ArticlePDF Available

Abstract and Figures

Freshwater turtles are commonly kept in captivity as pets, bred in zoos for conservation programs, and commercially farmed for pet markets and human consumption, but their nutrition can be challenging. However, based on practical experience, two main strategies may be identified: the use of non-calculated raw diets and the use of balanced commercial feeds. Raw diets are based on fresh, frozen and dried components including invertebrates, fish, rodents and plant matter; they imitate the variety of foods that are accessible to turtles in the wild and are considered most useful when turtles are bred for reintroduction into their natural habitat as part of conservation programs. Granulated, pelleted or extruded commercial diets are frequently used for farmed and pet turtles; they contain animal- and plant-based materials supplemented with vitamin and mineral premixes and calculated to reach the nutrient levels assumed to be optimal for most species. Until more species-specific information on the nutritional requirements of freshwater turtles is available, the Chinese softshell turtle (Pelodiscus sinensis), a commonly commercially farmed species for human consumption, may be used as a reference for other species in terms of suggested nutrients levels. Based on experimental data, the most important nutrients and their levels that should be included in turtle diets are crude protein (39.0 - 46.5%), crude fat (8.8%), Ca (5.7%), P (3.0%), methionine (1.03%), and cysteine (0.25%). The diet composition for freshwater turtles should be based on scientific knowledge and practical experience, so this paper aimed to present and discuss the available data on the nutrient requirements of turtles and the characteristics of the feed materials used in their nutrition.
Content may be subject to copyright.
Ann. Anim. Sci., Vol. 18, No. 1 (2018) 17–37 DOI: 10.1515/aoas-2017-0025
Mateusz Rawski1,2♦, Christoph Mans3, Bartosz Kierończyk1
, Sylwester Świątkiewicz4, Aneta Barc1,
Damian Józeak1
1Department of Animal Nutrition and Feed Management, Poznań University of Life Sciences,
Wołyńska 33, 60-637 Poznań, Poland
2Division of Inland Fisheries and Aquaculture, Institute of Zoology,
Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland
3Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison,
2015 Linden Drive, WI 53706, Madison, United States of America
4Department of Nutrition Physiology, National Research Institute of Animal Production,
Balice n. Kraków, Poland
Corresponding author:
Freshwater turtles are commonly kept in captivity as pets, bred in zoos for conservation programs,
and commercially farmed for pet markets and human consumption, but their nutrition can be
challenging. However, based on practical experience, two main strategies may be identied: the
use of non-calculated raw diets and the use of balanced commercial feeds. Raw diets are based on
fresh, frozen and dried components including invertebrates, sh, rodents and plant matter; they
imitate the variety of foods that are accessible to turtles in the wild and are considered most useful
when turtles are bred for reintroduction into their natural habitat as part of conservation pro-
grams. Granulated, pelleted or extruded commercial diets are frequently used for farmed and pet
turtles; they contain animal- and plant-based materials supplemented with vitamin and mineral
premixes and calculated to reach the nutrient levels assumed to be optimal for most species. Until
more species-specic information on the nutritional requirements of freshwater turtles is avail-
able, the Chinese softshell turtle (Pelodiscus sinensis), a commonly commercially farmed species
for human consumption, may be used as a reference for other species in terms of suggested nutri-
ent levels. Based on experimental data, the most important nutrients and their levels that should
be included in turtle diets are crude protein (39.0–46.5%), crude fat (8.8%), Ca (5.7%), P (3.0%),
methionine (1.03%), and cysteine (0.25%). The diet composition for freshwater turtles should be
based on scientic knowledge and practical experience, so this paper aimed to present and discuss
the available data on the nutrient requirements of turtles and the characteristics of the feed mate-
rials used in their nutrition.
Key words: freshwater turtles, turtle nutrition, nutrient requirements, metabolic diseases, Pelo-
discus sinensis
* The current study was supported by the grant NCN PRELUDIUM: UMO-2013/11/N/NZ9/04624,
nanced by National Science Centre (Poland).
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
Freshwater turtles are widely distributed in almost all types of aquatic habitats
(Bonin et al., 2006), so their diets and feeding strategies in the wild vary substan-
tially. However, most are opportunistic carnivores or omnivores, consuming inver-
tebrates, small vertebrates, and aquatic vegetation (Bouchard and Bjorndal, 2006;
Gibbons, 1990; Luiselli et al., 2011; Ottonello et al., 2005; Rhodin et al., 2008;
Spencer et al., 1998). The wide spectrum of feeding strategies among freshwater
turtles and their slow metabolism may explain their high tolerance for unbalanced
diets, but their longevity and the energetic expense required for shell mineralization
make them vulnerable to nutritional deciencies in captivity (McWilliams, 2005).
Moreover, the nutrient requirements for most species, especially those not routinely
used in large-scale turtle farming, are poorly documented. It should be highlighted
that the nutritional needs of freshwater turtles are affected by numerous factors such
as the species, environmental conditions, digestion and assimilation efciency, sex,
age, health status and history of specimen (Figure 1), but diet composition should be
both species-specic and suitable for raising turtles in captivity. Therefore, diets used
in commercial turtle farming may not be adequate for non-commercial purposes in
terms of feed ingredients or physical form of the feed which are optimized in terms
of feed utilization and economic results. However, the available data on the nutri-
tional requirements of turtle species that are commonly raised commercially (i.e., the
Chinese softshell turtle (Pelodiscus sinensis) may be an important source of general
information for other turtle species kept as pets, in zoological institutions or as part
of conservation programs. This paper aimed to present and discuss the available sci-
entic data on the nutrient requirements of turtles and the characteristics of the feed
materials used in their nutrition.
Figure 1. Extrinsic and intrinsic factors and their interactions that affect the nutritional requirements of
turtles (Bouchard, 2004; Gibbons, 1990; Luiselli et al., 2011; McCauley and Bjorndal, 1999; Seebacher
et al., 2004; Spencer et al., 1998; Zhang et al., 2009)
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 19
Gastrointestinal tract anatomy and physiology of freshwater turtles
Turtles are monogastric animals, and their gastrointestinal tract (GIT) begins with
an oral cavity that has no lips or teeth (Mitchell and Tully, 2009). Therefore, they
are unable to chew their food but instead swallow entire prey or large bites. In some
species, feed cutting and shredding is performed with the use of a beak-like keratin
layer on the upper and lower jaw (rhamphotheca) as well as the claws. The shape and
function of the rhamphotheca is very similar among omnivorous turtle species, such
as pond turtles (Emydidae), but in highly specialized turtles, the structure reects
their feeding habits. The rhamphotheca may be very well developed as in the alliga-
tor snapping turtle (Macrochelys temminckii), which has powerful jaws, or reduced
as in the matamata turtle (Chelus mbriata), which has a limited bite force (Lemell et
al., 2010). Due to the large feed intake by a turtle during a single meal, the pharynx,
esophagus and stomach are highly exible. In the stomach, the low pH and enzy-
matic activity starts the digestion process. The stomach is curved to the left, shorter
and wider than the esophagus, and its mucosal surface is divided into the proper gas-
tric and cardiac glandular mucosa regions (Stevens and Hume, 1998). There are two
kinds of gastric glands in the stomach, peptic cells and oxyntic cells, which indicates
that turtles are well adapted for omnivory (Rahman and Sharma, 2014).
The small intestine is the longest organ in the turtle GIT (Figure 2), but the duo-
denum, jejunum and ileum are not well distinguished and difcult to identify (Rah-
man and Sharma, 2014). The length and capacity of the intestines is diet-dependent
and may vary signicantly between species and different diets (Bouchard, 2004).
The mucosa of the small intestine is composed of a single columnar epithelium,
and the lining of the intestinal villi includes three types of cells: simple columnar
cells, goblet cells and endocrine cells (McArthur et al., 2008; Rahman and Sharma,
2014; Wurth and Musacchia, 1964). The large intestine seems to be a site for wa-
ter absorption, microbial fermentation and short-chain fatty acid (SCFA) produc-
tion (Bouchard, 2004); its proximal part is the caecal extension of the colonic wall
(Bouchard, 2004; McArthur et al., 2008). The colon is typically divided into three
parts: ascending, transverse and descending. The reptile GIT ends with the cloaca,
the site where the terminal parts of the GIT, urinary and reproductive tracts join,
which is subdivided into the coprodeum, urodeum and proctodeum (McArthur et al.,
2008; Mitchell and Tully, 2009). Turtle saliva does not contain digestive enzymes,
which are instead secreted by the stomach, pancreas and intestines. Chelonian stom-
achs secrete amylase, pepsin, trypsin, chitinase and chitobiase; the pancreas secretes
amylase, ribonuclease, trypsin, chymotrypsin, carboxypeptidase A and chitinase; and
the intestines secrete proteinase, invertase, amylase, maltase, chitobiase, trehalase,
isomaltase and sucrase (McArthur et al., 2008). Protease and amylase are considered
the two main digestive enzymes in the turtle GIT (Sun et al., 2007), and the opti-
mal conditions for their specic activities vary among GIT segments. In the pond
slider (Trachemys scripta), pancreatic protease shows the highest activity (36 U/mg
of protein), and in the stomach, maximal protease activity (24 U/mg of protein) was
recorded at pH 2.5 and 40°C. In contrast, amylase had the highest activity (12 U/mg
of protein) in the anterior intestine under neutral conditions (Sun et al., 2007). The
liver is, to some extent, divided into triangular lobes (Rahman and Sharma, 2014),
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
and it plays a key role in vitamin D3 synthesis and storage and the transformations of
lipids, proteins and glycogen. Another important GIT gland is the pancreas, which
is situated along the proximal segment of the duodenum (McArthur et al., 2008).
Because turtles are ectothermic, their metabolic rate and digestion mainly depends
on the temperature of the environment and external heat sources.
For most turtle species, feed intake and enzyme secretion and activity, as well
as the absorptive capacity of the intestinal mucosa, are highest and feed passage
is shortest in the preferred optimal temperature zone (POTZ), above which these
parameters decrease (Figure 3) (McArthur et al., 2008; Seebacher et al., 2004; Sun
et al., 2007). In most species, this zone is between 25 and 34°C (Table 1) (Gibbons,
1990; Mitchell and Tully, 2009), and turtles can even reach their POTZ in lower air
temperatures through basking behavior. However, there are exceptions, especially
in species that naturally inhabit cold mountain creeks such as the big-headed turtle
(Platysternon megacephalum), whose POTZ is 22–25°C (Jianwei et al., 2013; Zhang
et al., 2009). Due to the above-mentioned behavioral mechanism and the lack of
energetic expenses for heat production, the average reptile energy expenditure is
only 25–35% that of mammals (Mader, 2005). In reptiles, energy utilization mainly
depends on feeding strategy and diet composition. Carbohydrates are a source of
75% of the metabolizable energy for herbivorous and 50% for omnivorous reptilian
species. In carnivores, carbohydrates provide only 5% of the dietary matabolizable
energy, while protein provides 50% and fat 45% (Hand et al., 2000; Mader, 2005).
