Molecular and phenotypic diversity of ICARDA spring barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) collection

Plant breeders are interested in using diverse genotypes in hybridization that can segregate for traits of importance with possibility of selection and genetic gain. Information on molecular and agro-morphological diversity helps the breeders reduce the effort for parental selection and helps the advancement of generations. A phenotypic and molecular diversity study, using 24 traits (agronomic and disease) and 6519 SNPs in a diverse collection of 336 spring barley genotypes, was carried out at Marchouch and Jemma Shiam research stations in Morocco. Based on structure and multivariate analyses, strong differentiation between the two- and six-row types were observed. The linkage disequilibrium (LD) decay of the current collection (for the combined population) was up to 3.58 cM (r ² = 0.15) while LD decay were estimated 3.91 and 2.36 cM for two- and six-row barley, respectively. PCA of agro-morphological traits revealed grain per spike, net form of net blotch (NFNB), spot form of net blotch (SFNB), and 1000 kernel weight were the most discriminatory traits in the current collection. Association mapping in the two independent populations will be ideal for identification of markers, and QTL related to traits. The generated information on relatedness between individuals will help identify diverse genotypes for breeding programs.     

Modulation of biochemical indices in common carp (Cyprinus carpio L.) under the influence of toxic cyanobacterial biomass in diet

Cyanobacteria are producers of potent and environmentally abundant microcystins, representing an emerging global health issue. In the present study, we investigated the impact of cyanobacterial biomass on biochemical indices of common carp (Cyprinus carpio L., average weight of 246 ± 73 g) under laboratory conditions. The fish were fed a diet containing cyanobacterial biomass with microcystins in high concentration (0.4 mg/kg of fish weight and day) for 28 days. Statistical evaluation of the influence of the cyanobacterial biomass in food on the biochemical indices of the juvenile carp showed only minor differences. The activity of aspartate aminotransferase value and the urea concentration were significantly reduced compared to control group. The biochemical parameters of fish blood plasma significantly rose during the experiment in the control group as well as in the experimental group. This state was probably influenced by the environmental conditions and the fish diet. A significant rising value was established in calcium creatinine, total protein, phosphorus, lactate, urea and natrium. The present study demonstrates that the oral exposure of toxic cyanobacterial biomass has a minor influence on the biochemical indices of common carp and that the effect of other factors, e.g., nutrition is more visible.     

Compensatory growth,feed intake and body composition of Labeo rohita fingerlings following feed deprivation

Ten‐week study was performed on Labeo rohita fingerlings (av. wt. 3.75 ± 0.06 g) to investigate the nature of compensatory growth. Fingerlings were deprived of food for 0 (control), 1 (D1), 2 (D2) or 3 (D3) weeks and refed to satiation for 5 weeks. The feed deprivation was carried out in D3 group on week 3, 4 and 5; D2 group on week 4 and 5; D1 group on week 5, and refeeding of all the groups were started from week 6 onwards. The D1 and D2 groups caught up in body weight with that of control fish within 2 weeks and 4 weeks of refeeding, respectively, but the D3 group had significantly (P < 0.05) lower body weight than the control after 5 weeks of refeeding. Higher growth efficiency was observed in all the feed deprived groups in the 1st week of refeeding only. Feed intake in D1 group became similar with the control after 5 weeks of refeeding, but the D2 and D3 groups were still hyperphagic when the experiment terminated. Thus, compensatory growth was due to hyperphagia and improved growth efficiency. In conclusion, complete compensatory growth was observed in L. rohita fingerlings after feed deprivation of 1 and 2 weeks.     

Haematological indices are modulated in juvenile carp, Cyprinus carpio L., exposed to microcystins produced by cyanobacterial water bloom

This study evaluated the influence of toxic cyanobacterial water blooms on the blood indices of the common carp, Cyprinus carpio L. Experimental fish were exposed to a natural population of cyanobacterial water blooms (mainly Microcystis aeruginosa and M. ichthyoblabe), which contained microcystins [total concentration 133–284 μg g^?1 (DW), concentration in water 2.8–7.4 μg L^?1]. Haematological indices showed marked changes in fish exposed to the cyanobacterial population in comparison with the control group. Statistical evaluation of the influence of cyanobacterial water blooms on biochemical indices of the juvenile carp showed a distinct decrease in albumin, alanine aminotransferase, total bilirubin, calcium, cholesterol, glucose, phosphorus and iron when compared to controls. Values of red blood counts [haemoglobin, haematocrit (PCV), mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration] and lactate were significantly increased compared to controls. After exposure to cyanobacterial water bloom, the carp were kept in clean water to monitor the persistence of biochemical indices. The influence of cyanobacterial populations on calcium, cholesterol, glucose, lactate, phosphorus and PCV persisted up to 28 days after conclusion of the experiment. Duration of exposure, toxicity and density of cyanobacterial water blooms had an important impact on individual haematological indices.     

