Gut-Loading Diet Evaluation for Crickets (Acheta domesticus), Mealworms (Tenebrio molitor), and Superworms (Zophobas morio) for the Purposes of Optimizing Institutional Protocols

For captive insectivorous birds, reptiles, and amphibians, gut-loading has become an essential part of a balanced diet when feeding commercial feeder insects. The captive bred crickets, mealworms, and superworms being fed have inadequate Ca and vitamin A to meet the nutritional needs of these animals. The trials conducted for this study were to determine which gut-loading diet would be the...

Carotenoid Gut-Loading of Crickets and Mealworms

The lack of diversity of invertebrate prey items available to feed captive animals limits available nutrients, requiring manipulation of the diet fed to these prey items prior to offering to other animals. Of late, much of the gut-loading research and recommendations focused on correcting the Ca:P imbalance inherent to the insects available through commercial production. More recently, attention has shifted...

Practical Investigation of Cricket Dust Supplements Commonly Used to Enhance Diets Provided to Insectivore Species under Human Care

Amphibians and reptiles commonly managed under human care are commonly fed farmed feeder crickets (Acheta domesticus) that are deficient in calcium. Calcium deficiency can lead to the development of nutritional metabolic bone disease in animals consuming the crickets; therefore, feeder crickets are commonly supplemented with calcium by either dusting the crickets’ exoskeleton or by providing crickets with a calcium enriched...

Development of an Artificial Diet to Support Conservation Efforts of the Atala Hairstreak Butterfly (Eumaeus atala)

The rare atala hairstreak butterfly (Eumaeus atala) is native to Florida, and coontie, a small cycad, is its only native host plant. In the early 1900’s, coontie was eradicated due to unsustainable agricultural practices, so atala populations plummeted.  The butterfly was thought to be extinct in the mid-1900s but has seen a comeback since its rediscovery near Miami in the...

Practical investigation of cricket dust supplements commonly used to enhance diets provided to insectivore species under human care.

Amphibians  and  reptiles  commonly  managed  under  human  care  are  commonly  fed  farmed  feeder  crickets  (Acheta  domesticus)  that  are  deficient  in  calcium.  Calcium  deficiency  can  lead  to  the  development  of  nutritional  metabolic  bone  disease  in  animals  consuming  the  crickets;  therefore,  feeder  crickets  are  commonly  supplemented  with  calcium  by  either  dusting  the  crickets’exoskeleton  or  by  providing  crickets  with  a  calcium  enriched  diet. ...

Development of an artificial diet to support conservation efforts of the Atala Hairstreak Butterfly (Eumaeus atala)

The rare atala  hairstreak  butterfly  (Eumaeus  atala)  is  native  to  Florida,  and  coontie,  a  small  cycad,  is  its  only  native  host  plant.  In  the  early  1900’s,  coontie  was  eradicated  due  to  unsustainable  agricultural  practices,  so  atala  populations  plummeted.    The  butterfly  was  thought  to  be  extinct  in  the  mid-1900s  but  has  seen  a  comeback  since  its  rediscovery  near  Miami  in  the ...

Body Condition Scoring Resource Center

  The following body condition scoring (BCS) scales have been obtained from a variety of sources.  We have credited the authors where we can, and encourage you to submit newly developed or modified scales or corrections to attributions.

The following body condition scoring (BCS) scales have been obtained from a variety of sources.  We have credited the authors where we can, and encourage you to submit newly developed or modified scales or corrections to attributions.

Click to expand

Pangolins, Aardvarks, & Xenarthrans (Sloths, Anteaters, Armadillos)

About BCS Scales

Body condition scoring (BCS) is a subjective measurement of an animal’s muscle definition and superficial fatty tissue.

BCS for Zoo Animals

BCS has been used for many years in the livestock industry to evaluate and improve the productivity, health, reproduction and longevity of herds.  BCS has become increasingly common in zoological settings for many of the same reasons.  Our greatest challenge in zoos is to develop practical systems or scales for the diverse species with which we work.  Some scales have been well-developed and validated, while others remain works in progress.  The NAG encourages the careful and thoughtful development of new scales, the refinement of those that already exist, and the diligent attention to their implementation for the good of the animals in our care.

