A comparison of the effects of two low‐calcium diets on egg production in the domestic fowl

1. Hens fed on a diet containing 0–05% calcium virtually ceased egg laying (production <4%) whereas those fed on a diet containing 0–5% Ca maintained production at between 20 and 30%.

2. After a return to a normal diet (3% Ca) egg weight, shell weight, ovarian characteristics and oviduct size were of a similar nature in the two groups, though the differences in egg weight, shell weight and shell calcium were significant at the 1 % level.

3. Bone weight and bone ash did not differ significantly between the groups but after a return to normal rations, bone weight and bone ash became higher in the group that had received the 0.05% Ca diet.

4. There were no clinical signs of bone demineralisation during the experiments.     

Rapeseed Meal and egg taint

1. Certain rapeseed meals in the diet of hens laying brown eggs result in the production, from some birds, of eggs which have a “ fishy ” or “ crabby ” odour because of the presence of trimethylamine.

2. Such susceptible birds have been used to demonstrate that the activity can be extracted from rapeseed meal with appropriate solvents.     

A study of the mechanical properties of egg shell

1. The mechanical behaviour of the egg shell of the domestic fowl was investigated by cutting strips from the shell and testing the flection either in a four‐point load test or in a cantilever beam test.

2. It was found that moisture content, temperature and load rate have important effects on shell properties ; both the strength and stiffness of the shell are greater in snapping‐inward tests than in snapping‐outward tests; residual stress exists in the egg shell; the correlation between failure moment and shell thickness was highly significant, on average about 0.9, and was dependent on the spread in the thickness data.

3. Estimates were made of the ultimate strength and Young's modulus of egg shell material and it is concluded that a substantial size effect exists in the egg shell.     

Conversion of the aldrin/dieldrin metabolite dihydrochlordene dicarboxylic acid-14C in rats

Upon intravenous application of dihydrochlordene dicarboxylic acid-¹⁴C to rats, the radioactivity is quickly excreted, and 44% of the excreted radioactivity consists of metabolites. Nine metabolites have been isolated from feces and urine extracts. Three metabolites could be identified by means of authentic samples by thin layer chromatography, gas chromatography, and mass spectrometry: two isomers of dechlorodihydrochlordene-dicarboxylic acid (metabolites I and II, total 22.5%) and dihydrochlordene-dicarboxylic acid-dimethyl-ester (metabolite III, 11.3%).     

Microsomal oxidase activities in relation to age and chlorcyclizine induction in American cockroach,Periplaneta americana,fat body,midgut and hindgut

Female adult American cockroaches, Periplaneta americana L., showed definite age-dependent changes in levels of activity of the microsomal mixed-function oxidases. Cytochrome P-450 levels, EPN-detoxication, and p-nitroanisole O-demethylation activities were very low in young adult insects but increased steadily reaching a natural peak at about 100 days in fat body and at about 90 days in midgut and hindgut. The activities then declined rapidly reaching levels of young insects at about 130 to 140 days of age. NADPH-neotetrazolium-reductase activity was high in young insects, declined later in adult life, and returned to a peak at about 100 days.Injections of chlorcyclizine, a known microsomal enzyme inducer, significantly increased levels of cytochrome P-450, EPN-detoxication, p-nitroanisole O-demethylation, and NADPH-NT-reductase activities in young cockroaches. The drug injections were effective, however, only before the natural activity peak was reached. Beyond this point the injections had no inductive effect indicating that the microsomal oxidases in this insect are uninducible when normal enzyme levels are falling.NADPH-NT-reductase activity in male cockroaches, while being somewhat higher than in females, showed a similar age-dependent curve with the peak occurring at about 120 days.Age-dependent carbaryl resistance in male and female insects tended to follow levels of the microsomal oxidase activities. Fifty to 60-day-old insects, however, tended to be more resistant to the insecticide than microsomal enzyme levels would indicate.RNA levels of normal female insects showed age-dependent curves similar to those of the microsomal enzyme activities, being low in young adults and reaching a peak at about 100 days. Chlorcyclizine injections had little or no effect on total microsomal RNA levels.     

Behavior of 14C oryzalin in soil and plants

Radiochemical studies of field soil treated with ¹⁴C oryzalin (3,5-dinitro-N⁴,N⁴-dipropylsulfanilamide) indicated that the compound was readily degradable. One year after soil treatment with oryzalin, 45% of the original radioactivity had dissipated, 25% was extractable, and 30% was “soil bound”. The extractable fraction contained oryzalin and several degradation products, some of which were isolated and identified. No single degradation product accounted for more than 3% of the applied oryzalin. The “soil-bound” radioactivity was extractable with hot alkali. No significant radioactive residues were detectable in either seed or forage of soybean and wheat plants. No specific metabolites of oryzalin were identified in soybean plants. Trace amounts of radioactivity found in plant tissue appeared to be associated with the various plant constituents.