The function of the GIT microbiota has not been well studied in reptiles, but it seems
to play an important role in the secretion of bacterial enzymes and the immuno-
logical response. Similar to other animals, microbial homeostasis in reptiles may
improve gut health, while disturbances in composition may lead to depressed growth
and subclinical and clinical infections (Lei and Yaohong, 2010; Zhang et al., 2014;
Rawski et al., 2016). The microbial GIT symbionts in turtles signicantly support
plant matter digestion and produce SCFAs, which may be an important energy source
for omnivorous or herbivorous animals (Bouchard and Bjorndal, 2005). Based on its
SCFAs concentrations, the anterior large intestine should be considered the main site
of microbial fermentation of carbohydrates of plant origin in T. scripta. In the Florida
red-bellied cooter (Pseudemys nelsoni), microbial fermentation may also occur in the
small intestine (Bjorndal and Bolten, 1990; Bouchard and Bjorndal, 2005). It has been
suggested that the importance of SCFAs as energy source increases with an increase
in the amount of plant matter in the turtle diet, but it may also depend on fermentation
capacity (Bouchard, 2004; Bouchard and Bjorndal, 2005). The pattern of the relative
proportions of SCFAs in T. scripta was described as acetate > propionate > butyrate >
valerate (Bouchard and Bjorndal, 2005). During development, several species undergo
an ontogenetic diet shift from carnivorous hatchlings to omnivorous adults (Bouchard,
2004; Bouchard and Bjorndal, 2006; McCauley and Bjorndal, 1999); this occurs in
Emydidae and Chelidae as well as in other reptile species (Bouchard, 2004; Bouchard
and Bjorndal, 2005, 2006; Kennett and Tory, 1996). Both juvenile and adult turtles
digest animal and plant matter, but animal matter has a higher digestibility compared
to plant matter in juvenile T. scripta (97.2% vs. 89.4%) and results in greater growth
(0.2 vs. 0.6 g/week). In adults, plant matter is more digestible (Bouchard and Bjorndal,
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 21
2006). However, in most cases, adult turtles do not become predominately herbivo-
rous; in T. scripta, the animal to plant matter ratio in the diet was recorded as 77:23
(Gibbons, 1990). This diet composition may by highly nutritive for GIT microbiota,
and the nutrients supplied from animal matter may support plant matter microbial
fermentation (Bjorndal, 1991). It is assumed that adult turtles can meet their meta-
bolic demands on a plant-based diet, which would be insufcient to meet juvenile
growth requirements due to the low concentration of protein and energy (Bouchard
and Bjorndal, 2006).
Figure 2. Gastrointestinal tract (GIT) segment proportions (% of the entire GIT length) in selected turtle
species. Data for Trachemys scripta (n=40, 1 year old non-sexed specimens), Sternotherus odoratus
(n=36, 1 year old non-sexed specimens) and Apalone ferox (n=40, 1 year old non-sexed specimens),
M. Rawski unpublished data. *Data for Pangshura tenoria (n=20, adult specimens, both sexes) based on
the literature (Rahman and Sharma, 2014)
*POTZ – preferred optimal temperature zone.
Figure 3. Dependence of turtle nutritional performance (including feed intake, digestion efciency,
enzyme secretion, digesta turnover) on environmental temperature (Seebacher et al., 2004; Zhang et al., 2009)
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
Table 1. A summary of published reports on body temperature in free-ranging turtles and the
preferred body temperature
body temperature
body temperature
Chelydra serpentina 22.7 (SD=2.8) 27–30 (hatchlings)
27–33 (yearlings)
Brown et al., 1990; Bury et
al., 2000
19.96 (12.21–27.76) NA*Fitzgerald and Nelson, 2011
19.3–22.2 25.3 (juveniles) Jianwei et al., 2013
Chrysemys picta 25–32
(basking temperature)
34 (juveniles) Grayson and Dorcas, 2004;
Tamplin and Cyr, 2011
Glyptemys insculpta 23.2 (SD=3.9)
5–30 (basking temperature)
30 (juveniles) Ernst, 1986; Tamplin, 2009
Pseudemys nelsoni NA*30 (hatchlings) Nebeker and Bury, 2000
Terrapene ornata 28.0 (15.3–35.3) 28.3 (fasted)
29.8 (recently fed)
Gatten Jr, 1974; Legler, 1960
Trachemys scripta 27.2–38.0 30 (hatchlings) Bury et al., 2000; Gibbons,
Ocadia sinensis NA*25.4–29.2 (juveniles) Pan et al., 2002
Apalone spinifera NA*30 (juveniles) Feltz and Tamplin, 2007
Pelodiscus sinensis NA*30.3 (juveniles) Sun et al., 2002
Chelodina longicollis 20.2–24.4 NA*Seebacher et al., 2004
*NA – data not available.
Nutritional requirements
In contrast to domesticated animals, no standardized nutritional requirements are
available for most freshwater turtles, which makes the provisioning of a proper diet
in captivity challenging. There are general rules for feeding different age groups of
turtle species that inhabit a wide range of ecological niches, but it should be em-
phasized that in the case of highly specialized species, such as the matamata (Che-
lus mbriata), only species-specic diets that reect their feeding ecology in the
wild should be provided. Nutritional requirements are best known for commonly
farmed freshwater turtle species, and they may be used as a reference and by analogy
for other turtles until better information is published. The Chinese softshell turtle
(Pelodiscus sinensis) is the best-known species due to large-scale farming in Asia,
and many studies on its nutritional requirements have been published (the results
are summarized in Table 2). In the rst days after hatching, turtles may not con-
sume any food due to yolk sac absorption, which satises some of the nutritional
needs of hatchlings (Mitchell and Tully, 2009). The hatchlings of most freshwa-
ter turtle species are almost strictly carnivorous (Bouchard, 2004; Bouchard and
Bjorndal, 2006), so their growth performance is correlated with the concentration
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 23
of crude protein (CP) in the diet (Gibbons, 1990). The optimal CP level for young
Pelodiscus sinensis is assumed to be as high as 39–46.5% (Jia et al., 2005; Nu-
angsaeng and Boonyaratapalin, 2001; Zhou et al., 2013) and is likely dependent on
the energy content of the diet (Nuangsaeng and Boonyaratapalin, 2001). A study of
P. sinensis suggests that the optimal CP to energy ratio of the diet should be at the
level of 32–36 mg/kJ–1 (Zhou et al., 2013). This ratio should be considered an impor-
tant factor in diet suitability; when the ratio is too low, it may not only limit growth
but feed intake as well. Crude protein characteristics, such as the quantity, ratios and
bioavailability of essential amino acids, are key factors in animal nutrition (Ei and
Kavas, 1996). Methionine and cysteine seem to be limiting amino acids in P. sinensis
with estimated optimal levels of 1.03% and 0.25% of the diet, respectively (Huang
and Lin, 2002). No experimental information is available for lysine. Exogenous tau-
rine also seems to be essential and should constitute 0.9% of the diet, especially
when CP of plant origin is used (Hou et al., 2013). The CP concentration in captive
turtle diets may be lowered when the animals reach sexual maturity and their growth
rate decreases, and plant matter should be provided to achieve this goal. A nutritional
experiment using the scorpion mud turtle (Kinosternon scorpioides) indicated that
slow-growing adults may be fed CP at a lower level than young turtles (26%), but
in the case of breeding stock females, diets containing 61–66% animal-derived CP
increased laying performance and egg quality compared to 26% dietary CP (da Costa
Araújo et al., 2013). Furthermore, in the case of slow-growing, non-breeding stock
adult males or females, the balance of protein and energy should be only slightly
above zero to avoid obesity (Rawski and Józeak, 2014).
Nutritional recommendations for P. sinensis diets are optimized to maintain high
growth performance, so when turtles are not maintained under commercial farming
conditions, energy and protein concentrations may be lowered to prevent too-rapid
growth and poor skeletal system development. Due to the low energetic expenses of
turtles and the high availability of feed in captivity, no additional source of dietary
fat is needed in most cases. However, in fast-growing P. sinensis, the optimal fat con-
tent in the diet is estimated to be 8.8%, and there is no apparent effect of fat source
on growth performance (Lin and Huang, 2007). Turtles probably have the highest
skeletal mass to body weight ratio among all vertebrates. Calcium and phosphorus
should be given at a ratio of approximately 2:1, i.e., 5.7% and 3.0% of the diet, re-
spectively, according to studies of P. sinensis (Huang et al., 2003); a lower Ca:P ratio
may cause shell malformations or lower growth rates. Other minerals such as Mg,
Fe, Zn and Cu also seem to be important for turtle metabolism and shell mineraliza-
tion (Chen et al., 2014; Chu et al., 2007; Huang et al., 2003; Huang et al., 2010; Wu
and Huang, 2008). Vitamins are a group of complex organic compounds that are
present in small amounts in plant and animal matter. Their ingestion is essential for
normal metabolism, and deciencies can lead to various diseases (McDowell, 1989).
Vitamin C has been shown to have an important role in the ability of turtles to with-
stand stress (Zhou et al., 2002). The diet of P. sinensis should contain 2500 mg/kg of
vitamin C and 88 IU/kg of vitamin E (Huang and Lin, 2004; Zhou et al., 2002). For
vitamin A, 2000–8000 IU/kg of the diet on a dry matter basis seems to be adequate
(Mader, 2005), but this vitamin may be synthesized by turtles using β-carotene, of
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
which 50–90 mg/kg should be provided in the P. sinensis diet (Chen and Huang,
2011). In contrast, lutein and canthaxanthin may be equally or more effective forms
of provitamin A in reptiles, which may selectively absorb carotenoids (Raila et al.,
2002). Vitamin D3 synthesis occurs in reptilian skin and is stimulated by UVB radia-
tion; in carnivorous and omnivorous species, dietary sources of this vitamin seem
to play an important role (Hoby et al., 2010). However, despite being the key for
shell mineralization, the vitamin D3 requirements of turtles are still poorly known
(McArthur et al., 2008).
Table 2. Summary of the published reports on the nutritional requirements of young Chinese softshell
turtles (Pelodiscus sinensis)
Item Unit Optimal level References
Protein to energy ratio mg/kj–1 32–36 Zhou et al., 2013
Protein % 39.0–46.5 Jia et al., 2005; Nuangsaeng and
Boonyaratapalin, 2001; Xie et al.,
2012; Zhou et al., 2013
Fat % 8.8 Huang et al., 2005
Calcium % 5.7 Huang et al., 2003
Phosphorus % 3.0 Huang et al., 2003
Methionine % 1.03 Huang and Lin, 2002
Methionine % of protein 2.48 Huang and Lin, 2002
Cysteine % 0.25 Huang and Lin, 2002
Cysteine % of protein 0.60 Huang and Lin, 2002
Taurine % 0.90 Hou et al., 2013
Magnesium mg/kg 970–980
(phytic acid free diet)
Chen et al., 2014
Iron mg/kg 266–325 Chu et al., 2007
Zinc mg/kg 35–46 Huang et al., 2010
Copper mg/kg 4–5 Wu and Huang, 2008
β-carotene mg/kg 49–89 Chen and Huang, 2011
Vitamin C mg/kg 2500–5000 Zhou et al., 2002
Vitamin A mg/kg 2.58–3.84 Chen and Huang, 2014
Vitamin E IU/kg–1 40 Huang and Lin, 2004
Feeding strategies in captivity
Due to the practical experience of zoos and breeders, two main strategies may
be distinguished for providing adequate nutrition for turtles in captivity. The rst is
the use of non-calculated, raw diets based on unprocessed or minimally processed
components, such as live, fresh, dried or frozen food items; the main aim is to imitate
the natural diets of freshwater turtles with undetermined nutritional requirements
(examples of natural diet compositions are shown in Table 3). The second strategy
is based on commercial diets, which may be considered suitable for the most com-
monly kept turtle species (in the Emydidae and Pelomedusidae families). Another
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 25
important issue is feeding frequency and quantity, which are restricted under natural
conditions by prey availability, season and predation success. These factors lead to
periodic starvation that results in the use of body energy reserves, which tends to
result in lower growth and breeding performance than would have been possible
based on the genetic potential of the animals. This is in contrast to the situation in
captivity, where regular access to an appropriate diet will lead to the fulllment of
the genetic potential. However, it should be emphasized that food restriction seems
to have health benets and promotes longevity in animals (Lawler et al., 2005). Ad-
ditionally, high nutrient and energy availability may result in accelerated growth and
poor bone mineralization in turtles, as observed in fast-growing poultry and other
animals (Julian, 1998), and it may also cause obesity in adult animals, including
turtles (Mader, 2005; Mitchell and Tully, 2009; Rawski and Józeak, 2014). Turtles
can achieve high feed intake; T. scripta elegans may consume up to 12% of its body
weight during one meal (Rawski, unpublished data). Under experimental conditions,
4% of body weight was reported to be an optimal meal size for suitable growth per-
formance in P. sinensis since higher feed intake may decrease nutrient digestibility
(Lei, 2006). In contrast, commercial feed producers frequently advise that turtles be
fed ad libitum or during restricted time periods, sometimes even more than once dai-
ly. However, in the opinion of this author, restricting the amount, not feeding time,
of commercial feeds containing a high amount of dry matter may be more effective
at preventing overfeeding, excessive growth and obesity.