About BCS Scales

Body condition scoring scales are numerical, and they typically range from 1 (emaciated) to either 5 or 9 (obese).  When using a 5-point scale, many people will assign half points (2.5 or 4.5 out of 5), which effectively turns the 5 point scale into a 9 point scale.  Whenever possible, we recommend the use of a 9 point scale.


Implications of BCS Scores


Low BCS scores have been associated with lowered reproductive success, poor recovery from illness, and may be a sign of disease or age.  High BCS scores have been associated with an increased risk of dystocia (difficulty giving birth), reproductive disorders, arthritis, diabetes, and other chronic conditions (Chan-McLeod et al. 1994; Burkholder 2000; Aeberhard et al. 2001; Busato et al. 2002; Berry et al. 2007; Boudreau 2012).  Despite the known risks of being too far at either end of the BCS spectrum, a BCS score should be non-judgmental.  You may be pleased that an animal recovering from a serious illness has moved from a 2 to a 3 (on a 9-pt scale), yet worry that a healthy animal has dropped from a 4 to a 3.  You may be glad that an obese animal has dropped from an 8 to a 5, yet endeavor to raise an animal preparing for hibernation from a 5 to an 8 or 9 (which may be “normal,” physiologically, for the species in question).  Keep in mind that just because it may be “normal” for a species to be over-conditioned at a specific time of year or life stage, this does not impact the BCS scale (a score of 8/9 remains 8/9, even if declared “appropriate” in terms of animal management; the scale does not “slide” to make that over-conditioned animal a 5/9). In addition, the scale is does not slide for growing, geriatric, or pregnant animals (regardless of stage of life, metabolic status, etc, the scale is designed to assess condition as objectively as possible).

Tips for Body Condition Scoring

  • BCS is best learned and implemented through consistent practice.  Often, it helps to have multiple staff involved at the start (animal managers, keepers, veterinarians, nutritionists, etc.) to make sure everyone is on the same page regarding terminology, anatomy, and the scoring system being used.  In the end, however, it is often best to have a limited number of scorers so that consistency can be maintained.  In addition, having someone who does not see the animals every day perform the scoring can be helpful.
  • Scorers should be familiar with the anatomy of each species.  If multiple scorers are utilized, they should be objectively evaluated for consistency with the same animals.  It can be helpful to note the initials of the scorer when a BCS is performed and recorded.
  • Although there are many different systems/scales (even for a single species), it is a good idea to pick one scoring system for each species and stick with it.  This allows for increased familiarity and proficiency, over time.
  • BCS is a particularly useful tool for animals that aren’t very tractable or for those who are unable to be weighed regularly.  If body weights are available, BCS acts as a complementary assessment for management purposes.  Ensure that the interval between BCS is reasonable and practical.
  • For growing animals, body weights can be paired with appropriate growth curves to assess development. However, body weights in growing individuals often vary, even within species, and may not be the best assessment of growth. In these cases, BCS can be used not only to assess appropriate growth, but also to establish target weights for individuals.

Developing BCS Scales

If your species of interest does not have a scale established, please consider developing one.  If you do, look at those that have already been thoughtfully developed.

Ideal BCS scales are easy to use, distinguish biologically relevant changes in status, provide enough description that multiple observers will obtain similar results, and, ideally, have been validated through other means (ultrasound, TOBEC, necropsy).  Photographs and drawings should clearly show points of interest and be coupled with clear written descriptions.   The NAG encourages you to share your systems by presenting a poster or presentation at our conference, or publishing in another format that can be accessed by the zoo community.

