Biomedical subjects
C R Douglas
Publications and source records attributed to C R Douglas.
An evaluation of a stepdown amino-acid feeding program for commercial pullets to 20 weeks of age.
Two experiments were conducted to study the use of a feeding program based on dietary amino-acid levels for commercial egg-production replacement pullets from 8 to 20 wk of age. HyLine W-36 pullets were used in Experiment 1; and HiSex White pullets were used in Experiment 2. All pullets were fed a starter diet calculated to contain 21% CP for the first 8 wk of age. From 8 to 20 wk of age, they were fed 10 series of diets calculated to provide various levels of TSAA, lysine (Lys), tryptophan (Trp), and arginine (Arg) at various ages. The levels of each of these amino acids were lowered every 2 weeks. The following levels of amino acids, based on calculated values suggested for corn and soybean meal, were found to be adequate from 8 to 20 wk, with linear reductions at biweekly intervals: .54 to .42% TSAA (.28 to .21% methionine), .64 to .48% lysine, .18 to .14% tryptophan, and .96 to .78% arginine.
Performance of Leghorn type hens fed two levels of energy and a synthetic estrogen during the growing period.
Feeding of an estrogen, dienestrol diacetate, at 352 mg/kg of diet to December-hatched White Leghorn type pullets, from 16 to 20 wk of age, caused onset of production to be delayed approximately 3 wk. The dietary dienestrol diacetate also resulted in increased body weights at 30 and 46 wk in one experiment. Hens receiving the estrogen laid significantly (P less than .05) heavier but fewer eggs during most of the production year than did those fed diets without the estrogenic compound. The addition of 2.2% fat to diets of pullets from 0 to 20 wk of age failed to influence their performance in the layer house.
Increased susceptibility of mice to MHV 3 infection induced by hypercholesterolemic diet: impairment of Kupffer cell function.
Nutritionally induced hypercholesterolemia in A/J mice causes susceptibility to Mouse Hepatitis type 3 (MHV 3), whereas normal A/J mice are fully resistant. A/J mice fed with a hypercholesterolemic diet for 15 to 60 days develop 5 to 7 days after MHV 3 infection an acute hepatitis which led to high levels of mortality. A direct relationship was found between the high levels of plasma and hepatic cholesterol and the mortality. In attempting to define the dietary-induced physiological changes which led to the loss of resistance, the Kupffer cells were shown to exhibit an impairment of functions in their ability to become activated by LPS in order to take up C3-coated IgM opsonized sheep red blood cells, C3(IgM)SRBC, or 3H-thymidine Escherichia coli, and the susceptibility to interferon (IFN) for the induction of an antiviral state. Peritoneal macrophages which were studied in comparison with the Kupffer cells showed no impaired functions. The findings presented here indicate an inhibition of host resistance, by nutritional hypercholesterolemia, of A/J mice to MHV 3 infection and that, at least one site of impairment occurs specifically at the stage of Kupffer cells function.
Effect of mast cell stimulators or inhibitors on plasma lipids and aortic content of lipids, hexosamine and hydroxyproline in rats.
Twenty-one-day-old rats were treated with mast cell stimulators or inhibitors. Mast cell inhibition produced decrease of total cholesterol in plasma and aorta, while the stimulation led to an increase. Both stimulation and inhibition produced increased levels of plasma and aorta triglycerides, and decrease of aorta content of hexosamine, hydroxyproline and total protein; these same effects could be due to different release of specific mast cell mediators.
Effects of mast cell inhibition on plasma and aortic content of lipids, hexosamine, and hydroxyproline in rats. Role of thyroid gland.
Twenty-one-day-old rats were treated with mast cell inhibitors for four weeks. Some of the rats were thyroidectomized in the beginning of the experiment. Mast cell impairment decreased plasma cholesterol and increased plasma triglyceride levels; in aorta, there was a decrease in total protein, hexosamine and hydroxyproline levels, while triglyceride concentration increased and total cholesterol did not change. In thyroidectomized rats, mast cell impairment led to decreased plasma cholesterol and aortic triglyceride content, increased aortic hexosamine and hydroxyproline levels and did not change plasma triglycerides, aortic total cholesterol and total protein content. It was concluded that some effects of mast cell inhibition on arterial wall metabolism are mediated through the thyroid gland.
Biochemical observations on rat aorta: interaction of dietary protein and cholesterol.