Table 3. Diet composition of selected turtle species in nature
Species Diet composition Sampling method References
Animal matter: Gastropoda: Physidae,
Insecta: Coleoptera, Diptera, Hymenoptera,
Odonata: Anisoptera, Zygoptera,
Orthoptera: Locustidae
Fish, unknown claws and bones, craysh, shrimps
Plant matter: Algae, Bacopa caroliniana, Brasenia schre-
beri, Najas guadelupensis, Nymphaea odorata, Potamo-
geton spp., Sagitaria spp., Utricularia spp., Lemna spp.
stomach ushing Gibbons,
Gastropoda: Bithyniidae, Lymnaeidae, Physidae, Pla-
Arachnida: Acarina, Araneae,
Crustacea: Conchostraca, Decapoda
Insecta: Coleoptera, Diptera, Heteroptera, Hymenop-
tera, Odonata Trichoptera
Vertebrata and plant matter
fecal samples Ottonello et
al., 2005
Arthropoda: Arachnida, Decapoda
Insecta: Hemiptera, Coleoptera, Diptera, Trichoptera
Vertebrates, lamentous algae, plant detritus
stomach content Spencer et
al., 1998
Rodents, Birds, Lizards, Snakes, Tadpoles, Frogs, Fish,
Gastropoda, Bivalvia, Anellida, Arachnida, Chilo-
poa, Crustacea, Odonata larvae, Rhynochota, Coleop-
tera adult, Coleoptera larvae, plant matter, fungi
stomach ushing,
fecal samples
Luiselli et
al., 2011
Fish, tadpoles, insects, freshwater gastropods, water
observations Rhodin et al.,
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
Table 4. Nutritional composition of a whole prey used in captive turtle diets
Prey species Notes DM*CP*EE*Ash Ca*P*References
% as feed % on a DM basis
Blood worm - 9.9 53 9.7 12 0.38 0.85 Bernard et al., 1997
Black soldier y Larvae 30 38–60 9–26 3–17 0.30–0.80 0.90–2.4 Józeak et al., 2016
American cockroach - 39 54 28 3.3 0.20 0.50 Bernard et al., 1997
American cockroach Nymph 37 54–73 18–26 4.6–5.4 0.02 0.06–0.07 Józeak et al., 2016
Domestic cricket Imago 27–38 40–68 14–44 2.7–5.7 0.14 0.99 Bernard et al., 1997; Mader, 2005
Domestic cricket Larvae 33 40–50 10 9.1 0.1–0.2 0.8 Mader, 2005
Domestic cricket Imago, high Ca diet 30 65 13 9.8 0.90 0.92 Bernard et al., 1997
Jamaican eld cricket Imago 31 56 24 6.4 0.80 0.99 Józeak et al., 2016
Earthworm - 20 62 18 5.0 1.7 0.90 Bernard et al., 1997; Mader, 2005
Night crawler Wild 15–26 31–81 6–13 9–46 0.97–1.5 0.79–0.96 Bernard et al., 1997; Mader, 2005
Night crawler Commercial 16–24 50–81 11–13 25 1.2 0.86 Mader, 2005
Mealworm Larvae 38–43 53 31–60 3.0–7.0 0.04–0.12 0.83–1.4 Bernard et al., 1997; Mader, 2005
Superworm Larvae 41–43 40–50 41–44 2.9–3.5 0.03–0.12 0.6–0.8 Mader, 2005
Tubifex worm - 12 46 15 6.9 0.19 0.73 Bernard et al., 1997
Wax moth Larvae 34 42 46 2.7 0.11 0.62 Bernard et al., 1997
Wax moth Larvae, high Ca diet 40 NANA2.5 0.50 0.33 Bernard et al., 1997
Domestic mouse Neonatal, <3 g 19–26 51–64 17–34 8.0–9.7 1.2–3.5 1.6 Crissey et al., 1999; Dierenfeld et
al., 2002; Douglas et al., 1994
Domestic mouse Juvenile, 3–10 g 18–29 44–59 24–30 8.5–10 1.5–3.0 1.4 Crissey et al., 1999; Dierenfeld et
al., 2002; Douglas et al., 1994
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 27
Domestic mouse Adult or > 10 g 33 56 24 11-12 2.6-3.0 1.7–1.9 Clum et al., 1996; Crissey et al.,
1999; Dierenfeld et al., 2002;
Douglas et al., 1994
Domestic rat Neonatal, <10 g 21 65 16 12 1.9 NADierenfeld et al., 2002; Douglas et
al., 1994
Domestic rat Juvenile, 10–50 g 23–30 58–60 24–27 12–15 2.1 NADierenfeld et al., 2002; Douglas et
al., 1994
Domestic rat Adult or > 50 g 34 56 12 9.8 2.6 1.72 Clum et al., 1996; Dierenfeld et al.,
2002; Douglas et al., 1994
Chicken One-day-old 26 65 22 6.4 1.7 1.2 Dierenfeld et al., 2002
European smelt Dried 91 47 34 11 NANADeclared by producer (Katrinex,
*Abbreviations: DM – dry matter, CP – crude protein, EE – ether extract (crude fat), Ca – calcium, P – phosphorus, NA – data not available.
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
Raw diets
Raw diets are considered most suitable for turtles designated for reintroduction
into the wild as well as for those used as breeding stocks in conservation programs.
The diets should be as similar as possible to the variety of food resources accessible
to specic turtle species in their natural environment, including live prey, and in most
cases, these diets are based on invertebrates, insects and their larvae, as well as small
vertebrates to maintain foraging and hunting abilities of animals at optimal level.
Many turtle breeders and zoos use gelatin-based diets (puddings) that fall some-
where between raw and commercial diets. These diets are multi-ingredient mixtures
solidied by gelatin and represent the easiest way to maintain a diverse diet based
on fresh and frozen ingredients. The main advantage of these diets is the possibility
for modifying recipes according to changes in scientic knowledge, experience and
the available components. All raw components should be used fresh or after a sin-
gle freezing; prolonged storage or refreezing may promote microbial contamination
and nutrient degradation, which can result in negative side effects for the animals.
Gelatin-based diets should be offered at a temperature similar to that of the turtles’
environment and not frozen. If raw diets are aimed at imitating natural ones, inverte-
brates, sh, rodents and aquatic plants should be used. The nutritional values of ma-
terials of animal origin that are commonly used in turtle nutrition are given in Tables
4 and 5. It should be suggested that even in the case of raw, nature imitating diets
use, their nutritive value should be calculated and at the diet composition optimized
according to current knowledge about nutritional requirements of turtles.
Table 5. Nutritional composition of commercial turtle feeds based on producers declarations
Nutrient (%)
Nonspecic feeds1Age specic feeds2
turtles hatchling growth
Crude protein (min) 38 39 35 25
Fat (min) 7.4 10 5 5
Fiber (max) 3.4 358
Ca (min) 2.2 ND3ND3ND3
P (min) 1.2 1 1 1
1Based on average of declared nutritional values of 15 commercial feeds recommended by producers as for-
mulations for all turtles.
2 Based on declared nutritional values of feeds recommended by producer as age specic formulations.
3 ND – no declaration.
Insects are a rich source of high-quality protein, essential amino acids and other
nutrients. Additionally, they have short life cycles and are easy to produce and handle
(Józeak et al., 2016; Ramos-Elorduy et al., 2002). Due to a high amount of inver-
tebrates in the natural diets of many turtle species (Table 3), insects are an important
dietary component in captivity, but the high fat content in insect larvae, e.g., meal
worms (Tenebrio molitor) or wax worms (Pyralidae), may lead to excessive energy
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 29
intake. Chitin is the main component of insect exoskeletons, and it seems to be well
digested by chitinases and chitobiases produced by the stomach and pancreas in tur-
tles (McArthur et al., 2008). An important disadvantage of feeder insects is that their
Ca:P ratio is less than optimal (2:1), and most contain low amounts of vitamin A and
D3. Therefore, supplementation of additional Ca and vitamin A and D3 is required.
Feeding insects a vitamin-and-mineral-rich diet shortly before feeding them to tur-
tles, which is also known as “gut-loading,” will improve their nutritional content
(Finke, 2003). Earthworms and night crawlers are also suitable turtle feed; they have
high mineral contents because of the high volume of soil in their guts (Bernard et al.,
1997). Similarly, a variety of shellsh may also be used due to their high nutritive
value, but negative effects may result from the long-term use of shellsh-based diets
due to the high concentrations of environmental pollutants in shellsh, especially
heavy metals (Sivaperumal et al., 2007).
Fish are a natural and valuable component of captive turtle diets. They contain,
on average, 15–20% high-quality protein that is rich in essential amino acids, i.e.,
lysine, methionine and cysteine. Moreover, sh are a good source of vitamins A, B
complex and D3 as well as minerals, such as Ca, P, Fe, and S, and long-chain polyun-
saturated fatty acids (Tacon and Metian, 2013). Whole small sh should be fed fre-
quently to most freshwater turtles and should be the main diet component for Chelus
mbriata and other piscivorous species. The presence of live small sh (Poeciliidae
or Danio spp.) in the turtle tank may serve as a food source but also stimulate turtle
foraging behavior. However, when a sh-based diet is used, frequent use of sh in
the Cyprinidae family should be avoided due to their high amounts of thiaminase,
a B1 antivitamin (Mader, 2005).
Mammals and birds
For many years, the main component of captive turtle diets was animal matter
derived from commercially raised domestic mammals or birds, which do not account
for a signicant proportion of natural freshwater turtle diets. However, whole car-
casses (e.g., mice and rats or quails and chicks) are frequently used in captive turtle
feeding. The skeletons and GIT contents of vertebrates provide valuable vitamins and
minerals (Hand et al., 2000), and fur and feathers mechanically stimulate the GIT,
similar to the function of the ber in plant matter. Among the most commonly used
rodents, adult mice seem to be most suitable for freshwater turtles due to their high
mineral content and adequate Ca:P ratio (Mader, 2005). In contrast, lleted meat,
an excellent protein source, should not be fed as one of the main diet components
because of its low content of minerals and vitamins. If the abovementioned feeds,
such as insects, whole sh or rodents, are not available or they are refused by the
turtles, internal organs, particularly the liver and kidneys, are good alternatives due
to their high protein quality and high concentrations of fat-soluble vitamins (Acker
et al., 1959). However, care should be taken not to feed raw liver in large quanti-
ties since hypervitaminosis A, which is often fatal, can develop (Mans and Braun,
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
Plant matter
To simulate their natural diet, most adult freshwater turtles should be provided
with various amounts of plant matter. In captivity, aquatic plants such as duckweed
(Lemna spp.), pondweed (Elodea spp.), and hornwort (Ceratophyllum spp.) are fre-
quently used. Algae such as Spirulina spp. are also used in commercial sh and turtle
diets, and they are also available in a dried form and may be used as a separate feed
component. Aquatic plants may be permanently present in turtle tanks and be ingest-
ed between main meals. For some tropical and subtropical turtle species, fruits may
also be used, but in the case of T. scripta elegans, we observed digestive disturbances
after feeding fruits, such as bananas (Rawski, unpublished data).
