Long-term effects of vermicompost manure leachate (powder) inclusions on growth and survival,biochemical composition,total carotenoids,and broodstock reproductive performance of <Emphasis Type="Italic">Artemia franciscana</Emphasis> (Kellogg, 1906)

Long-term effects of different levels of dietary vermicompost manure leachate powder (VCL) were investigated on the nauplii growth and survival, biochemical composition, total carotenoids, and reproductive performance of broodstock Artemia franciscana in laboratory cultures. The instar I nauplii were fed in five treatments including 100% of the microalga Dunaliella salina (Alg; control group, with a density of 18?×?10⁶ cells mL^?1) and mixtures of 75% Alg-25% VCL, 50% Alg-50% VCL, 25% Alg-75% VCL, and 100% VCL for 3 weeks. At maturity, 35 pairs (males and females) were individually isolated from each treatment and transferred to 50-mL falcon tubes in which the reproduction and longevity of females were monitored until mortality. Results showed that the total length of Artemia in the control, 75 Alg-25 VCL, and 50 Alg-50 VCL treatments was significantly different from the other groups at the end of the 2nd and 3rd weeks. The pre-puberty survival rate was severely affected by the increased dietary levels of VCL declining from 52% (control) to 6.7% (100 VCL). The adults’ body protein levels in the control and 75 Alg-25 VCL (54–57%) were similar, but both groups were significantly different from the other treatments. However, the lipid content (13.7–19.8%) and total carotenoids (36.5–47.7 μg mg^?1) were significantly different between treatments. Many broodstocks’ reproductive characteristics were affected by the diet so that the total number of offspring in the control was markedly higher than the other groups. However, the number of offspring per brood revealed no differences between the control and 75 Alg-25 VCL treatment, but both were significantly dissimilar with the other groups. The interval between two successive brood productions detected in 100 VCL was almost double those in the other groups. The lifetimes of Artemia were not significantly different in the treatments received varied algal diets with the lowest lifespan in 100 VCL treatment. By increasing VCL to over 25%, the growth, survival, and particularly females’ reproductive performance decreased significantly so that Artemia had to be fed only up to 25% VCL (with 75% Alg). These findings indicate an inefficiency of VCL powder supply in long-term feeding to A. franciscana. Moreover, the use of only 25% VCL is apparently appropriate in small-scale laboratory cultures.     

Higher taxa are effective surrogates for species in the selection of conservation reserves in estuaries

• 1. The lack of information about marine biodiversity is problematic for the selection of conservation reserves that aim to protect representative samples of biodiversity. A number of surrogate measures for biodiversity have been suggested as a potential solution to this problem.
• 2. The present study tested the effectiveness of using higher taxa of macroinvertebrates as a surrogate for species‐level identification to depict spatial variation in species richness and assemblage variation and to select conservation reserves in one estuary in south‐east Australia.
• 3. Spatial patterns of richness and assemblage variation for species were significantly correlated with patterns defined from genera, families, orders, classes, and phyla with a decline in the magnitude of correlation coefficients from finer to coarser resolutions. A network of reserves selected to include representatives of all phyla, classes, orders, families and genera coincidentally included 54%, 61.7%, 75%, 92.6%, 98.8% species in 8.3%, 13.9%, 17.7%, 44.4% and 58.3% of grid cells, respectively. However, only reserves selected for genera, families and orders performed significantly better than random selection.
• 4. Percentage of species represented by orders, families and genera in a realistic level of available grid cells for conservation (i.e. 13.9%) were very close ranging between 70 and 73.5%. A factor diminishing the performance of order as surrogate for species richness was related to the difficulty of identifying many macroinvertebrates to the order level. Therefore, it is concluded that genus‐ and family‐level identification is an effective surrogate for species‐level identification for conservation planning in estuaries.

Copyright © 2008 John Wiley & Sons, Ltd.     

Dietary potassium requirement of fingerling Indian major carp,Labeo rohita (Hamilton), based on growth parameters,gill Na+‐K+ ATPase activity,tissue mineralization and antioxidant activities

To quantify the dietary potassium requirement of fingerling Labeo rohita (6.2 ± 0.12 cm; 1.98 ± 0.06 g), seven purified experimental diets (350 g/kg crude protein and 16.72 kJ/g gross energy) with graded levels of potassium (0.32, 1.35, 2.41, 3.46, 6.48, 9.47 and 12.39 g/kg diet) were fed to triplicate groups of fishes at 08:00, 12:00 and 16:00 hr to apparent satiation for 8 weeks. Live weight gain (LWG; 671.46%), specific growth rate (3.65%/day), protein efficiency ratio (2.16), protein gain (PG; 2.41 g/fish) and feed conversion ratio (1.32) were found to be best in fish fed diet containing 3.46 g/kg potassium. Gill Na⁺‐K⁺ ATPase activity was also highest in fish fed diet with 3.46 g/kg potassium. Potassium content of whole‐body, vertebrae and scales increased significantly with the increase in dietary potassium level up to 6.48 g/kg. Significant changes were also noted in serum malondialdehyde content, superoxide dismutase, catalase, glutathione peroxidase and alkaline phosphatase activity. Based on the maximum live weight and protein gain observed in the present study, the inclusion of 3.55 g/kg potassium is recommended for developing potassium‐balanced commercial feeds for intensive culture of fingerling L. rohita.     

