Growth-promoting effects of sustained swimming in fingerlings of gilthead sea bream (Sparus aurata L.)

Abstract

Fish growth is strongly influenced by environmental and nutritional factors and changing culture conditions can help optimize it. The importance of early-life experience on the muscle phenotype later in life is well known. Here, we study the effects of 5 weeks of moderate and sustained swimming activity (5 BL s(-1)) in gilthead sea bream during early development. We analysed growth and body indexes, plasma IGF-I and GH levels, feed conversion, composition [proximate and isotopic ((15)N/(13)C)] and metabolic key enzymes (COX, CS, LDH, HOAD, HK, ALAT, ASAT) of white muscle. Moderate and continuous exercise in fingerlings of gilthead sea bream increased plasma IGF-I, whereas it reduced plasma GH. Under these conditions, growth rate improved without any modification to feed intake through an increase in muscle mass and a reduction in mesenteric fat deposits. There were no changes in the content and turnover of muscle proteins and lipid reserves. Glycogen stores were maintained, but glycogen turnover was higher in white muscle of exercised fish. A lower LDH/CS ratio demonstrated an improvement in the aerobic capacity of white muscle, while a reduction in the COX/CS ratio possibly indicated a functional adaptation of mitochondria to adjust to the tissue-specific energy demand and metabolic fuel availability in exercised fish. We discuss the synergistic effects of dietary nutrients and sustained exercise on the different mitochondrial responses.

Dietary sodium heptanoate helps to improve feed efficiency, growth hormone status and swimming performance in gilthead sea bream (Sparus aurata)

“…The increase in circulating levels of GH has been reported in coho salmon and rainbow trout (Barrett & McKeown, , ; Nielsen, Boesgaard, Sweeting, McKeown, & Rosenkilde, ) submitted to maximum swimming. A close association between exercise‐induced growth and circulating levels of GH has also been reported in gilthead sea bream (Blasco et al., ), but to our knowledge, this is the first report indicating that measures of circulating GH could reflect the swimming and metabolic performance in fish challenged in swim test chambers. At the same time, it is noteworthy that basal circulating concentration of IGF‐I remained mostly unaltered at the end of the trial, which is perhaps indicative that systemic IGFs mostly reflect changes in growth rates rather than in metabolic efficiency.…”

Ghrelin and Its Receptors in Gilthead Sea Bream: Nutritional Regulation

“…These results are in line with previous works ( 63 , 66 ). The inverse correlation between Gh and Igf-1 plasma levels during fasting was pointed out in gilthead sea bream previously ( 38 , 67 , 68 ), and has been described in several other fish species (e.g., coho salmon, chinook salmon, channel catfish, Nile tilapia or gilthead sea bream) in diverse conditions ( 26 , 47 , 66 , 69 – 71 ). Moreover, the results support that the circulating Gh/Igf-1 ratio is a good indicator of metabolic state in gilthead sea bream and that it is clearly affected by feeding condition ( 67 , 72 ).…”

Somatotropic Axis Regulation Unravels the Differential Effects of Nutritional and Environmental Factors in Growth Performance of Marine Farmed Fishes

“…Likewise, the recovery of plasma Igf-i during refeeding highly reflects the increase in weight gain during the phase of compensatory growth ( 74 ). More recently, the circulating level of Igf-i was concordant with the growth-promoting effects of moderate exercise in juveniles of gilthead sea bream ( 75 , 76 ). Also in gilthead sea bream, a linear increase in growth rates and circulating Igf-i was reported in fingerlings in response to a single dose of recombinant bovine GH ( 77 ).…”