Resistance of the rice variety Utri Rajapan to ragged stunt and tungro viruses

Utri Rajapan, a rice variety tolerant to the brown planthopper, Nilaparvata lugens, was resistant to rice ragged stunt virus transmitted by N. lugens and to rice tungro virus transmitted by the green leafhopper, Nephottetix virescens. Although some Utri Rajapan plants became infected with tungro virus, symptoms were mild and disappeared as the plant matured. Of the two tungro-associated viruses, only rice tungro bacilliform virus was present in Utri Rajapan. The infected plants thus did not serve as a source of inoculum for transmission to healthy plants, as rice tungro spherical virus must also be present for transmission to occur.     

Die Bestimmung repräsentativer Mittelwerte von Schwermetall-Konzentrationen in den Niederschlägen und im Sickerwasser von Wald-Standorten des Soiling

Heavy metals in precipitation and seepage water from forest sites in the Soiling: Determination of representative averages of heavy metal concentrations Concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb were determined in open land precipitation, in precipitation below canopy and in seepage water in two different soil depths, over the period of 3 years, in monthly and half-yearly intervals, in a beech and a spruce forest of the Soiling mountains. The results of the concentration measurements and the element fluxes calculated from these data were treated statistically. The coefficients of variation of the concentrations and the fluxes within a given time period often exceeded 100%. It is proposed that, in order to determine meaningful average values, weighted samples are taken in half-year or year intervals, over the time span of several years, in a number of local replicates sufficient to reduce the error of the mean to less than 30%. For the investigation of time variations in the concentrations and fluxes the sampling of single rain events or of seepage water within short time periods (a few days) is suggested.     

Tiger,Bengal and Domestic Cat Embryos Produced by Homospecific and Interspecific Zona‐Free Nuclear Transfer

The aim of this study was to evaluate three different cloning strategies in the domestic cat (Felis silvestris) and to use the most efficient to generate wild felid embryos by interspecific cloning (iSCNT) using Bengal (a hybrid formed by the cross of Felis silvestris and Prionailurus bengalensis) and tiger (Panthera tigris) donor cells. In experiment 1, zona‐free (ZP‐free) cloning resulted in higher fusion and expanded blastocyst rates with respect to zona included cloning techniques that involved fusion or injection of the donor cell. In experiment 2, ZP‐free iSCNT and embryo aggregation (2X) were assessed. Division velocity and blastocyst rates were increased by embryo aggregation in the three species. Despite fewer tiger embryos than Bengal and cat embryos reached the blastocyst stage, Tiger 2X group increased the percentage of blastocysts with respect to Tiger 1X group (3.2% vs 12.1%, respectively). Moreover, blastocyst cell number was almost duplicated in aggregated embryos with respect to non‐aggregated ones within Bengal and tiger groups (278.3 ± 61.9 vs 516.8 ± 103.6 for Bengal 1X and Bengal 2X groups, respectively; 41 vs 220 ± 60 for Tiger 1X and Tiger 2X groups, respectively). OCT4 analysis also revealed that tiger blastocysts had higher proportion of OCT4‐positive cells with respect to Bengal blastocysts and cat intracytoplasmic sperm injection blastocysts. In conclusion, ZP‐free cloning has improved the quality of cat embryos with respect to the other cloning techniques evaluated and was successfully applied in iSCNT complemented with embryo aggregation.     

Strepsipteran parasitism of white leafhoppers,Cofana spp. (Hemiptera: Cicadellidae) in lowland rice in Cote d'Ivoire

Three tests were conducted over a 2-year period in lowland irrigated rice fields on the WARDA Research Station at Bouake, Cote d'Ivoire, to obtain information on the strepsipteran parasitism of white leafhoppers, Cofana spectra and C. unimaculata. Rice cultivars were sampled with a sweep net to collect leafhoppers for determination of the relative abundance of the two leafhopper species and the effect of rice cultivar and rice crop age on the leafhopper populations and percent strepsipteran parasitism. Dissections of the leafhoppers were made to determine the relative number of the various parasitic stages in the leafhoppers. Cofana unimaculata populations were higher than those of C. spectra while C. spectra parasitism by Halictophagus australensis Perkins (Strepsiptera: Halictophagidae) was higher than that of C. unimaculata. In two tests, there was a relationship between length of rice cultivar duration and C. unimaculata populations with populations being highest on the short duration cultivars. On most cultivars there was no correlation between Cofana populations and percentage parasitism, nor was there a relationship between cultivar growth duration and percent parasitism. The number of the various stages of the parasite was similar in both Cofana species with the male pupal parasitic stage being most common.     