Genetic analysis of growth rate and Kleiber ratio in Zandi sheep

Genetic parameters for average daily gain from birth to weaning (ADGa), birth to 6 months (ADGb), weaning to 6 months (ADGc), weaning to yearling age (ADGd), and corresponding Kleiber ratios (KRa, KRb, KRc, and KRd) were estimated by using records of 3,533 Zandi lambs, descendent of 163 sires and 1265 dams, born between 1991 and 2005 at the Zandi Sheep Breeding Station at Khojir National Park, Tehran, Iran. A derivative-free algorithm combined with a series of six single-trait linear animal models was used to estimate phenotypic variance and its direct, maternal, and residual components. In addition, bivariate analyses were done to estimate (co)variance components between traits. Estimates of direct heritability (h ² ) were 0.11, 0.15, 0.09, 0.10, 0.10, 0.10, 0.06, and 0.07 for ADGa, ADGb, ADGc, ADGd, KRa, KRb, KRc, and KRd, respectively, thereby indicating the presence of low additive genetic variation for growth rate and Kleiber ratio in this population of Zandi sheep. Maternal genetic component was found to be significant on ADGa and KRa and contributed 3% and 5%, respectively, in total phenotypic variance of ADGa and KRa. A widespread range of genetic correlations among traits studied was observed. Except for negative genetic correlations between ADGa and KRc, ADGa and KRd, and between KRa and KRc, in other cases, genetic correlations were positive and moderate to very high. Phenotypic correlations ranged from −0.49 (ADGa/KRd) to 0.94 (ADGc/KRc). These results indicate that selecting for improved growth rate or Kleiber ratio in Zandi sheep would generate a relatively slow genetic progress.     

Evaluation of the optimum dietary protein level for the maximum growth of juvenile beluga (Huso huso L.1758)

A 10‐week feeding trial was carried out to evaluate the optimum dietary protein level for the maximum growth of juvenile beluga, Huso huso. Fish averaging 1.34 ± 0.07 g (mean ± SD) was randomly distributed into 18 circular fibreglass tanks of 500 L capacity (20 fish per tank). Six iso‐caloric diets were formulated to contain 30 (CP₃₀), 35 (CP₃₅), 40 (CP₄₀), 45 (CP₄₅), 50 (CP₅₀) and 55% (CP₅₅) crude protein (CP). Fish were fed each of the six experimental diets in triplicate groups. At the end of feeding trial, weight gain (WG) and specific growth rate (SGR) in fish fed CP₄₀ and CP₄₅ diets were significantly higher than those of fish fed CP₃₀, CP₃₅, CP₅₀ and CP₅₅ diets (P < 0.05). Lipid retention increased significantly from 24.7% to 31.6%, but protein retention decreased from 54.6% to 35.6% with increasing protein levels from 30% to 50%. Muscle total essential and non‐essential amino acid (EAA & NEAA) concentrations increased with the dietary protein level up to CP₄₅ diets. Muscle total EAA concentrations (%) of fish fed CP₄₅ were significantly higher than those of fish fed CP₃₀, CP₃₅, CP₅₀ and CP₅₅, but there was no significantly different between those of fish fed CP₄₀ and CP₄₅. Muscle total NEAA concentration (%) of fish fed CP₄₅ were significantly higher than those of fish fed CP₃₀ and CP₃₅ diets. Broken‐line analysis of WG suggested that the optimum dietary protein level could be 38.9% for maximum growth performance in juvenile beluga (1.3–77 g).     

Effect of different dietary zinc sources on seminal plasma enzymatic activity,antioxidant, and immune-related gene expression in rainbow trout (Oncorhynchus mykiss)

Aquaculture International - The objective of the present work was to survey the effects of different sources of zinc supplements on serum enzymatic activities, the expression of genes related to...     

Optimization of stocking density of freshwater prawn Macrobrachium rosenbergii (de Man) in carp polyculture in Bangladesh

A study was conducted to optimize stocking density of freshwater prawn, Macrobrachium rosenbergii, in carp polyculture for 3 months in 10 experimental ponds of 80 m². Five stocking densities of prawn, 2500, 5000, 7500, 10 000 and 12 500 ha^?1, were assigned to treatments T₁, T₂, T₃, T₄ and T₅ respectively. The densities of catla, Catla catla, rohu, Labeo rohita and silver carp, Hypophthalmicthys molitrix, were 2500, 5000, and 2500 ha^?1, respectively, in each treatment. Each treatment had two replicate ponds. The mean initial weights of prawn, catla, rohu and silver carp were 1.1±0.02, 8.28±0.1, 25.2±1.1 and 36.32±1.2 g respectively. A pelleted diet containing 30% protein was prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses, and was fed twice daily at a rate of 5% of fish biomass. Water quality parameters were measured fortnightly and the ranges of temperature, pH and dissolved oxygen were 27.5–1.3°C, 6.9–8.6 and 4.5–8.6 mg L^?1 respectively. Feed conversion ratios ranged from 2.05 to 2.20 among the treatments. Per cent survival (%) of prawns ranged from 72% to 78%, while it varied from 80% to 93%, 90% to 95% and 90% to 92% for catla, rohu and silver carp respectively. The results showed that there were no significant differences among the weight gains of prawn and carp in different treatments. However, the overall total production of prawn and fish together was significantly (P<0.05) higher in T₃ and T₄ compared with other treatments. The total production for 3 months ranged between 2618 and 2916 kg ha^?1. The production of prawn was significantly higher (361.3 kg ha^?1) in T₅ with a highest stocking density of 12 500 prawn ha^?1. Although there was no significant difference (P>0.05) between the total production of prawn and fish together in T₃ and T₄, the highest net profit (Tk. 69 006 ha^?1) was obtained in T₄. Therefore, from the result of the study it may be concluded that a stocking ratio of 4:1:2:1 of prawn:catla:rohu:silver carp at a total density of 20 000 ha^?1 may be recommended for prawn–carp polyculture in ponds.