Faecal characteristics as markers of Chelonia mydas feeding

et al. 2019

Animals

Simple SummaryNorthern river terrapins can adapt physiologically or behaviorally across a salinity gradient, so that they can move between freshwater habitats and brackish water or estuaries. However, there is no available information on the optimal salinity of this species for supporting captive husbandry programs before release to natural habitat. In the current study, the optimal salinity for the terrapins was investigated to serve the well-being of turtles. At the end of the rearing period, various observed parameters related to growth, feed utilization, and health indicated that optimal salinity for rearing the terrapins is about 4 ppt, while rearing in freshwater (0 ppt) or other brackish (8 and 12 ppt) water conditions had negative effects on some key parameters that reflect well-being. A polynomial regression fit to terrapin weight gain as function of salinity predicts the optimal salinity as 4.35 ppt. Findings from the current study could be directly used in ex situ conservation programs of northern river terrapins before release to natural habitat. Additionally, concurrent conservation and restoration of the wild habitats with preferred salinity is essential for flourishing terrapin population.AbstractNorthern river terrapins (Batagur baska Gray, 1831) are Asia’s largest turtles living in both freshwater and brackish water. In the current study, the optimal salinity for head-starting programs of this critically endangered species was investigated in order to serve the well-being of turtles before release to natural habitat. Forty-eight terrapins (54.64 ± 0.18 g initial body weight) were randomly distributed to four salinity levels (0, 4, 8, and 12 ppt) and reared for eight weeks, using three replicates with four terrapins each. At the end of rearing trial, growth performance and feed utilization parameters were superior in terrapins reared at 4 ppt, followed by 8 ppt in the rank order of treatments. Negative stress responses were observed in terrapins reared at 12 ppt, as the fecal activity of amylase-to-trypsin ratio was changed significantly, but not that of proteolytic enzymes. The fecal thermal transition properties indicated an abundance of nutrients in the post-absorptive phase for terrapins reared at 4 ppt, followed by the 8 ppt treatment group. The preferred 4 ppt salinity had no negative effects on the health status of the terrapins in terms of carapace elemental composition or hematological parameters. Second-order polynomial regression suggests 4.35 ppt as the optimal salinity for maximal weight gain. Findings from the current study could be directly used in ex situ conservation programs of northern river terrapins before release to natural habitat.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal Salinity for Head-Starting Northern River Terrapins (Batagur baska Gray, 1831)

Jualaong¹,

Songnui²,

et al. 2019

Animals

“…After digestion, the enzymes are excreted in the feces, and are protected by membranes that prevent leakage (Córdova-Murueta et al, 2003). Therefore, these enzymes, as well as physicochemical characteristic of the feces, could be used for assessing feed utilization efficiency in green turtles, although without performing digestibility trials (Kanghae et al, 2014bThongprajukaew et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Water depth and feed pellet type effects on growth and feed utilization in the rearing of green turtle (Chelonia mydasLinnaeus, 1758)

Songnui¹,

Kanghae

et al. 2017

Aquat. Living Resour.

Self Cite

The rearing of green turtles (Chelonia mydas Linnaeus, 1758) before their release to natural habitats has been practiced in several countries, whereas little information is available for inferring optimal husbandry protocols. This study aimed to improve the growth performance and feed utilization of posthatching green turtles by varying the water depth (15 or 30 cm) and feed pellet type (sinking or floating pellets). The 20-day-old turtles (23.49 ± 0.02 g initial body weight) were subjected to a 2 Â 2 factorial experiment (3 replications with 5 animals per tank) over a two-month duration. Growth, feed utilization, fecal digestive enzymes and hematological parameters were recorded to evaluate the effects of different treatments. No mortality was observed in any treatment group. Turtles reared in 15 cm water depth and fed with floating pellets exhibited superior growth (specific growth rate 2.76% body weight day À1 ) and feed utilization (feeding rate 1.42% body weight day À1 , feed conversion ratio 0.61 g feed g gain À1 , protein efficiency ratio 3.76 g gain g protein À1 ), relative to the other treatments. This treatment improved the utilization of nutrients by modulating trypsin specific activity but had no negative effects on hematological characteristics. Overall these findings indicate that the rearing program of post-hatching green turtles should be run with about 15 cm water depth and the preferred type of feed is floating pellets. These preferred conditions can also be applied in public displays, such as zoos or aquaria.

“…Significant changes in digestive enzyme activities relate with fecal thermal properties, since the thermogram from DSC reflects the native amount of nutrients present in feces after digestion and absorption [ 9 , 18 , 21 , 49 ]. Generally, the low temperature peaks (peaks 1 and 2) detect available nutrients, mainly protein, nitrogen-free extract, and lipid, while the high temperature peaks (peaks 3 and 4) refer to unavailable composition, probably crude fiber [ 40 ].…”

Section: Discussionmentioning

confidence: 99%

“…The optimal conditions for fecal digestive enzyme assays were chosen from the previous report on green turtles [ 21 ]. Hemoglobin was used as non-specific substrate for determination of pepsin activity (EC 3.4.23.1), according to the method of Worthington [ 22 ].…”

Section: Methodsmentioning

confidence: 99%

Optimal Feeding Frequency for Captive Hawksbill Sea Turtle (Eretmochelys imbricata)

Jualaong¹,

Kanghae

et al. 2021

Animals

Self Cite

Hawksbill sea turtle (Eretmochelys imbricata) has been reared in head-starting captivity programs, while the feeding regimens have never been optimized. In the current study, the feeding frequency of hawksbill sea turtle was investigated in indoor experimental conditions. Two-month-old turtles (38.98 ± 0.02 g) were distributed to triplicates of five treatments containing three turtles each and they were fed at different frequencies: one meal daily at 12.00 h (1M12), two meals daily at 08.00 and 12.00 h (2M8–12), two meals daily at 08.00 and 16.00 h (2M8–16), two meals daily at 12.00 and 16.00 h (2M12–16), or three meals daily at 08.00, 12.00 and 16.00 h (3M8–12–16). At the end of an 8-week trial, growth performance (specific growth rate 2.39 ± 0.02% body weight day−1) and feed consumption (feeding rate 2.00 ± 0.43 g day−1) were highest for turtles fed 2M8–16, followed by 2M12–16 or 3M8–12–16 relative to the other treatments (p ˂ 0.05). These treatments had significantly higher trypsin specific activity and trypsin/chymotrypsin ratio, and vice versa for lipase specific activity and amylase/trypsin ratio, relative to the remaining treatments. These match well with the fecal thermal properties that indicate amounts of available and unavailable nutrients present in the feces. Hematological parameters and carapace elemental composition showed no negative effects to turtles in 2M8–16 treatment. Therefore, two meals daily with long time interval were optimal for feeding hawksbill sea turtle. Findings from the current study could be directly used as a feeding guideline supporting the head-starting programs of this species.