Dietary cobalt supplementation improves growth and body composition and induces the expression of growth and stress response genes in Tor putitora

A 90-day randomized feeding experiment was performed to assess the effects of dietary cobalt (Co) supplementation on the growth performance, muscle composition, status of iron and manganese in the muscle as well as the expression of growth-related genes in the muscle (myoblast determination protein 1 homolog (MyoD) and myogenin) and the stress-related gene heat shock protein 70 KDa (Hsp-70) in the liver of mahseer (Tor putitora). Feeding trial was conducted in triplicate under controlled semi-static conditions, and graded levels of dietary cobalt (0.5-3 mg/kg) were fed to six groups of advanced fry of T. putitora. The results obtained indicated a curvilinear relationship of dietary Co levels with body crude protein content and weight gain (%). A positive correlation was observed with up to 2 mg Co/kg diet. However, a decreasing trend was found with values over 2 mg Co/kg diet. The expression of muscle growth biomarkers MyoD and myogenin showed a similar response, upregulation up to 2 mg Co/kg diet and decreased expression at 3 mg Co/kg diet. Indeed, the highest dietary Co supplementation increased the expression of Hsp-70, a key gene expressed in response to stress. Moreover, the muscle content of iron and manganese showed an inverse relationship with the dietary Co supplementation. Our findings suggest that 2 mg/kg Co dietary supplementation stimulates myogenesis and optimize muscle growth and body composition, while higher levels enhanced the expression of stress response genes and impaired growth of T. putitora

Some morphometric relationship traits of Labeo bata (Hamilton, 1822) from Head Panjnad, Pakistan

In the present research work, 127 Labeo bata having diverse body size ranging from 8.20 to 16.00 cm total length collected from Head Panjnad, Pakistan were used for the analysis of some morphometrics, that is, length-weight and length-length relationships. Condition factor and their relationships to investigate growth external morphometric characters, that is, total length (TL), standard length (SL), fork length (FL), head length (HL), head width (HW), body girth (BG), dorsal fin length (DFL), dorsal fin base (DFB), pectoral fin length (PtFL), pectoral fin base (PtFB), pelvic fin length (PvFL), anal fin length (AFL), caudal fin length (CFL) and caudal fin width (CFW) showed highly significant correlation with both cases, that is, increasing total length and body weight. A significant positive relationship was found between condition factor (K) and body weight, while no significant correlation was found in condition factor and total length.Key words: Morphometry, length-weight, length-length relationship, condition factor, Labeo bata

Induced breeding of Labeo rohita through single application of ovaprim-C at Faisalabad Hatchery, Pakistan

A study was conducted to observe the effect of intramuscular injection of ovaprim-C on the number of eggs/kg, fertilization rate and hatching percentage at a private fish hatchery and research center at Faisalabad, Pakistan, during May to June 2008, on Labeo rohita (Rohu). Studied fish specimens were spawned successfully following a single dose of injection of ovaprim-C (LH-RH analogue) with 0.4 ml kg-1 for female and 0.05 ml kg-1 for male brooders. Ova and milt were stripped simultaneously and mixture was stirred for 15 to 30 s during which fertilization occurred. Hatching occurred within 18 to 30 h after fertilization. The experiment was conducted in circular spawning tank with 2 m diameter. If it is impossible to determine the absolute and relative fecundity, then these parameters can be determined from the body weight. Average number of eggs/kg, fertilized eggs/kg and hatchlings/kg was 63574, 49067 and 39952, respectively. Overall fertilization and hatchling %age was 77.50% and 81.39% respectively. Wet body weight was observed to have a positive influence on absolute (r=0.983) and relative fecundity (r = 0.910) in log-log scale.Keywords: Induced spawning, ovaprim-C, fecundity, Labeo rohita.African Journal of Biotechnology Vol. 12(19), pp. 2722-272

Commercially available probiotic enhanced growth, digestion and immune response of Rohu (Labeo rohita) reared in earthen pond

The use of Probiotics in aquaculture got an importance in the previous years. Hence, present study was carried out to evaluate the effects of the commercially available dietary probiotic (a consortium of Bacillus subtilis and Saccharomyces cerevisiae) on the growth, proximate body composition, digestive enzymes, hematological parameters and immune response of rohu (Labeo rohita) in a polyculture system. Fingerlings with average body weight and length of 11.00 ± 2.34 g and 9.50 ± 5.50 cm, respectively, were stocked in 6 earthen ponds, at the rate of 200 fingerlings/pond making a total of 1200 fingerlings. The experiment was extended for 3 months in two groups i.e. probiotics treated and control groups. After three months feeding trial glucose, aspartate aminotransferase (AST), moisture content, ash contents and feed conversion rate (FCR) were significantly decreased in the probiotics supplemented group. At the same time point, Hb, MCH, HCT, total protein, plasma protein, lipid contents, final body mass and final body weight, percent weight gain, cellulase activity, protease activity and amylase activity and white blood corpuscles were significantly increased in the probiotics supplemented group. In conclusion, the use of probiotic enhanced growth, digestive enzyme activities and immune response of L. rohita in a polyculture system

A Non-invasive assay for monitoring stress responses : a comparison between wild and captive-reared rainbowfish (Melanoteania duboulayi)