Commercial diets
Most commercial diets are extruded or hot pelleted and are based on animal and
plant materials with dry matter contents close to 90%. The declared average nutri-
tional values of various commercial diets are presented in Table 6, and in many of
them, the Ca:P ratio is close to 2:1. However, the levels of these nutrients are low
relative to the optimal levels for P. sinensis, not exceeding 2.1% for Ca and 1.4% for
P. Frequently, the declared nutritional content is not described in detail or given just
as minimal or maximal levels, but based on research carried out on P. sinensis, the
chemical composition of commercial diets appears to meet the main requirements of
turtles in terms of the CP and fat contents. In contrast to fresh components, the vita-
min levels of commercial diets may be partially decreased relative to the declarations
of the producers due to improper storage as well as processing, i.e., extrusion. Prac-
tically, the use of commercial feeds supplemented with natural components seems
to be a good strategy for maintaining diet diversity in captivity (Mitchell and Tully,
2009), but from the nutritional point of view, this strategy leads to an unknown sup-
ply of energy and nutrients. In commercial diets, the main components are meals of
animal origin, cereals and soybean meal supplemented with vitamin and minerals,
and in the case of plant matter-based diets, the levels of essential amino acids may be
not sufcient for strict carnivores. Moreover, the phosphorus in plant matter, and in
cereals in particular, is bound in a phytate form, which is unavailable to monogastric
animals (Pen et al., 1993). When plant matter is used as an animal protein replace-
ment in diets for mainly carnivorous turtles, Ca, Mg and P supplementation or the
use of endogenous phytase may be needed, as was shown in P. sinensis (Chen et al.,
2014). If commercial diets are offered, the trends of lower CP requirements and on-
togenetic diet shifts during different life stages are often not considered, but several
commercial diets are now available that provide formulations for hatchlings, grow-
ing turtles and adults that contain approximately 40, 35 and 20% CP, respectively
(Table 5).
Consequences of improper nutritional practices
In the available literature we can nd frequent reports on diet related and meta-
bolic disorders in turtles. Most of them deal with nutritional metabolic bone disease
and hypovitaminosis A which are well discussed (Mader, 2005; Boyer, 2006; Dono-
ghue, 2006; Mans, 2013; Mans and Braun, 2014). However in the case of captive
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 31
turtles issues which are not directly caused by inaccuracy of diet composition seem
to be neglected. They involve environmental factors, form and amount of feed as
well as feeding frequency which all together affect metabolism and feed acceptance.
Most of diet and environmental-related issues are caused by lack of knowledge. In
some cases turtle keepers are not able to identify whether the animal is turtle or tor-
toise and keep freshwater species with no or limited access to water which results in
dehydration and malnutrition (Köbölkuti et al., 2016).
Stress, improper environmental conditions and diet form
Captive reptiles are subjected to many stressors, however, this is frequently ig-
nored due to common opinion that they are less likely to be negatively affected by
them than higher vertebrates. The time to response after stressors including improper
environmental conditions vary from several minutes to even weeks after the factor
occurs (Silvestre, 2014). A very frequent stress-related issue in turtles is anorexia
which may be caused by hypothermia, diseases, injuries, chronic pain or harassment.
Particularly prone to anorexia are hatchlings, wild-caught individuals and animals in
short period after transfer between facilities. They frequently refuse to ingest food
for a long period of time due to poor acclimatization to captivity. Hatchlings may
not accept the food until full yolk sack resorption, in adults food refusal up to two
weeks after the transfer may be interpreted as normal. In their case, longer periods of
starving should be interpreted as a sign of illness or improper environmental condi-
tions. For young and wild-caught animals anorexia may be also caused by improper
form of the diet – they may not accept pelleted feeds, and prefer live prey. In adult
females 2–4 weeks of decreased feed intake coincidental with increased locomotory
activity may be a symptom of egg development and physically decreased capac-
ity of the gastrointestinal tract. In the above case egg binding occurrence should
be excluded. Authors’ observations suggest that in newly settled turtles presence of
the hiding areas, constant temperature in preferred optimal temperature zone, single
animal enclosures and 24/24h of light photoperiod supports acclimatization. In tur-
tle enclosure gradient temperature areas should be present to avoid hypothermia or
heat stress and allow the animal for selection of its preferred temperature – optimal
for metabolism in the moment. It should be underlined that too low temperatures
negatively affect energy and nutrient assimilation efciency, feed intake as well as
digestive turnover rates, as it is shown in Figure 1 (Kepenis and McManus, 1974;
Parmenter, 1981) Too high temperatures and heat stress when no possibility of cool-
ing is given may also cause anorexia. Long-term nutritional deciencies such as
insufcient energy, CP, minerals or vitamin intake may lead to cachexia. When it is
of nutritional origin, improper environmental conditions like low temperatures and
underlying disease also contribute to development of cachexia. Treatment of both
anorexia and cachexia should focus on an increase in diet energy content and opti-
mizing environmental conditions. The type of food offered should be re-considered
for cachexic wild-caught turtles which usually prefer live prey. Suboptimal environ-
mental conditions and protein deciency may not only reduce growth performance,
but may also lead to regression in shell development in hatchlings (Gibbons, 1990).
However, turtles have the ability of growth compensation, if dietary imbalances are
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
corrected (Xie et al., 2012). To avoid hypophosphatemia and hypocalcaemia, re-
feeding of cachexic animals should not be too rapid, and energy level should be
increased by 10–50% only when the animal shows improvement during treatment
(Mader, 2005). All together, above-mentioned issues may cause growth depression
which is frequent, however, non-specic symptom of improper nutrition. It is present
in most cases of non-balanced diet in young turtles.
Stereotypic-like nutritional behavior
In many cases, reptile keepers use one or a few kinds of feed for many years
without diversifying the diet of captive turtles. It may be the reason not only for
development of metabolic disorders, but may also cause stereotypical-like behavior
when animals do not accept other kinds of components than those they were fed for
years. Turtles will imprint on food and prefer a diet that they are used to, instead
of newly introduced feeds (Burghardt and Hess, 1966). If new food items are not
accepted, then the most effective seems to be the use of live feeds – sh, shrimps,
bloodworms or other insects larvae, and small vertebrates – to enrich turtle diet and
stimulate feed intake.
Another issue in the case of captive animals is positive energy balance – higher
intake than expenditures of metabolic energy may accelerate growth in young ani-
mals and have positive effects if there are no deciencies in the diet. However, it may
lead to obesity in adults, which is dened as an accumulation of excessive amounts
of adipose tissue in the body (Hand et al., 2000). More prone to obesity are species
that are sedentary “bottom walkers” like snapping turtles (Chelydra spp.) or musk
turtles (Sternotherus spp.) and African sidenecks (Pelomedusa spp. and Pelusios
spp.). The best method of obesity prevention is regular body condition score (BCS)
monitoring (Rawski and Józeak, 2014). In chelonians, BCS is assessed mainly on
the basis of comparison of straight carapace length and BW. However, additional
visual assessment should be performed, and conditions, which may mimic obesity
excluded (Jackson, 1980; Willemsen and Hailey; 2002; Rawski and Józeak, 2014).
Obese turtles store adipose tissue mainly in the coelom and internal organs, which
may severely impair their function (Divers and Cooper, 2000). According to screen-
ing in Pelomedusa spp. and Pelusios spp. up to 22% of captive turtles may be over-
weight and obese (Rawski and Józeak, 2014). Treatment of obesity should focus
on restriction of energy intake. It should be lowered progressively to no less than
60% of usual intake. The body weight loss in that case should not exceed 0.5 to
1% weekly (Mader, 2005). According to practical experience of the authors feed-
ing regime in terms of frequency of feeding may be one of the most effective in
obesity prevention. It may be suggested that hatchlings should receive feed 6 times
per week, animals between 6 months to 2 years of age 3-4 times per week and older
ones 1 or 2 times per week. Additionally, turtles should undergo seasonal environ-
mental stimulation for breeding; lipogenesis which occurs as a part of preparation
for folliculogenesis is an important obesity-preventing factor in reptiles (Divers and
Cooper, 2000).
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 33
Despite the recent increase in our scientic knowledge of turtle nutrition, the
statement by Kollias and Gentz from 1996 that “reptile feeding is an art not a sci-
ence” may still be partially valid. Due to the lack of suitable nutritional guidelines
for most turtle species, observations of animal development as well as the experience
and knowledge of keepers are still the most important sources of information for
feeding freshwater turtles. Diet composition should be veried through long-term
experiments, including digestibility studies at each turtle life stage. However, the
basic rules for reptilian nutrition may be stated as follows:
1. The diversication of feed sources and their similarity to natural diet compo-
nents are key to achieving sustainable growth and shell mineralization.
2. Commercial diets, if properly used without overfeeding, provide appropriate
nutrition for turtles in captivity. However, in many cases, their formulation should be
more specically tailored to the needs of turtles with similar natural diets.
3. The exact nutritional requirements of turtles are still largely unknown, but
large-scale farming and scientic experiments provide an opportunity to gain impor-
tant knowledge that is applicable to this problem.
A c k e r R.F., H a r tm an P.A., P e mb er to n J.R., Q u in n L.Y. (1959). The nutritional potential of
poultry offal. Poultry Sci., 38: 706–711.
B e r n a r d J.B., A l l e n M.E., U l l r e y D.E. (1997). Feeding captive insectivorous animals: nutri-
tional aspects of insects as food. Nutrition Advisory Group Handbook, Fact Sheet, 3: 1–7.
B j o r n d al K.A. (1991). Diet mixing: nonadditive interactions of diet items in an omnivorous freshwa-
ter turtle. Ecology, 72: 1234–1241.
B j o r n d al K.A., Bo lt en A.B. (1990). Digestive processing in a herbivorous freshwater turtle: con-
sequences of small-intestine fermentation. Physiol. Zool., 63: 1232–1247.
B o n i n F., D e va ux B., D u p ré A. (2006). Turtles of the World. Baltimore, USA, Johns Hopkins
University Press, 416 pp.
B o u c h a rd S.S. (2004). Diet selection in the yellow-bellied slider turtle, Trachemys sripta: ontoge-
netic diet shifts and associative effects between animal and plant diet items. Doctoral dissertation,
University of Florida.
B o u c h a rd S.S., B jo r n d a l K.A. (2005). Microbial fermentation in juvenile and adult pond slider
turtles, Trachemys scripta. J. Herpetol., 39: 321–324.
B o u c h a rd S.S., B jo rn da l K.A. (2006). Ontogenetic diet shifts and digestive constraints in the
omnivorous freshwater turtle Trachemys scripta. Physiol. Biochem. Zool., 79: 150–158.
B o y e r T.H. (2006). Hypovitaminosis A and hypervitaminosis A. Reptile Medicine and Surgery,
D.R. Mader (ed). St. Louis, MO, Elsevier: pp. 831–835.
B r o w n G.P., B r o o k s R.J., L a y f i e l d J.A. (1990). Radiotelemetry of body temperatures of free-
ranging snapping turtles (Chelydra serpentina) during summer. Can. J. Zool., 68: 1659–1663.
B u r g h a r d t G.M., H e s s E.H. (1966). Food imprinting in the snapping turtle, Chelydra serpentina.
