Studies on the Pathogenicity of Newcastle Disease Virus Isolates in Guinea Fowl

Newcastle disease viruses isolated from chickens and guinea fowl were characterized as viscerotropic, velogenic strains on the basis of their mean death time, intracerebral pathogenicity index, intravenous pathogenicity index and cloacal and conjunctival mean death time. The pathogenesis of the disease caused by both the strains was studied in 4-week-old guinea fowl. Both strains had an incubation period of 5 days and the birds showed dullness, depression, anorexia, diarrhoea and paralysis of the legs. They also exhibited nervous signs such as incoordination, muscle tremors and trembling of the neck at the advanced stage of the disease. Mortality reached 52% in the group infected with the chicken isolate but it was only 8% in the birds infected with the guinea fowl isolate. No specific changes were observed at post-mortem examination except haemorrhages at the tip of the glands of the proventriculus and in the caecal tonsil. Changes in the lymphoid organs and brain were always present in both the groups. Despite the low mortality, the guinea fowl isolated had multiplied in various organs in the birds. In both groups, the frequency of virus isolation increased from 5 to 10 days post infection.     

Potential Yields and On-Farm Ethanol Production Cost of Corn, Sweet Sorghum, Fodderbeet, and Sugarbeet

Field experiments were conducted during 1980-82 at the Agronomy Farm of the University of California, Davis, to compare fermentable carbohydrate production and cost of potential ethanol from fodderbeet, sweet sorghum, sugarbeet, and corn in relation to the requirements of these crops for fertilizer nitrogen and irrigation. The response of hexose yields of these crops to fertilizer N varied in the two experiments. When all crops responded, sweet sorghum and sugarbeet required 36 % and fodderbeet 68 % of the fertilizer N needed for corn. Twelve weeks following a mid-season irrigation cut off, hexose yield of sugarbeet was decreased by 18 % as compared to an adequately watered crop. Water stressed sweet sorghum extracted higher amounts of soil moisture, increased in hexose concentration and produced 29 % higher hexose yield than when adequately watered. Stressed sugarbeet, however, had a higher hexose yield due to its higher sugar concentration.
When fertilized and irrigated adequately, fodderbeet produced 13.4, sugarbeet 11.9, sweet sorghum 10.0, and corn 8.15 Mg hexose ha⁻¹. Comparative on-farm ethanol production costs of these four crops were very close ($0.38 to 0.40 L⁻¹). Thus, growing established crops like corn and sugarbeet for which processing facilities and alternative markets already exist would be preferred.     

Assessment of critical limit of boron for cowpea in piedmont soils of Arunachal Pradesh

A study was conducted with 24 piedmont soils of Arunachal Pradesh (India) to estimate the critical limit of available boron (B) in soil and cowpea plant for predicting the response of cowpea (Vigna unguiculata L. Walp.) to B application. The critical concentration of available B in these soils was established by graphical procedure at 0.48 mg kg^?1 for soil and at 24.5 mg kg^?1 in the plant tissues. Soil containing available B below the critical limit responded appreciably to B fertilization. A negative response to B application was also observed in soils at higher level of available B. The average dry matter yield increased with the increasing level of B application up to 1.5 mg kg^?1. The yield response to B application in cowpea on B deficient soils was 34.5%. Based on the critical value of 0.48 mg kg^?1, 10 soils were rated to be adequate and 20.0% soils belonging to this category responding to B application, whereas 85.7% soils below the critical value showed a positive response to B application. The hot water soluble B was significantly and positively correlated with organic carbon, cation exchange capacity and clay contents and negatively correlated with pH, silt and sand contents of soils.     

Performance stability of maize genotypes across diverse hill environments in Nepal

The national maize improvement program in Nepal regularly receives elite maize (Zea mays L.) genotypes from CIMMYT and other countries and tests them for their performance stability in highly diverse environments. Studies were conducted on research stations and farmers’ fields at five sites in three years to determine performance stability of exotic maize genotypes. Replicated on-station and on-farm studies were conducted using 25 and 10 genotypes, respectively, including a local check and an improved check (Manakamana-3), in 2004–2006. We analyzed grain yield, days to flowering, plant and ear height, plant population, husk cover, and plant and ear aspect. Stability and genotype superiority for grain yield was determined using genotype and genotype × environment (GGE) biplot analysis that compares among a set of genotypes with a reference ‘ideal’ genotype, which has the highest average value of all genotypes and is absolutely stable. Several genotypes produced significantly higher grain yield than the local check. Four genotypes (‘Across9942 × Across9944’, ‘Open Ended White Hill Population’, ‘Population 44C10’ and ‘ZM621’), that produced significantly higher grain yield than the improved check, also had other agronomic traits (days to flowering, plant and ear height, number of ears, resistance to leaf blight, plant and ear aspect and husk cover tightness) equal to or better than the improved check. GGE-biplot analysis showed that Across9942 × Across9944 and ZM621 were the most superior genotypes in the on-station and on-farm trials, respectively. The findings from this study provide new information on the stability of the maize genotypes that are also adapted to other regions of the world. Such information could be useful for maize improvement program for the highlands in Nepal and other similar environments.     

Further studies on anthelmintic resistance in sheep at an organised farm in arid region of Rajasthan

Faecal egg count reduction test (FECRT) and in vitro egg hatch assay (EHA) was performed on Indian Karakul (3/4 crosses of Karakul with Malpura, Marwari and Sonadi) transported from arid region campus, Bikaner, where resistance was reported in 1996. FECRT revealed that fenbendazole and levamisole were 100% effective in reducing the egg counts. LC50 value on EHA was 0.074 +/- 0.015 microg thiabendazole ml(-1). The faecal culture examination revealed the presence of Haemonchus contortus only. It was concluded that H. contortus was fully susceptible to both benzimidazole and levamisole.     

Purification and development of ELISAs for two forms of vitellogenin in Indian walking catfish, <Emphasis Type="Italic">Clarias batrachus</Emphasis> (L.)

Two forms of vitellogenin (Vg: Vg1 and Vg2) were purified from the plasma of estradiol-17β (E₂)-treated Indian walking catfish, Clarias batrachus, by gel filtration and adsorption chromatography. Native Vg1 and Vg2 had apparent molecular masses of 375 and 450 kDa, respectively, and both Vgs resolved into two similar major bands (95 and 67 kDa) in SDS-PAGE under reducing condition. Polyclonal antisera raised against each form of Vg were absorbed with a combination of hypophysectomized male catfish serum proteins and alternate Vg to ensure specificity. Immunological analyses verified the presence of Vg1 and Vg2 in the plasma of female catfish. Homologous ELISAs were developed for Vg1 and Vg2 using their respective harvested antisera, which exhibited the detection limit of 100 ng ml^?1 for Vg1 and 40 ng ml^?1 for Vg2, and low level of cross-reactivity (not parallel to the standard) was found with alternate Vg in each assay. Treatment of male catfish with E₂ induced both Vgs showing a proportionate ratio of Vg1 to Vg2 at 5.6:1. Plasma concentrations of both Vgs measured by ELISAs at different reproductive phases of field collected female catfish increased in accordance with the ovarian development, keeping the proportionate ratio of Vg1 to Vg2 at about 2:1 in fish undergoing vitellogenesis during prespawning period and 1:20 during spawning period, suggesting that Vg1 may be the major Vg to contribute in yolk formation, whereas Vg2, besides its role in yolk formation, may facilitate other physiological functions. The present study, thus, demonstrates the occurrence of two unequally synthesized Vgs in the catfish.