The stress response of wild and captive reared rainbowfish (Melanoteania duboulayi) following chasing by a simulated predator was examined. Cortisol release rate was monitored using a flow through system by measuring water borne hormone levels. Tests using known cortisol concentrations revealed that the technique yielded 95% of the cortisol present in the water. Cortisol release rates increased several fold in both populations after being chased but peaked at different time periods. Wild fish showed a typical stress response with release rate rising to (2.29±0.22ngg-1h-1) 2h after exposure followed by rapid recovery. The captive-reared population by contrast showed an atypical response with cortisol release rate peaking 4h post exposure but reaching only half the level of the wild fish (1.19±0.11ngg-1h-1). The implications for the release of hatchery-reared fish for stock enhancement are discussed.6 page(s

A Non-Invasive Assay for Monitoring Stress Responses: A Comparison Between Wild and Captive-Reared Rainbowfish (Melanoteania duboulayi)

The stress response of wild and captive reared rainbowfish (Melanoteania duboulayi) following chasing by a simulated predator was examined. Cortisol release rate was monitored using a flow through system by measuring water borne hormone levels. Tests using known cortisol concentrations revealed that the technique yielded 95% of the cortisol present in the water. Cortisol release rates increased several fold in both populations after being chased but peaked at different time periods. Wild fish showed a typical stress response with release rate rising to (2.29±0.22 ng g−1 h−1) 2 h after exposure followed by rapid recovery. The captive-reared population by contrast showed an atypical response with cortisol release rate peaking 4 h post exposure but reaching only half the level of the wild fish (1.19±0.11 ng g−1 h−1). The implications for the release of hatchery-reared fish for stock enhancement are discussed

Effect of confinement on water-borne and whole body cortisol in wild and captive-reared rainbowfish (Melanoteania duboulayi)

Whole body and water-borne cortisol levels were measured in captive reared and wild Rainbowfish (Melanoteania duboulayi Castelnau 1878) subjected to social isolation by confining them in a beaker for 30 min to induce an acute stress response. Wild fish had higher levels of cortisol before and after exposure to a mild stressor and also showed the greatest stress response. The differences in stress responses are likely the result of artificial selection in the captive environment. Importantly, there was a strong linear relationship between whole body and water-borne cortisol in wild and captive reared populations (r2 =0. 95 and 0.84, respectively) suggesting that non- invasive assays for cortisol provide a valuable alternative for whole body cortisol levels in small fishes.6 page(s

Blood cortisol concentrations predict boldness in juvenile mulloway (Argyosomus japonicus)

There is a growing interest in animal personality because individual variation is the substrate of the evolutionary process. Despite revelations that personality traits affect key fitness variables, little is known about the proximate mechanisms generating consistent behavioural differences between individuals. Boldness, the propensity to take risks, is one of the most widely studied aspects of personality in fishes. We assessed the position of juvenile Argyosomus japonicus on the "boldness-shyness" continuum by repeatedly recording the time taken to exit a refuge and explore a novel environment. Stress-related hormone concentrations after exposure to a mild stressor were analysed 1 month before behavioural assays and found to be significantly linked to boldness scores. Shy fish had significantly higher plasma cortisol concentrations in response to handling stress than bold fish. Spontaneous switching between personality categories occurred between trials, highlighting the importance of repeated testing of personality traits over time to correctly attribute personality.8 page(s

Blood Cortisol Concentrations Predict Boldness in Juvenile Mulloway (Argyosomus japonicus)

There is a growing interest in animal personality because individual variation is the substrate of the evolutionary process. Despite revelations that personality traits affect key fitness variables, little is known about the proximate mechanisms generating consistent behavioural differences between individuals. Boldness, the propensity to take risks, is one of the most widely studied aspects of personality in fishes. We assessed the position of juvenile Argyosomus japonicus on the ‘‘boldness–shyness’’ continuum by repeatedly recording the time taken to exit a refuge and explore a novel environment. Stress-related hormone concentrations after exposure to a mild stressor were analysed 1 month before behavioural assays and found to be significantly linked to boldness scores. Shy fish had significantly higher plasma cortisol concentrations in response to handling stress than bold fish. Spontaneous switching between personality categories occurred between trials, highlighting the importance of repeated testing of personality traits over time to correctly attribute personality

Blood Cortisol Concentrations Predict Boldness in Juvenile Mulloway (Argyosomus japonicus)

There is a growing interest in animal personality because individual variation is the substrate of the evolutionary process. Despite revelations that personality traits affect key fitness variables, little is known about the proximate mechanisms generating consistent behavioural differences between individuals. Boldness, the propensity to take risks, is one of the most widely studied aspects of personality in fishes. We assessed the position of juvenile Argyosomus japonicus on the ‘‘boldness–shyness’’ continuum by repeatedly recording the time taken to exit a refuge and explore a novel environment. Stress-related hormone concentrations after exposure to a mild stressor were analysed 1 month before behavioural assays and found to be significantly linked to boldness scores. Shy fish had significantly higher plasma cortisol concentrations in response to handling stress than bold fish. Spontaneous switching between personality categories occurred between trials, highlighting the importance of repeated testing of personality traits over time to correctly attribute personality