Phytic Acid‐Induced Inhibition of Digestive Protease and α‐Amylase in Three Indian Major Carps: An in vitro Study

Antinutritional effects of phytic acid (myoinositol hexaphosphate, IP6) on growth and digestibility in fish have been reported. However, specific effect of IP6 on the digestive enzymes in fish has not been addressed. In this study, inhibitory effect of synthetic IP6 (Phytic acid sodium salt, 90% purity) on the activity of the digestive protease and α‐amylase in rohu, Labeo rohita; catla, Catla catla; and mrigal, Cirrhinus mrigala has been investigated in vitro. Graded levels (12.5, 25, 50, 100, 150, and 200 µg/mL) of IP6 were added to the reaction mixtures containing enzyme extracts and substrate solution in triplicate to detect any change in enzyme activity. Results of the experiment revealed that IP6 significantly inhibit/lower activities of the digestive enzymes in a dose‐dependent manner, as evident from the regression equations (F values significant at P < 0.001 level). Apparently, irrespective of the fish species studied IP6‐induced inhibition of α‐amylase activity was greater than protease activity. Among the three fish species studied, C. mrigala appeared to be more sensitive to IP6 for both α‐amylase and protease activity. Enzyme activity was least affected in C. catla. Results of the study might raise concern while incorporating IP6 rich plant‐derived feed ingredients in aqua feed preparation.     

Evaluation of the nutritive value of Leucaena leucocephala leaf meal, inoculated with fish intestinal bacteria Bacillus subtilis and Bacillus circulans in formulated diets for rohu, Labeo rohita (Hamilton) fingerlings

Nine isonitrogenous (35% crude protein approximately) and isocaloric (18.37 kJ g^?1) experimental diets (RLL20–BCFL40) were formulated with either raw or treated (inoculated with fish intestinal bacteria) Leucaena leucocephala leaf meal at 20%, 30% and 40% levels replacing other ingredients partially from a fish meal based reference diet (RD). Two specific strains of fish intestinal bacteria, Bacillus subtilis (isolated from Cyprinus carpio) and B. circulans (isolated from Oreochromis mossambicus) having extracellular cellulolytic and amylolytic activities, were used to inoculate Leucaena leaf meal for 15 days at 37°C. The crude fibre, cellulose and hemicellulose contents and the antinutritional factors, tannin, phytic acid and mimosine in the leaf meal decreased due to inoculation. However, free amino acids and fatty acids increased in the treated leaf meal. The response of rohu, Labeo rohita, fingerlings fed the experimental diets for 80 days was compared with fish fed a RD. Both the inclusion level and type of Leucaena leaf meal in diets significantly affected the growth performance of rohu. Fish fed diets containing inoculated Leucaena leaf meal performed better in comparison with those with the RD. On the basis of growth response, feed conversion ratio, protein efficiency ratio and apparent net protein utilization, diet formulated with 30%Leucaena leaf meal inoculated with B. circulans resulted in the best performance of rohu fingerlings followed by diet with 40%B. subtilis inoculated Leucaena leaf meal. The apparent protein digestibility (APD) was better in fish fed diets containing B. circulans inoculated leaf meal. An increasing level of raw Leucaena leaf meal was associated with a decrease in the carcass protein content of rohu fingerlings. The activity of α‐amylase increased with the increasing level of treated leaf meal in diets. Cellulase activity increased with increasing level of inclusion of raw leaf meal, and was comparatively lower in fish fed diets with treated leaf meal. Activities of protease and lipase were higher in fish fed the RD. The results showed that it is possible to incorporate Leucaena leaf meal inoculated with enzyme‐producing fish intestinal bacteria in carp diets up to 40% level of inclusion.     

Economic analysis of dairy farming in Bangladesh

Tropical Animal Health and Production - A study was conducted to analyze the dairy farming sector of Bangladesh from an economic viewpoint. Primary data was collected from smallholder dairy farms...     

