Effect of ethanolic extract of Zingiber officinale on growth performance and mucosal immune responses in rainbow trout (Oncorhynchus mykiss)

This study was conducted to examine the effect of ethanolic ginger (Zingiber officinale) extract on growth performance and some skin mucus immune parameters in rainbow trout (Oncorhynchus mykiss). A total of 600 rainbow trout fingerling (10.07 ± 0.21 g) were randomly assigned to four groups in triplicate and fed for 45 days with 1, 2.5 and 5 g kg^?1 of ginger extract and with unsupplemented basal diet as the control. The total protein content and lysozyme, alkaline phosphatase and protease activities of skin mucus were investigated following 15, 30 and 45 days of feeding. Results showed that administration of 2.5 and 5 g kg^?1 of ethanolic ginger extract for 45 days improved weight gain, feed utilization efficiency and feed conversion ratio of O. mykiss (P < 0.05). Significantly higher (P < 0.05) skin mucus lysozyme, alkaline phosphatase and protease activity and protein level were observed in the 2.5 and 5 g kg^?1 ginger extract groups on the 30th and 45th day compared to the controls. The findings suggest that ethanolic extract of ginger enhances growth performance and skin mucus immune parameters of rainbow trout.     

Comparing the efficacy of dietary α-tocopherol with that of dl-α-tocopheryl acetate, both either alone or in combination with ascorbic acid, on growth and stress resistance of angelfish, Pterophylum scalare, juveniles

This study aimed to compare the efficacy of dietary α-tocopherol with that of dl-α-tocopheryl acetate, both either alone or in combination with vitamin C (ascorbic acid), on the growth performance, survival, and stress resistance of angelfish, Pterophylum scalare, juveniles. Juveniles were fed ad libitum for four weeks with Artemia enriched with no vitamins (control), vitamin C (T_c), α-tocopherol (T_α), dl-α-tocopheryl acetate (T _dl ), α-tocopherol and vitamin C (T_α+C), and dl-α-tocopheryl acetate and vitamin C (T _dl+C). After four weeks, an osmotic stress test was performed using seawater (25 g/L) to evaluate juvenile’s resistance to stress. Whole-body glucose and cortisol were used as stress indicators. At the end of the feeding trial, growth performance and survival of the juveniles fed vitamin-enriched Artemia were significantly (P < 0.05) higher than for the control fish. Best performance was recorded for the T_α+C group. Survival, however, was not significantly (P > 0.05) different between the vitamin-fed groups. Osmotic stress significantly elevated the stress indicators, whole-body cortisol and glucose levels (P < 0.05), highest and lowest values being observed in control and T_α+C groups, respectively. Survival after osmotic stress of juveniles fed the T_α+c diet was significantly higher (by 46.2%, P < 0.001) than for controls. Results suggested that α-tocopherol has greater efficacy than dl-α-tocopheryl acetate and enriching Artemia with α-tocopherol and vitamin C together improves growth performance, survival, and stress resistance of angelfish juveniles.     

Comparative study of Hargreaves’s and artificial neural network’s methodologies in estimating reference evapotranspiration in a semiarid environment

The Penman–Monteith equation (PM) is widely recommended because of its detailed theoretical base. This method is recommended by FAO as the sole method to calculate reference evapotranspiration (ET_o) and for evaluating other methods. However, the detailed climatological data required by the Penman–Monteith equation are not often available especially in developing nations. Hargreaves equation (HG) has been successfully used in some locations for estimating ET_o where sufficient data were not available to use PM method. The HG equation requires only maximum and minimum air temperature data that are usually available at most weather stations worldwide. Another method used to estimate ET_o is the artificial neural network (ANN). Artificial neural networks (ANNs) are effective tools to model nonlinear systems and require fewer inputs. The objective of this study was to compare HG and ANN methods for estimating ET_o only on the basis of the temperature data. The 12 weather stations selected for this study are located in Khuzestan plain (southwest of Iran). The HG method mostly underestimated or overestimated ET_o obtained by the PM method. The ANN method predicted ET_o better than HG method at all sites.     

Growth performance,immune response and disease resistance of rainbow trout (Oncorhynchus mykiss) fed Thymus vulgaris essential oils

Efficacy of Thymus vulgaris essential oils was assessed on growth, immune response and disease resistance of rainbow trout (Oncorhynchus mykiss). Fish weighing 10 g were fed with dietary supplemented of the oils at 0.5, 1.0 and 2.0 ml/kg feed for 2 months. Fish fed with the oils at 0.5 ml/kg feed demonstrated a better weight gain and specific growth rate, compared to other treatments (p < .05). Fish fed with 1.0 ml the oils showed the highest up‐regulation of complement component 3 (C3) and (cluster of differentiation 4) (CD4) genes expression (p < .05), while lysozyme gene expression level significantly increased in fish fed with 2.0 ml of the oils. In addition, at the end of the experiment, the expression of C3 and CD4 genes were significantly up‐regulated in fish fed with 1.0 and 2.0 ml of the oils, while IL‐1ß and lysozyme genes expression levels were significantly decreased in fish fed 2.0 ml oils, towards the end of the trial (p < .05). There was a fluctuation in the levels of Alanine aminotransferase, Aspartate aminotransferase and Alkaline phosphatase in all treatments during the experiment. When treated fish were challenged with Aeromonas hydrophila, the highest survival rate was observed in 0.5 ml/kg treatment, followed by 2 and 1 mg/kg treatments. Overall, these findings demonstrated that dietary administration of T. vulgaris oils especially at 0.5 mg/kg feed can be considered as a potential component for enhancing of the growth, immune responses and disease resistance of trout against motile Aeromonas septicemia caused by A. hydrophila.     

