Immersion in bovine insulin stimulates growth of tilapia

Abstract

Summary ― The objective of this study was to investigate the effects of bovine insulin on growth responses in tilapia. Juvenile hybrid male tilapia (Oreochromis niloticus x 0 aurea; n = 135) were subjected to 1 of 3 treatments. Each treatment was subdivided into 3 replicates of 15 fish each. The fish were immersed into 1 of 2 doses (10 and 100 pg/100 ml water) of insulin or no hormone for 15 min per week for 8 weeks. Body weight, growth and feed conversion efficiency were significantly higher as a result of the first 4 weeks of insulin treatment as compared to control fish. The lower dose of insulin had a better stimulation effect than that of the higher doses. Insulin also stimulated feed consumption. Liver protein and protein/DNA ratio were higher in both insulin-treated groups than in the control group. Muscle proximate composition and hepatosomatic index were similar in the insulin-treated and control groups. The experimental findings suggest that insulin administered by immersion can enhance growth, feed consumption, food utilization and liver cell size in tilapia.insulin / growth stimulation / feed conversion efficiency / tilapia Résumé ― L'immersion en présence d'insuline bovine stimule la croissance du tilapia. L'objet de ce travail est de tester les effets d'insuline bovine sur la croissance du tilapia. Des hybrides mâles juvéniles de tilapia (Oreochromis niloticus x 0 aurea ; n = 135) ont été soumis à l'un des 3 traitements suivants. Chaque traitement a été appliqué à 3 lots de 15 poissons. Les animaux ont été immergés dans l'eau (0, 10 ou 100 gg d'insuline par ml d'eau) pendant 15 min par semaine durant 8 sem. Le poids corporel, la croissance et l'indice de consommation étaient significativement supérieurs au témoin après 4 sem de traitement. La dose inférieure était plus stimulante que la dose supérieure. L'insuline induisait aussi la consommation d'aliments. Les protéines du foie et le rapport protéineslADN dépassaient les niveaux des témoins dans les 2 groupes de poissons stimulés. La composition des muscles et l'index hépatosomatique étaient semblables dans tous les groupes. Les résultats suggèrent que l'insuline administrée par immersion peut modifier la croissance, la consommation de nourriture, l'utilisation des aliments et la taille des cellules hépatiques chez le tilapia.

What hormones may regulate food intake in fish?

“…This hypothesis is not supported by the hungerinducing effect of an insulin injection previously observed in different inammals (Martin et al, 1984). More recently, Chang and Lin (1995) have induced an incrcase of feed consumption by tilapia, after insulin administration by immersion. In fact, the potential stimulatory effect of insulin is inhibitcd by the increase of glucagon (an inhibitory food intake factor) during the first part of the post-prandial period.…”

Effect of Immersion Treatment in Bovine Insulin on Growth, Nutrient Retention and Proteolytic Enzyme Activity in Chaivna Punctatus (BLOCH)

“…Eels given insulin at 20 and 40 mg/kg in the diet grew faster than a control group fed on a diet without insulin or the group given insulin at 5 mg/kg (Degani and Abraham, 1992). Chang and Lin (1995) also obtained a higher growth in tilapia when immersion treatment with lower dose (10 pg) of insulin as compared with the higher dose (100 pg).…”

“…In view of this and high dietary protein needs of most fish species for growth (Davis and Stickney, 1978;Hepher, 1988), it is possible that the reported anabolic action of insulin may have greater significance on proteogenic and lipogenic pathways (Dickhoff, 2001). Except for few prolonged administration studies (Ludwig et al, 1977, Ablett et al, 1981Chang and Lin, 1995), not much information is available for the long-term effects of insulin on protein, lipid and carbohydrates contents in fish tissues. In the present study two dose levels (10 and 50 pg) of bovine insulin were used to examine the effect of immersion treatment on growth parameters and also on liver glycogen, proteolytic enzyme activity and carcass composition in Channa punctatus fingerlings.…”