Mercury residues in breast muscle of wild ducks, 1970-71.

Samples of breast muscle from 327 ducks collected from October 1970 to March 1971 in the conterminous United States were analyzed for total mercury by flameless atomic absorption spectrometry. Mercury levels for the entire collection ranged from less than 0.01 to 3.91 ppm wet weight with a median of 0.10 ppm. Twenty-five ducks had levels equalling or exceeding the 0.5 ppm guideline for fish and shellfish established by the Food and Drug Administration, U.S. Department of Health, Education, and Welfare. Dabbling ducks, which are shallow-water feeders and mostly vegetarian in fall, winter, and spring, usually had lower levels than diving and sea ducks. Levels were generally higher in ducks collected in areas where environmental mercury levels were known to be greater than in ducks from nonsuspect areas. Despite the mobility of the ducks, levels seemed more closely linked to local environmental contamination than to various factors associated with large geographic areas.     

Hemagglutinating encephalomyelitis virus (HEV) infections in swine. Serologic indication for infectional occurrence in Denmark]

In 1956 a disease of nursing pigs previously unreported in Denmark, was observed in several swine herds. The disease syndrome appeared identical with that later described by Roe and Alexander in 1958 and by S. F. Cartwright and M. Lucas in 1968. Since 1956 there have been no reports of such outbreaks in Danish herds. To investigate whether the virus is still present, a survey was carried out to detect neutralizing antibodies in sera from a number of boars using a micro technique. In 144 sera from Jutland 12% had titers ranging from 10 to 32 ND-50, 22% from 32 to 90, 37% from 90 to 256, 14% from 256 to 724 and 3% above 724 ND-50 with a total of 86% positive. Of 174 sera from the rest of the country 16% had titers ranging from 10 to 32 ND-50, 18% from 32 to 90, 28% from 90 to 256, 13% from 256 to 724 and 3% exceeding 724 ND-50 with a total of 79% positive.     

Studies on pentagastrin-induced hypocalcaemia in lactating cows.

During recent years it has been evident that a number of gastrointestinal hormones are potent calcitonin secretagogues, and it has been suggested that a gastrointestinal-thyroid C cell system exists as a part of post prandial calcium homeostasis. In the present study the hypocalcaemic effect of pentagastrin, a synthetic peptide with gastrin effects, was studied in lactating cows. Intravenous infusion of pentagastrin caused marked hypocalcaemia and hypophosphataemia in the cows. Thyroidectomy completely abolished the hypocalcaemic and hypophosphataemic effects of the peptide. The results thus suggested that the effects of the peptide were due to release of endogenous calcitonin.     

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.