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Nutrition Research

In 1974, Toronto Zoo was the first zoo in North America to employ a full-time nutritionist and, to date, remains the only zoo in Canada to do so. The Wildlife Nutrition Centre (WNC) has developed balanced diets to ensure the optimal health and wellbeing of a wide variety of species. Like the Reproductive Physiology Centre, the WNC is also divided into two components that work together seamlessly to improve animal health and care: the Food Production Unit and the Nutrition Research Unit.

On this page:



AN EVALUATION OF BROWSE SILAGE PRODUCTION AS A FEED COMPONENT FOR ZOO HERBIVORES

FORMULATION OF A NEW CRICKET DIET AND DEVELOPMENT OF PROPER FEEDING PROCEDURES FOR FEEDER CRICKETS AT THE TORONTO ZOO

FUTURE RESEARCH INTO THE NUTRITION OF AMPHIBINS AND REPTILES

PILOT STUDY: PALATABILITY STUDY WITH SURPLUS INVERTEBRATES

GORILLA BEHAVIOUR AND NUTRITION STUDY

CAPTIVE STUIDIES TO IMPROVE DIET ESTIMATES AND BIOENERGETIC MODELLING OF POLAR BEARS IN THE WILD

MASS PRODUCING NATIVE INSECTS FOR THE PANAMA FROG RESCUE PROGRAM

POLAR BEAR ENERGETICS STUDY - Captive Studies to Improve Diet Estimates and Bioenergetics Modeling of Polar Bears in the Wild

AN EVALUATION OF BROWSE SILAGE PRODUCTION AS A FEED COMPONENT FOR ZOO HERBIVORES


(T. Lachance, J. Wensvoort and J. Atkinson).

This study was part of a M.Sc. study by thesis through the University of Guelph and has been completed in 2011. The MSc degree by thesis was successfully defended in 2012.

Browse is the collective term for edible leaves, twigs, bark, buds and flowers from trees and shrubs. The availability of browse is for many zoo animals an essential daily requirement for nutrition and welfare and there is a strong demand for browse at Toronto Zoo.

Scientific studies have indicated that browse provides unique nourishment and is essential for the animal's well-being. Zoo-animals that are genetically predisposed to consume browse and are provided significant amounts of it every day generally have better health, increased welfare and increased longevity. Common nutrients and also very specific compounds are provided by browse. Along with this supply comes the variable morphology of branches, volume and generally a low nutritional density typing browse as a "Slow Food" important to provide essential psychological stimulation for captive animals. For example: Recent research findings at Toronto Zoo (Gorilla behaviour/nutrition study 2010) indicate significantly reduced negative behaviour (i.e. Regurgitation and Re-ingestion of food), more time spent foraging and digesting by captive Gorillas when browse supply was increased daily.

At Toronto Zoo, the plant species suitable to be used as browse have already been identified and fresh browse is normally supplied from pruning in pavilions, greenhouses and open areas throughout the Zoo site; however, especially in the winter season the amount supplied is not enough. For this reason a research project has started to better provide preserved browse in the winter. Nutritional comparisons of browse silage and bark, packing browse silage partly-mechanical instead of manual and evaluations of browse harvesting were done. Besides the fresh browse, trees provided major amounts (approximately 20 truckloads per year) of branches (2-1/2 " thick) which are being used throughout the zoo as nutriment and enrichment. These branches are debarked by the animals and are very much preferred.

In order to better fulfill the large demand for browse during the summer, new sites dedicated for fresh browse supply had to be established inside the TZ perimeter fence and close to animal enclosures. The collection and packing for preservation of browse (i.e. browse silage for use in the winter) can be done farther away from enclosures because it is done with the mobile browse press.

Dedicated browse silage plantation

Collection and packing of browse silage has to be done efficiently as cost of labour is high. To secure efficiency, plantations have to be relatively close by, large and easily accessible with an efficient lay-out.