Science, 151: 108–109.
B u r y R.B., N eb ek er A.V., A da ms M.J. (2000). Response of hatchling and yearling turtles to
thermal gradients: comparison of Chelydra serpentina and Trachemys scripta. J. Therm. Biol., 25:
C h e n L.P., H u a n g C.H. (2011). Effects of dietary β-carotene levels on growth and liver vitamin
A concentrations of the soft-shelled turtle, Pelodiscus sinensis (Wiegmann). Aquac. Res., 42:
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
C h e n L.P., Huang C.H. (2014). Estimation of dietary vitamin A requirement of juvenile soft-shelled
turtle, Pelodiscus sinensis. Aquacult. Nutr., 21: 457–463.
C h e n C.Y., C he n S.M., H u a ng C.H. (2014). Dietary magnesium requirement of soft-shelled tur-
tles, Pelodiscus sinensis, fed diets containing exogenous phytate. Aquaculture, 432: 80–84.
C h u J.H., C he n S.M., H u an g C.H. (2007). Effect of dietary iron concentrations on growth, hema-
tological parameters, and lipid peroxidation of soft-shelled turtles, Pelodiscus sinensis. Aquaculture,
269: 532–537.
C l u m N.J., F it zp at ri c k M.P., D i e r e nf el d E.S. (1996). Effects of diet on nutritional content of
whole vertebrate prey. Zoo Biol., 15: 525–537.
Costa Araújo J. da, Vieira P., Palha M., Rodrigues P.B., de Freitas R.T., da Si-
l v a A. (2013). Effect of three feeding management systems on some reproductive parameters of
Scorpion mud turtles (Kinosternon scorpioides) in Brazil. Trop. Anim. Health. Pro., 45: 729–735.
C r i s s e y S.D., S l if ka K.A., L i n t z e n i ch B.A. (1999). Whole body cholesterol, fat, and fatty acid
concentrations of mice (Mus domesticus) used as a food source. J. Zoo Wildlife Med., 30: 222–227.
D i e r e n fe ld E.S., A lc or n H.L., J ac ob se n K.L. (2002). Nutrient composition of whole verte-
brate prey (excluding sh) fed in zoos. US Department of Agriculture, Agricultural Research Ser-
vice, National Agricultural Library, Animal Welfare Information Center, 20 pp.
D i v e r s S.J., C o o p e r J.E. (2000). Reptile hepatic lipidosis. Seminars in Avian and Exotic Pet Medi-
cine, Elsevier.
D o n o g h ue S. (2006). Nutrition. In: Reptile Medicine and Surgery, Mader D.R., Divers S. (eds).
Elsevier, pp. 251–298.
D o u g l a s T.C., P en ni ne M., D i er en fe ld E.S. (1994). Vitamins E and A, and proximate compo-
sition of whole mice and rats used as feed. Comp. Biochem. Phys. A, 107: 419–424.
E i S.N., K a v a s A. (1996). Determination of protein quality of rainbow trout (Salmo irideus) by in
vitro protein digestibility-corrected amino acid score (PDCAAS). Food Chem., 55: 221–223.
E r n s t C.H. (1986). Environmental temperatures and activities in the wood turtle, Clemmys insculpta.
J. Herpetol., 20: 222–229.
F e l t z J., Ta m p l i n J. (2007). Effect of substrate on selected temperature in juvenile spiny softshell
turtles (Apalone spinifera). Chelonian Conserv. Biol., 6: 177–184.
F i n k e M.D. (2003). Gut loading to enhance the nutrient content of insects as food for reptiles: a math-
ematical approach. Zoo Biol., 22: 147–162.
F i t z g e ra ld L.A., N e ls o n R.E. (2011). Thermal biology and temperature-based habitat selection
in a large aquatic ectotherm, the alligator snapping turtle, Macroclemys temminckii. J. Therm. Biol.,
36: 160–166.
G a t t e n R.E. Jr (1974). Effect of nutritional status on the preferred body temperature of the turtles
Pseudemys scripta and Terrapene ornata. Copeia, 1974: 912–917.
G i b b o n s J.W. (1990). Editor. Life history and ecology of the slider turtle. Washington D.C., USA,
Smithsonian Institution Press, 368 pp.
G r a y s o n K.L., D o r ca s M.E. (2004). Seasonal temperature variation in the painted turtle (Chrys-
emys picta). Herpetologica, 60: 325–336.
Hand M.S., Thatcher C.D., Remillard R.L., Roudebush P., Novtony B.J. (2000). Edi-
tors. Small Animal Clinical Nutrition. Mark Morris Institute, USA, 1192 pp.
Hoby S., Wenker C., Robert N., Jermann T., Hartnack S., Segner H., Aebis-
c h e r C.P., L i e se ga ng A. (2010). Nutritional metabolic bone disease in juvenile veiled chame-
leons (Chamaeleo calyptratus) and its prevention. J. Nutr., 140: 1923–1931.
H o u J., Ji a Y., Ya n g Z., L i Y., C h e n g F., L i D., J i F. (2013). Effects of taurine supplementation
on growth performance and antioxidative capacity of Chinese soft-shelled turtles, Pelodiscus sinen-
sis, fed a diet of low sh meal content. J. World Aquac. Soc., 44: 786–794.
H u a n g C.H., L in W.Y. (2002). Estimation of optimal dietary methionine requirement for softshell
turtle, Pelodiscus sinensis. Aquaculture, 207: 281–287.
H u a n g C.H., L i n W.Y. (2004). Effects of dietary vitamin E level on growth and tissue lipid peroxida-
tion of soft-shelled turtle, Pelodiscus sinensis (Wiegmann). Aquacult. Res., 35: 948–954.
H u a n g C.H., L i n W.Y., Wu S.M. (2003). Effect of dietary calcium and phosphorus supplementa-
tion in sh meal-based diets on the growth of soft-shelled turtle Pelodiscus sinensis (Wiegmann).
Aquacult. Res., 34: 843–848.
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 35
H u a n g C.H., L i n W.Y., C h u J.H. (2005). Dietary lipid level inuences fatty acid proles, tissue
composition, and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis. Comp. Biochem.
Physiol., Part A Mol. Integr. Physiol., 142: 383–388.
H u a n g S.C., C h e n S.M., Hu an g C.H. (2010). Effects of dietary zinc levels on growth, serum zinc,
haematological parameters and tissue trace elements of soft-shelled turtles, Pelodiscus sinensis.
Aquac. Nutr., 16: 284–289.
J a c k s o n O. (1980). Weight and measurement data on tortoises (Testudo graeca and Testudo her-
manni) and their relationship to health. J. Small Anim. Pract., 21: 409–416.
J i a Y., Ya ng Z., H a o Y., G ao Y. (2005). Effects of animal–plant protein ratio in extruded and
expanded diets on nitrogen and energy budgets of juvenile Chinese soft-shelled turtle (Pelodiscus
sinensis Wiegmann). Aquacul. Res., 36: 61–68.
J i a n w e i S., F a n w e i M., Yo n g pu Z h a n g W.D. (2013). Field body temperature and thermal
preference of the big-headed turtle Platysternon megacephalum. Curr. Zool., 59: 626–632.
Józefiak D., Józefiak A., Kierończyk B., Rawski M., Świątkiewicz S., Dłu-
g o s z J., E n g b e rg R.M. (2016). Insects – a natural nutrient source for poultry – a review. Ann.
Anim. Sci., 16: 297–313.
J u l i a n R. (1998). Rapid growth problems: ascites and skeletal deformities in broilers. Poultry Sci.,
77: 1773–1780.
K e n n e t t R., T or y O. (1996). Diet of two freshwater turtles, Chelodina rugosa and Elseya dentata
(Testudines: Chelidae) from the wet-dry tropics of northern Australia. Copeia, 1996: 409–419.
K e p e n i s V., M cM an us J.J. (1974). Bioenergetics of young painted turtles, Chrysemys picta.
Comp. Biochem. Phys. A: Physiology, 48: 309–317.
K ö b ö l k ut i L., et al. (2016). Effects of malnutrition and improper captive maintenance on European
pond turtle (Emys orbicularis): a case report. J. Anim. Plant Sci., 26: 874–879.
Lawler D.F., Evans R.H., Larson B.T., Spitznagel E.L., Ellersieck M.R., Kealy R.D.
(2005). Inuence of lifetime food restriction on causes, time, and predictors of death in dogs. J. Am.
Vet. Med. Assoc., 226: 225–231.
L e g l e r J.M. (1960). Natural history of the ornate box turtle, Terrapene ornata ornata Agassiz. Kansas,
USA, University of Kansas Publications, Museum of Natural History, 157 pp.
L e i G., Yaohong Z. (2010). Effects of Bacillus subtilis on growth performance, digestive enzyme ac-
tivities and blood biochemical indices of Pelodiscus sinensis. Chinese J. Anim. Nutr., 1: 42.
L e i S. (2006). Effects of ration level and feeding frequency on digestibility in juvenile soft-shelled
turtle, Pelodiscus sinensis. J. Zhejiang Univ. Sci. B., 7: 580–585.
Lemell P., Beisser C.J., Gumpenberger M., Snelderwaard P., Gemel R., Weis-
g r a m J. (2010). The feeding apparatus of Chelus mbriatus (Pleurodira; Chelidae) – adaptation
perfected? Amphib-Reptil., 31: 97–107.
L i n W.Y., H ua n g C.H. (2007). Fatty acid composition and lipid peroxidation of soft-shelled turtle,
Pelodiscus sinensis, fed different dietary lipid sources. Comp. Biochem. Phys. C., 144: 327–333.
Luiselli L., Akani G.C., Ebere N., Rugiero L., Vignoli L., Angelici F.M., En-
i a n g E.A., B e h an ga n a M. (2011). Food habits of a pelomedusid turtle, Pelomedusa subrufa,
in tropical Africa (Nigeria): The effects of sex, body size, season, and site. Chelonian Conserv. Bi.,
10: 138–144.
M a d e r D.R. (2005). Editor. Reptile Medicine and Surgery. St. Louis, USA, Elsevier Health Sciences,
1241 pp.
M a n s C. (2013). Clinical update on diagnosis and management of disorders of the digestive system of
reptiles. J. Exotic Pet Med., 22: 141–162.
M a n s C., Br au n J. (2014). Update on common nutritional disorders of captive reptiles. Vet. Clin.
North Am. Exot. Anim. Pract., 17: 369–395.
M c A r t h ur S., W i l k i n s o n R., M e y e r J. (2008). Editors. Medicine and Surgery of Tortoises and
Turtles. Oxford, UK, Wiley-Blackwell, 600 pp.
M c C a u l ey S.J., B j o r n d a l K.A. (1999). Response to dietary dilution in an omnivorous freshwater
turtle: implications for ontogenetic dietary shifts. Physiol. Biochem. Zool., 72: 101–108.
M c D o w e ll L.R. (1989). Vitamins in animal nutrition: comparative aspects to human nutrition. San
Diego, USA, Academic Press, Inc., 496 pp.
M c W il li am s D. (2005). Nutrition research on calcium homeostasis. II. Freshwater turtles (with
recommendations). Int. Zoo Yearbook, 39: 77–85.
Download Date | 2/26/18 5:27 PM
M. Rawski et al.
M i t c h e ll M.A., T u ll y T.N. (2009). Manual of exotic pet practice. St. Louis, USA, Elsevier Health
Sciences, 546 pp.
N e b e k e r A.V., B u r y R.B. (2000). Temperature selection by hatchling and yearling Florida red-
bellied turtles (Pseudemys nelsoni) in thermal gradients. J. Herpetol., 34: 465–469.
