Optimal feeding frequency of captive head‐started green turtles (Chelonia mydas)

Abstract

Optimal feeding frequency was investigated to improve head-started propagation programme of juvenile green turtles (Chelonia mydas). The 15-day-old turtles (25-26 g body weight) were fed for ad libitum intake at one (1MD), two (2MD), three (3MD) or four (4MD) meals daily over a 3-month trial. Responses in growth, feed utilization, faecal characteristics, haematological parameters and carapace elemental composition were used to compare treatment effects. At the end of the feeding trial, no treatment had induced mortality. Growth performance in terms of weight gain and specific growth rate was similar in turtles fed 2MD, 3MD or 4MD (p > 0.05), but 1MD differed from these (p < 0.05), and feeding at excess frequency (3MD and 4MD) increased the within-group size variation. Turtles fed 2MD had significantly lower feed intake than in 3MD and 4MD groups, but the feed conversion ratios were similar. Faecal digestive enzyme analysis indicated higher catabolism of lipid and protein in the deprivation group (1MD), when compared with turtles fed at least twice daily. The feeding frequency did not affect the specific activities of carbohydrate-digesting enzymes. The results on enzymes activities were corroborated by the transition enthalpy characteristics of faeces, indicating nutrients remaining after digestion. The 2MD treatment also improved the haematological characteristics and the carapace quality, relative to low or excess feeding. Overall, the findings indicate that feeding juvenile green turtles twice a day is the preferred option in their head-started propagation. This promotes growth, reduces feed consumption, and improves health and carapace quality.

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

“…However, this kind of comparative study can be performed with other non-endangered model turtle species, such as soft-shelled turtles (Pelodiscus sinensis), to collect more evidence prior to application in endangered species. Recently, the specific activities of gastric and pancreatic enzymes in fecal samples have been used as indicators for monitoring feed utilization in green turtles [18][19][20]26,33]. In the current study, the effects of background color on the specific activities of these digestive enzymes were clearly observed.…”

“…Major changes in thermal properties of fecal samples were observed across the five treatments. The low temperature peak indicates the presence of available nutrients, mainly proteins and carbohydrates, in the feces [20,26]. The absence of this peak with the blue background suggests complete digestion and absorption of nutrients along the alimentary tract.…”

“…Among the eleven chemical elements observed, significant differences were prominent in oxygen, sulfur, and calcium. Oxygen is the major element present in various chemical compounds [26]. Replacement of oxygen with sulfur and calcium was observed in terrapins reared in the optimal treatment conditions.…”

“…Fresh feces (n = 3 per treatment) were prepared according to the method described by Kanghae et al [26]. Three milligrams of dried feces were heated from 40 to 400 • C at a rate of 10 • C min −1 in an empty pan.…”

“…The carapace sampling and preparation (n = 3 per treatment) were conducted as described in Kanghae et al [26]. The carapace elemental composition was carried out with a scanning electron microscope (Quanta 400; Field Electron and Ion Co., Ltd. (FEI), Brno, Czech Republic) equipped with an energy dispersive X-ray spectrometer (X-MAX, Oxford, UK).…”