Reproductive efficiency of heifers in the new guinea highlands

Summary Bos indicus × Bos taurus heifers were exposed to bulls at four different liveweights. The age and weight at first and second conception and first calf growth rates were studied to examine the effects of uncontrolled mating prior to or at a target mating weight of 295 kg. Initial conception rate was not affected although lighter conception weights were recorded for three groups of heifers that were served when below the target weight. However, at subsequent calving only the two heavier groups calved within the 36-month trial period. The results indicated a seasonal effect on conception, 94% of the heifers conceiving during the wet season. The effect of season also influenced post-partum body weight loss, calf growth rate to weaning and subsequent conception. It is therefore an advantage to have heifers conceiving during the latter part of the wet season so that they calve early in the following wet season, provided a minimum target weight of 285 kg is reached prior to initial conception.

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Eficiencia Reproductiva De Terneras En La Sierra De Nueva Guinea

Resumen Se cruzaron ternerasBos indicus ×Bos taurus de diferentes pesos con toros reproductores. Se estudiáron así los pesos y edades a la primera y segunda parición y las tasas de crecimiento de los recién nacidos, para medir los efectos de cruzamientos incontrolados versus controlados al alcanzar las hembras un peso de 295 kg. La tasa de concepción inicial no se afectó, aunque los recién nacidos de los grupos de hembras servidas cuando tenían pesos inferiores a 295 kg, pesaron menos. Sinembargo en pariciones sucesivas, solamente las hembras servidas con pesos de 295 kg, parieron en el lapso de 36 meses que duró el experimento. Los resultados indicaron también, que la estación del año afectó las pariciones, el 94% de las hembras concibieron durante la época lluviosa. La época del año también afectó el peso posparto de los recién nacidos, la tasa de crecimiento hasta el destete y las concepciones posteriores. Es por lo tanto ventajoso cruzar las hembras durante el final de la estación lluviosa para que paran en la siguiente estación lluviosa, procurando que éstas alcancen un peso mínimo de 285 kg, antes del apareamiento.

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Efficacite Reproductrice Des Genisses Des Hautes Terres De Nouvelle Guinee

Résumé Des génisses métissesBos indicus ×Bos taurus ont été mises en présence de taureaux à 4 poids vifs différents. L'age et le poids à la première et la seconde conception ainsi que les taux de croissance du premier veau ont été étudiés pour déterminer les effets l'accouplement incontrôlé avant ou à un poids cible d'accouplement de 295 kg. Le taux initial de conception n'a pas été affecté bien que des poids plus faibles à la conception aient été observés chez trois groupes de génisses qui étaient en dessous du poids cible au moment de la saillie. Cependant, lors du vêlàge suivant, seuls les deux groupes les plus lourds ont mis bas pendant la période d'observation de 36 mois. Les résultats montrent que la saison a une influence sur la conception. 94 p. 100 des génisses conçoivent pendant la saison des pluies. La saison a aussi influencé la perte de poids après la mise-bas, le taux de croissance des veaux jusqu'au sevrage et la conception suivante. Il est donc avantageux de faire féconder les génisses pendant la seconde moitié de la saison des pluies afin qu'elles mettent bas au début de la saison des pluies suivante pourvu qu'un poids cible minimum de 285 kg soit atteint avant la fécondation.

     

Further characterization of dandelion yellow mosaic virus from lettuce and dandelion

A damaging virus isolated in the Netherlands from lettuce was studied and compared with a virus isolated from dandelion orginating from Czechoslovakia. It was found to biologically resemble dandelion yellow mosaic virus incompletely described from dandelion and lettuce in Great Britain (Kassanis, 1944, 1947) and from dandelion in Germany (Hein, 1963). Mechanical transmission was greatly improved by buffer solution and transmission byMyzus persicae seemed to be in the non-persistent manner. Longevity in vitro of the virus hardly exceeded one day. Thermal inactivation was between 60 and 65 °C and the dilution end-point was between 10 000 and 100 000. It was still infectious in leaf material dried and stored over CaCl₂ at 4 °C for 6 1/2 years. The virus was isolated and purified with difficulty and was found to consist of one type of spherical particle of ca 30 nm diameter, with a sedimentation coefficient of 159 S, a buoyant density of 1.42 g.cm^?3 and an A₂₆₀/A₂₈₀ ratio of 1.67. An antiserum was prepared with a titre of 256 in the agar double-diffusion test. The virus could be identified in crude extracts from lettuce andChenopodium amaranticolor by enzyme-linked immunosorbent assay (ELISA), but not by agar double diffusion. It could only be visualized in crude sap in the electron microscope after trapping of virus particles on antiserum-coated grids. The virus cannot yet be assigned to any known virus group. It is of potential economic importance to lettuce because of its occurrence in widely differing regions in Europe, its aggressiveness and virulence on 22 out of 23 lettuce cultivars tested (and on endive) and its pathogenicity toLactuca genotypes which are resistant to lettuce mosaic virus and other important pathogens of lettuce. ‘Laibacher Eis’ was the only cultivar showing some tolerance.     