N u a n g s ae ng B., B o o n y a r a t a pa li n M. (2001). Protein requirement of juvenile soft-shelled
turtle Trionyx sinensis Wiegmann. Aquacult. Res., 32: 106–111.
O t t o n e ll o D., Sa lv i d i o S., Ro se cc hi E. (2005). Feeding habits of the European pond terrapin
Emys orbicularis in Camargue (Rhône delta, Southern France). Amphib-Reptil., 26: 562.
P a n Z., Z h a n g Y., J i X. (2002). Diel variation in body temperature, thermal tolerance, and thermal
dependence of locomotor performance in hatchling Chinese striped-necked turtles (Ocadia sinen-
sis). Acta Zool. Sinica, 49: 45–52.
P a r m e n te r R.R. (1981). Digestive turnover rates in freshwater turtles: the inuence of temperature
and body size. Comp. Biochem. Physiol. A: Physiology, 70: 235–238.
Pen J., Verwoerd T.C., van Paridon P.A., Beudeker R.F., van den Elzen P.J.M.,
Geerse K., van der Klis J.D., Versteegh H.A.J, van Ooyen A.J.J., Hoeke-
m a A. (1993). Phytase-containing transgenic seeds as a novel feed additive for improved phospho-
rus utilization. Nat. Biotech., 11: 811–814.
R a h m a n M.S., S h ar ma D.K. (2014). Morphometric, anatomical and histological features of gas-
trointestinal tract (GIT) of freshwater turtle, Pangshura tentoria. Int. J. Sci. Eng. Res., 7: 90–94.
R a i l a J., S c hu h m a c h e r A., G r op p J., S c h we ig er t F.J. (2002). Selective absorption of ca-
rotenoids in the common green iguana (Iguana iguana). Comp. Biochem. Phys. A., 132: 513–518.
Ramos-Elorduy J., González E.A., Hernández A.R., Pino J.M. (2002). Use of Tene-
brio molitor (Coleoptera: Tenebrionidae) to recycle organic wastes and as feed for broiler chickens.
J. Econ. Entomol., 95: 214–220.
R a w s k i M., Jó ze fi ak D. (2014). Body condition scoring and obesity in captive African side-neck
turtles (Pelomedusidae). Ann. Anim. Sci., 14: 573–584.
Rawski M., Kierończyk B., Długosz J., Świątkiewicz S., Józefiak D. (2016). Di-
etary probiotics affect gastrointestinal microbiota, histological structure and shell mineralization in
turtles. PLOS ONE, 11(2): e0147859.
Rhodin A., Ibarrondo B., Kuchling G. (2008). Chelodina mccordi Rhodin 1994 – Roti Is-
land snake-necked turtle, McCord’s snake-necked turtle, kura-kura rote. Chelonian Conserv. Bi.,
5: 001–008.
Seebacher F., Sparrow J., Thompson M.B. (2004). Turtles (Chelodina longicollis) regulate
muscle metabolic enzyme activity in response to seasonal variation in body temperature. J. Comp.
Physiol. B., 174: 205–210.
S i l v e s tr e A.M. (2014). How to assess stress in reptiles. J. Exotic Pet Med., 23: 240–243.
S i v a p e ru ma l P., S a n k a r T.V., V i sw an at ha n N a ir P.G. (2007). Heavy metal concentra-
tions in sh, shellsh and sh products from internal markets of India vis-a-vis international stan-
dards. Food Chem., 102: 612–620.
S p e n c e r R.J., Th om ps o n M.B., Hu me I.D. (1998). The diet and digestive energetics of an Aus-
tralian short-necked turtle, Emydura macquarii. Comp. Biochem. Phys. A., 121: 341–349.
S t e v e n s C.E., H u m e I.D. (1998). Contributions of microbes in vertebrate gastrointestinal tract to
production and conservation of nutrients. Physiol. Rev., 78: 393–427.
S u n J.Y., D u J., Q ia n L.C., J i n g M.Y., We ng X.Y. (2007). Distribution and characteristics of
endogenous digestive enzymes in the red-eared slider turtle, Trachemys scripta elegans. Comp.
Biochem. Phys. A., 147: 1125–1129.
S u n P., X u X., C h e n H., J i X. (2002). Thermal tolerance, diel variation of body temperature, and
thermal dependence of locomotor performance of hatchling soft-shelled turtles, Trionyx sinensis. J.
Appl. Ecol., 13: 1161–1165.
Ta co n A.G., M e ti an M. (2013). Fish matters: importance of aquatic foods in human nutrition and
global food supply. Rev. Fish. Sci., 21: 22–38.
Ta mp l i n J. (2009). Effect of age and body size on selected temperature by juvenile wood turtles
(Glyptemys insculpta). J. Therm. Biol., 34: 41–48.
Ta mp l i n J.W., C y r A.B. (2011). Effects of acclimation and egg-incubation temperature on select-
ed temperature by hatchling western painted turtles (Chrysemys picta bellii). J. Therm. Biol., 36:
Download Date | 2/26/18 5:27 PM
Freshwater turtle nutrition – a review 37
W il le ms en R.E., H a il ey A. (2002). Body mass condition in Greek tortoises: regional and inter-
specic variation. Herpetol. J., 12: 105–114.
W u G.S., H u a n g C.H. (2008). Estimation of dietary copper requirement of juvenile soft-shelled tur-
tles, Pelodiscus sinensis. Aquaculture, 280: 206–210.
W ur th S.M.A., M us ac ch ia X.J. (1964). Renewal of intestinal epithelium in the freshwater turtle,
Chrysemys picta. Anat. Rec., 148: 427–439.
X i e Q.S., Y a n g Z.C., L i J.W., L i Y.J. (2012). Effect of protein restriction with subsequent re-ali-
mentation on compensatory growth of juvenile soft-shelled turtles (Pelodiscus sinensis). Aquacult.
Int., 20: 19–27.
Zhang X., Peng L., Wang Y., Liang Q., Deng B., Li W., Fu L., Yu D., Shen W.,
Wa ng Z. (2014). Effect of dietary supplementation of probiotic on performance and intestinal
microora of Chinese soft-shelled turtle (Trionyx sinensis). Aquacult. Nutr., 20: 667–674.
Z h a n g Y.P., D u W.G., S h e n J.W., S h u L. (2009). Low optimal temperatures for food conversion
and growth in the big-headed turtle, Platysternon megacephalum. Aquaculture, 295: 106–109.
Z h o u F., D in g X.Y., F e n g H., X u Y.B., X u e H.L,, Z h a n g J.R., N g W.K. (2013). The dietary
protein requirement of a new Japanese strain of juvenile Chinese soft shell turtle, Pelodiscus sinen-
sis. Aquaculture, 412: 74–80.
Z h o u X., N i u C., S u n R., L i Q. (2002). The effect of vitamin C on the non-specic immune re-
sponse of the juvenile soft-shelled turtle (Trionyx sinensis). Biochem. Phys. A., 131: 917–922.
Received: 30 V 2017
Accepted: 23 VIII 2017
Download Date | 2/26/18 5:27 PM
... Los datos obtenidos se utilizaron en un modelo estadístico de tipo descriptivo, para obtener valores de medidas de tendencia central como el promedio, la desviación estándar, valores mínimo y máximo (Llínas-Solano & Rojas-Álvares, 2005). Los resultados obtenidos para el contenido medio de cada mineral, se compararon con los valores recomendados según Chen et al. (2014), Corcoran y Roberts-Sweeney (2014), de Blas y Wiseman (2010), Donoghue y McKeown (1999), Hand et al. (2000), Mulder (2012), National Research Council (19771995;2006), Rawski et al. (2018) y Velasco-Santamaría y Corredor-Santamaría (2011), para cada animal de compañía evaluado (Cuadro 1). ...
... Las muestras de alimentos para tortuga presentaron menor contenido de Ca y P que el recomendado por Donoghue y McKeown (1999); Hand et al. (2000) y Rawski et al. (2018). Los niveles de Mg también fueron inferiores a la recomendación mínima. ...
... Los niveles de Mg también fueron inferiores a la recomendación mínima. Además, se encontró un alimento con un contenido menor de Cu que la recomendación mínima, descrita por Chen et al. (2014) y Rawski et al. (2018). ...
Full-text available
Introducción. El contenido mineral de los alimentos para mascotas no siempre está presente en la etiqueta. Es importante conocer esta información para valorar el aporte nutricional del alimento. Objetivo. Determinar el contenido de Ca, P, K, Na, Mg, S, Cu, I, Fe, Mn y Zn en 34 alimentos importados para perros, gatos, conejos, hámsters, peces ornamentales y tortugas, y comparar los resultados con las recomendaciones encontradas en la literatura. Materiales y métodos. Durante los meses de agosto y diciembre del año 2018, se obtuvieron diez muestras de alimentos para perros y gatos, cinco para peces ornamentales, cuatro para tortugas, tres para hámster y dos para conejos. Estas se adquirieron de manera directa en diferentes puntos de venta en la Gran Área Metropolitana, San José, Costa Rica. Las muestras se analizaron en el Centro de Investigación en Nutrición Animal de la Universidad de Costa Rica. Se cuantificaron los minerales Ca, P, K, Mg, S, Cu, I, Fe, Mn, y Zn con base en la metodología recomendada por la Association of Official Analytical Chemists. Se calculó el contenido promedio por grupo de alimento según la especie animal, la desviación estándar, valores máximo y mínimo; se comparó con las recomendaciones nutricionales para minerales encontradas en la literatura. Resultados. Los alimentos estudiados cumplieron, en promedio, con los requerimientos minerales de los animales de compañía. Se observaron desbalances en el contenido de Ca, P y Mg para el caso de alimentos para tortugas, altos contenidos de yodo en alimentos para perros y relaciones desbalanceadas entre minerales. Conclusiones. Se generó una base de datos con valores promedios y su dispersión en once minerales en 34 muestras de alimentos comerciales de siete animales de compañía en Costa Rica. Se observó la poca información sobre límites superiores recomendados y requerimientos en especies como hámster, peces ornamentales o tortugas.
... However, most are opportunistic carnivores or omnivores, consuming invertebrates, small vertebrates, and aquatic vegetation (Luiselli et al., 2011). Adult freshwater turtles live in water body and feed with aquatic plants such as duckweed (Lemna spp.), pondweed (Elodea spp.), and hornwort (Ceratophyllum spp.) are frequently used (Rawski, 2018). For some tropical and subtropical turtle species, fruits may also be used (Rawski, 2018). ...
... Adult freshwater turtles live in water body and feed with aquatic plants such as duckweed (Lemna spp.), pondweed (Elodea spp.), and hornwort (Ceratophyllum spp.) are frequently used (Rawski, 2018). For some tropical and subtropical turtle species, fruits may also be used (Rawski, 2018). Turtles are diapsids of the order Testdines characterized by a special bony or cartilaginous shell developed from their ribs and act as a shield. ...
... However, the BOD (56.40±0.32 a -58.50±1.13 a ppm), COD (11.18±0.24 a -11.70±0.22 a ppm) observed in the study was in line with (Craig, 2014) who reported that raising carbonate hardness levels most good aquarium, should be below 80 ppm. The mean nitrates (0.02±0.01 a -0.04±0.02 a ppm), nitrites (0.001±0.01 a ppm -0.002±0.01 a ), ammonia (0.002±0.01 a -0.003±0.02 a ppm) were within the acceptable limits of the reproductive and production of freshwater small turtle in Nigeria (Luiselli et al., 2011).Habitat of freshwater turtles had various amounts of plant matters, aquatic plants such as duckweed (Lemna spp.), pondweed (Elodea spp.), and hornwort (Ceratophyllum spp.) are frequently used (Rawski, 2018), and Neem tree. Algae such as Spirulina spp (Fig. 1) are also used in commercial fish and turtle diets, and they are also available in a dried form and may be used as a separate feed component. ...
