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Biomedical subjects

J M Forbes

Publications and source records attributed to J M Forbes.

At least 55 records · Page 3Linked to original sources
PubMed1995

Selection of foods by broiler chickens following corticosterone administration.

1. The effects of corticosterone (CORT) on diet selection of broiler chickens offered a choice of a high protein concentrate (381 g CP/kg, 17.5 MJ/kg ME) and whole wheat (113 g CP/kg, 15.9 MJ/kg ME) in relation to age were examined in two experiments. 2. Daily intramuscular injections of 2 and 4 mg/kg of CORT for a 5-d period in both 2- and 5-week-old chickens resulted in increases in total food, protein and energy intakes. This led to a decrease in protein accretion in older but not younger chicks, an increase in total lipid contents of the carcase at both ages, and produced changes in internal organs. 3. CORT significantly reduced body weight gain of young but not old chickens, suggesting that mature birds respond better than young ones to the physiological changes caused by treatment, by making subsequent appropriate food choices. 4. Administration of CORT in young chicks increased wheat intake at 2 and 4 h after injection, while in older birds a similar increase was maintained up to 24 h after injection. Intake of HP food was decreased by both doses of CORT in young chicks but there was no significant effect in older chickens. 5. Changes in energy: protein ratio in the chosen diet appeared at 4 h after treatment in old chickens and at 24 h in younger chicks. 6. The results suggest that birds are able to detect metabolic changes caused by CORT administration and attempt to redress them by modifying their food pattern. The time course of the response of birds to these changes is age related. However, the food selection pattern did not completely compensate for the physiological defects.

Aging↗
PubMed1994

Exogenous cholecystokinin octapeptide in broiler chickens: satiety, conditioned colour aversion, and vagal mediation.

Intraperitoneal injections of 3.5, 7.0, 14.0, and 28.0 micrograms/kg of CCK-8 into free-feeding broiler chickens significantly reduced food intake and delayed feeding (p < 0.05). To determine whether CCK can condition preference or aversion and to investigate the latency and the reversal of the effect, a low (2 micrograms/kg) and a high (14 micrograms/kg) dose of CCK-8 were administered using the coloured food paradigm. One colour, the conditioning stimulus (CS+), was paired with injections of CCK-8; the other colour was paired with injections of saline (CS-). The 2 micrograms/kg dose of CCK-8 neither reduced food intake nor conditioned a colour aversion. The 14 micrograms/kg dose significantly reduced food intake and conditioned a colour aversion (p < 0.05). When vagotomy was performed, the 14 micrograms/kg dose of CCK suppressed feeding in sham-operated birds (p < 0.05) but not in vagotomized birds (p > 0.05). A significant aversion for the food paired with CCK was obtained in sham-operated birds (p < 0.001) but not in vagotomized birds (p > 0.05). It was concluded that IP injections of CCK-8 reduce food intake in broiler chickens and that chicks can learn to associate the colour of the food with injections of CCK, developing an aversion. It was also shown that the vagus nerve mediates the CCK satiety effects and that aversion conditioning to CCK is dependent upon intact vagal innervation of the viscera.

Age Factors↗
PubMed1994

Effects of the CCK receptor antagonist MK-329 on food intake in broiler chickens.

The cholecystokinin (CCK) receptor antagonist MK-329 (previously L-364,718) was administered intraperitoneally to free-feeding broiler chickens and tested for conditioning effects using the colored food paradigm. The 8.0, 16.0, and 32.0 micrograms/kg doses of MK-329 did not exert any effect on food intake and failed to condition a color preference or aversion. When higher doses were used (90, 180, and 360 micrograms/kg) MK-329 caused a significant increase in food intake during the 2-h test period. Intravenously injected MK-329 (70, 140, and 280 micrograms/kg) produced an increase in food intake, with maximum increases occurring at a dose of 70 micrograms/kg. CCK (14 micrograms/kg) caused a reduction in feeding, and this effect was not blocked by pretreatment with intraperitoneal injection of MK-329 (32, 90, 180, and 360 micrograms/kg). The results question the role of endogenous CCK in satiety in chickens.

Animals↗
PubMed1994

Blood collections by community blood centers, 1988 through 1992.

