High feeding and growth rates in common octopus (Octopus vulgaris) fed formulated feeds with an improved amino acid profile and mixture of binders

Four semi‐moist formulated feeds were supplied to Octopus vulgaris subadults (664 ± 70 g; 18.4 ± 0.7°C) in two different experiments. In the experiment #1, two diets were prepared with a new mixture of binders (gelatine 150 g kg^?1, starch 100 g kg^?1 and gum 50 g kg^?1). The GEL15‐Squid and GEL15‐Hake feeds included 100 g kg^?1 freeze‐dried squid (Todarodes sagittatus) or hake (Merluccius sp.) respectively. Both feeds showed low water disintegration rates at 24 h (13.6–15.0% dry weight). The specific feeding rate was higher in animals fed GEL15‐Hake (2.7%BW day^?1), but the growth and feed efficiency were significantly better in animals fed GEL15‐Squid (1.4%BW day^?1 and 61.2% respectively; P < 0.05). The proximate composition of the digestive gland, carcass and whole animals was similar. In the experiment #2, the GEL15‐Squid amino acid profile was improved by replacing 50 g kg^?1 gelatine by 50 g kg^?1 freeze‐dried squid (GEL10‐Squid) or freeze‐dried fish (GEL10‐Fish). These feeds showed higher water disintegration rates (31.7–36.3% dry weight). The feeding rates (2.2–2.3%BW day^?1), growth (1.5%BW day^?1) and feed efficiency were similar for both diets. Total lipids were higher in the digestive gland and whole animals fed GEL10‐Fish diet (P < 0.05). Future effort could be directed towards alternative binders that allow improve amino acid balance with a minimum gelatine content or even supplementation trials including essential amino acids.     

Effects of biofloc technology on reproduction and ovarian recrudescence in Nile tilapia

The objectives of this study were to evaluate the reproductive cycle, morphological changes of ovary and mobilization of energy reserves in Nile tilapia reared with biofloc technology (BFT). In general, the growth and reproductive performance were highly similar between BFT and Control system (clear water). Difference between the systems was found in the hepatosomatic index (using mixed‐effects models), which suggested that BFT can alter the energy mobilization in the post‐spawning period. The absolute and relative fecundity, fertilization rate, number of larvae produced per female, gonadosomatic index, proportion of oogenesis cells, number of post‐ovulatory and atretic follicles were similar between the two systems. We also did not detect a reduction in the reproductive cycle length in Nile tilapia reared in BFT. Because there was no evidence of the negative effects of BFT on Nile tilapia reproduction, we concluded that BFT might be used for breeder stocking of this species.     

A new record of the freshwater pearl mussel Margaritifera margaritifera L. (Bivalvia,Unionoida) from the River Narcea (Asturias,north‐western Spain)

1. A population of the freshwater pearl mussel Margaritifera margaritifera L. was found in the River Narcea in the province of Asturias (north‐western Spain). Primary analysis of the population shows that it is well distributed along the river and is particularly abundant in shady river banks with a gravel substrate. 2. The length of living mussels ranges between a minimum of 22 mm and a maximum of 116 mm, with most in the size class between 65 mm and 70 mm. There is a good proportion of young mussels, although no fertile females were found in the course of the investigation. 3. Although there is no specific legislation in Spain for the protection of M. margaritifera, it has recently been proposed to include M. margaritifera in the Spanish List of Threatened Species as ‘vulnerable’. 4. Although the River Narcea seems to provide suitable conditions for the pearl mussel (water quality, available salmonid hosts, etc.), the main conservation measures must be directed at avoiding river fragmentation from dams, channelization and organic enrichment from individual farms or towns situated close to the river bank. Copyright © 2000 John Wiley & Sons, Ltd.     

Agronomic response and water productivity of almond trees under contrasted deficit irrigation regimes

We investigated the long-term effects of different deficit irrigation (DI) options on tree growth, shoot and leaf attributes, yield determinants and water productivity of almond trees (Prunus dulcis, cv. Marta) grown in a semiarid climate in SE Spain. Three partial root-zone drying (PRD) irrigation treatments encompassing a wide range of water restriction (30%, 50% and 70% of full crop requirements, ET_c) and a regulated deficit irrigation treatment (RDI, at 50% ET_c during kernel-filling) were compared over three consecutive growth seasons (2004–2006) to full irrigation (FI). The results showed that all deficit irrigation treatments have a negative impact on trunk growth parameters. The magnitude of the reduction in trunk growth rate was strongly correlated through a linear relationship with the annual volume of water applied (WA) per tree. Similarly, a significant relationship was found between WA and the increase in crown volume. In contrast, leaf-related attributes and some yield-related parameters (e.g., kernel fraction) were not significantly affected by the irrigation treatments. Except in PRD₇₀, individual kernel weight was significantly reduced in the deficit irrigated treatments. Kernel yield, expressed in percent of the maximum yield observed in the FI treatment, showed a linear decrease with decreasing WA and a slope of 0.43, which implies that a 1% decrease in water application would lead to a reduction of 0.43% in yield. Water productivity increased drastically with the reduction of water application, reaching 123% in the case of PRD₃₀. Overall, our results demonstrate the prevalence of direct and strong links between the intensity of the water restriction under PRD – i.e., the total water supply during the growing season – and the main parameters related to tree growth, yield and water productivity. Noteworthy, the treatments that received similar annual water volumes under contrasted deficit irrigation strategies (i.e., PRD₇₀ and RDI) presented a similar tree performance.     