VALIDITY OF LOWCOST LABORATORY GEOCHEMISTRY FOR ENVIRONMENTAL APPLICATIONS

A little known alternative to highcost environmental analysis, especially in Europe, is the use of commercially available, lowcost exploration geochemical laboratory analysis. To test for suitable accuracy and precision, both indicated parameters were monitored during several sample runs for environmental examinations at a selected commercial geochemical laboratory using various digestive methods and ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometry). By evaluating duplicate samples and repeated measurements of internal standards and comparing the results with precision needed for environmental investigations, exploration geochemical analysis is found to be more than adequate for most elements and digestive methods in environmental applications. Accuracy is highest for total digestion ICP-AES analysis, with expectedly greater error margins for aqua regia digestion. Lowcost exploration geochemical analysis is an inexpensive analytical tool for screening, detailed investigations and monitoring of contaminated sites.     

The estimation of aboveground biomass and nutrient pools of understorey plants in closed Norway spruce forests and on clearcuts

The estimation model PhytoCalc allows a non-destructive quantification of dry weight and nutrient pools of understorey plants in forests by using the relationship between species biomass, cover and mean shoot length. The model has been validated with independent samples in several German forest types and can be a useful tool in forest monitoring. However, in open areas within forests (e.g. clearcuts), the current model version underestimates biomass and produces unreliable nutrient pool estimations. Thus, tissue density, as approximated by leaf dry matter content (LDMC), is systematically higher under high light compared to low light conditions. We demonstrate that the ratio of LDMC under clearcut conditions to LDMC under forest conditions can be used to adjust the PhytoCalc model to clearcut conditions. We investigated the LDMC ratio of five exemplary species commonly occurring on clearcuts. Integrating the square of the ratio as a correction factor improved estimates of biomass to more than 70% fit between observations and predictions. Results also suggest this ratio can be used to correct nutrient concentrations modelled in PhytoCalc, which tend to be overestimated in clearcuts. As morphological groups of plant species exhibit significantly different ratios, we advise using group-specific correction factors for clearcut adjustments in the future.     

Residues of carbaryl,lindane and monocrotophos on rice treated for control of rice bug, Leptocorisa oratorius (Fab.)

This study investigated the correlation between insect mortality and insecticide residue levels in rice grain during the developing stages and at harvest, and also determined the relative toxicities of three insecticides, monocrotophos (Azodrin 16·8 EC), lindane (Agrocide 26 DP), and carbaryl (Sevin 85 WP) to Leptocorisa oratorius (Fab.), (Hemiptera: Alydidae). The insecticides were applied on field plots at 0·75 kg a.i./ha at the start of the milk stage of the developing grains. Sampling was conducted at 2 hours and 1, 2, 3, 4 and 5 days after spraying, which covered the milk stage to the soft dough stage. Mortality of insects exposed to the treated grain, the residue analysis of the treated grain during development and at harvest, and the LD₅₀s of the insecticides were determined. Monocrotophos was the most effective insecticide against the rice bug; lindane provided control for only one day; carbaryl was ineffective. Maximum residue levels of lindane and carbaryl in the harvested grains were below the established tolerance limits provided by FAO/WHO. There is no established tolerance for monocrotophos in rice.     