BACKGROUND: The provision of a safe and sufficient supply of blood is critical to patient care. STUDY DESIGN AND METHODS: A survey was conducted of the blood collection activity of the 189 community blood centers operating in the United States from 1988 through 1992. Data were analyzed by source of the donation (allogeneic or autologous), by center's collection volume, and by geographic region. Total collection figures were compared to historical blood collection activity since 1970. RESULTS: A total of 12.31 million units of blood were collected in 1992, an increase of 2.6 percent over the total number of units collected in 1988. For the 5-year period (1988-1992), total collections increased at a compound annual growth rate of 0.6 percent. The collection of allogeneic blood units declined by 0.2 percent annually, while that of autologous units increased by 23.2 percent annually. Autologous blood units accounted for 5.7 percent of total collections in 1992. Nationally, 48 units were collected per 1000 people in 1992, although substantial geographic variation (range, 38-64 units/1000) was observed across nine US census regions. CONCLUSION: The data from this study provide evidence that the total supply of blood grew more slowly from 1988 through 1992 than in the years before 1988.

Blood Banks↗
PubMed1993

Self-selection of ascorbic acid in coloured foods by heat-stressed broiler chicks.

Female broiler chicks were given red and green supplemented (200 mg ascorbic acid (AA)/kg) and unsupplemented foods on alternate days for 8 days under heat-stressed and unstressed conditions. After this training period, the birds were given access to both foods, and the intake of each was monitored. In both heated treatments the intake of the supplemented food was significantly higher (p < 0.05) than of the unsupplemented food (800 vs. 518 g/14 days), although in the unheated groups significantly more of the unsupplemented food was eaten (756 vs. 639 g/14 days). Birds were unable to select for AA when neither food was coloured, even when they were presented continuously in the same positions in the cage. It is concluded that chicks can learn to associate the colour of the food with its AA content and that they select proportions of supplemented and unsupplemented foods appropriate for their needs, as influenced by environmental temperature.

Age Factors↗
PubMed1993

Responses in the voluntary intake of hay or silage by lactating cows to intraruminal infusions of sodium acetate or sodium propionate, the tonicity of rumen fluid or rumen distension.

Rumen-fistulated lactating cows were individually fed on hay or silage and intakes were monitored during 3 h treatment periods and for 2 h after. Each experiment used five, six or seven animals and the treatments were applied in a Latin Square design. Sodium acetate infusions of 1.8-11.0 mol in 4.5 litres water caused a dose-related depression in hay intake, the extent being 82 g dry matter (DM)/mol infused (P < 0.01). Sodium acetate infusions of 6.0-15.0 mol in 4.5 litres water caused a dose-related depression in silage intake of 118 g DM/mol infused. Rumen fluid pH for both diets was unaffected by treatment. Acetate and Na concentrations were increased and significantly negatively correlated with intake of both diets. Infusions of 2-8 mol sodium propionate caused a dose-related depression of hay intake which was significant when cow and day effects were accounted for. Sodium propionate infusions of 4-8 mol significantly depressed silage intake by 140 g DM/mol infused (P < 0.001). Rumen fluid pH was unaffected by treatment while propionate and Na concentrations were elevated and significantly negatively correlated with intake for both diets. Inflation of a rubber balloon in the rumen with 12.5-20 litres warm water resulted in a dose-dependent depression in hay intake of 66 g DM/l distension (P < 0.05). There was significant overeating during the 2 h following the 20 litre treatment. With silage, 15-25 litres of balloon distension for 3 h resulted in a dose-dependent depression in intake of 28 g DM/l distension (P < 0.001). There was no significant overeating during the 2 h following distension. When given in physiological amounts, at the lower end of the range used in these experiments, acetate, propionate and distension of the rumen did not significantly affect hay intakes. However, in each case the linear relationship between intake depression and level of treatment suggested that these factors could contribute to the control of feed intake.

Acetates↗
PubMed1993

The voluntary intake of hay and silage by lactating cows in response to ruminal infusion of acetate or propionate, or both, with or without distension of the rumen by a balloon.

In order to test the hypothesis that negative feedback signals from abdominal receptors are integrated in an additive manner in the control of voluntary food intake, cows with rumen fistulas were given intraruminal infusions of sodium acetate or sodium propionate, or both, with or without distension of the rumen by balloon. Intakes were monitored during the 3 h experimental period and for 2 h after and samples of rumen fluid were taken for estimation of short-chain fatty acid concentrations and osmolality. Six cows in mid-lactation were fed on hay and concentrates and given, into the rumen, 5.5 mol sodium acetate, 5.2 mol sodium propionate and 7.5 l of distension. Compared with the control (water infusion), neither acetate, propionate nor distension significantly depressed hay intake when given separately. When given in combination, however, the following significantly depressed intake during the 3 h treatment period: propionate + distension, acetate + distension, acetate + propionate + distension. Seven cows in early lactation were fed on silage and concentrates and given, into the rumen, 9.0 mol sodium acetate, 4.0 mol sodium propionate and 10.0 litres of distension. Again, none of the three given alone depressed silage intake to a significant extent during the 3 h treatment period, whereas the following combinations had a significant effect: propionate + distension, acetate + distension, acetate + propionate + distension. Basal rumen osmolalities were similar for the two types of feed but infusion of the sodium salts caused a very much greater increase with silage than with hay.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1993

Growth and food intake responses to diets of different protein contents and a choice between diets containing two concentrations of protein in broiler and layer strains of chicken.