Non-gelatinized corn supplemented with α-amylase at sub-optimum protein level enhances the growth of Labeo rohita (Hamilton) fingerlings

A feeding trial was conducted for 60 days to delineate the effect of both gelatinized and non‐gelatinized corn with or without supplementation of exogenous α‐amylase at two level of protein 35% (optimum) and 27% (sub‐optimum) on growth, tissue composition and protein sparing effect of carbohydrate in the diet of Labeo rohita fingerlings. Three hundred and sixty fingerlings (average weight 10.00±0.15 g) were randomly distributed in 12 treatment groups with two replicates for each. Twelve semi‐purified diets containing either 35% or 27% CP were prepared with different levels of α‐amylase (0, 50, 100 and 150 mg kg^?1) and starch type [gelatinized (G)/non‐gelatinized, (NG)] viz. T₁ (NG, 35% CP, 0 mg kg^?1α‐amylase), T₂ (G, 35% CP, 0 mg kg^?1α‐amylase), T3 (NG, 27% CP, 50 mg kg^?1α‐amylase), T₄ (NG, 35% CP, 50 mg kg^?1α‐amylase), T₅ (G, 27% CP, 50 mg kg^?1α‐amylase), T₆ (G, 35% CP, 50 mg kg^?1α‐amylase), T₇ (NG, 27% CP, 100 mg kg^?1α‐amylase), T₈ (NG, 35% CP, 100 mg kg^?1α‐amylase), T₉ (G, 27% CP, 100 mg kg^?1α‐amylase), T₁₀ (G, 35% CP, 100 mg kg^?1α‐amylase), T₁₁ (NG, 27% CP, 150 mg kg^?1α‐amylase) and T₁₂ (NG, 35% CP, 150 mg kg^?1α‐amylase). The fish were acclimatized to the experimental condition for 24 days during which control diet (NG, 35% CP) was fed. Weight gain percentage, specific growth rate, protein efficiency ratio and apparent net protein utilization of NG corn‐fed groups at 42.43% were significantly higher (P<0.05) than the same level of G corn‐fed groups. We conclude that 42.43% NG corn supplemented with 50 mg α‐amylase kg^?1 feed at sub‐optimum level of CP (27%) significantly enhanced the growth and protein in L. rohita fingerling. Addition of dietary α‐amylase to G corn had no added advantage on growth of L. rohita fingerling.     

Gut melatonin response to microbial infection in carp <Emphasis Type="Italic">Catla catla</Emphasis>

The purpose of present study was to demonstrate the response of gut melatoninergic system to Aeromonas hydrophila infection for 3 or 6 days and search for its correlation with the activity of different antioxidative and digestive enzymes to focus their interplay under pathophysiological conditions in carp (Catla catla). Microscopic study of gut in infected fish revealed degenerative changes in the tunica mucosa and lamina propria layers with sloughed off epithelial cells in the lumen. The activity of each digestive enzyme was reduced, but the levels of melatonin, arylalkylamine-N-acetyl transferase protein, the key regulator of melatonin biosynthesis, and different enzymatic antioxidants in gut were gradually and significantly increased with the progress of infection. Gut melatonin concentrations in A. hydrophila challenged carp by showing a positive correlation with the activity of each antioxidative enzyme, and a negative correlation with different digestive enzymes argued in favor of their functional relation, at least, during pathological stress. Moreover, parallel changes in the gut and serum melatonin titers indicated possible contribution of gut to circulating melatonin. Collectively, present carp study provided the first data to suggest that endogenous gut melatonin may be implicated to the mechanism of response to microbial infections in any fish species.     

Comparative performance of Gamma Amino Butyric Acid (GABA) and 5-Hydroxytryptamine (5-HT) in the diet of larvae and post larvae of giant freshwater prawn, Macrobrachium rosenbergii: Effect of dose and route of administration on growth and survival

Three experiments were conducted to evaluate the effect of different dose and route of administration of 5-Hydroxytryptamine (5-HT) and Gamma Amino Butyric Acid (GABA) on growth, survival and pigmentation of giant freshwater prawn, Macrobrachium rosenbergii, larvae (experiment 1) and post larvae (experiment 2 and 3). In experiment 1 larva were stocked at 100 /L in seven different treatments with each of three replicates. The treatments were T1 (control), T2 (100 μg/ml of 5-HT bath exposure for 2 days), T3 (1 μM of GABA bath exposure for 2 days), T4 (0.5% 5-HT in feed), T5 (0.25% 5-HT in feed), T6 (0.5% GABA in feed) and T7 (0.25% GABA in feed). Highest growth, transformation rate, pigmentation and survival of larvae were recorded in T2 group in experiment 1. In experiment 2, post larvae were stocked at 70 per tank with 200 L of water for 45 days. This experiment consisted of 5 treatment groups with each of 3 replication viz. T1 (control), T2 (0.5% 5-HT in feed), T3 (0.25% 5-HT in feed), T4 (0.5% GABA in feed) and T5 (0.25% GABA in feed). At the end of this experiment growth was found to be higher in the control than the other treatment group showing inhibitory effect of 5-HT and GABA on growth of post larvae. To confirm the result, a third experiment was conducted for 30 days. Thirty numbers of post larvae having similar size were segregated from the previous experimental tanks (experiment 2) and stocked in the tanks of 100 L of water for experiment 3. All treatments were fed with control diet. There was similar growth pattern in all the treatments, which were higher (P < 0.05) than control, confirms the inhibitory effect of neurotransmitter in the diet of PL. Therefore, the overall results of the present study suggest that the bath treatment of neurotransmitter is superior to the dietary addition with regard to the growth, survival and pigmentation of M. rosenbergii larvae. 5-HT is more effective than the GABA for larvae of M. rosenbergii.     