1. The effect of cholesterol feeding during and after a period of protein malnutrition lasting 4 weeks was examined in the rat. Indices measured were plasma total cholesterol, triglycerides and protein levels, and aorta total cholesterol, triglycerides, hexosamine and hydroxyproline concentrations. 2. In both plasma and aorta, total cholesterol and triglycerides levels were higher in the low-protein diet group than in the standard-protein diet group, when cholesterol was supplied in both diets. 3. During the malnutrition period, cholesterol feeding led to a greater decrease in plasma protein than that promoted by the low-protein diet without cholesterol, while aorta hexosamine levels decreased to a lesser extent. 4. Cholesterol feeding with a standard-protein diet promoted a slight and temporary increase in aorta hydroxyproline levels, while a decrease in aorta hexosamine concentration was observed. Cholesterol feeding with the low-protein diet, on the other hand, also promoted a decrease in aorta hexosamine levels but to a lesser extent. 5. During the recovery period, cholesterol feeding impaired the return of plasma protein, aorta hexosamine and lipid levels to that of the control values. 6. These findings demonstrate that cholesterol feeding promotes different changes in aorta and plasma, depending on whether or not protein is supplied by the diet in adequate amounts. This point could be important in relation to the development of atherosclerosis during recovery from a period of malnutrition.
Phosphorus requirement of commercial Leghorn pullets from 8 to 20 weeks.
Hisex White pullets, hatched in November, were used to study the influence of the amount of dietary phosphorus in practical grower diets during the 8 to 20-week growing period. Measurement were made on 20-week body weight, bone ash, and layer house performance. All chicks were fed a 21% protein starter diet through 8 weeks at which time they were randomized into eight treatment groups. Grower diets were changed at 8, 12, and 16 weeks at which time different dietary phosphorus percents were used. Percents of total phosphorus used were .60, .55, .50, .45, and .32 for 8 to 12 weeks and .31 for 13 to 20 weeks. Lowering the phosphorus to .32% at 8 weeks or .31% at 12 weeks significantly reduced 20-week body weight. Lowering total phosphorus to .31% at 16 weeks did not significantly affect 20-week body weight. Bone ash measured at 20 weeks was not significantly affected by feeding less phosphorus. Laying house mortality, egg production, egg weight, and egg specific gravity were not influenced by lowering phosphorus in grower diets.
A step-down protein program for commercial pullets.
Three experiments were conducted to evaluate the protein requirement of commercial egg production pullets from 8 to 20 weeks of age. Hyline W-36 pullets were used in Experiments 1 and 3, and Hisex White pullets were used in Experiment 2. They were fed a 20% protein diet for the first 8 weeks. In Experiment 1, a diet containing 14% protein did not result in body weight at 16 weeks equal to that obtained from feeding a diet containing 17% protein. In Experiments 2 and 3, body weights of pullets fed a diet containing 17% protein from 8 to 10 weeks followed by 1% protein reduction biweekly thereafter (12% from 18 to 20 weeks) was equal to that obtained by feeding 18% for the entire period. Performance in the laying house for four 28-day periods was equal for the two treatment groups. Feeding diets with suboptimal protein from 8 to either 12 or 14 weeks of age resulted in reduced body weight. However, when 14% protein was fed for the remainder of the growing period, body weight was restored.
Biochemical observations on rat aortas: effect of protein refeeding after a protein depletion period.
Young male rats were fed standard (normal protein content) or low-protein diets for 4 weeks. Protein-deficient rats were refed the standard diet for an other 1, 2 or 4 weeks. Total cholesterol, triglycerides, phospholipids, total protein and hydroxyproline levels decreased in both aorta and plasma of rats receiving the low-protein diet. After the animals were refed the standard diet for 1 or 2 weeks, the lipid content of the arterial wall and plasma increased above basal values, returning to control values after the 4th week of standard-diet administration. Total protein levels increased slightly in plasma and arterial walls, reaching control values by the 4th week. The decreased hydroxyproline content in the arterial walls remained low after rats were refed the standard diet for 4 weeks.
Influence of mast cells on thyroid function.
The role of mast cells on thyroid gland function was studied with respect to two sites of thyroid control: 1. the thyroid gland; 2. the hypothalamus pituitary system. It was observed that the treatment with disodium cromoglycate (mast cells stabilizer) partially blocked the TSH actions on thyroid gland, thus evidencing the thyroidal mast cells as an intermediary factor of TSH actions on thyroid gland. Furthermore, both T4 and T3 serum concentrations were increased after compound BW48-80 (mast cells disrupter polymer) was administered, concomitantly with increased 1 and 24 h radioiodine uptake, T/S ratio, PB131I and TSH serum concentration. The alterations were not observed in the rats pre-treated with disodium cromoglycate and administered with BW48-80. Finally, BW48-80 promoted an elevation of TSH serum concentration in T4-primed thyroidectomized rats. This phenomenon was completely prevented by the pretreatment with cromoglycate, which confirmed the active participation of mast cells on TRH and/or TSH secretion.