1. Food intake, protein intake and body weight gain were measured in male broiler and layer strains of chickens offered approximately isocaloric diets containing various concentrations of protein from 4 to 9 weeks of age. The carcases were analysed for protein, fat and ash. 2. In the first experiment 5 birds of each strain were given diets containing either 65, 115, 172, 225 or 280 g protein/kg fresh matter. The sixth group was given a choice between 65 and 280 g/kg. There was an approximately linear increase in protein deposition with dietary protein content up to 280 g/kg with broilers and 225 g/kg with layers. When a choice of diets was offered, birds of both strains grew at a rate not significantly different from that of birds on the diets with the lowest protein content which gave maximal growth given singly, by making an apparently appropriate choice from the two diets. 3. In the second experiment broilers were offered a choice of two diets in the following combinations: 65 and 115, 65 and 225, 115 and 225, 225 and 280 and 280, and 320 g/kg protein. They were able to differentiate successfully between two diets on the basis of their protein content and, where the two diets were on either side of the optimum, to change the proportions selected as they grew to match their changing requirement for dietary protein. When given two diets, both of which had protein contents lower than the single diets which gave maximal growth, birds ate predominantly from that closer to that optimal diet. When both diets had a higher protein content than the optimum birds ate mostly from that closer to optimum. 4. The results show that growing chickens can match their protein intake closely to their requirements when given a pair of diets that allows this; if both diets are on the same side of the optimum then the one closest to that required is predominantly chosen.

Animal Feed↗
PubMed1992

Effects of intraruminal infusions of sodium acetate and sodium chloride on silage intake by lactating cows.

Lactating dairy cows prepared with rumen fistulas were fed on grass silage and concentrates and used in two experiments to compare the effects of sodium acetate and sodium chloride infused over 3 h into the rumen on the voluntary intake of silage. Silage intake was depressed in an approximately linear manner by increasing amounts (6-15 mol) of sodium acetate (NaOAc) and 15 mol NaCl had an effect similar to that of 12 mol NaOAc. Sodium in rumen fluid was significantly correlated with intake as was osmolality. 5.5, 7.4 or 9.1 mol of NaOAc significantly depressed silage intake, while 7.4 and 9.1 mol NaCl had significant effects. There were significant negative relationships between intake and the level of NaOAc or NaCl. It is concluded that the major effect of either salt was via the elevation of osmolality of rumen fluid and the relevance to normal control of feeding is discussed.

Acetates↗
PubMed1992

Effects of intraruminal infusions of sodium salts on selection of hay and concentrate foods by sheep.

Infusion of salts of short-chain fatty acids into the rumen of sheep depresses food intake but the relative importance of the effect of the acids and of osmolality are not fully understood. Three experiments were carried out in which sodium acetate (NaAc) and sodium chloride (NaCl) were infused for 3 h at 4 mM/min and compared with water controls. The effects on the intakes of a concentrate food and hay were examined to study the effect of osmotic and acid manipulation of the rumen on dietary choice. In the first experiment the foods were continuously available while in the second and third the foods were given for 3 min at 1.5-h intervals. Salt infusions depressed concentrate intake without significant effect on the intake of hay. The effect of NaAc tended to be greater than that of NaCl and persisted after the end of infusion. The weight of concentrate eaten during the 3-min tests was significantly and negatively related to both acetate and sodium concentrations in rumen fluid. The weight of hay eaten was negatively related to concentrate intake. The results demonstrate that the treatments imposed had a differential effect on intake, only depressing that of the concentrate food. They also suggest that, as NaAc has a greater effect than NaCl, the influence on feeding is due both to the osmotic load and the acid effect.

Acetates↗
PubMed1992

Abdominal chemo- and mechanosensitivity in ruminants and its role in the control of food intake.