These plantations require being limited to plants species already known to be acceptable to Zoo animals in general and having a high resilience against regular pruning. Before planting the soil needs to be prepared and tested, for residual herbicides. Planting should be in rows and spaced to allow efficient harvest. Advice has been obtained from a forestry specialist from the NRCan/Canadian Forest Service. Toronto Zoo has established one of such plantations (10.000 trees) in 2011, located just 10 minutes north of the Toronto Zoo on land arranged in cooperation with the Toronto Regional Conservation Authority (TRCA) and the Rouge Park (RP) and with help from NRCan/Canadian Forest Service and our community partners.

This project has been presented on the biannual 2011 Nutrition Advisory Group (NAG) conference in Kansas City, MO, USA and on the 2012 CAZA conference in Toronto, ON, Canada.

FORMULATION OF A NEW FEEDER CRICKET DIET AND DEVELOPMENT OF FEEDING PROCEDURES FOR FEEDER CRICKETS AT THE TORONTO ZOO


(L. Attard, J. Wensvoort, J. Atkinson) REF No. 2005-10-01

The purpose of this study is to formulate a Toronto Zoo feeder cricket diet and to evaluate this diet to be used as a gut loading agent to provide improved and more balanced nutrition for reptiles and amphibians at the Toronto Zoo. This study is part of a M.Sc. study by thesis through the University of Guelph and experimentation is planned to be completed in 2012.

The first part involved the development of a new diet to feed to the crickets and for use as a dusting powder to improve the nutritive quality of the crickets. The second part of the study involves the examination of different cricket feeding strategies in order to determine which one provides the most nutritious crickets. This strategy will then evolve into a new feeding protocol which will be implemented throughout the Zoo in order to improve the nutritive quality of crickets as they are fed to the collection.

This project has been presented on the biannual 2011 Nutrition Advisory Group (NAG) conference in Kansas City, MO, USA and a MSc thesis is in preparation.

FUTURE RESEARCH INTO THE NUTRITION OF AMPHIBIANS AND REPTILES


(J. Wensvoort, B. Johnson, A. Lentini, G. Crawshaw, L. Attard, T. Mason)

Strategies are currently worked out in cooperation with curators and veterinarians for further investigations in the next 10 years. These will include the dynamics of nutrients in feeder insects, the comparison of the nutritional values of a variety of feeder insects, the validation of a new cricket gut loading diet and investigations into the diets for tadpoles. It is currently considered as a Nutrition Intern or a Veterinary Resident project.

PILOT STUDY: PALATABILITY STUDY WITH SURPLUS INVERTEBRATES


(E. Lee, T. Mason and J. Wensvoort)

Insectivorous/omnivorous animals in their native environments will generally consume a wide range of insect species. In captivity such animals may not have the options to express these natural feeding behaviours which support a balanced diet and ensure that nutritional deficiencies do not develop.

A pilot study was carried out during the summer of 2011 in which several different surplus invertebrate species were fed to several insectivorous/omnivorous species. Observations were made and documented to establish the palatability of the invertebrate species.

Several successful prey and predator pairings have been identified. The collected data also indicate that palatable prey species can induce increased physical and mental activities in the form of predatory behaviours and learning.

There is a lot of scope in this project, including the dynamics of nutrients in feeder insects, the comparison of the nutritional values of a variety of feeder insects, comparisons of native diets with (captive) zoo diets, dynamics of nutritional behaviours and investigations into the diets for many species.

On a larger scale this project has the potential to expand and encompass various fields in conservation, natural resource management and environmental impact measurement.