A high-throughput glasshouse bioassay to detect crown rot resistance in wheat germplasm

A high-throughput and reliable seedling bioassay to screen wheat germplasm for crown rot resistance was developed. Single wheat seedlings were grown in square seedling punnets in a glasshouse and inoculated with a monoconidial Fusarium pseudograminearum isolate 10 days after emergence. The punnets were laid horizontally on their side and a 10- µ L inoculum droplet placed on the stem base. Seedlings were incubated at near-saturated relative humidity, and crown rot severity was assessed 35 days after inoculation. Studies on the duration of incubation period, inoculum concentration and temperature were carried out to optimize these parameters. Seedling growth at 25/15(±5)°C in a glasshouse and 48-h incubation at near-saturated RH in darkness gave the best results. When crown rot resistance rankings of 16 Australian cultivars from the bioassay were compared with their field performance, Spearman's rank correlation coefficient was highly significant. This indicated that the seedling bioassay mimicked field resistance to crown rot in adult plants. A bootstrap resampling analysis showed little or no improvement in the coefficient of variation with an increasing number of replications, indicating a high level of precision and reproducibility. By detecting small but consistent differences in crown rot severity, the bioassay proved effective in large-scale screening for partial resistance: already over 1400 wheat genotypes have been screened. The high degree of precision makes this an invaluable tool in the understanding of pathogen aggressiveness, host specialization and parasitic fitness.     

Determination of inter- and intra-species genetic relationships among six Eucalyptus species based on inter-simple sequence repeats (ISSR)

Eucalyptus is the most economically important hardwood plantation tree cultivated in tropical and subtropical countries. Inter-simple sequence repeat (ISSR) markers were used to evaluate genetic relationships within and between individuals of six Eucalyptus species. A total of 583 loci (265 to 1535 bp) were amplified from 149 individuals belonging to the six Eucalyptus species using seven ISSR primers (two to three nucleotide repeats anchored with one or two nucleotides at the 3' or 5' region). The ISSR fragments indicated significant polymorphism and genetic diversity among the individuals. Cluster analysis and principal component analysis revealed the occurrence of wide genetic diversity among populations of E. tereticornis Sm., E. camaldulensis Dehnh. and E. urophylla S.T. Blake and narrow genetic diversity among populations of E. citriodora Hook. and E. grandis W. Hill ex Maiden. Genetic diversity was high in E. tereticornis Sm. (47.27%) and low in E. citriodora (18.64%). Maximum Nei's genetic identity (0.897) was observed between E. camaldulensis and E. tereticornis species, whereas maximum genetic diversity (0.286) was found between individuals of E. citriodora and E. grandis.     

Somatic embryogenesis in Cymbopogon pendulus and evaluation of clonal fidelity of regenerants using ISSR marker

An efficient plant propagation system through somatic embryogenesis was established in Cymbopogon pendulus, an aromatic grass followed by analysis of genetic status of regenerants using ISSR markers. Optimum embryogenic callus induction was observed on MS basal medium supplemented with 13.57 μM 2,4-dicholorophenoxyacetic acid (2,4-D) with 8.88 μM N⁶-benzyladenine (BA). Subsequent culturing of embryogenic calli on MS medium containing 4.52 μM 2,4-D and 8.88–13.32 μM BA gave maximum number of somatic embryos. Addition of coconut water (CW) promoted induction, growth and differentiation of callus and somatic embryogenesis. Further development of embryos into plantlets was achieved on MS medium supplemented with lower concentration of biotin and calcium pantothenate (CaP) along with BA (4.44–13.32 μM) and kinetin (2.32–4.65 μM). The root meristems were established on half strength MS medium containing 2% sucrose and 2.46–9.84 μM Indole3-butyric acid (IBA) and successfully established in soil with 77.8% survival rate in field condition. Thirteen randomly selected regenerated clones were screened using six ISSR primers. Nine clones produced similar monomorphic amplification profiles while remaining clones showed minor variation with absence of certain parental bands and appearance of unique band. Majority of the regenerants maintained genetic fidelity with the generation of few variants as evidenced from similarity matrix estimates using Nei Li's coefficient of similarity data.