    • Aeberhard K, Bruckmaier RM, Kuepfer U, and Blum JW. 2001. Milk Yield and Composition, Nutrition, Body Conformation Traits, Body Condition Scores, Fertility and Diseases in High-Yielding Dairy Cows – Part 1. Journal of Veterinary Medicine Series A 48:97–110.
    • Berry DP, Lee JM, Macdonald KA, and Roche JR. 2007. Body Condition Score and Body Weight Effects on Dystocia and Stillbirths and Consequent Effects on Postcalving Performance. Journal of Dairy Science 90:4201–4211.
    • Boudreau L. 2012. Effect of Moderate Diet Restriction on Body Condition, Health, and Reproductive Performance in Female Mink (Neovison vison).
    • Burkholder WJ. 2000. Use of body condition scores in clinical assessment of the provision of optimal nutrition. Journal of the American Veterinary Medical Association 217:650–654.
    • Busato A, Faissler D, Küpfer U, and Blum JW. 2002. Body condition scores in dairy cows: associations with metabolic and endocrine changes in healthy dairy cows. Journal of Veterinary Medicine Series A 49:455–460.
  • Chan-McLeod ACA, White RG, and Holleman DF. 1994. Effects of protein and energy intake, body condition, and season on nutrient partitioning and milk production in caribou and reindeer. Canadian Journal of Zoology 72:938–947.

If you know of additional published resources for this page, we encourage you to submit them for potential inclusion:

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    A review of the nutrient content of commercial feeder insects and strategies for increasing their nutrient content

    Insects are an important source of nutrients for a wide variety of captive insectivores including many reptiles and amphibians. Nutrient analysis of many of the more common commercially available feeder insects has now been published. These data are reviewed and discussed in light of the fact that unlike many free ranging animals, insectivores in captivity are fed a limited number...

    Considerations to maximize nutrient supplementation of feeder insects

    Providing a nutritionally appropriate diet to amphibians and other insectivores under human care has long proved challenging. The number of available insect species is limited and typically deficient in key nutrients such as calcium and vitamin A. Until more nutritionally balanced options are available, actions should be undertaken to improve the nutritional quality of feeder insects such as the domestic...

    Gut loading as a method to effectively supplement crickets with calcium and vitamin A

    Limited quantities of vital nutrients such as calcium and vitamin A in crickets have led to the occurrence of diseases such as rickets, osteomalacia, metabolic bone disease (calcium deficiency) and more recently, squamous metaplasia or “short tongue syndrome” in amphibians. Gut loading has been an effective method to supplement feeder crickets with both calcium and vitamin A. A dose of...

    Vitamin A supplementation via cricket dusting: the effects of dusting fed and fasted crickets of three sizes using two different supplements on nutrient content

    This study was undertaken to determine the efficacy in delivering vitamin A supplementation via dusting feed crickets (Acheta domestica) to reptiles and amphibians, many of whom have shown vitamin A deficiencies at Disney’s Animal Kingdom and other institutions. While there have been multiple previous studies regarding supplementation in crickets, the majority have focused on calcium supplementation. Levels of vitamin A...

    Evaluation of nutrient composition of common invertebrate feeders fed different supplemental diets

    While the complete nutrient composition of invertebrates commonly fed to insectivorous animals has been studied, research evaluating the differences among supplemental diets marketed to improve their overall nutrient composition is limited. Previous studies have focused on calcium intake in crickets, and to a lesser extent in mealworms, but diets for superworms have not been evaluated. This study evaluated the proximate...

    Evaluating gut-loading diets and dusting to improve the calcium concentration of pin-head and adult crickets (Acheta domesticus)

    Four experiments were conducted to evaluate the effectiveness of dusting crickets with calcium carbonate versus feeding a custom or commercial high-calcium diet on the calcium and phosphorus concentration of pin-head (13.7 mg) and juvenile (320.9 mg) crickets. Crickets were housed in 37.9 L aquariums, provided with water and egg crates for hiding, maintained on a 12 h light: 12 h...

    The effect of terrarium size, egg crate area, stocking density, and time on cricket mortality and the ability to achieve a 1:1 calcium to phosphorus ratio

    In order to provide a nutritionally adequate diet for captive insectivorous animals, invertebrates such as crickets and mealworms must be supplemented with calcium. Current methods of supplementation include dusting and gut-loading. The size of the terrarium, the area of egg crates within the terrarium, cricket stocking density, and length of time on the gut loading diet, may all play a...