GORILLA BEHAVIOUR AND NUTRITION STUDY


(J. Wensvoort, E. Di Nuzzo, Allison Von Slack and E. Hoellein-Less)

The purpose of this study was to ascertain the effect of a diet change on unnatural Regurgitation and Re-ingestion of Food (R/R) behaviour. There were two parts to the study. The first part of the study began with observations taken on exhibit starting April 16th for a period of 32 days. During this time the gorillas were on a diet of vegetables, fruit, gorilla chow/biscuits, gels, flax meal, tofu, browse/silage, hay, and enrichment food including popcorn and cranberries. After this observation period ended, the gorillas were slowly transitioned onto a new diet consisting of vegetables, flax meal, tofu, unlimited fresh browse and enrichment food including almonds, sunflower seeds, and mixed shelled nuts. The second observation period began September 13th for a period of 14 days. The main differences in the two diets consisted of the absence of fruit and the addition of unlimited browse to the second diet. All gorillas received the new diet with the exception of Ngozi (nursing mother) and Nassir (infant) who received breakfast and dinner rations of gorilla chow and gel in addition to the new diet.

This study has been a great success because it has been found that by giving the gorillas more browse they have decreased the abnormal behaviour of R/R dramatically. In addition, foraging and feeding times seem to be increased and the gorillas may be moving towards a healthier lifestyle. By providing a variety of browse to the gorillas, they are occupied for longer periods of time and have a more natural method for foraging and eating. Quantity and variety of browse appear to both be important factors to consider when providing a suitable browse diet. As such, it is recommended that old browse be left on exhibit until consumed as dried browse offers further variety to the gorillas who seem to enjoy the differences provided by the dried leaves. Also, a small supply of fruit does not seem to affect the gorillas overall well-being negatively as they have been enjoying the apples from the apple browse during the study. Throughout the entire study, only one bout of repeated R/R could be linked to apple consumption. Overall, the gorillas showed positive outcomes during this study with a decrease in abnormal behaviour, an increase in foraging and feeding activity, and an overall weight loss to improve health. A paper is in preparation.

CAPTIVE STUIDIES TO IMPROVE DIET ESTIMATES AND BIOENERGETIC MODELLING OF POLAR BEARS IN THE WILD


(G. Thiemann and B. Laforest of York University, I. Duncan of Guelph University, G. Crawshaw, J. Young, E. Di Nuzzo and J. Wensvoort of Toronto Zoo, C. Robbins of Washington State University, Peter Molnar of Princeton University, K. Rode of US Fish and Wildlife Service, S. Cherry of Parks Canada.)

Sea ice habitat in many parts of the Arctic is changing rapidly through the effects of climate change. Many species depend on the predictable availability of sea ice for such key natural processes as feeding, migration and reproduction. One species which depends heavily on the sea ice for all three of these processes is the polar bear. The ongoing reduction of sea ice habitat has led to predictions that the foraging patterns and energy budgets of polar bears will shift accordingly, given the reduced hunting time and altered prey availability associated with decreased ice cover. A deeper understanding of these foraging shifts, and their consequences for polar bear energy budgets, will allow scientists to better predict the effects of climate change on polar bear populations and give managers and policy makers the ability to make more informed management decisions. An understanding of polar bear nutritional physiology is critical for wild polar bear conservation, and can only be obtained through studies of captive polar bears.

By carefully observing and quantifying the amount of food the polar bears consume, and through a detailed observation of their energy allocation to maintenance, movement and growth, an energy budget can be created. The proposed study will validate and improve two widely employed techniques for estimating the diets of free-ranging predators: stable isotope analysis and fatty acid signature analysis. The polar bears in this study will be fed a controlled, nutritionally complete, highly palatable diet over a time period sufficient to allow their bodily tissues to incorporate the components of the diet in a predictable fashion. In coordination with the Toronto Zoo veterinary staff, and in correspondence with periods when the bears are scheduled to be immobilized, small samples of blood, fat, fur and claw will be collected in a way to minimize any pain or disturbance to the animal. These samples will then be analyzed to determine how dietary components are integrated into the polar bears' tissues. These data will then be used to develop improved models for estimating the diets of polar bears in the wild. The results of this study will provide critical insights into the ecological impacts of ongoing and future environmental change on polar bears.

Within the framework of the above the following research projects were established at Toronto Zoo where implementation was possible.