Ruminant animals have evolved a large and complex set of stomachs which allow fermentation of fibrous food by symbiotic micro-organisms. These stomachs are well innervated and generate signals which are thought to be important in the control of voluntary food intake. Tension receptors in the muscular wall of the rumen and reticulum are slowly adapting and provide a measure of distension while epithelial receptors are rapidly adapting and provide information on the fibrousness of the digesta; they are involved in the control of stomach motility and voluntary food intake in order to prevent excessive distension. The epithelial receptors are also sensitive to the chemical nature of the digesta, particularly acidity. There are mechano- and chemoreceptors in the abomasum (true stomach) and duodenum and chemoreceptors in the liver, all of which have been implicated in the control of intake. It is relatively easy to prepare and maintain ruminants with a rumen fistula and many studies have shown the effects of such manipulations as distension of balloons in the rumen on voluntary intake. With fibrous, slowly digested feeds intake is primarily limited by rumen distension. With more rapidly digested feeds, however, the products of digestion play an important role in controlling intake. Short-chain fatty acids are the main products of fermentation and infusion of their salts into the rumen depresses food intake to a much greater extent than infusion into the general circulation. Acetate or propionate given into the rumen are more effective, mole for mole, than butyrate but must be given at rates exceeding the natural rate of production in order to have a significant effect. It has been suggested that much of the effect of sodium acetate is via the increase in the osmolality of rumen fluid but there is considerable uncertainty as to the physiological significance of osmotic effects, especially when animals have free access to water and can prevent excessive increases in tonicity by increasing their water intake. Other constituents of rumen fluid have been implicated in the control of food intake, particularly lactic acid and nitrogenous compounds, especially as these can be found in fermented feeds such as silage. The omasum controls the flow of digesta to the abomasum; it is therefore well placed to control rumen fill and thus intake but there has been little study in this area and this is also true for the abomasum.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Blood transfusion costs: a multicenter study.

The cost of delivering a unit of blood (whole blood or red cells) to a hospitalized patient was examined in 19 United States teaching hospitals. The average hospital acquisition cost was calculated by using the prices charged by regional blood centers for blood products. To this cost was added an estimate of costs incurred by hospitals for handling, testing, and administering blood. Across study sites, the average hospital cost per unit transfused was $155 and the average charge to the patient was $219. Acquisition cost, the price that hospitals pay for blood, was 37 percent of the total cost to the hospital; the other 63 percent of the hospital cost included costs for blood bank handling (13%), laboratory tests (43%), and blood administration (7%). Significant variations in blood transfusion cost were found within our sample. Most of the variability can be attributed to geographic location of the blood supply source, type of red cell product transfused, prices charged by blood transfusion services, and the frequency of laboratory tests. The results of this transfusion cost study may be helpful in determining the costs of health care delivery, especially when blood transfusions are indicated.

Blood Transfusion↗
PubMed1989

Feed intakes and meal patterns of sheep during pregnancy and lactation, and after weaning.

Four cross-bred ewes were kept in individual pens from the last month of pregnancy until the third week of weaning after a 5-week lactation; lambing occurred in late March. The ewes were offered a complete pelleted feed ad libitum, and every few days the feeding behaviour of each was monitored by continuous recording of the weight of the feed container. The weight and timing of each meal was used to calculate mean meal size and length, intermeal interval, hunger and satiety ratios. The increase in daily intake which occurred after parturition was due to increases in meal size, rate of eating and meal frequency. Intake was lower in the period of the day from 0400 hrs to 0800 hrs than during any of the 4-h periods between 0800 hrs and 2400 hrs, with intermediate values at 2400-0400 hrs. The time of day had no effect on meal size or rate of eating. These results are compared with the predictions of a model designed to predict meal occurrences in sheep and the differences used to suggest improvements to the model.

Animals↗
PubMed1989

Growth, food intake and energy balance of layer and broiler chickens offered glucose in the drinking water and the effect of dietary protein content.

1. Four experiments were carried out to study the effect of offering a 91.5 g/l solution of glucose, compared to tap water, on fluid intake, food intake and growth of individually-caged immature chickens of both layer and broiler strains. 2. Male chicks of an egg-laying strain were offered glucose solution or tap water from 27 to 62 d after hatching. There was no effect of glucose on fluid intake but it depressed food intake (P less than 0.01) to give equal total energy intakes for each treatment. Body weight gain was reduced (P less than 0.001) and carcase fat content increased (P less than 0.001) by the glucose to yield no difference to total carcase energy. 3. When birds were placed in a respiration chamber for two 23-h periods there was no effect of treatment on outputs of energy as faeces + urine or as heat. 4. Male broilers were offered glucose solution or tap water with diets containing either 150 or 195 g protein/kg from 20 to 55 d after hatching. With the low-protein diet glucose depressed food intake (P less than 0.01) but total energy intake and carcase energy were not significantly affected. With the high-protein diet glucose did not depress food intake but increased total energy intake and total body fat. 5. Layer and broiler chicks were offered either a choice of the low- and high-protein diets or a single diet intermediate in protein content, with glucose solution or tap water. With broilers total food intake was depressed by glucose, mainly by a reduced intake of the low-protein diet. Intake of neither diet by the layer chicks was significantly affected by glucose. 6. It is concluded that provision of extra energy in glucose solution depresses food intake when the resultant energy:protein ratio becomes limiting. With a higher protein diet, or with birds having lower protein requirements, glucose solution does not depress food intake and increased fat deposition occurs.