    The effect of a produce based gut loading diet on mineral and vitamin content of adult crickets (Acheta domestica)

    Adequate supplementation of calcium and other nutrients including vitamin A is integral to successfully holding insectivorous amphibians and reptiles in captivity. Dusting and gut loading insects are two commonly used methods of supplementation. A produce based gut loading diet may be more palatable and thus may gut load more successfully and for an extended period of time. Adult crickets (Acheta...

    Calcium gut loading of mealworms (Tenebrio molitor) and the benefit of gel water over apple slices for maximum calcium gut loading

    The importance of gut loading insects with calcium is a critical component of an insectivorous animal’s diet. The insect used in this study for calcium supplementation was the regular mealworm (Tenebrio molitor). The standard operating procedure for most gut loading protocols includes feeding high-water produce items (i.e., apples, leafy green vegetables, etc.) in conjunction with a high calcium insect supplement....

    Nutrient composition of whole crayfish eaten by hellbender salamanders (Cryptobranchus alleganiensis spp.)

    Four species of native Missouri crayfish identified as foods of the Ozark hellbender salamander (Cryptobranchus alleganiensis bishopi), were analyzed for nutrient content including water, proximate composition (crude protein, crude fat, crude fiber, and ash), as well as vitamin A, vitamin E, total carotenoids, and select mineral concentrations. Additionally, fatty acids in crayfish were examined and compared with krill as a...

    Investigations into the nutritional composition of moon jellyfish, Aurelia aurita

    Proximate nutrients, fat-soluble vitamins A and E, and mineral composition of the moon jellyfish, Aurelia aurita, were measured in wild specimens from Jamaica Bay, NY, and in captive cultured specimens from the New York Aquarium (reported as mean ± SE). Crude protein content of free-ranging jellyfish was approximately twice that seen in captive animals (9.20% ± 0.40% dry matter (DM)...

    Preference of supplemental nectar by three native butterfly species

    Two diets, a sugar-water solution (Diet A) and nutritionally complete nectar solution (Diet B), provided in a mixed species enclosure as a source of nutrients for multiple nectivorous species were evaluated for preference among three North American species of butterflies. Preference was defined as number of visits to one of two nectar feeders. The feeder containing Diet B was preferentially...

    Influence of diet and time on fat and retinol concentrations in adult feeder crickets

    Many captive amphibians are fed supplemented crickets (Acheta domesticus) as a basal diet. There is concern that some amphibians have unique requirements for certain vitamins, particularly vitamin A due to its association with squamous metaplasia of mucous producing epithelia, resulting in inability to capture prey. Because vitamin A is fat soluble, it was hypothesized that increasing fat concentration of crickets...

    Calcium and insect gut-loading: the development of a protocol for achieving the best CA:P ratio for insectivorous animals

    Commercially raised insects have inverse calcium to phosphorus ratio. Captive insectivorous animals are potentially at risk for metabolic bone disorders if the calcium to phosphorus ratio is not equalized. This is achieved through an active supplementation program where the feeder insect is given access to a calcium rich diet prior to ingestion by the insectivore. A zoo-wide insect supplementation survey...

    A zoo-wide evaluation into the current feeder insect supplementation program at the Brookfield Zoo

    Commercially raised insects are an important food source for captive animals. For those animals that are purely insectivorous, the nutrient concentrations of the food source are vitally important for the health and welfare of the animal, particularly the Ca to P ratio. In the summer of 2002, a zoo-wide evaluation of the current methods of insect supplementation was conducted at...

    Effects of a high calcium diet on gut loading in varying ages of crickets (Acheta domestica) and mealworms (Tenebrio molitor)

    Insects are a poor source of calcium. Consequently, it is a common practice for zoos to supplement them in order to provide a nutritionally balanced diet to many species. Current methods of supplementation include dusting and gut-loading. The experiment was conducted in order to determine the effect of a high calcium diet on gut loading in varying ages of crickets...

    Feeding captive insectivorous animals: nutritional aspects of insects as food

    To successfully manage captive insectivorous species, data on nutritional composition of invertebrate prey are especially important. Since live insects may be the only food offered to some species, nutritional deficiencies can quickly arise if the nutrient levels in the live prey are imbalanced. Unfortunately, the few commercially available invertebrates are an incomplete nutrient package without appropriate supplementation, and may adversely...