Synthetic pyrethroids and avermectin for controlling the grapevine pestsLobesia botrana,Cryptoblabes gnidiella andDrosophila melanogaster

Field treatments in a vineyard with 0.015 or 0.01% a.i. of cypermethrin, fenvalerate, fenpropathrin or AC-222,705 were more efficient in controlling the grape-berry moth (Lobesia botrana Schiff.) and the honeydew moth (Cryptoblabes gnidiella Mill.) than four standard treatments consisting of two with 0.05% a.i. fenitrothion and two with 0.075% a.i. diazinon. In pyrethroid-treated plots, infestation at the end of the trials ranged between 2.5 and 12%, compared with 21% in the standard treatment plots and 34% in the untreated plots. Cypermethrin, fenpropathrin and AC-222,705 exhibited similar field activity, while that of fenvalerate was somewhat lower. Under laboratory conditions, cypermethrin at 0.005 and 0.01% a.i. was significantly more potent than fenvalerate, fenpropathrin and AC-222,705; at a higher concentration, 0.015% a.i., all pyrethroids were highly active, with mortality ranging between 75 and 95%. Under laboratory conditions the vinegar fly (Drosophila melanogaster Meig.) was in general more susceptible to pyrethroids than was the grape-berry moth. Cypermethrin and AC-222,705 at 0.005% a.i. and avermectin at 0.0035% a.i. were potent compounds against the vinegar fly and more active than fenvalerate and fenpropathrin.     

Biochemical properties of the pathogenesis-related proteins from tobacco

This review describes the discovery and identification of the pathogenesis-related proteins (PRs) from tobacco. In crude leaf extracts the PRs are distinguished from the proteins in uninfected plants by their solubility at pH 3, resistance to a range of proteases, and mobility in polyacrylamide gels upon electrophoresis (PAGE) in non-denaturing conditions. PAGE has been used as a qualitative and semi-quantitative assay for PRs, and their migration in gels made from different acrylamide concentrations has been used to identify charge and size isomers and electrophoretically identical PRs in different tobacco cultivars. The subunit composition and molecular weight (mol. wt) of the four PRs identified first in Xanthi-nc were determined by SDS-PAGE; staining the gels has shown that these same four proteins in Samsun NN did not contain carbohydrate, lipid or nucleic acid, nor were they isozymic forms of twenty five enzymes known to increase in activity following infection with TMV. Evidence suggests that most of the PRs in Xanthi-nc and Samsun NN are extracellular.The purification of several PRs from Xanthi-nc, Samsun NN and other tobaccos is described, as well as their mol. wt, subunit and amino acid composition. PRs 1a, b and c consist of a single polypeptide and have similar mol. wt and amino acid compositions. Antisera prepared against purified Xanthi-nc b₁ protein have been used to determine serological relationships between PRs and form the basis of a very sensitive quantitative assay using ELISA. The regulation of synthesis of some PRs has been shown to involve translational control.     

FACTORS AFFECTING THE LOSS OF TRI-ALLATE FROM SOILS

Summary. Electron-capture gas chromatography was used to detect tri-allate residues in persistence studies with two soils. At rates equivalent to 0–75, 15 and 3 Ib/ac, 50% of the amount applied was degraded in 8–11 weeks at 25°C in moist Regina heavy clay and Weyburn loam. No loss occurred in sterile soils, indicating that microbial degradation may be a, major factor contributing to tri-allate breakdown.
When aqueous solutions buffered at pH 4–8 were held at 25° G, only 10–15% of the tri-allate was chemically degraded during 24 weeks.
At the normal field rate of 1·25 Ib/ac, tri-allate was not readily leached. From soil columns of Weyburn loam, 5–7% was eluted by 9 in. of water; with clay the corresponding value was 12–13% of the amount applied. When field plots were sprayed with 125 lb/ac in April, tri-allate could still be detected until the soil froze in November.
Facteurs agissant sur la perte de tri-allate dans les sots     

TRANSLOCATION OF AMINOTRIAZOLE AND DALAPON IN AG ROPY RON REPENS (L.) BEAUV.

Summary. Tracer studies using single drops of solutions containing 3–amino-1,2,4–triazole-5–¹⁴C (aminotriazole-¹⁴C) or 2,2–dichloropropionic acid-2–¹⁴C (datapon-¹⁴C) revealed that in couch plants (Agropyron repens (L.) Beauv.) growing under field conditions in the autumn and at the stage where the aerial shoots were 40–50 cm long, both compounds moved in both symplast and apoplast. Dalapon was less mobile in the symplast than aminotriazole and only negligible amounts of dalapon were translocated to the rhizomes. The nodes of the treated shoots appeared to act as barriers to translocation, a phenomenon more pronounced for dalapon than for aminotriazole.
Application to a basal green leaf led to a more uniform distribution of the compounds within plants and rhizomes than when the application was made to the youngest fully-expanded leaf.
In couch plants with aerial shoots 10–15 cm long treated in the stubble, the distribution of both aminotriazole and dalapon was mainly restricted to the treated shoots. Even 15 days after application only trace amounts of radioactivity could be found in the rhizomes and untreated shoots.     

EFFECT OF PYRAZON ON PHOTOSYNTHESIS OF VARIOUS PLANT SPECIES

Summary. Studies were conducted to determine the influence of pyrazon (5-amino-4-chloio-2-phenyl-3(2H)-pyridazinone) on photosynthesis. A strong inhibiting effect on O₂ evolution from leaf discs of several species was recorded. For most species a concentration of 5 × 10⁻⁵ M caused a reduction of about 50% in the rate of photosynthesis. Photosynthesis of sugar beet, highly resbtant to pyrazon, was reduced to 50% by a concentration of 7–5 × 10⁻⁵ M. Since these differences cannot account for the great divergence in susceptibility to pyrazon, it is suggested that the selectivity of this herbicide results from degradation and differential accumulation in the foliage.
Pyrazon was phytotoxic to plants of tomato and pigweed (Amaranthus retrofiexus L.) kept in the light but not when kept in the dark, after foliage application. The conclusion that pyrazon inhibits the mechanism of photosynthesis and causes starvation for carbohydrates, was strengthened by the fact that external feeding of glucose overcame the toxicity of the compound in tomato plants. These results and a possible mode of selectivity are discussed.