Search PubMed⌕ Search

Biomedical subjects

M H Stevenson

Publications and source records attributed to M H Stevenson.

26 records · Page 2Linked to original sources
PubMed1981

An attempt to distinguish between the direct and indirect effects, in the laying domestic fowl, of added dietary copper sulphate.

1. An experiment is reported in which the effects of giving copper sulphate-supplemented diets and control unsupplemented pair-fed diets to laying hens were compared. 2. The level of food intake significantly adversely affected mean body-weight, egg number, egg weight, liver, kidney, oviduct and ovary weights. Gizzard weight/kg body-weight was significantly increased both with decreasing levels of food intake and increased CuSO4 supplementation. 3. There was evidence of a depressing effect of CuSO4 per se on egg production and possibly on oviduct and ovary weight. 4. Liver lipid concentration was significantly decreased with decreasing levels of food intake and the results also suggest a depressing effect of CuSO4. 5. The Cu concentrations and total contents in liver and kidneys were significantly increased by dietary added CuSO4. Liver and kidney Zn and Fe concentrations were increased with decreasing levels of food intake rather than by CuSO4 addition.

Animals↗
PubMed1981

A study of the effects of dietary added cupric oxide on the laying, domestic fowl and a comparison with the effects of hydrated copper sulphate.

1. An experiment is reported in which copper, as cupric oxide, was fed to two breeds of laying hen for 336 d at levels equivalent to 150, 300, 450, 600 and 750 mg added Cu/kg diet. The results obtained were compared with those found using similar diets to which the Cu was added as CuSO4.5H2O. 2. Addition of the CuO had no effect on food intake, food conversion efficiency, body-weight or egg production. The CuSO4 addition caused the quadratic response of food intake and the adverse effects on food intake, egg production and body-weight noted in previous experiments. 3. The CuO had no effect on liver, kidney, ovary, oviduct or gizzard weight per unit body-weight while the CuSO4 decreased these with the exception of gizzard weight which was significantly increased. 4. CuO addition did not affect liver Cu concentration but CuSO4 caused a substantial increase of liver Cu especially at the 750 mg Cu/kg level of addition. 5. CuO addition had no effect on liver lipid concentration but this was depressed at the highest level of CuSO4 addition. Effects on individual fatty acids are presented but no specific conclusions have been reached.

Adipose Tissue↗
PubMed1980

Effects of level of dietary copper sulphate and period of feeding on the laying, domestic fowl, with special reference to tissue mineral content.

1. A cereal-based diet containing 7.6 mg copper/kg was fed ad lib. to laying hens for up to 48 d. Four other groups were given the control diet to which was added hydrated copper sulphate to provide 250, 500, 1000 and 2000 mg added Cu/kg. 2. Hens were killed on day 0 and after 3, 6, 12, 24 and 48 d. Records were kept of body-weight, food consumption, egg production and egg weight. 3. After slaughter blood haemoglobin, packed cell volume, serum Cu and aspartate aminotransferase (AAT; EC 2.6.1.1) were measured. The liver, kidneys, a sample of breast muscle, oviduct, ovary and gizzard were weighed. Gizzard, spleen, liver and kidney tissue were examined histologically. 4. The Cu, zinc and iron concentrations of liver, kidneys and breast muscle and the manganese concentrations of liver and kidneys were determined. 5. Body-weight loss occurred at 500-2000 mg added Cu/kg diet. Egg production was depressed by level of added Cu and period of time on the Cu-containing diets. 6. Mean liver, kidney, oviduct and ovarian weights per unit body-weight were depressed by Cu in the diet and the effect increased with period of time on the diets. Mean gizzard weight per unit body-weight was increased by dietary added Cu and by time. 7. Cu concentrations in the liver were increased by dietary level of added Cu and period of time on the diet. Zn concentration in liver increased at 1000 and 2000 mg added Cu/kg diet and liver Fe concentration was increased at these levels. Histological examination of the gizzard indicated that the Cu content of the gizzard lining increased with dietary added Cu.

Animals↗
PubMed1980

Effects of withdrawal of copper sulphate from the diet of the mature domestic fowl with special reference to production and tissue mineral content.

1. Cereal-based diets containing 0, 500, 1000 or 2000 mg added copper/kg were offered ad lib. to laying hens for 8 weeks. All the hens were subsequently offered the control diet (no added Cu, 7.5 mg Cu/kg). 2. Hens from each treatment were killed at 0, 2, 4, 6 and 8 weeks after removal of the Cu-supplemented diets. Records were kept of body-weight, food consumption and egg production. 3. After slaughter, blood haemoglobin, packed cell volume, serum Cu and asparate aminotransferase (AAT; EC 2.6.1.1) were assayed. The liver, kidneys, oviduct, ovary, gizzard, caeca and bile duct were weighed. 4. Mean Cu, zinc and iron concentration of liver, kidneys and caecal contents were determined. 5. The adverse effects of Cu on body-weight, food intake, egg production and liver, oviduct, ovary, gizzard and bile weights were rapidly reversed by removal of added Cu from the diets. 6. Greatly enhanced liver Cu concentration resulted from feeding the high-Cu diets but this effect was rapidly reversed on removal of added Cu from the diets. Liver Fe concentration showed a less marked but similar effect. 7. The Cu concentration of caecal contents was increased by Cu supplementation and rapidly reduced after withdrawal of the Cu-containing diets.

