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.     

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.     

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.     

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.     

Yeast extract, brewer’s yeast and spirulina in diets for Labeo rohita fingerlings affect haemato-immunological responses and survival following Aeromonas hydrophila challenge

A feeding trial was conducted for 60 days to study the immunomodulatory role of three different immunostimulants yeast extract (YE), brewer’s yeast (BY) and spirulina (SP) in Labeo rohita fingerlings. Four hundred and fifty fingerlings (avg. wt 3.35 ± 0.15 g) were randomly distributed in ten treatments and fed with either of ten iso-nitrogenous and iso-caloric semi-purified diets, prepared with three incremental levels (1%, 2% and 4%) of different immunostimulants except the control. Growth parameters did not vary significantly (p > 0.05) among the experimental groups. Haematology and serum parameters was performed before Aeromonas hydrophila challenge whereas respiratory burst activity was analysed following challenge. The respiratory burst activity, total leucocyte count, serum total protein and globulin was significantly higher (p < 0.05) in YE 1% supplemented group. The survival (%) after challenging with A. hydrophila was also highest in the YE fed groups. The results indicate that among the different sources and levels of immunostimulants, YE at lower inclusion level is more effective in promoting the immune status of L. rohita fingerlings.     

Robust genetic transformation of sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> L.) using differentiating embryogenic callus induced from immature embryos

Background

Sorghum (Sorghum bicolor L.) is one of the world’s most important cereal crops grown for multiple applications and has been identified as a potential biofuel crop. Despite several decades of study, sorghum has been widely considered as a recalcitrant major crop for transformation due to accumulation of phenolic compounds, lack of model genotypes, low regeneration frequency and loss of regeneration potential through sub-cultures. Among different explants used for genetic transformation of sorghum, immature embryos are ideal over other explants. However, the continuous supply of quality immature embryos for transformation is labour intensive and expensive. In addition, transformation efficiencies are also influenced by environmental conditions (light and temperature). Despite these challenges, immature embryos remain the predominant choice because of their success rate and also due to non-availability of other dependable explants without compromising the transformation efficiency.

Results

We report here a robust genetic transformation method for sorghum (Tx430) using differentiating embryogenic calli (DEC) with nodular structures induced from immature embryos and maintained for more than a year without losing regeneration potential on modified MS media. The addition of lipoic acid (LA) to callus induction media along with optimized growth regulators increased callus induction frequency from 61.3 ± 3.2 to 79 ± 6.5% from immature embryos (1.5–2.0 mm in length) isolated 12–15 days after pollination. Similarly, the regeneration efficiency and the number of shoots from DEC tissue was enhanced by LA. The optimized regeneration system in combination with particle bombardment resulted in an average transformation efficiency (TE) of 27.2 or 46.6% based on the selection strategy, 25% to twofold higher TE than published reports in Tx430. Up to 100% putative transgenic shoots were positive for npt-II by PCR and 48% of events had < 3 copies of transgenes as determined by digital droplet PCR. Reproducibility of this method was demonstrated by generating ~ 800 transgenic plants using 10 different gene constructs.

Conclusions

This protocol demonstrates significant improvements in both efficiency and ease of use over existing sorghum transformation methods using PDS, also enables quick hypothesis testing in the production of various high value products in sorghum.

     

Effects of contrasting biochars on the leaching of inorganic nitrogen from soil

Journal of Soils and Sediments - The use of excessive nitrogen (N) fertilizers usually causes soil N leaching, eutrophication, and water pollution. Nevertheless, biochars may play an important role...     

Experimental verification of two calculation methods for relating horizontal infiltration to soil-water diffusivity

Two recently proposed methods are used to relate horizontal infiltration data to soil- moisture diffusivity. The theoretical background is only discussed briefly and more emphasis is given to an experimental verification. With the described methods numerous experiments were performed on two soils under varying initial moisture content in the same soil samples. Data of four representative experiments are summarized in a table and a number of figures.The horizontal infiltration into a silty loam soil with an initial moisture content of 0.08 cm³/cm³ is not in accordance with theoretical expectations, whereas that into a fine sand with the same initial moisture content is in accordance with theory. The latter may be due to the building up of a soil-air pressure in the silty loam which was recorded to be in the order of 40 mbar.It further appears that the approximate method of the two referred to above yields similar results in terms of D(θ) as compared with the exact but more laborious method only if the soil was air dry.Finally two examples of (re)-using the obtained D(θ) data are given.     

