Influence of oral administration of 3,5,3′‐triiodo‐thyronine on growth, digestion, food conversion and metabolism in the underyearling red sea bream, <i>Chrysophrys major</i> (Temminck &amp; Schlegel)

Section: Discussionmentioning

confidence: 93%

Effect of oral administration of l-thyroxine (T4) on growth performance, digestibility, and nutrient retention in Channa punctatus (Bloch) and Heteropneustes fossilis (Bloch)

Garg

2007

“…Literature on thyroid hormone supplementation of fish feed has indicated an anabolic effect in some species (Higgs et al 1979;Saunders et al 1985;Woo et al 1991) with no effect in others (Leatherland et al 1987;Gannam and Lovell 1991).…”

Section: Discussionmentioning

confidence: 98%

Dietary effects on thyroid hormones in the red drum, Sciaenops ocellatus

MacKenzie

Moon

Gatlin

et al. 1993

Juvenile red drum (Sciaenops ocellatus) were cultured at 25°C on a variety of diets and blood sampled over eight weeks to examine the relationship between growth and plasma thyroid hormone levels. Maximum growth rates were achieved on formulated experimental diets and a simulated natural shrimp diet. Associated with these maximal rates was a significant increase in triidothyronine (T3), but no consistent change in thyroxine (T4). Reduced rations of diets resulted in low growth rates associated with significantly lowered levels of T3 but not T4. To determine whether weight gain could be increased by application of exogeneous hormone, diets were supplemented with T3 or T4 at 2, 10, and 50 mg hormone/kg diet. Significantly elevated T3 was induced by supplementation with 10 and 50 mg T3/kg diet, although there were no indications of an anabolic effect of T3 incorporation, and 50 mg T3/kg diet was in fact associated with decreased weight gain. Incorporation of T4 into diets had no effect on growth or T3, and had effects on T4 which were small and inconsistent, indicating that T4 may not be effectively absorbed from the gut. No difference was found in response to hormone feeding between low (6 ppt) or high (35 ppt) water salinity. T3 levels thus appear to closely parallel growth in fish on unsupplemented diets, whereas T4 which were small and manipulation. Supplementation with T3 is not an effective means of stimulating growth in red drum fed optimum diets. Whereas thyroid hormones may function to regulate intermediary metabolism in red drum, elevated endogenous thyroid hormone levels appear adequate to supply tissue needs during juvenile growth in culture.

“…It has been shown that thyroid hormones could influence fish growth (Woo et al 1991;Higgs et al 1992) and survival (Brown et al 1989;Reddy and Lam 1992), especially at larvae and juvenile stages. Therefore, investigation of these hormones may provide a greater understanding of the endocrine control of growth in teleost fish (Nankervis et al 2000).…”

Section: Discussionmentioning

confidence: 99%

Protein-sparing effect of dietary lipid in practical diets for blunt snout bream (Megalobrama amblycephala) fingerlings: effects on digestive and metabolic responses

Jiang

Liu

et al. 2011

174

109

This study aimed to evaluate the protein-sparing effect of dietary lipid on digestive and metabolic responses of fingerling Megalobrama amblycephala. Fish were fed nine practical diets with three protein levels (270, 310 and 350 g kg(-1)) and three lipid levels (40, 70 and 100 g kg(-1)) for 8 weeks. Weight gain was significantly affected only by dietary lipid levels with the highest found in fish fed 70 g kg(-1) lipid. Relative feed intake and whole-body protein content showed little difference among all the treatments. Activities of intestine lipase and amylase increased significantly as dietary lipid levels increased, whereas little difference was observed in protease activities. Liver lipid content was significantly affected only by protein levels with the lowest found in fish fed 310 g kg(-1) protein. Liver aspartate aminotransferase (GOT) activities increased significantly with decreasing lipid levels, whereas the highest GOT activity was obtained in fish fed 310 g kg(-1) protein in terms of dietary protein levels. Activities of liver lipoprotein lipase, total lipase and plasma cholesterol concentration of fish fed 350 g kg(-1) protein were significantly lower than that of the other groups, whereas the same was true for plasma 3, 5, 3'-triiodothyronine level of fish fed 270 g kg(-1) protein. The results indicated that an increase of dietary lipid content from 40 to 70 g kg(-1) can enhance the growth and digestive enzyme activities of this species and reduce the proportion of dietary protein catabolized for energy without inducing hepatic steatosis; meanwhile, decreasing protein level from 350 to 310 g kg(-1) leads to the increase of lipase activities both in intestine and liver coupled with the reduced liver lipid content.