Image Analysis of Grain and Chemical Composition of the Barley Plant as Predictors of Malting Quality in Mediterranean Environments

We have explored the possibility of predicting the malting quality of barley grain, indicated by malt extract yield, by characteristics measured either on plants at anthesis or in mature dry grain by image analysis. To produce barley samples with varying levels of all the characteristics studied, we used grain from an experiment designed to study the influence of lowinput husbandry practices on malting quality of barley by growing five malting genotypes at each of four environments (site × season) and with two different agronomic treatments (N fertilization and herbicide-mechanical roguing of weeds). The results showed that nitrogen content in the plant at anthesis was a good predictor of grain protein content, this characteristic in turn being positively correlated with embryo size and grain volume, as estimated by image analysis, and negatively correlated with nonstructural carbohydrate content in the plant at anthesis. Extract yield was positively correlated with Kolbach index (ratio of soluble to total wort protein) and negatively correlated with wort viscosity and barley grain protein content. Thus, the only practical predictor of malt extract was grain protein content.     

Measuring and Modeling Grain Sorption Equilibria of Amaranth Grains

Water activity (a_w)of Amaranthus cruentus were measured at 35, 45, and 65°C at different moisture contents by means of an electronic water activity meter. Experimental curves were fitted to one three-parameter equation (GAB equation). The equilibrium values and temperature shifts were modeled with a three-parameter equation in the approximate a_w range of 0.03–0.88. An analytical expression to calculate the isosteric heat of sorption and its moisture content dependence was used, and the results were compared with the isosteric heat calculated from the experimental equilibrium data by means of the Clausius-Clapeyron equation.     

Algal and Cyanobacterial Lectins and Their Antimicrobial Properties

Lectins are proteins with a remarkably high affinity and specificity for carbohydrates. Many organisms naturally produce them, including animals, plants, fungi, protists, bacteria, archaea, and viruses. The present report focuses on lectins produced by marine or freshwater organisms, in particular algae and cyanobacteria. We explore their structure, function, classification, and antimicrobial properties. Furthermore, we look at the expression of lectins in heterologous systems and the current research on the preclinical and clinical evaluation of these fascinating molecules. The further development of these molecules might positively impact human health, particularly the prevention or treatment of diseases caused by pathogens such as human immunodeficiency virus, influenza, and severe acute respiratory coronaviruses, among others.     

Kinetic Study of the Degradation of Ethiofencarb in Aqueous Solutions

A kinetic study of the hydrolysis of ethiofencarb (α-ethylthio-o-tolyl methylcarbamate) in pure water and in aqueous solutions at pH 2, 6, 9 and 12 and at three different temperatures (4, 20 and 50(±1)°C) has been carried out using a gas chromatographic nitrogen-phosphorus detection method. The values of the first-order rate constants (k) for the degradation reaction were calculated. The values for k were found to be dependent on pH and temperature. No acid hydrolysis was observed in any case. Complete degradation of ethiofencarb was observed at pH 12 at all three temperatures; it was practically instantaneous at room temperature. Ethiofencarb was also completely degraded at pH 9 at 20 and 50°C, while in pure water (pH 6) degradation took place at 50°C but not at 20°C. Ethiofencarb was not degraded in pure water at lower temperatures and, due to the reversible nature of the reaction, at equilibrium about 80% of the pesticide remained undegraded at room temperature. © 1997 SCI.     

Effect of dietary protein source and time on alkaline proteolytic activity of Nile tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>)

A 4 × 3 factorial study was conducted to evaluate the effect of four experimental diets (a control diet and a 0, 50, and 100% fish meal replacement diet) and the period of time Nile tilapia, Oreochromis niloticus, were fed those diets (0, 20, and 40 days) on the alkaline proteolytic activity of the animals’ digestive tract, as well as their potential interaction. Significant differences (at P < 0.05) and a significant interaction were observed among dietary treatments for the alkaline proteolytic activity of tilapia after 40 days of feeding. This study confirmed that, under these experimental conditions, a 50% fish meal replacement formulation elicited the highest alkaline proteolytic activity in the digestive tract of tilapia, which resulted in the highest final weight and specific growth rate (SGR), but further research is needed to establish the relative contribution of the alkaline proteases to the overall proteolytic activity of this omnivorous fish species.