The influence of low protein grower diets on spring housed pullets.
Two experiments were conducted using Leghorn-type pullets, hatched in November and December, to study the influence of level of protein (9, 14, and 21%) fed from 8 to 20 weeks of age on performance in the laying house. Feeding the diet containing 9% protein resulted in decreased body weight at 20 weeks of age compared to weight of those birds fed the two higher protein levels. The lighter body weight persisted throughout the laying period. Throughout the laying period the birds of lighter weight laid less eggs of lower weight.
The effect of low protein pullet growing diets on performance of laying hens housed in the fall.
A total of 6000 layer-type pullet chicks were fed either a low protein (9.1%) or a high protein (15.4%) diet from 8 through 18 weeks of the growing period in two experiments. All chicks were fed a commercial starter for the first 8 weeks and the high protein diet from 18 to 21 weeks of age. All chicks were grown in floor pens and were supplied feed and water ad libitum throughout the growing trial. They were placed in either a cage- or floor-laying house and fed a commercial layer diet for 12 periods of 28 days each. The experiment was repeated in the subsequent year. The low protein regimen was found to produce a smaller pullet, delay sexual maturity, delay production peaks, and maintain higher levels of production near the end of the laying period. Pullets fed the low protein grower diet had higher mortality during the growing period, greater feed intake during the laying period, eggs with higher Haugh unit values, and reduced egg production in the laying house.
Possible mechanism of action of cholesterol enriched diet on the thyroid.
Groups of male Sprague Dawley rats aged 60 days were fed either a control diet (CD) or the same diet enriched with 1% cholesterol (CHD) for 30 days. In CHD fed animals an increase of 131I uptake by thyroid, PB131I and TSH level in plasma was found, while the level of thyroxine (T4) was unchanged and that of triiodothyronine (T3) was decreased. In the animals treated with T3 (20 micrograms i.p. daily) a decrease of 131I uptake by thyroid and of T4 and TSH level in plasma was found irrespectively of a cholesterol content in the diet. However, PB131I level was decreased in CHD fed and T3 treated animals compared to those fed CD under the same treatment. Finally, in the animals treated with cimetidine (10 mg i.p. daily) no changes of any measure was found after CD feeding as compared to untreated ones, while CHD in such animals resulted in a decreased of T3 level. The site of cholesterol action appears to be at the hypothalamus-pituitary system since TSH suppressed animals (i.e. T3 treated) did not show any thyroid stimulation when fed with a cholesterol excess. Furthermore, thyroidectomized animals showed increased TSH in plasma after cholesterol feeding. In the present study, chronic administration of cimetidine completely abolished thyroid gland stimulation promoted by cholesterol feeding thus suggesting that central histamine may play a considerable role in this process.
Feed consumption and protein efficiency by Bobwhite quail in response to dietary energy levels.
Two experiments were conducted to determine if Bobwhite quail chicks would adjust feed consumption according to energy intake from hatching to five weeks of age. Three starter diets, which were calculated to contain 2850, 3010 and 3170 Kcal. M.E./Kg., were fed throughout the five-week experiments. As energy was increased, the protein level was increased proportionally. Each treatment group consisted of four replicate pens containing 125 chicks each. Body weight at two and five weeks of age was not affected by treatment, except for a reduction at two weeks for birds on the 3170 Kcal./Kg. diet. There were no significant treatment effects on mortality. The feed consumed/bird/day decreased as dietary energy was increased. The calculated energy consumption/bird/day was 15.44, 15.31 and 14.79 Kcal., respectively, for the 2850, 3010 and 3170 Kcal. M.E./Kg diets during the five-week period. The energy and protein consumption per gram of body weight was slightly reduced at the high energy level indicating a more efficient use of energy and protein of the high energy diet. These data indicate that the Bobwhite quail adjusts feed intake according to the energy content of the diet.
Response of laying hens to a low salt diet.
Two experiments were conducted with commercial Leghorn-type hens in advance state of production (16 months of age) to determine response to a 16% protein, corn-soy diet with no added salt. There was an immediate and significant decline in feed consumption. Body weight decreased significantly. After 14 days, there were no ova in the rapidly maturing stage. The ovary may have been reduced in size but apparently was not regressed. Egg specific gravity was significantly reduced but egg weight was unaffected. Egg production dropped to 0% in 17-21 days. On the return of 0.25% salt to the diet, recovery as measured by production rate was initiated immediately with production reaching 79% in 16 days compared to a pre-experimental production of 68%.
[The importance of prostaglandins in modern medicine].
Explore the source record for details and available documents.