401 research outputs found
Carnitina dietĂ©tica mantem reservas energĂ©ticas e evita a fatiga de bagre-africano durante exercĂcio
LipĂdios e proteĂnas sĂŁo tradicionalmente considerados combustĂveis primários durante natação aerĂłbica. Nesse ensaio foi investigado o efeito da suplementação de vários nĂveis de gordura e carnitina no metabolismo de 100 bagres africanos juvenis (Clarias gariepinus). Os peixes foram arraçoados com quatro dietas isoprotĂ©icas, cada uma contendo 100 ou 190 g gordura kg-1 dieta, e um dos dois nĂveis de carnitina (15 e 1000 mg kg-1). Os peixes cresceram de 61 a 162 g em 10 semanas. No final do ensaio de alimentação, grupos de seis peixes por tratamento foram induzidos a nadar vigorosamente por 3 h e em seguida vários parâmetros foram determinados no tecido muscular e plasma, e os resultados observados nos grupos exercitados foram comparados com grupos controles (nĂŁo exercitados). Os peixes arraçoados com 1,000 mg carnitina acumularam de duas a trĂŞs vezes mais carnitina que os peixes arraçoados com 15 mg carnitina. O nĂvel de acyl-carnitina no plasma foi influenciado pela interação entre os tratamentos dietĂ©ticos e exercĂcio fĂsico (P < 0.05). As concentrações de adenosina trifosfato (ATP) e fosfocreatina no tecido muscular branco (WM) foram mais elevadas em peixes arraçoados com alto nĂvel de carnitina dietĂ©tica, mas sĂł aqueles peixes exercitados (P < 0.05). Os peixes arraçoados com 190 g gordura e 1,000 mg carnitina obtiveram um nĂvel elevado de potencial energĂ©tico adenilado (AEC) e uma redução da concentração de amĂ´nia plasmática. A suplementação de carnitina dietĂ©tica Ă© importante para peixes criados em sistemas intensivos e em fase inicial de crescimento, uma situação tĂpica que o consumo de gordura Ă© elevado. A utilização de dietas ricas em carnitina poderá evitar que o animal vivencie uma redução brusca das reservas energĂ©ticas, durante perĂodos de atividade fĂsica exaustiva, um estresse fisiolĂłgico relativamente comum no habitat natural e em sistemas de aqĂĽicultura intensiva.Lipids, together with proteins, are traditionally considered as primary fuels during aerobic swimming. The effects of dietary fat and carnitine supplements and exercise on the energy metabolism of juvenile fish were investigated. One hundred African catfish (Clarias gariepinus) were fed four isonitrogenous diets containing a fat level of 100 or 190 g kg-1 diet and one of the two levels of carnitine (15 and 1000 mg kg-1). Fish grew from 61 to 162 g in 10 wk. Thereafter, 6 fish per group swam vigorously for 3 h and the results were compared with unexercised groups. Fish receiving 1,000 mg carnitine accumulated 2- to 3-fold more carnitine than fish receiving 15 mg carnitine. Plasma acyl-carnitine level was affected by an interaction between dietary treatment and exercise (P < 0.05). Adenosine triphosphate and phosphocreatine concentrations were higher in the white muscle (WM) of exercised fish fed the high-carnitine supplements, compared with the low-carnitine fed fish (P < 0.05). Adenilate energy charge indexes were higher and ammonia concentrations were lower in WM of fish fed high-carnitine and high-fat diets. Dietary carnitine supplements may be needed in growing fish when dietary lipid level is high. In that case extra dietary carnitine can maintain the body energy reserves at adequate level when fish is exposed to a short-term, exhaustive exercise, a physiologic stress common both in nature and in intensive aquaculture systems
Beta-adrenergic control of plasma glucose and free fatty acid levels in the air-breathing African catfish Clarias gariepinus Burchell 1822
In several water-breathing fish species, P-adrenergic receptor stimulation by noradrenaline leads to a decrease in plasma free fatty acid (FFA) levels, as opposed to an increase in air-breathing mammals. We hypothesised that this change in adrenergic control is related to the mode of breathing. Therefore, cannulated air-breathing African catfish were infused for 90 min with noradrenaline or with the nonselective P-agonist, isoprenaline. To identify the receptor type involved, a bolus of either a selective beta(1)-antagonist (atenolol) or a selective beta(2)-antagonist (ICI 118,551) was injected 15 min prior to the isoprenaline infusion. Both noradrenaline and isoprenaline led to an expected rise in glucose concentration. Isoprenaline combined with both the beta(1)- and beta(2)-antagonist led to higher glucose concentrations than isoprenaline alone. This could indicate the presence of a stimulatory P-adrenoceptor different from beta(1) and beta(2)-adrenoceptors; these two receptors thus seemed to mediate a reduction in plasma glucose concentration. Both noradrenaline and isoprenaline led to a significant decrease in FFA concentration. Whereas the beta(1)-antagonist had no effect, the beta(2)-antagonist reduced the decrease in FFA concentration, indicating the involvement of beta(2)-adrenoceptors. It is concluded that the air-breathing African catfish reflects water-breathing fish in the adrenergic control of plasma FFA and glucose levels
The Effect of Drag and Attachment Site of External Tags on Swimming Eels: Experimental Quantification and Evaluation Tool
Animal science
Genomics in eels — towards aquaculture and biology
Animal science
Male silver eels mature by swimming
<p>Abstract</p> <p>Background</p> <p>If European silver eels are prevented from reproductive migration, they remain in a prepubertal stage by dopaminergic inhibition of pituitary activity. Because this inhibition is likely a requirement for an extended female growth stage, we tested if it is sex-specific by subjecting both sexes to stimulation by GnRHa (Gonadotropin-Releasing Hormone agonist) – injection or 3-months swimming in seawater.</p> <p>Results</p> <p>In contrast to females, males showed a two- to three-fold higher LHβ (luteinising hormone β subunit) – expression, a three- to five-fold higher GSI (Gonadosomatic index) and induced spermatogenesis when compared with the untreated control group.</p> <p>Conclusion</p> <p>Dopaminergic inhibition is thus not effective in males and swimming results in natural maturation, probably via GnRH-release.</p
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