Use of femur bone density to segregate wild from farmed Dybowski's frog (Rana dybowskii)

Shu, Yang; Huang, Xiao Ming; Xia, Rui; Xu, Yanchun; Dahmer, Thomas D.

doi:10.1016/j.forsciint.2010.09.001

Cited by 13 publications

(15 citation statements)

References 30 publications

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“…Age of each frog was determined by the tibiofibula slice procedure as described in Yang et al (2011). 60 frogs (32 males and 28 females) at the age of two years were collected from a frog farm located in the same region (126°29′ E, 44°10′ N, altitude 174 m) where the wild frogs were captured.…”

Section: Methodsmentioning

confidence: 99%

“…Bone structure and density are associated with diet and activity. Animals in the wild tend to be more active than those in the farm; therefore, femur bone density is a stable index useful for discriminating wild and farmed animals (Yang et al 2011). However, these approaches require bones to be isolated from the test animals and are often impracticable for use on live animals.…”

Section: Introductionmentioning

confidence: 99%

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Morphometric discrimination of wild from farmed Dybowski’s frog (Rana dybowskii) based on hindlimb length

Xia

Huang

Yang

et al. 2011

Journal of Forestry Research

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Commercial farming of anuran species that are declining in the wild raises a need to discriminate wild from farmed frogs. We hypothesized wild frogs might have extended hindlimbs due to greater frequency or intensity of jumping relative to farmed frogs, highlighting a morphometric approach to discrimination of wild from farmed frogs using hindlimb length. In the present study, Dybowski's frog (Rana dybowskii) was used to test this hypothesis. We measured body mass (M b ) and hindlimb length (L h ) of 2-year old farmed frogs and wild frogs aged 2 to 5 years. Dybowski's frog demonstrated significant dimorphism in M b and L h . M b was significantly greater among farmed 2-year old frogs in both sexes (p=0.000), while only among females was L h significantly greater for wild frogs (p=0.000). L h /M b was used as an index for origin discrimination to eliminate the influence of M b due to variation of husbandry conditions among farms. Mean L h /M b for farmed frogs was significantly lower than for wild frogs (p=0.000) in the 2-year old age class. Discrimination correctly classified 84.4% of farmed and 96.3% of wild male frogs. Among females, 92.9% of farmed frogs and 90.1% wild frogs were correctly classified. The overall correctness of classification was 92.1% and 90.8% for males and females, respectively. However, L h /M b Foundation project: This study was supported by the Project of Tackling Responsible editor: Chai Ruihai revealed variation with age, resulting in reduced discriminative power for frogs ≥3 years old. We introduced a coefficient C e to adjust the L h /M b of frogs ≥3 years to the level equivalent to 2-year frogs. The adjustment achieved 89.5% for overall correctness of origin for wild males and 92.4% for wild females ≥3 years old. These results show that L h /M b is an effective index to discriminate wild from farmed Dybowski's frog. Since the physical demands of jumping are common among anurans, this index is also potentially applicable to other anuran species.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Morphometric discrimination of wild from farmed Dybowski’s frog (Rana dybowskii) based on hindlimb length

Xia

Huang

Yang

et al. 2011

Journal of Forestry Research

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“…A third approach proposed in our previous reports was based on the femur, which is very simple to isolate and measure. The major differences between the femurs of farmed and wild Dybowski's frog ( Rana dybowskii ) are the volume density and the ratio of femur length to body mass . These differences result from the fact that wild animals have higher intensity of movements than farmed animals as they search for food and shelter, catch prey, and avoid predators.…”

mentioning

confidence: 99%

“…For most terrestrial animals, from amphibians, reptiles, birds to mammals, the movement intensity and diet spectrum are different between the wild and the farmed individuals, which may influence femur morphometric characteristics and density, as indicated in the Dybowski's frog . Thus, it is reasonable to predict that the effectiveness of the femur in segregating wild from farmed frogs is applicable to all terrestrial animals.…”

mentioning

confidence: 99%

Effectiveness of Femur Bone Indexes to Segregate Wild from Captive Minks, Mustela vison, and Forensic Implications for Small Mammals