Full-text available
The study surveyed the aspects of breeding ecology of freshwater Turtle (Pelusios niger) in the Wild in Zaria, Kaduna State Nigeria. Three points were sampled at A, B, and C of the water pool, morning (7.00am-8.00am) and evening (5.00pm-6.00am) daily. Data collected were subjected to One-way analysis of variance (ANOVA) using SAS 9.1 version to determine significant difference (P<0.05). The means were separated using Duncan Multiple Range Test (DMRT) where differences exist.The results revealed that water quality parameters during rearing of breeding period of freshwater small turtle in all the locations A, B, and C in Zaria: mean temperature(27.98±0.17 ao C-28.60±2.31 ao C), mean pH (9. a ppm),and ammonia (0.002±0.01 a-0.003±0.02 a ppm). Therefore, the water quality parameters were all within the acceptable ranges for reproduction and production of aquatic organisms.
... Across turtle species, only dietary protein requirement for Chinese soft-shelled turtles (Pelodiscus sinensis) has been reported as being within the range of 39.0-46.5% (Jia et al., 2005;Nuangsaeng & Boonyaratapalin, 2001;Xie et al., 2012;Zhou et al., 2013). Nonspecific feed for all turtles (≥38% protein), and age-specific feeds for hatchling (≥38% protein), growth phase (≥35% protein), and adults (≥25% protein), have been suggested by feed producers (Rawski et al., 2018). Generally, insufficient dietary protein can cause growth reduction in reared animals since the restricted amount is used to generate new growth in tissues whereas surplus protein is metabolized as energy source. ...
... The size variation of turtles, as well as rearing conditions, may cause different results. Findings from the current study are in agreement with the dietary protein levels suggested by feed producers; all turtles (≥38% protein), and agespecific feeds for hatchling (≥38%), growth phase (≥35%), and adults (≥25%) (Rawski et al., 2018). Results from the current report suggest that captive juvenile green turtles grow well on the test diet, higher in protein than the herbivorous or omnivorous diets (Wilson, 2002). ...
Full-text available
Head-starting programs are extremely important for restoring the population of sea turtles in wild whereas husbandry conditions and feeding regimens of captive turtles are still limited. In the current study, the optimal dietary protein requirement for green turtle (Chelonia mydas) was investigated to support rearing in head-starting programs. Twenty-five-day-old turtles (44.5-46.2 g body weight, n = 45) were randomly distributed into 15 experimental plastic tanks, comprising three treatment replications of 3 turtles each. They were fed fishmeal-based feeds containing different levels of protein (30%, 35%, 40%, 45%, and 50%) for 8 weeks. At the end of feeding trial, growth performance (specific growth rate = 1.86% body weight/day) and feed utilization (protein efficiency ratio = 3.30 g gain/g protein) were highest in turtles fed with 40% protein in feed (p < .05). These nutritional responses were significantly supported by specific activities of fecal digestive enzymes, especially trypsin, chymotrypsin, amylase, and the amylase/trypsin ratio. Also, this dietary level improved the deposition of calcium and phosphorus in carapace, supporting a hard carapace and strong healthy bones. There were no negative effects in general health status of reared turtles, as indicated by hematological parameters. Based on a broken-line analysis between dietary protein levels and specific growth rate, the optimal protein level for green turtles was estimated as 40.6%. Findings from the current study support the use of artificial diets of specific protein levels to rear captive green turtle before release to natural habitats.
... En tortugas los requerimientos de Ca y P, son de especial importancia por la frecuencia de la enfermedad ósea metabólica, ya que al tener una proporción esquelética mayor (caparazón), tienen necesidades especiales en cuanto a los minerales y vitaminas relacionados a este tipo de tejido (Donoghue & McKeown, 1999;Rawski et al., 2018). ...
Full-text available
Introduction. The regulations that govern balanced pet food ensure the welfare of pets, public health, and consumer safety, making it valuable to verify the nutritional content declared on labels. Objective. To determine the of the guaranteed analysis of 34 imported foods for dogs, cats, hamsters, rabbits, ornamental fish, and turtles and compare the results with the nutritional recommendations found in the literature. Materials and methods. During the months of August and December of 2018, food samples of dog (10), cat (10), ornamental fish (5), turtles (4), hamster (3), and rabbits (2) food were obtained by direct purchase at different points of sale in San José, Costa Rica. The content of moisture, crude protein (CP), ether extract (EE), crude fiber (CF), calcium, phosphorus, salt, and carbohydrates were analyzed. The average content, standard deviation, maximum and minimum value of each nutrient in each group of food were calculated according to the animal species. The individual and average values obtained were compared with the values declared on the label and the nutritional recommendations found in the literature. Results. The nutrients that presented non-compliances were: salt (27), calcium (16), and energy (14). Additionally, it was found that some foods did not declare the content of salt (14), calcium (9), and phosphorus (7). With respect to the minimum nutritional requirements, twenty-two samples presented deficiencies or excesses in at least one nutriment [carbohydrates (11) and ether extract (7)]. Conclusions. Imported balanced foods for dogs, cats, rabbits, hamsters, turtles, and ornamental fish presented non-compliances in the guaranteed content of CP, EE, CF, ME, Ca, P, and salt declared on the label. The nutritional composition of the evaluated foods limits compliance with the nutritional requirements of the animals, except for rabbits that do comply with the requirements.
... En tortugas los requerimientos de Ca y P, son de especial importancia por la frecuencia de la enfermedad ósea metabólica, ya que al tener una proporción esquelética mayor (caparazón), tienen necesidades especiales en cuanto a los minerales y vitaminas relacionados a este tipo de tejido (Donoghue & McKeown, 1999;Rawski et al., 2018). ...
Full-text available
Introducción. La normativa que regula los alimentos balanceados asegura el bienestar de las mascotas, la salud pública y la seguridad al consumidor, por lo que es valioso corroborar el contenido de los nutrimentos declarados en las etiquetas. Objetivo. Determinar el cumplimiento del análisis de garantía de 34 alimentos importados para perros, gatos, hámsters, conejos, peces ornamentales y tortugas, y comparar los resultados con las recomendaciones nutricionales encontradas en la literatura. Materiales y métodos. Durante los meses de agosto y diciembre del año 2018, se obtuvieron muestras de alimento de perros (10), gatos (10), peces ornamentales (5), tortugas (4), hámster (3) y conejos (2); mediante compra directa en diferentes puntos de venta en San José, Costa Rica. Se analizó el contenido de humedad, proteína cruda (PC), extracto etéreo (EE), fibra cruda (FC), calcio, fósforo, sal y carbohidratos. Se calculó el contenido promedio, la desviación estándar, el valor máximo y mínimo de cada nutrimento en cada grupo de alimento, según la especie animal. Los valores individuales y promedios obtenidos se compararon con los valores declarados en la etiqueta y las recomendaciones nutricionales encontradas en la literatura. Resultados. Los nutrimentos que presentaron incumplimientos fueron: sal (27), calcio (16) y energía (14). Además, se encontró que alimentos no declaraban el contenido de sal (14), calcio (9) y fósforo (7). Con respecto a los requerimientos mínimos nutricionales, veintidós alimentos presentaron deficiencias o excesos en al menos un nutrimento [carbohidratos (11) y extracto etéreo (7)]. Conclusiones. Los alimentos balanceados importados para perros, gatos, conejos, hámster, tortugas y peces ornamentales presentaron incumplimientos en los contenidos de PC, EE, FC, EM, Ca, P y sal garantizados en la etiqueta. La composición nutricional de los alimentos evaluados limita el cumplimiento de requerimientos nutricionales de los animales, excepto para conejos que sí se cumple con los requerimientos.
... These species are also sold as feeders for other non-native pets such as reptiles (snakes, lizards and turtles), amphibians (frogs and toads) and invertebrates (spiders) (Cartwright et al., 2016;Cooper & Williams, 2014;Kanagarajah et al., 2018;Rawski et al., 2018;Sincage & Hardin, 2015). ...
Full-text available
Murid rodents are considered globally important invasive species, yet they are still sold in the pet trade. Little is known about the genetic diversity of traded rodents, and many species are incorrectly identified in the pet trade. We used mitochondrial gene regions to assess the taxonomy and genetic diversity of 149 rodents sold in pet shops across eight South African provinces. We identified a total of 112 specimens as Mus musculus, while 31 were Rattus norvegicus, and six were identified as the southern African endemic, southern multimammate mouse Mastomys coucha. Phylogenetic analyses revealed that the three species were monophyletic. Mus musculus and R. norvegicus showed higher levels of genetic diversity, with 19 unique mtDNA haplotypes recovered for M. musculus and eight haplotypes for R. norvegicus. KwaZulu‐Natal, Western Cape and Gauteng Provinces had the most unique haplotypes than other provinces. Our findings showed that non‐native species are widely distributed in the South African pet trade industry, while M. coucha was not widely traded, although recorded in three provinces. This suggests that most provinces comply with the trade regulations on native species, but the threat of invasive rodents to South Africa's unique biodiversity is highlighted.
... Under the dual pressure of aqueous ecological environment protection and the rapidly increasing price of feedstuffs, there is a desperate need to develop a high-efficiency and environmentally friendly compound feed for this species based on its nutrient requirements. Although some literature exists on its protein, carbohydrate, lipid, vitamins, and mineral requirements [5][6][7][8][9][10], little information is available regarding dietary phosphorus requirement of this animal. ...
Full-text available
A 60-day feeding trial was performed to assess the effects of dietary phosphorus levels on growth performance, body composition, phosphorus utilization, plasma physiological parameters and intestinal Ca and P transport-related gene expression of juvenile Chinese soft-shelled turtle (P. sinensis). Four diets containing available P at graded levels of 0.88%, 1.00%, 1.18% and 1.63% (termed as D0.88, D1.00, D1.18 and D1.63, respectively) were formulated and each diet was fed to turtles (5.39 ± 0.02 g) in sextuplicate. The turtles were randomly distributed to 24 tanks with 8 turtles per tank. The results indicated that final body weight, specific growth rate, feed conversion ratio and protein efficiency ratio performed best in turtles fed 1.00% available P diet. The crude lipids of the whole body exhibited a decreasing trend with the dietary available P, whereas the calcium and phosphorus of the whole body and bone phosphorus showed an opposite tendency. The apparent digestibility coefficient of phosphorus declined with the dietary available P. Turtles fed 1.00% available phosphorus had the highest phosphorus retention ratio compared with other treatments. Simultaneously they had significantly lower phosphorus loss than turtles fed D1.18 and D1.63 and had no differences in this respect from turtles fed a low-phosphorus diet. It was noteworthy that the lowest plasma calcium concentrations, and alkaline phosphatase activities in plasma and liver, were discovered in turtles fed the diet containing 1.63% available phosphorus. In addition, the high-phosphorus diet resulted in significantly down-regulated expression of intestinal phosphorus and calcium transport-related key genes. In conclusion, the available phosphorus requirement of juvenile P. sinensis was determined at 1.041% (total phosphorus was 1.80%) based on quadratic regression of weight gain rate, and excessive dietary phosphorus stunted turtle growth possibly via inhibiting intestinal calcium absorption.
... Consequently, zoos and protected areas in Argentina annually receive hundreds of tortoises that have been seized or abandoned (López et al. 2010). In recent years, scientific research focusing on animal populations kept in zoos has been incorporated in projects for the conservation of different species (Rawski et al. 2018;Chusyd et al. 2018;Eguizabal et al. 2019;Prystupczuk et al. 2019;Rose et al. 2019). Indeed, zoo environments are useful for the study of species whose behavior is difficult to observe in the wild, as is the case of the C. chilensis. ...