Estimation of Arachidonic Acid Requirement for Improvement of Pre‐maturation Growth and Egg and Larval Quality in the Female Blue Gourami (Trichopodus trichopterus; Pallas, 1770): A Model for the Anabantidae Family

This study investigates the dietary arachidonic acid (ARA) requirement from juvenile to maturation stage in an anabantid model fish, the blue gourami, Trichopodus trichopterus. Specifically we determined the optimum dietary ARA content to maximize juvenile growth and subsequent sexual maturation and to improve the quality of their eggs and offspring. Five experimental diets containing 0.02, 0.53, 1.05, 1.60, and 2.12% ARA (of dry weight) were fed to juveniles over 5 mo. The results showed that whole‐body fatty acid profile of broodstock significantly changed in fish fed diets of different ARA content (ANOVA, P < 0.003). The highest contents of 18:2n‐6 and Σn‐6 were obtained in fish fed 0.53% ARA, and a decreasing trend was observed with elevated dietary ARA levels. Monthly specific growth rate (SGR) measurements revealed significant differences in the juvenile stage, but the SGR of broodstock was unaffected by dietary ARA. Protein and ash content of whole‐body broodstock showed no differences among groups, while lipid content decreased as ARA levels increased. Maximum volume of the oocyte was obtained in the 1.05% ARA group, while the yolk sac size increased as dietary ARA increased. The optimum growth and survival of the larvae produced by broodstock were recorded in the 2.12 and 1.6% ARA groups, respectively. It was concluded that despite the presumed ability of freshwater fish to synthesize and meet their highly unsaturated fatty acid requirements, dietary ARA higher than 1.05% had significant stimulatory effects on growth of juveniles but no obvious influence on the growth of matured fish. Also, higher ARA levels (1.6–2.12%) were found to improve the quality of eggs and offspring.     

Molecular genetic diversity and population structure of Iranian honey bee (Apis mellifera meda) populations: implications for breeding and conservation

Journal of Plant Diseases and Protection - The honey bee (Apis mellifera), as one of the most important pollinating insects, plays a critical role in biodiversity conservation and global food...     

The effect of organic and chemical fertilizers on oilseed rape productivity and weed competition in short rotation

Abstract

A two-year field experiment was conducted to investigate the impact of short crop rotation and organic amendments on rapeseed yield under weed competition conditions. The primary experimental plots consisted of either triticale or pea as a prior crop, consisting of four subplots with either 25 tons of composted cattle manure (CCM), 150?kg urea N ha^?1 (N), 25 tons composted cattle manure + 75?kg urea N ha^?1 (CCM?+?N), or no urea N or manure added as the control (C0). Rapeseed seed yield was not significantly affected by previous crops, except for rapeseed grown after pea which had slightly higher seed yield (2058?kg ha^?1) than those grown after triticale (1942?kg ha^?1). Plants that received CCM?+?N produced the highest amount of seed yield (2447?kg ha^?1), but were not significantly different from plants that received just urea N (2218?kg ha^?1). Weeds gained more biomass when the previous crop was pea compared to those whose previous crop was triticale. Weeds in plots that received CCM?+?N produced the greatest biomass, followed by N, and CCM plots, respectively.     

Evaluation of different methods for the prediction of saturated hydraulic conductivity in tilled and untilled soils

The larger the bulk density of the soil, the smaller the saturated hydraulic conductivity (K_s), however, the relationship between K_s and dry bulk density for tilled and untilled conditions is different. K_s is lower in tilled soil than in untilled soil with the same texture at the same bulk density. The purpose of this study was to compare different models for the prediction of K_s for two soil textures under both tilled and non-tilled conditions. We compred two models based on the non-similar media concept (NSMC-0, NSMC-1), a model based on the similar media concept (SMC) and a model based on the Kozeny equation and Poiseuille law for prediction of K_s (KC-1 and KC-2). This study was conducted at two areas with loam and silty clay loam soils under tilled and untilled conditions. It is concluded that the SMC model is not able to predict K_s under either tilled or untilled conditions. Further, the NSMC-0 model, along with an equation to estimate the shape factor, was able to predict K_s versus dry bulk density for tilled soils. According to our study, under untilled conditions, the KC-1 and NSMC-1 models, and under tilled conditions, the NSMC-1 and NSMC-0 models, predicted K_s accurately. It is concluded that the NSMC models together with the optimized Kozeny–Carman models could reliably be used to predict K_s in different soil textures.     

Remobilization efficiency and photosynthetic characteristics of five barley (Hordeum vulgare L.) cultivars under terminal drought stress

Drought is an important limiting factor which can cause major loss in barley productivity. A field experiment was conducted to investigate the effects of irrigation regimes on assimilate remobilization and photosynthetic characteristics of five barley cultivars in 2012 and 2013. There were four levels of irrigation including well-watered [soil moisture content in root depth kept at 100% field capacity (FC)], mild drought (75% FC), severe drought (50% FC), and very severe drought (25% FC). Results showed that Karoon and Valfajr cultivars had the maximum net photosynthetic rate (P_n) ranged from 16.3 to 19.3 µmol CO₂ m^?2 s^?1 under very severe drought. Stomatal conductance (gs) was affected by drought so that Karoon and Valfajr had the lowest gs under severe and very severe drought. By improving the drought, remobilization efficiency in Karoon and Valfajr increased from 18.3% in well-watered to 54.1% under severe drought. In both years under severe and very severe drought, maximum 1000-grain weight and grain yield was obtained in Valfajr and Karoon. Overall, in arid areas, applying suitable irrigation regimes such as mild or severe drought can control soil drying, so that suitable cultivars such as Karoon and Valfajr can rehydrate overnight, and yield might not be inhibited severely.