  • A study of energy intake, growth and activity in a captive polar bear cub.
    The 'orphaned' polar bear cub, Hudson, provided a unique opportunity to study food (energy) intake, growth rate and activity in a growing polar bear. His daily food intake was regimented and intake and growth were measured and documented from 16 weeks of age until 1 year. During the summer of 2012 ethograms were made during a period of 6 weeks and local weather data were documented. These data will be combined and evaluated.

  • Stable isotope and fatty acid signature validations.
    Samples from a female polar bear (Aurora) were opportunistically obtained. Her "zoo diet" will be homogenized for sampling.

    Two male polar bears (Inukshuk and Ganuk) currently stationed at the Cochrane Polar Bear habitat will be fed a mimicked wild diet (Meat bone and blubber) from sustainably harvested harp Seal (Pagophilus groenlandicus) or Ring Seal (Pusa hispidia) for a period of 8 -12 weeks. The diet will be homogenized and sampled. The bears will be immobilized and sampled after the feeding period.

    These samples will be analysed for stable isotopes (carbon 13C and nitrogen 15N) and fatty acid profile and the results will be used for validation.

  • Validation of a body composition model as prepared by Molnar et al, 2009.
    Whenever the opportunity arises the body mass and the recumbent body length of polar bears will be measured and documented to validate Molnar's model.
Potential additional projects are:
  • Calibration of photographic techniques for measuring body length to relate to recumbent body length.
  • Collaboration in testing new Collar hardware.
  • Body mass changes and appetite patterns in relation to season and psychological status.
  • Development of Fecal Near Infra-Red Scans (FNIRS) related to diet.

MASS PRODUCING NATIVE INSECTS FOR THE PANAMA FROG RESCUE PROGRAM


(T. Mason, L. Perrotti of Roger Williams Park Zoo, Rhode Island)

For several years Toronto Zoo has helped with the Panama Frog Rescue Program run by Houston Zoo. This has involved financial and active aid directly involved with the frogs. In 2007, Lou Perrotti, Manager of Conservation Projects at Roger Williams Park Zoo in Rhode Island found out that EVACC, the El Valle Amphibian Conservation Center in Panama was having to collect insects from the wild to feed the 500 + frogs in their collection. He was asked to develop a system whereby native Panamanian insects could be mass reared to be used as food for the frogs. This would reduce the time taken in procuring the food, provide more consistent food for the frogs and reduce the impact on the insect populations in the wild. In 2008, Lou asked Tom Mason to join him in the program. In two trips to El Valle, the facility has been successful in developing methods of producing 4 species of katydids and taught staff at EVACC how to collect insect species such as termites in an efficient manner. Other invertebrates such as springtails and sow bugs have also been cultured. It is hoped that the systems developed will aid in the maintenance and conservation of the frogs and that what is learned can be transferred to similar conservation programs around the world.

POLAR BEAR ENERGETICS STUDY - Captive Studies to Improve Diet Estimates and Bioenergetics Modeling of Polar Bears in the Wild


(G. Thiemann)

The proposed study will validate and improve two widely employed techniques for estimating the diets of free-ranging predators: stable isotope analysis and fatty acid signature analysis. The polar bears in this study will be fed a controlled, nutritionally complete, highly palatable diet over a time period sufficient to allow their tissues to incorporate the components of the diet in a predictable fashion.

In coordination with the Toronto Zoo veterinary staff, and in correspondence with periods when the bears are scheduled to be immobilized, small samples of blood, fat, fur and claw will be collected in a way to minimize any pain or disturbance to the animal. These samples will then be analyzed to determine how dietary components are integrated into the polar bears' tissues. These data will then be used to develop improved models for estimating the diets of polar bears in the wild. By carefully observing and quantifying the amount of food the polar bears consume, and through a detailed observation of their energy allocation to maintenance, movement and growth, an energy budget will be created. At this time the Zoo's bears will not be immobilized for this study alone, although this may be requested subsequently if there is no opportunity for sample collection. Attempts will be made to train animals for these procedures.

The results of this study will provide critical insights into the ecological impacts of ongoing and future environmental change on polar bears.


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