Full-text available
Ectothermic animals depend on environmental temperature to regulate their body temperature. The Chaco Tortoise (Chelonoidis chilensis) is widespread in South America; however, populations are threatened mainly because of the pet trade. We described the activity pattern of C. chilensis relative to environmental temperature under semi-natural conditions in a zoo enclosure. We also estimated thermal parameters under controlled laboratory conditions: selected temperature (T sel) and critical maximum temperature (CT max) between sex and size indicators. In the enclosure, 81% of the observations were from inactive tortoises and 19% from active tortoises. Tortoises were active over a wide thermal range (12.0°-38.0° C) and T sel was 34.4° ± 0.3° C (mean ± standard error), with no significant differences among sizes or between sexes. Heavier tortoises spent significantly more time at the lowest temperature than lighter ones. The range of CT max was 36.3°-42.0° C and this parameter was inversely related to tortoise length but did not differ between sexes. The results suggest a wide thermal range in C. chilensis, dependence of thermal behavior on body size but not on sex, and a wider range of body temperatures in smaller individuals than in larger ones. Knowing the parameters that influence thermoregulation contributes to the improvement of management strategies under semi-natural conditions, which, in turn, can be extrapolated to wild populations.
... Turtles are carnivores that mainly feed on worms, insects, fishes, mollusks, and frogs (37). Insects are the main part of their diet in the natural environment as well as a pet (38). Çiçek and Ayaz (39) stated that almost 84% of all stomach content consisted of insects during the breeding season. ...
Full-text available
The world population is increasing swiftly and expected to reach 109 billion by 2100. As compared to population increment, food resources to feed a huge population are not increasing. Similarly, in the future country having enough food to feed its inhabitants will be considered more powerful. There are two main protein sources used by living beings which are from plant origin and animal origin. Furthermore, animal protein sources are more crucial for humans due to the presence of essential amino acids. It is a need of the time to find alternative sources to fulfill the requirements. The insect protein source is one of them especially for animal feed leading to the usage of that protein being consumed by animals in human food. Especially pets food companies use hygiene meat of human consumption standards which can be replaced with an insect-based protein source. Insects are a rich source of proteins (40-60%), lipids (14-37%), energy, vitamins, and minerals having variation with species (black soldier fly, mealworm, cricket, and locust) and developmental stage of life (larva, pupa, nymph and adult one). Many trials have been conducted by using insect meal as an alternative protein source in pet’s food (dogs, cats, rabbits, reptiles, sugar gliders, birds, and ornamental fishes), which has been explained in this study. It can be concluded that insect-derived products can be used in pet food as an alternative source of protein to conventional protein sources (soybean meal, fish meal) with improved performance.
Full-text available
Soybean meal is widely applied in the aquafeeds due to the limitation of fish meal resources. Numerous studies have manifested that dietary soybean saponin, an anti-nutrient factor in soybean meal, may slow growth and induce intestinal inflammation in aquatic animals, but the possible causes are unclear. The juvenile Pelodiscus sinensis (mean initial body weight: 6.92 ± 0.03 g) were fed basal diet (CON group) and 2.46% soybean saponin Bb-supplemented diet (SAP group) for 35 days to further explore the effects of dietary soybean saponin Bb on the growth performance, apparent digestibility coefficients, intestinal morphology, the gut microbiota, intestinal transporters/channels, and immune-related gene expression. The results indicated that dietary soybean saponin Bb significantly decreased final body weight, specific growth rate, protein deposition ratio, and apparent digestibility coefficients (dry matter, crude protein, and crude lipid) of nutrients in Pelodiscus sinensis, which may be closely correlated with markedly atrophic villus height and increased lamina propria width in the small intestine. In addition, plasma contents of cholesterol, calcium, phosphorus, potassium, lysozyme, and C3 were significantly decreased in the SAP group compared with the control group. Soybean saponin Bb significantly downregulated the mRNA levels of glucose transporter 2, fatty acid binding protein 1 and fatty acid binding protein 2, amino acid transporter 2, b0,+-type amino acid transporter 1, and sodium-dependent phosphate transport protein 2b in the small intestine. At the same time, the expressions of key transcription factors (STAT1, TBX21, FOS), chemokines (CCL3), cytokines (TNF-α, IL-8), and aquaporins (AQP3, AQP6) in the inflammatory response were increased by soybean saponin Bb in the large intestine of a turtle. Additionally, dietary supplementation of SAP significantly reduced the generic abundance of beneficial bacteria (Lactobacillus, Bifidobacterium, and Bacillus) and harmful bacteria (Helicobacter and Bacteroides). In a nutshell, dietary supplementation of 2.46% soybean saponin not only hindered the growth performance by negatively affecting the macronutrients absorption in the small intestine but also induced an inflammatory response in the large intestine possibly by damaging the intestinal morphology, disturbing the intestinal microbiota and decreasing intestinal epithelial cell membrane permeability.
Full-text available
The consumption of poultry meat and eggs is expected to increase considerably in the nearest future, which creates the demand for new poultry feed ingredients in order to support sustainable intensive production. Moreover, the constant improvement of the genetic potential of poultry has resulted in an increased nutrient density in poultry feeds, which limits the possibility to include low quality feed ingredients. Therefore, the feed industry needs new sources of highly digestible protein with a desirable amino acid composition to substitute other valuable but limited protein sources of animal origin, such as fishmeal. With estimated 1.5 to 3 million species, the class of insects harbours the largest species variety in the world including species providing a high protein and sulphur amino acids content, which can be successfully exploited as feed for poultry. The aim of this paper is to review the present state of knowledge concerning the use of insect protein in poultry nutrition and the possibilities of mass production of insects for the feed industry. There is no doubt that insects have an enormous potential as a source of nutrients (protein) and active substances (polyunsaturated fatty acids, antimicrobial peptides) for poultry. It can be concluded, basing on many experimental results, that meals from insects being members of the orders Diptera (black soldier fly, housefly), Coleoptera (mealworms) and Orthoptera (grasshoppers, locust, crickets and katylids), may be successfully used as feed material in poultry diets. However, legislation barriers in European Union, as well as relatively high costs and limited quantity of produced insects are restrictions in the large-scale use of insect meals in poultry nutrition.
Full-text available
Probiotics are widely used in nutrition, and their mode of action is intensively studied in mammals and birds; however, it is almost unknown in reptiles. In the present study, Trachemys scripta scripta and Sternotherus odoratus were used to assess the effects of dietary probiotics on chelonian gastrointestinal tract microecology. In the first, 20-week experiment, 40 young T. s. scripta were randomly distributed to four experimental groups: 1st, (CON)-with no additives; 2nd, (SSPA) with Bacillus subtilis PB6; 3rd, (MSP)-with multiple strain probiotic; and 4th, (SSPB) with Bacillus subtilis C-3102. The first study has shown that SSPA and MSP decreased the numbers of total bacteria, Enterobacteriace, Staphylococcus sp. and Streptococcus sp. excreted to water and increased the villous height and mucosa thickness in duodenum. SSPB improved the duodenal microstructure; however, it also increased numbers of kanamycin and vancomycin resistant bacteria, Staphylococcus sp. and Streptococcus sp., in water. In the second, 52-week experiment, 30 S. odoratus were randomly assigned to three dietary treatments. CON, SSPA and MSP groups. The MSP preparation increased the body weight gain, crude ash, Ca and P share in the turtles' shells. Both probiotics affected duodenal histomorphology. SSPA decreased the villous height, while MSP increased the villous height and mucosa thickness, and decreased the crypt depth. SSPA decreased the concentrations of bacteria excreted to water. In the case of intestinal microbiota, bacteria suppressing effects were observed in the case of both probiotics. MSP increased the number of Bifidobacterium sp. and Lactobacillus sp./Enteroccoccus sp., and decreased the number of Clostridium perfringens and Campylobacter sp. in the small intestine. In the large intestine it lowered, amongst others, Bacteroides-Pervotella cluster, Clostridium leptum subgroup and Clostridium perfringens numbers. The above-mentioned results suggest that probiotics are useful in turtle nutrition due to their positive effects on growth performance, shell mineralization, duodenal histomorphology and microbiota.
This outstanding clinical reference provides valuable insights into solving clinical dilemmas, formulating diagnoses, developing therapeutic plans, and verifying drug dosages for both reptiles and amphibians. The information is outlined in an easy-to-use format for quick access that is essential for emergency and clinical situations. Discusses veterinary medicine and surgery for both reptiles and amphibians Features complete biology of snakes, lizards, turtles, and crocodilians Provides step-by-step guidelines for performing special techniques and procedures such as anesthesia, clinical pathology, diagnostic imaging, euthanasia and necropsy, fracture management, soft tissue surgery, and therapeutics Covers specific diseases and conditions such as anorexia, aural abscesses, and digit abnormalities in a separate alphabetically organized section 53 expert authors contribute crucial information to the study of reptiles and offer their unique perspectives on particular areas of study The expansive appendix includes a reptile and amphibian formulary A new full-color format features a wealth of vivid images and features that highlight important concepts and bring key procedures to life 29 new chapters covering diverse topics such as stress in captive reptiles, emergency and critical care, ultrasound, endoscopy, and working with venomous species Many new expert contributors that share valuable knowledge and insights from their experiences in practicing reptile medicine and surgery Unique coverage of cutting-edge imaging techniques, including CT and MRI.
The only book of its kind with in-depth coverage of the most common exotic species presented in practice, this comprehensive guide prepares you to treat invertebrates, fish, amphibians and reptiles, birds, marsupials, North American wildlife, and small mammals such as ferrets, rabbits, and rodents. Organized by species, each chapter features vivid color images that demonstrate the unique anatomic, medical, and surgical features of each species. This essential reference also provides a comprehensive overview of biology, husbandry, preventive medicine, common disease presentations, zoonoses, and much more. Other key topics include common health and nutritional issues as well as restraint techniques, lab values, drug dosages, and special equipment needed to treat exotics. Brings cutting-edge information on all exotic species together in one convenient resource. Offers essential strategies for preparing your staff to properly handle and treat exotic patients. Features an entire chapter on equipping your practice to accommodate exotic species, including the necessary equipment for housing, diagnostics, pathology, surgery, and therapeutics. Provides life-saving information on CPR, drugs, and supportive care for exotic animals in distress. Discusses wildlife rehabilitation, with valuable information on laws and regulations, establishing licensure, orphan care, and emergency care. Includes an entire chapter devoted to the emergency management of North American wildlife. Offers expert guidance on treating exotics for practitioners who may not be experienced in exotic pet care.
The big-headed turtle Platysternon megacephalum is a stream-dwelling species whose ecology is poorly known. We carried out field and laboratory investigations to determine field body temperatures and thermal preference of this species. In the field, the body temperatures of the turtles conformed to the water temperature, with little diel variation in either summer or au-tumn. Over the diel cycle, the mean body temperatures ranged from 20.8°C to 22.2°C in summer and from 19.3°C to 21.2°C in autumn; the highest body temperatures ranged from 22.1°C to 25.0°C in summer and from 20.6°C to 23.8°C in autumn. In the laboratory, the preferred body temperature (Tp) was 25.3°C. Food intake was maximized at 24.0°C, whereas locomotor perfor-mance peaked at 30.0°C. Consequently, Tp was closer to the thermal optimum for food intake than for locomotion. Therefore, this freshwater turtle has relative low field body temperatures corresponding to its thermal environment. In addition, the turtle prefers low temperatures and has a low optimal temperature for food intake.