Studies on digestibility and digestive enzyme activities in Labeo rohita (Hamilton) juveniles: effect of microbial α-amylase supplementation in non-gelatinized or gelatinized corn-based diet at two protein levels

A 60-days feeding trial was conducted to delineate the effect of both gelatinized and non-gelatinized corn with or without supplementation with exogenous α-amylase at two dietary protein levels (35% and 28%) on dry matter digestibility, digestive enzymes and tissue glycogen content of Labeo rohita juveniles. Three hundred and sixty juveniles (average weight 10±0.15 g] were randomly distributed into 12 treatment groups with each of two replicates. Twelve semi-purified diets containing either 35% or 28% crude protein were prepared by including gelatinized (G) or non-gelatinized (NG) corn as carbohydrate source with different level of microbial α-amylase (0, 50, 100 and 150 mg kg⁻¹). The dry matter digestibility of G corn fed groups was significantly higher (P < 0.05) than that of the NG corn fed groups. Hepatosomatic index (HSI), liver glycogen and intestinal amylase activity of G starch fed groups were significantly higher (P < 0.05) than those of the NG corn fed groups. However, the reverse trend was found for gastrosomatic index (GSI), muscle glycogen and intestinal protease activity. Addition of 50 mg α-amylase kg⁻¹ feed improved the dry matter digestibility of NG starch fed groups, which was similar to that of the G corn fed groups or NG corn supplemented with 100/150 mg α-amylase kg⁻¹ feed. HSI, liver glycogen and intestinal amylase activity were significantly increased (P < 0.05) at minimum level of α-amylase in the feed (50 mg kg⁻¹) and did not increase due to further inclusion of amylase in the diet. Supplementation with α-amylase at 50 mg kg⁻¹ increased the intestinal amylase activity beyond which no significant changes were observed. Protease activity of liver and intestine was highest (P < 0.05) in higher crude protein (CP) fed groups, but protease activity of the intestine was significantly higher in the α-amylase supplemented groups. Hence, it was concluded that feed with 28% CP containing either G corn without α-amylase or NG corn with 50 mg α-amylase kg⁻¹ may be used as the alternative carbohydrate source for L. rohita juveniles.     

Field study indicating susceptibility differences between salmonid species and their lineages to proliferative kidney disease

Tetracapsuloides bryosalmonae (Myxozoa: Malacosporea) is the causative agent of proliferative kidney disease (PKD), which affects both wild and farmed salmonid fish. The objective of this study was to outline differences in susceptibility to PKD in different salmonid species, hybrids and breeding lineages. Susceptibility to T. bryosalmonae infection was established based on cumulative mortality, pathological findings and detection of T. bryosalmonae in the kidney using immunohistochemistry and molecular methods. Determination of pure and hybrid individuals of different species in the genus Salvelinus, and dissimilarity of rainbow trout lineages, was performed using traditional polymerase chain reaction (PCR) and microsatellite analyses. Rainbow trout displayed higher disease severity compared with brook trout and Alsatian charr. Moreover, the results indicated differences in infection susceptibility, not only among different salmonid species but also among different lineages of charr and rainbow trout. Our study indicated that some salmonid species and even different lineages of the same species are more suitable for farming under PKD pressure.     

Acclimation of <Emphasis Type="Italic">Anabas testudineus</Emphasis> (Bloch) to three test temperatures influences thermal tolerance and oxygen consumption

Teleost fish have developed their own specific adaptive mechanism, both behavioral and physiological, to maintain homeostasis in response to unfavorable temperatures. Therefore, this study was aimed at assessing the critical thermal maxima (CT_Max), critical thermal minima (CT_Min), and oxygen consumption rate of Anabas testudineus (17.03 ± 1.2 g) after acclimating to three preset temperatures (25, 30, and 35°C) for 30 days. The CT_Max and CT_Min were 40.15, 41.40, 41.88°C and 12.43, 13.06, 13.94°C, respectively, and were significantly different (P < 0.05). The thermal tolerance polygon for the specified temperatures was 278.30°C². The oxygen consumption rate (117.03, 125.70, 198.48 mg O₂ kg⁻¹ h⁻¹, respectively) increased significantly (P < 0.05) with increasing acclimation temperatures. The overall results indicate that the thermal tolerance and oxygen consumption of A. testudineus are dependent on acclimation.