Survival of faecal streptococci in raw and pasteurised egg products

1. The ability of Streptococcus faecalis and Streptococcus faecium strains to survive in egg albumen and liquid whole egg before and after laboratory pasteurisation was studied.

2. Pasteurisation of egg albumen caused a decrease in viable cells of less than 10‐fold, while pasteurisation of whole egg caused decreases of more than 100‐fold in only two of the eight strains studied. After growth in whole egg, some strains were more resistant to pasteurisation in whole egg.

3. Strep, faecalis multiplied in raw and pasteurised whole egg but not in egg albumen.

4. Strep, faecium multiplied in raw and pasteurised whole egg only after an initial decline in viability which was not shown by cells adapted to whole egg. Together with storage temperature this affected the number of viable cells after a storage period of 5 d.

5. In raw and pasteurised egg albumen Strep, faecium strains lost viability; this was maximal at 37 °C and more cells survived as the storage temperature decreased.     

Genetic variation in feather‐pecking behaviour

1. Chicks reared from 1 d old were classified as either feather peckers or feather pecked at about 3 weeks of age.

2. Subsequent analysis of the pecking propensities of the birds showed that there was an inherited component in this behaviour.     

The choline and sulphur amino acid requirements of broiler chickens fed on semi‐purified diets

1. Growth and food conversion efficiency of broilers were reduced at low dietary choline concentrations. These effects were accentuated by low dietary total sulphur amino acids (TSAA).

2. Increased mortality, perosis and other pathological changes involving a number of tissues were observed in birds fed on a low‐choline diet.

3. Methionine replaced part of the dietary requirement for choline at low dietary choline concentrations.

4. High dietary concentrations of choline (> 1 750 mg/kg) increased the requirement for dietary TSAA.

5. Increasing the dietary choline while maintaining the TSAA at an inadequate level may decrease performance.     

The incidence of bruising in broiler flocks

1. The amount of down‐grading due to bruising in 55 flocks of broilers was investigated.

4. Bruising was classified as light or bad bruising and it is suggested that this division represents two distinct types of bruises with different causes.

3. The incidence of bruising was greater in female flocks than in male although the bruising in the former tended to be less severe.

4. The relationships between incidence of bruising and several variables associated with the flock and the environment were examined using regression analysis. The factors shown to have a significant influence on the incidence of bruising were: the age and mean weight of the flock, and the temperature and humidity on the day of processing.     

Embryo transfer: a discussion on its potential for infectious disease control based on a review of studies on infection of gametes and early embryos by various agents

Studies on laboratory animals have shown that viruses vary as to whether or not they are transmissible by the gametes or are capable of passing through the zona pellucida and infecting the embryo.

Methods of studying early embryos for the presence of infectious agents include electron microscopy, immunocytochemistry and cell cultivation.

Determination that early bovine embryos do not become infected by certain agents might allow for easing of restrictions in the current import and export regulations for cattle embryos.

Embryo transfer could be used as a means of controlling or eliminating disease in a herd or flock if the causal agent does not infect the early embryo via the gametes or by penetrating the zona pellucida.

     

Tests of soil fertility following repeated applications of MCPA, tri-allate, simazine and linuron

The following herbicides were applied annually from 1963 to experimental plots of appropriate crops grown in monoculture: MCPA 1.7 kg ha^?1, triallate 1.7 kg ha^?1, simazine 1.7 kg ha^?1 and linuron 0.84 kg ha^?1 (applied twice per year). Before the eighth treatment in 1970, nutrient status, pH and growth in greenhouse tests of a range of plants were similar in soils from treated and control plots. There were no significant differences in yield when several test crops were grown in the field plots in 1977. In a similar experiment which ran for 6 years, the same herbicides were applied twice per year at twice the above rates on each occasion (three times a year at 1.7 kg ha^?1 in the case of linuron) to uncropped plots. Three years after the last treatment, there were no differences in extractable nutrients, pH, soil structure and crop yield on treated or control plots. These results support the conclusion from the main monitoring of the experiments reported elsewhere that annual treatments with these herbicides have had no adverse affect on the soil.     

Determination of extractable and non-extractable radioactivity from prairie soils treated with carboxyl- and ring-labelled [14C]2,4-D

Ring- and carboxyl-labelled [¹⁴C]2,4-D were incubated under laboratory conditions, at the 2 g/g level, in a heavy clay, sandy loam, and clay loam at 85% of field capacity and 20 1C. The soils were extracted at regular intervals for 35 days with aqaeous acidic acetonitrile, and analysed for [¹⁴C]2,4-D and possible radioactive degradation products. Following solvent extraction, a portion of the soil residues were combusted in oxygen to determine unextracted radioactivity as [¹⁴C]carbon dioxide. The remaining soil residues were then treated with aqueous sodium hydroxide, and the radioactivity associated with the fulvic and humic soil components determined. In all soils there was a rapid decrease in the amounts of extractable radioacitivity, with only 5% of that applied being recoverable after 35 days. All recoverable radioactivity was attributable to [¹⁴C]2,4-D, and no [¹⁴C]-containing degradation products were observed. This loss of extractable radioactivity was accompanied by an increase in non-extractable radioactivity. Approximately 15% of the applied radioactivity, derived from carboxyl-labelled [¹⁴C]2,4-D, and 30% from the ring-labelled [¹⁴C]2,4-D was associated with the soil in a non-extractable form, after 35 days of incubation. After 35 days, less than 5% of the radioactivity from the carboxyl-labelled herbicide, and less than 10% of the ringlabelled material, was associated with the fulvic components derived from the three soils. Less than 5% of the applied radioactivities were identifiable with any of the humic acid components. It was considered that during the incubation [¹⁴C]2,4-D did not become bound or conjugated to soil components, and that non-extractable radioactivity associated with the three soil types resulted from incorporation of radioactive degradation products, such as [¹⁴C]carbon dioxide, into soil organic matter.     

The use of separate root and shoot tests in the screening of herbicides for strawberries

The tolerance of strawberries to herbicides was tested by applications to the roots of plants growing in sand and by foliage applications to plants grown in compost, and compared with tolerance in the field. Dimefuron was safe as a foliar application but much more toxic than simazine when applied in sand or in the field. Metamitron caused slight injury as a foliar spray; in sand and in the field it was intermediate in toxicity between simazine and lenacil. At normal rates propachlor was safe as a foliar spray and much safer than lenacil when applied in sand. High rates had no adverse effect in the field. Ethofumesate and pendimethalin caused some temporary stunting when applied to foliage, but were less toxic than lenacil when applied to roots in sand. Field applications of both herbicides at 1–1.5 kg/ha were safe. Foliage sprays of bentazone, oxadiazon and oxyfluorfen severely damaged the sprayed leaves, but these herbicides were less active than lenacil when applied to the roots. In the field they caused severe leaf damage, but by the end of the growing season the plants had recovered. The experiments demonstrated the value of separate root and shoot activity tests for indicating which herbicides merit further field testing.