Animals↗
PubMed1979

Effects of the protracted feeding of copper sulphate-supplemented diets to laying, domestic fowl on egg production and on specific tissues, with special reference to mineral content.

1. Two experiments are reported. In both experiments a cereal-based diet containing 5 mg copper/kg was fed to two breeds of laying hens for 336 d. In Expt 1 four other groups were given this diet with the addition of CuSO4.5H2O to give added levels of 200, 400, 600 and 800 mg Cu/kg diet. In Expt 2 the levels of added dietary Cu used were 100, 200, 300 and 400 mg/kg. 2. In Expt 1 records were kept of food intake, water intake, body-weight and egg production for eight 28 d periods and body-weight and egg number only were recorded for the full twelve periods. In Expt 2 full records, excluding water intake, were taken for all twelve periods. 3. Food and water intake showed a quadratic response to level of added dietary Cu, being enhanced at lower levels and depressed at higher levels of addition. 4. There was a quadratic response of total egg weight, mean egg weight and egg number to added dietary Cu. In Expt 1 egg number was maximum at 235 mg added Cu/kg diet for Warren Studler SSL (breed 1) and at 170 mg added Cu/kg diet for Shaver 288 (breed 2). In Expt 2 no breed effect occurred, the maximum egg number being calculated to occur at 176 mg added Cu/kg diet. 5. Depression of body-weight gain occurred at high levels of Cu addition. The depression of liver and oviduct weight found at high levels of addition appeared to be directly related to body-weight. A marked amount of feather loss also occurred at a high inclusion of CuSO4 in the diet. 6. The reproductive systems of the hens did not appear to be adversely affected at the levels of additive used. Gross and microscopic examination of specific tissues revealed no pathological effects although gizzard and intestinal weights were increased and caecal weight decreased by high levels of added Cu. THose aspects of the blood chemistry examined did not reveal any consistent effect between the two experiments. 7. The liver Cu analyses indicate that between 600 and 800 mg added Cu/kg diet the liver Cu concentration rises sharply. Both liver Fe and Zn concentrations showed a positive linear response to added dietary Cu. In the kidney Cu and Zn concentrations were increased but only to a limited extent, while the concentration of Fe was unaffected.

Animals↗
PubMed1978

Studies on the absorption of calcium, phosphorus, magnesium, copper and zinc by sheep fed on roughage-cereal diets.

1. Two groups of four 18-month-old ewes fitted with a rumen cannula and re-entrant cannulas in the proximal duodenum were fed on one of two diets based on varying proportions of dried-grass meal, ground straw and barley. 2. The apparent availability, retention and amount of the mineral reaching the proximal duodenum were measured for calcium, phosphorus, magnesium, copper and zinc. Significant differences were found between diets for Ca only. Net absorption of Mg occurred before the proximal duodenum and also, lower down the alimentary tract. Marked increases were observed in the amount of Cu, Zn and P reaching the proximal duodenum relative to that ingested.

Animals↗
PubMedDate not supplied

The effect of irradiation dose and storage time on the ESR signal in the cuticle of different components of the exoskeleton of Norway lobster (Nephrops norvegicus).

This paper examines the potential of ESR spectroscopy to determine if Norway lobsters have been irradiated. Ninety samples, each containing 3 whole Norway lobsters, were prepared, thirty were used as controls while the remaining sixty were given irradiation doses of approximately either 1 or 3 kGy. Following irradiation the samples were stored at 1 degree C for 0, 7, 14, 21 or 28 d. After each storage period the cuticle of the tail, carapace, claws and walking legs was removed, freeze-dried and ground prior to analysis using ESR spectroscopy. The control spectra were subtracted from their respective irradiated spectra thereby leaving the radiation-induced signal. Peak heights of the signals were measured. The ESR signals derived from the different components of the exoskeleton were similar in shape and varied only in their intensities. The claw samples gave the most intense signal while that from the walking legs was the weakest. There was a significant decay in the signal intensity over the storage period with the signal derived from cuticle of the claws showing the greatest diminution (44%) and that of the tail the least (17%). The signal intensities of the walking legs and carapace decreased by 22% and 30% respectively. In conclusion ESR spectroscopy is a useful technique for the qualitative detection of irradiated Norway lobster and shows considerable potential for quantification of dose received.

Animals↗