Determining the Effects of Serial Injections of Pregnant Mare Serum Gonadotropin on Plasma Testosterone Concentrations, Testicular Dynamics, and Semen Production in Leopard Geckos (Eublepharis macularius).

Reptiles are highly susceptible to anthropogenic activities as a result of their narrow geographical ranges and habitat specialization, making them a conservation concern. Geckos represent one of the mega-diverse reptile lineages under pressure; however, limited assisted reproductive technologies currently exist for these animals. Exogenous pregnant mare serum gonadotropin (PMSG) has been found to exhibit follicle stimulating hormone-like action and has been routinely used to alter reproductive hormones of vertebrates in assisted reproductive protocols. The purpose of this study was to determine the effects of serial injections of 20 IU and 50 IU PMSG on circulating testosterone concentrations, testicular dynamics, and semen production in a model species of gecko. Twenty-four captive-bred, adult, male leopard geckos (Eublepharis macularius) were divided into three treatment groups and administered a once-weekly injection of either PMSG or saline for a total of nine weeks. Ultrasonographic testicular measurements, electrostimulation for semen collection, and venipuncture were performed on days 0, 21, 42, and 63. Right unilateral orchidectomies and epididymectomies were performed in all animals on day 63; tissues were submitted for histopathology. PMSG treated geckos had significantly higher testicular volumes and weights, spermatozoa motility, and spermatozoa concentrations compared with controls. However, there were no significant differences in testosterone concentrations by treatment or time. Under the conditions outlined, PMSG is effective at stimulating spermatogenesis and increasing testicular size, but not effective at increasing testosterone concentrations in the leopard gecko between October-December in the Northern hemisphere.

Evaluation of vitamin A gut loading in black soldier fly larvae (Hermetia illucens).

Black soldier fly (BSF) larvae are potentially an excellent source of calcium for insectivores; however, previous studies have identified that they lack appreciable amounts of fat-soluble vitamins (A, D3 , and E). To make BSF larvae a more complete food item, fat-soluble vitamins should either be provided via gut loading or with a multivitamin dusting supplement. The purpose of this study is to identify factors associated with gut loading vitamin A into BSF larvae and to develop feeding recommendations for a more consistent gut-loading process. Factors that were addressed include the vitamin A concentration added to the diet, length of time given to gut load, moisture content of the diet, and density of larvae during feeding. Diets and larvae were analyzed for vitamin A concentration using high-performance liquid chromatography. Larval vitamin A concentrations increased in a nonlinear fashion with increasing dietary vitamin A. Length of time (F = 150.818, p < .001), moisture content of the diet (F = 41.436, p < .001), and larval density (F = 78.407, p < .001) were all found to be significant factors contributing to the larvae's gut-loading capacity. On the basis of our results and vitamin A recommendations from the National Resource Council for rats and poultry, gut-loading recommendations for BSF larvae when fed to insectivorous reptiles and amphibians are as follows: vitamin A concentration of diet between 16,000 and 20,000 mcg retinol equivalents/kg, gut-loading time period of 24 h, moisture content of the diet approximately 60%, and larval density between 0.1 and 1 larvae per each gram of moist substrate.

Digestibility of black soldier fly larvae (Hermetia illucens) fed to leopard geckos (Eublepharis macularius).

Black soldier fly (BSF) larvae have been marketed as an excellent choice for providing calcium to reptiles without the need of dusting or gut loading. However, previous studies have indicated that they have limited calcium digestibility and are deficient in fat soluble vitamins (A, D3, and E). In this feeding and digestibility trial, 24 adult male leopard geckos were fed one of three diets for 4 months: 1) whole, vitamin A gut loaded larvae; 2) needle pierced, vitamin A gut loaded larvae; or 3) whole, non-gut loaded larvae. Fecal output from the geckos was collected daily and apparent digestibility was calculated for dry matter, protein, fat, and minerals. There were no differences in digestibility coefficients among groups. Most nutrients were well digested by the leopard geckos when compared to previous studies, with the exception of calcium (digestibility co-efficient 43%), as the calcium-rich exoskeleton usually remained intact after passage through the GI tract. Biochemistry profiles revealed possible deficits occurring over time for calcium, sodium, and total protein. In regards to vitamin A digestibility, plasma and liver vitamin A concentrations were significantly higher in the supplemented groups (plasma- gut loaded groups: 33.38 ± 7.11 ng/ml, control group: 25.8 ± 6.72 ng/ml, t = 1.906, p = 0.04; liver- gut loaded groups: 28.67 ± 18.90 µg/g, control group: 14.13 ± 7.41 µg/g, t = 1.951, p = 0.03). While leopard geckos are able to digest most of the nutrients provided by BSF larvae, including those that have been gut loaded, more research needs to be performed to assess whether or not they provide adequate calcium in their non-supplemented form.