I . The physiological response of rainbow trout (Salmo gairdneri] reared on different levels of available carbohydrate in practical trout diets having the same levels of energy and nitrogen for 1 6 2 4 weeks was determined.2 However, no significant effect was noted on the activity of these liver enzymes above a dietary cerelose level of 140 g/kg.5. Liver fructose diphosphatase (EC 3.1 .3.11) activity increased with increasing dietary carbohydrate has been interpreted as meaning a recycling of triosephosphate to glucose-6-phosphate.6. Dietary carbohydrate level had no significant effect on the liver pyruvate kinase (EC 2 . 7 . 1 .40) activity, the rate of glucose utilization or the percentage conversion of [*4C]alanine to glucose in the plasma of trout.7. The results indicate that rainbow trout have a limited ability to adapt to increased dietary carbohydrate and a level in excess of 140 g/kg of the diet is not efficiently utilized.

Relative performances of dietary acid-insoluble ash, celite (a source of acid-insoluble ash), and chromic oxide as digestibility references were compared. Apparent digestibilities of dry matter, crude protein, and gross energy in a practical diet fed to rainbow trout (Salmo gairdneri) were similar regardless of indicator used. Acid-insoluble ash can bean effective indicator for digestibility trials with fish. Its natural occurrence in fish foods and feedstuffs and ease of analysis make it preferable to added indicators, such as chromic oxide, in many circumstances. When the acid-insoluble ash content of a diet is low, the addition of celite can improve the precision of the analysis without affecting absolute values of digestibility coefficients.

The effects of growth hormone (GH) and dietary protein on expression of IGF-I and GH receptor (GHR) genes in liver, muscle, and fat of pigs were investigated. Forty-eight intact male Large White x Landrace pigs were allotted to eight treatment groups (four diets with or without GH). The pigs were restriction-fed one of four diets, which differed only in their protein content (9.9, 13.1, 16.2, and 19.4%, as-fed basis), for a total of 3 wk. The pigs were then injected intramuscularly with either porcine GH (50 micrograms.kg-1.d-1 of rpST) or vehicle for the last 7 d. Pigs were slaughtered 4 h after the final injection. Total RNA was extracted from all tissues and then RNase protection assays were performed to measure expression of IGF-I and GHR genes. Expression of IGF-I mRNA was found to be GH responsive in the liver, semitendinosus (ST), and adipose tissue (P < .01) but not in longissimus muscle (LD). Dietary protein increased IGF-I expression only in the adipose tissue (P < .01). Expression of class 2 transcripts of IGF-I were observed only in the livers of GH-treated pigs, with no effect of dietary protein. Expression of GHR mRNA was found to increase with GH administration in liver and skeletal muscle (LD and ST, P < .05) but not in adipose tissue. There were diet x GH interactions on GHR expression in liver, ST, and adipose tissue, resulting in the highest GHR expression being in the high protein-fed, GH-treated group for liver, but in the low protein-fed, GH-treated group for muscle and adipose tissue. This study demonstrates tissue-specific control of expression of the two genes and also tissue-specific promoter usage (IGF-I exon 2 in liver) in response to GH administration.

Juvenile rainbow trout (Salmo gairdneri) reared for 12 wk on different levels of dietary fiber showed a significant growth depression at levels of 10 and 20% alpha-floc (α-cellulose). The trout adapted to increased dietary fiber by increasing feed consumption, gastric evacuation time, and possibly by increasing the stomach volume and/or distensibility. The dry matter digestion coefficients of the diets declined as the fiber level increased, indicating that the digestibility of α-cellulose was not significantly different from zero. No effect of increased dietary fiber (alpha-floc) was detected on the liver glycogen levels, liver–body weight ratios, hemoglobin, hematocrit, plasma glucose, and plasma protein levels or the kidney, liver, and carcass levels of copper, iron, and zinc. We conclude that dietary fiber levels for rainbow trout should be less than 10% of the diet.Key words: rainbow trout, dietary fiber, maximum fiber level, fiber digestibility

Amphibian biology is intricate, and there are many inter-related factors that need to be understood before establishing successful Conservation Breeding Programs (CBPs). Nutritional needs of amphibians are highly integrated with disease and their husbandry needs, and the diversity of developmental stages, natural habitats, and feeding strategies result in many different recommendations for proper care and feeding. This review identifies several areas where there is substantial room for improvement in maintaining healthy ex situ amphibian populations specifically in the areas of obtaining and utilizing natural history data for both amphibians and their dietary items, achieving more appropriate environmental parameters, understanding stress and hormone production, and promoting better physical and population health. Using a scientific or research framework to answer questions about disease, nutrition, husbandry, genetics, and endocrinology of ex situ amphibians will improve specialists’ understanding of the needs of these species. In general, there is a lack of baseline data and comparative information for most basic aspects of amphibian biology as well as standardized laboratory approaches. Instituting a formalized research approach in multiple scientific disciplines will be beneficial not only to the management of current ex situ populations, but also in moving forward with future conservation and reintroduction projects. This overview of gaps in knowledge concerning ex situ amphibian care should serve as a foundation for much needed future research in these areas.