Influence of bovine growth hormone on growth rate, appetite, and food conversion of yearling coho salmon (Oncorhynchus kisutch) fed two diets of different composition

Abstract

Paired groups of yearling coho salmon at 10 °C and on a natural photoperiod were fed twice daily either Oregon moist pellets (OMP) or a diet with poultry offal (PO) as the main protein source. The fish were fed either 0.8% body weight per day (dry weight of food (g)/wet weight of fish (g)) or to satiation. Coho in one of the groups for each diet–ration combination received, by intramuscular injection, 10 μg (0.0092 IU) of bovine growth hormone (bGH) per gram body weight one time per week for 56 days. Those in the other group were not treated.Administration of bGH significantly enhanced growth and improved food and protein conversion. Ration level altered the effect of bGH on food and protein conversion as did diet formulation at satiation. The voluntary food intake of bGH-treated fish fed OMP was higher but not significantly different from that of the controls. Diet formulation differences did not significantly affect the growth rate of either bGH-treated or untreated coho at each ration level. Irrespective of the diet–ration combination, bGH administration lead to a significant decline in condition factor.At 56 days, bGH-treated fish had a significantly lower percentage of muscle protein and a significantly higher percentage of muscle water than untreated fish. At present, the use of bGH as a growth promoter for coho salmon is not economical.

Increased food intake in growth hormone-transgenic common carp (Cyprinus carpio L.) may be mediated by upregulating Agouti-related protein (AgRP)

“…In fish, it is well established that administration of exogenous GH increases food intake and feeding behavior (Johnsson and Bjornsson, 1994;Markert et al, 1977). Similarly, elevated GH in transgenic salmon induced heightened feeding motivation, increased food intake and feeding behavior (Abrahams and Sutterlin, 1999;Devlin et al, 1999;Sundstrom et al, 2003).…”

Comparative Aspects of GH and Metabolic Regulation in Lower Vertebrates

“…The increase in weight associated with growth in fish appears to be due to a combination of increased appetite [14, 15] and increased feed conversion [[14, 16, 17]; for review,see [18]]. In fish, both GH administration [19, 20] and GH transgenesis [21] result in increased growth that might be attributed to increased feeding and improved food assimilation [20, 22].…”

Physiological functions of growth hormone in fish with special reference to its influence on behaviour

“…In addition to SRIF, noradrenaline and serotonin have been shown to act inhibitory on GH release. Stimulatory action on GH secretion, on the other hand, has been demonstrated by everal factors including growth-hormone releasing hormone (GHRH), dopamine (DA), neuropeptide Y (NPY), gonadotropin-releasing hormones (GnRHs), thyrotropin-releasing hormone (TRH), cholecystokinin (CCK), bombesin and activin 4,5) Using different treatment protocols and GH of both heterologous and homologous origin, it has been shown that GH increases specific growth rates in length and weight in a variety of teleost species 14,1 ,16,1,7) Similarly , in several fish species, germline GH-transgenic strains exhibit enhanced growth rates compared with non-transgenic strains18,19,20,21) The increase in weight has been suggested to be caused by a GH-induced increase in appetite 22,23,24), and/or in creased feed conversion efficiency22, 25,26) Although some data indicate a positive correlation between specific growth rate and plasma GH levels 27, there seems to be no general relationship between growth rate and circulating GH levels in fish28,29. There may be multiple reasons for this.…”

“…The GH-induced increase of growth in fish is usually accompanied by a decrease in condition factor, indicating that the fish become relatively leaner dur ing GH treatment 34,35,22,25) This is most likely due to the strong stimulatory effect of GH on length growth, even during periods of starvation24), in combination with its effects on metabolism.…”