Rumen fermentation pattern of dairy heifers fed restricted amounts of low, medium, and high concentrate diets without and with yeast culture

Restricted feeding and high concentrate diets are potential strategies for growing dairy heifers. Ruminal manipulation with additives such as Saccharomyces cerevisiae yeast culture (YC) has been shown to alter digestibility when added to this type of diet. An experiment was conducted to investigate the ruminal fermentation and in situ digestibility of diets with 3 different levels of forage to concentrate (F:C) fed at restricted intake without and with YC addition. Three cannulated post-pubertal Holstein heifers (age 18.0 ± 1.2 months; body weight 449.6 ± 19.7 kg) were fed diets consisting of corn silage as the sole forage source in a 3 period (35-day) Latin square design. Heifers were fed diets for 21 days with no YC addition, followed by 14 days where YC was added to the diet (1 g/kg as fed basis). Low (LC), medium (MC), and high (HC) concentrate diets (20, 40, and 60% concentrate) were fed once daily on a restricted basis to provide 0.22 Mcal ME/kg empty BW^0.75. Rumen fluid was sampled on days 18 and 32 of each period, and rumen contents were evacuated on days 21 and 35 of each period. An in situ study was done on days 14 to 17 and on days 28 to 31. Mean ruminal pH was not different between dietary treatments and no YC effect was detected. Mean total volatile fatty acids (VFA) and ruminal ammonia-nitrogen (NH₃-N) concentration was also not different among diets with different F:C. Molar proportions of acetate were decreased, and propionate were increased; while the acetate-to-propionate ratio was decreased as the concentrate level increased from LC to HC. Total VFA, propionate, and acetate as well as isoacids concentration increased, yet NH₃-N concentration decreased with YC addition in all diets. From these results we conclude that feeding HC diets in restricted amounts had minimal effects on rumen fermentation rate between different F:C diets. The addition of YC modified NH₃-N and volatile fatty acid concentrations in the rumen in all 3 diets in this study, presumably through alterations in end-product production and utilization.     

Processing, mixing, and particle size reduction of forages for dairy cattle

Adequate forage amounts in both physical and chemical forms are necessary for proper ruminal function in dairy cows. Under conditions in which total amounts of forage or particle size of the forage are reduced, cows spend less time ruminating and have a decreased amount of buoyant digesta in the rumen. These factors reduce saliva production and allow ruminal pH to fall, depressing activity of cellulolytic bacteria and causing a prolonged period of low ruminal pH. Insufficient particle size of the diet decreases the ruminal acetate-to-propionate ratio and reduces ruminal pH. The mean particle size of the diet, the variation in particle size, and the amount of chemical fiber (i.e., NDF or ADF) are all nutritionally important for dairy cows. Defining amounts and physical characteristics of fiber is important in balancing dairy cattle diets. Because particle size plays such an important role in digestion and animal performance, it must be an important consideration from harvest through feeding. Forages should not be reduced in particle size beyond what is necessary to achieve minimal storage losses and what can be accommodated by existing equipment. Forage and total mixed ration (TMR) particle sizes are potentially reduced in size by all phases of harvesting, storing, taking out of storage, mixing, and delivery of feed to the dairy cow. Mixing feed causes a reduction in size of all feed particles and is directly related to TMR mixing time; field studies show that the longest particles (>27 mm) may be reduced in size by 50%. Forage and TMR particle size as fed to the cows should be periodically monitored to maintain adequate nutrition for the dairy cow.     

Effects of weaning age and milk feeding frequency on dairy calf growth, health and rumen parameters

Various methods can be used to feed dairy calves that may influence calf performance and these include changing frequency of feeding or age at weaning. Two trials were conducted to determine effects of feeding frequency and weaning age on calf growth, health and rumen development, where 124 Holstein heifer and bull calves were weaned at 3, 4, 5 or 6 weeks of age. During Trial 1, milk replacer (12.5% DM; 22% CP, 15.6% fat) was fed at 10% BW twice per day until 1 week prior to weaning when intake was reduced to 5% BW. During Trial 2 calves were fed at 10% BW in two feedings until 14 days, then at 10% BW once daily until 1 week prior to weaning when milk replacer was reduced to 5% BW. Blood glucose and urea nitrogen, BW 4 h post-feeding, heart girth, hip height, and withers height 4 h post-feeding were obtained weekly. Growth and structural measurements were similar for all treatments up to 8 weeks of age in both trials. Blood constituents and health observations were not different between trials. Similar growth and performance between treatments in both trials through 8 weeks of age indicate that calf performance is not affected by weaning early and feeding once daily.