Microtopography as a factor in the degradation of Vertisols in central India

Earlier studies on soil degradation in Vertisols of the Purna Valley of central India indicated that the semiarid climate characterized by a mean annual rainfall (MAR) of 875 mm and a tropustic moisture regime is responsible for the development of calcareous sodic soils. Recent observations, however, indicate that in the adjacent east upland of the Purna Valley, namely in the Pedhi Watershed, Vertisols have drainage problems, although the area receives a higher MAR than the Purna Valley, the total MAR being 975 mm. The Pedhi Watershed covers an area of 44 321 ha, and is characterized by a tropustic moisture regime and a hyperthermic temperature regime. Vertisols of the Pedhi Watershed are deep, calcareous, clayey and very dark greyish‐brown to dark yellowish‐brown in colour. Vertisols occur on both microhigh (MH) and microlow (ML) positions. The distance between the MH and ML positions is approximately 6 km and the elevation difference is 0.5–5 m. Cracks > 1 cm wide extend down to the slickenside zones in soils of ML whereas they cut these zones in some soils in MH positions. The soils of the MH positions are strongly alkaline and those of ML are mildly alkaline. The present study attempts to relate the distinctly different morphological and chemical properties of Vertisols in the MH and ML positions to pinpoint the prime factor responsible for the impairment of drainage on the basis of physical, chemical, mineralogical and micromorphological data. These data were obtained from 13 Vertisol pedons of methodically selected sites in the Pedhi Watershed. Despite their similar coefficient of linear extensibility (COLE), volumetric shrinkage potential (VSP), clay contents and amounts of fine smectite clay, the plasmic fabric of the slickenside horizons in soils of ML is porostriated, whereas in soils of MH it is stipple speckled to mosaic speckled, indicating weak plasma separation. The soils have both pedogenic and non‐pedogenic calcium carbonates (CaCO₃). The semiarid climate induces the precipitation of CaCO₃ with a concomitant development of subsoil sodicity. The degree of development of sodicity (Exchangeable sodium percentage (ESP) ≥ 5) is more in soils of MH as evidenced by the higher amount of pedogenic CaCO₃ (PC). The lack of water in soils of MH position is the reason for weak swelling of smectite, for larger amounts of PC, for higher alkalinity and sodicity, and for cracks cutting through the slickenside zones. Formation of sodic Vertisols in MH alongside non‐sodic Vertisols in ML positions is a unique phenomenon. It develops because of microtopographic differences which modify distribution of water across the landscape and facilitate greater penetration of rainwater in ML positions. The development of sodicity due to microtopographic differences assumes a great importance when a future land resource management programme on Vertisols in the higher MAR zone of overall a semiarid climate is considered. Copyright © 2002 John Wiley & Sons, Ltd.     

Microbial Biomass and Activity in a Laterite Soil Amended with Municipal Solid Waste Compost

The dynamics of soil quality indicators, such as microbial biomass-C, soil respiration, and urease and acid phosphatase activities, in a laterite soil (Typic Haplustalf ) amended with different doses of Calcutta municipal solid waste compost (MSWC) were studied over 120 days of incubation at 30 °C under 60 % soil water holding capacity. The parameters were found to increase with the increase in doses of MSWC. Soil microbial biomass-C (MBC) and soil respiration activity reached peak values at 30 days of incubation and then gradually decreased up to 120 days of incubation. Urease and acid phosphatase activities showed peak values at 60 and 90 days of incubation, respectively. The increase in soil enzyme activities with the fall in MBC suggested that the release of enzymes was associated with lysis of microbial cells at the end of their life cycle. There was no indication of any detrimental effect on soil quality indicators of application of MSWC to soil.