Zhou

Shu

et al. 2014

Journal of Forensic Sciences

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Utilization of free-living populations of endangered wildlife species is usually strictly prohibited or restricted. Farming of endangered species can provide products that are in demand as a countermeasure. A novel forensic issue arises because it becomes necessary to discriminate the origin of given wildlife products. We tested the effectiveness of five measurements and four indexes of femur bone using farmed minks (n = 40) and escapees (n = 32). Results showed all measurements, namely body mass (L(f)), body length (M(f)), femur mass (V(f)), femur length (M(b)), and femur volume (L(b)), were highly discriminatory. However, they are susceptible to the influence of nutrition level and sex. Femur length index (I(fl)), femur linear density (D(l)), and femur volume density (D(v)) eliminated the influence of level of nutrition and were highly effective. However, I(fl) and D(l) were influenced by sex (p = 0.000). Because D(v) was not influenced by sex (p = 0.683) and was highly effective, it was the preferred index.

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“…Different attempts were made to shed light on the identity of traded species, but to know which species are involved does not necessarily allow conclusions if they were farmed or wild‐caught (Veith, Kosuch, Feldmann, Martens, & Seitz, ). Another promising attempt was measuring femoral bone density, where frogs from captivity show lighter bones (Yang, Huang, Xia, Xu, & Dahmer, ). However, this method is rather complex and difficult to standardize.…”

Section: Introductionmentioning

confidence: 99%

Stable isotope analyses—A method to distinguish intensively farmed from wild frogs

Dittrich

Struck

Rödel

2017

Ecology and Evolution

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Consumption of frog legs is increasing worldwide, with potentially dramatic effects for ecosystems. More and more functioning frog farms are reported to exist. However, due to the lack of reliable methods to distinguish farmed from wild‐caught individuals, the origin of frogs in the international trade is often uncertain. Here, we present a new methodological approach to this problem. We investigated the isotopic composition of legally traded frog legs from suppliers in Vietnam and Indonesia. Muscle and bone tissue samples were examined for δ15N, δ13C, and δ18O stable isotope compositions, to elucidate the conditions under which the frogs grew up. We used DNA barcoding (16S rRNA) to verify species identities. We identified three traded species (Hoplobatrachus rugulosus, Fejervarya cancrivora and Limnonectes macrodon); species identities were partly deviating from package labeling. Isotopic values of δ15N and δ18O showed significant differences between species and country of origin. Based on low δ15N composition and generally little variation in stable isotope values, our results imply that frogs from Vietnam were indeed farmed. In contrast, the frogs from the Indonesian supplier likely grew up under natural conditions, indicated by higher δ15N values and stronger variability in the stable isotope composition. Our results indicate that stable isotope analyses seem to be a useful tool to distinguish between naturally growing and intensively farmed frogs. We believe that this method can be used to improve the control in the international trade of frog legs, as well as for other biological products, thus supporting farming activities and decreasing pressure on wild populations. However, we examined different species from different countries and had no access to samples of individuals with confirmed origin and living conditions. Therefore, we suggest improving this method further with individuals of known origin and history, preferably including samples of the respective nutritive bases.

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Use of femur bone density to segregate wild from farmed Dybowski's frog (Rana dybowskii)

Cited by 13 publications

References 30 publications

Morphometric discrimination of wild from farmed Dybowski’s frog (Rana dybowskii) based on hindlimb length

Morphometric discrimination of wild from farmed Dybowski’s frog (Rana dybowskii) based on hindlimb length

Effectiveness of Femur Bone Indexes to Segregate Wild from Captive Minks, Mustela vison, and Forensic Implications for Small Mammals

Stable isotope analyses—A method to distinguish intensively farmed from wild frogs

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