a primiparous chimpanzee at the North Carolina Zoo gave birth to a full-term, healthy infant (242 days after conception).  Maternal competence was questionable as improper positioning of the infant prevented nursing (Photo I).  On Days 1 and 2 of the infant’s life no bouts of nursing were observed and the infant appeared weak. The mother was anesthetized on both days and the infant was allowed to nurse.  Through cooperation with the mother, on Days 3 through 5 zoo keepers were able to periodically bottle feed the infant through the mesh caging.  During these feeding sessions the mother brought the infant to the cage front and zoo keepers used a nipple extension to offer it Pedialyte® and/or a human infant formula.  Unfortunately, cooperation with the mother declined during Days 4 through 5 preventing reliable feeding.  The mother also began leaving the infant on the floor and unattended for prolonged periods of time.  As a result of the inappropriate maternal behaviors, on Day 6 the decision was made to remove the infant for hand-rearing.

Once the decision to hand-rear was made, a team of trained neonatal volunteers was assembled to assist zoo staff in caring for the infant chimpanzee.  It is the practice of AZA zoos to mimic natural mother-infant behavior as closely as possible during hand-rearing.  Hand-rearing therefore involves almost 24-hour body-to-body contact between the infant and the caretaker, species-specific handling of the infant (including feeding the infant in a ventro-ventral position (Photo II), and exposure to<img class="size-full wp-image-2566 alignright" title="pic22" src="http://aecetia.net/gws/aazk/wp-content/uploads/pic22.jpg" alt="pic22" width="419" height="572" />
conspecifics (AZA Ape TAG, 2010).

The hand-rearing team recorded food offered and consumed, daily weights and temperatures, urination frequencies, fecal output and its consistency, and any behavioral or developmental data.  Dietary changes, including frequencies and amounts, were approved by the area supervisor, the Curator of Mammals, and the attending veterinarian.  Factors for diet changes were: total diet consumption, consumption at certain periods of the day, fecal output, weight, behavior, and social and developmental needs.

Scheduled feeding was instituted, rather than on-demand feeding, due to the large number of individuals caring for the infant.  We chose a fixed schedule to avoid reliance on different individuals’ subjective judgment of hunger cues from the infant and the desire not to over or under feed.

For the first six weeks the infant was fed using a preemie bottle and nipple from Enfamil®.  At six weeks we changed to Evenflo® Classic™ bottles and silicone nipples (3-6 month, medium flow) due to issues with the preemie nipples flowing too fast.  We were concerned with aspiration and bloating due to rapid consumption.

Initially the infant was provided the human infant formula Similac® Advance® Early Shield® with iron (see Table I for dietary offerings).  At just over two weeks of age the formula was changed to a soy formula (Enfamil® Prosobee® Infant Formula for Sensitive Tummy Soy formula with iron) due to several days of diarrhea and possible lactose intolerance.  The infant remains on this formula to date. When bouts of diarrhea occurred, the infant was taken off formula and offered Pedialyte® solution at 100% for 1-5 feeds (depending on length and frequency of diarrhea), then switched back to 100% formula over the course of three feeds.

Rice cereal was offered at eight weeks.   Novel fruits and vegetables in the form of baby food were introduced at 13 weeks.  Each item was offered for four consecutive days before offering a new item.  This was done to monitor for food allergies or adverse effects of each new food.   At each feeding cereal and/or fruits/vegetables were supplemental foods.  Formula was and continues to be the primary source of nutrition….
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