Animals↗
PubMed1988

The roles of hepatic nerves in the reduction of food intake as a consequence of intraportal sodium propionate administration in sheep.

Like other mammals, ruminants can also control their food intake. One of the potential sites where feed-back signals arise is the liver. We have already shown in our previous study that intraportal administration of propionate depresses intake and that this action is dependent on an intact nerve supply to the liver because sectioning the hepatic plexus abolishes the effect of propionate. In the following work the relative importance and the possible roles of different hepatic nerves were investigated. Three-hour continuous infusions of sodium propionate or saline into the hepatic portal vein of sheep were carried out following applications of different surgical procedures and food intakes were measured. In experiment 1 bilateral splanchnotomies were sufficient to prevent the effect of propionate on food intake. The subsequent total hepatic denervations also resulted in the removal of the depressing effect of propionate. Experiment 2 was designed to compare the involvement of the splanchnic afferents from the liver and the hepatic vagal afferents. Intraportal propionate was demonstrated to depress feeding in the intact animal whereas splanchnic nerve blockade with local anaesthetic removed this effect. Paradoxically selective hepatic vagotomy also abolished this effect. It was concluded that there may be more than one pathway involved in transmitting information from the liver to the central nervous system. Possible implications of the results are discussed and attempts are made to explain the mechanism of action and compare different theories by other workers.

Animals↗
PubMed1987

A role for the liver in the effects of glucagon on food intake in domestic fowl.

Adolescent cockerels of an egg-laying strain were prepared with catheters into the hepatic portal vein (HPV) and offered a standard poultry ration ad lib. Injection of 10, 100 and 1000 micrograms of bovine glucagon into the HPV caused a depression in intake which was significantly different from the control from 60 to 90 minutes after injection and was related to the logarithm of the dose. In birds prepared with HPV and jugular vein catheters, 1000 micrograms of glucagon had a similar depressing effect on intake irrespective of route of administration. In cockerels vagotomised at the level of the proventriculus, doses of glucagon up to 1000 micrograms injected into the HPV had no significant effect on intake. When vagotomised and sham-operated birds, in direct comparison, were injected with 0, 5 and 50 micrograms glucagon, there was s significant depression with both doses in the sham-operated cockerels but no effect in those which were vagotomised. However, the vagotomised birds had low control food intakes and the data obtained from them must be interpreted with caution. The conclusion is drawn that glucagon affects liver metabolism to influence the information transmitted via the vagus nerves to the central nervous system circuits involved in the control of feeding.

Animals↗
PubMed1987

Food intake of domestic fowl injected with adrenergic agonists and antagonists into the hepatic portal vein.

Cockerels of an egg-laying strain were used to study the mode of action of epinephrine on food intake in chickens. Intraperitoneal injection of 2500 micrograms epinephrine significantly depressed intake from 1-6 hr after injection. This effect was not modified by vagotomy at the level of the proventriculus (equivalent of subdiaphragmatic vagotomy in the mammal). Injection of 25, 50 or 100 micrograms epinephrine into the hepatic portal vein depressed intake in a dose-related manner. One hundred micrograms epinephrine had similar effects when injected into the jugular vein as into the portal vein, although the latter injection had longer-lasting effects. As the liver is the major site of inactivation of epinephrine this suggests that it acts mainly at that organ. In order to find which type of receptor is stimulated by epinephrine in its action on feeding an alpha-adrenergic agonist, phenylephrine, was injected into the portal vein at doses ranging from 63-3000 micrograms; there was no effect on intake at any dose. A beta-adrenergic agonist, salbutamol (500-2000 micrograms), depressed intake in a dose-related manner following portal vein injection. This effect was not attenuated by vagotomy. Aminophylline, an inhibitor of cAMP breakdown, had no effect on intake when injected into the portal vein (2500-10000 micrograms) and the depressing effect of 200 micrograms epinephrine was not modified by simultaneous injection of 10000 micrograms aminophylline. It is concluded that epinephrine acts on the liver to suppress intake via a vagally-mediated pathway, but that the mechanisms of action are not known.

Albuterol↗