Lack of advantage of high‐fibre,moderate‐carbohydrate diets in dogs with stabilised diabetes§

Objectives : To assess the influence of high‐fibre, moderate‐carbohydrate diets with two levels of dietary fat, compared with a commercial diet with moderate‐fibre, low‐carbohydrate and higher fat, on insulin requirement, glycaemic control and lipid profile of dogs with stabilised diabetes. Methods : Twelve dogs with spontaneous diabetes mellitus were studied. Glycaemic control was evaluated by plasma fructosamine, glycosylated haemoglobin and 48‐hour serial blood glucose measurements. The insulin dosage required to maintain clinical stability was also determined. Lipid profiles comprised serial measurements of plasma cholesterol, triglyceride, free glycerol and free fatty acids. Data were analysed using analysis of variance. Results : There were no significant differences in insulin requirement or glycaemic control among diets. Weight loss occurred when the dogs were fed the high‐fibre, moderate‐carbohydrate, moderate‐fat diet (P<0·002), whereas weight was maintained with the other two diets. The high‐fibre, moderate‐carbohydrate, moderate‐fat diet resulted in lower mean plasma cholesterol compared with either of the higher‐fat diets (P≤0·003), and lower mean plasma triglyceride (P=0·060), free fatty acid (P<0·001) and free glycerol (P=0·015) than the commercial diet. Clinical Significance : For stable diabetic dogs, high‐fibre, moderate‐carbohydrate diets offered no significant advantage compared with a commercial diet with moderate fibre and low carbohydrate. Diets with high fibre, moderate carbohydrate and moderate fat should not be routinely recommended for dogs with thin body condition.     

Spontaneously obese dogs exhibit greater postprandial glucose, triglyceride, and insulin concentrations than lean dogs

Dogs do not appear to progress from obesity-induced insulin resistance to type 2 diabetes mellitus. Both postprandial hyperglycemia and postprandial hypertriglyceridemia have been proposed to cause or maintain beta cell failure and progression to type 2 diabetes mellitus in other species. Postprandial glucose, triglyceride, and insulin concentrations have not been compared in lean and obese dogs. We measured serum glucose, triglyceride, and insulin concentrations in nine naturally occurring obese and nine age- and gender-matched lean dogs. After a 24-h fast, dogs were fed half their calculated daily energy requirement of a standardized diet that provided 37% and 40% of metabolizable energy as carbohydrate and fat, respectively. Fasting and postprandial glucose and triglyceride concentrations were greater in the obese dogs (P < 0.001), although the mean insulin concentration for this group was five times greater than that of the lean group (P < 0.001). Most of the 0.6 mM (11 mg/dL) difference in mean postprandial glucose concentrations between lean and obese dogs was attributable to a subset of persistently hyperglycemic obese dogs with mean postprandial glucose concentrations 1.0 mM (18 mg/dL) greater than that in lean dogs. Persistently hyperglycemic obese dogs had lower triglyceride (P = 0.02 to 0.04) and insulin (P < 0.02) concentrations than other obese dogs. None of the dogs developed clinical signs of diabetes mellitus during follow-up for a median of 2.6 yr. We conclude that pancreatic beta cells in dogs are either not sensitive to toxicity because of mild hyperglycemia or lack another component of the pathophysiology of beta cell failure in type 2 diabetes mellitus.     

Effect of an extruded pea or rice diet on postprandial insulin and cardiovascular responses in dogs

Peas are increasing in popularity as a source of carbohydrate, protein and fibre in extruded canine diets. The aim of this study was to test the health effects of two canine diets with identical macronutrient profiles, but containing either yellow field peas or white rice as the carbohydrate source on metabolism, cardiovascular outcomes and adiposity. First, the acute glycemic, insulinemic and cardiovascular responses to the pea‐ or rice‐based diets were determined in normal weight beagles (n = 7 dogs). The glycemic index did not differ between the pea diet (56 ± 12) and rice diet (63 ± 9). Next, obese beagles (n = 9) were fed the yellow field pea diet or white rice diet ad libitum for 12 weeks in a crossover study. Adiposity (measured using computed tomography), metabolic (oral glucose tolerance test, plasma leptin, adiponectin, C‐reactive protein) and cardiovascular assessments (echocardiography and blood pressure) were performed before and after each crossover study period. After 12 weeks on each diet, peak insulin (p = 0.05) and area under the curve (AUC) for insulin after a 10 g oral glucose tolerance test (p = 0.05) were lower with the pea than the rice diet. Diet did not show a significant effect on body weight, fat distribution, cardiovascular variables, adiponectin or leptin. In conclusion, a diet containing yellow field peas reduced the postprandial insulin response after glucose challenge in dogs despite continued obesity, indicating improved metabolic health.     

Postprandial glycaemia in cats fed a moderate carbohydrate meal persists for a median of 12 hours -- female cats have higher peak glucose concentrations

The postprandial increase in glucose concentration is typically not considered in selecting diets to manage diabetic and pre-diabetic cats. This study describes increases in glucose and insulin concentrations in 24 clinically healthy, neutered adult cats following one meal (59 kcal/kg) of a moderate carbohydrate diet (25% of energy). Median time to return to baseline after feeding for glucose was 12.2 h (1.8-≥24 h) and for insulin was 12.3 h (1.5-≥24 h). Time to return to baseline for glucose was not different between male (10.2 h) and female (17.2 h) cats. There was evidence female cats had a longer return to baseline for insulin (18.9 h versus 9.8 h) and females had higher (0.9 mmol/l difference) peak glucose than males. This demonstrates that the duration of postprandial glycaemia in cats is markedly longer than in dogs and humans, and should be considered when managing diabetic and pre-diabetic cats.     

Dietary fibre and post prandial hyperglycaemia in normal and diabetic dogs

Blood glucose responses to three different diets were measured in six normal dogs and in five diabetic dogs stabilised on insulin replacement therapy. In all animals a control canned diet was compared with the same diet containing 20 g wheat bran, and with the same diet containing 20 g guar granules. Reductions in hyper-glycaemia were demonstrated for 240 minutes following the test meal containing guar in comparison with the control diet in all but one dog, and moderate reductions were demonstrated following the test meal containing bran. These findings suggest that, as in man, feeding restricted carbohydrate diets to diabetics is an outdated concept. As in human medicine, high fibre diets or dietary supplementation with soluble fibre, such as guar, reduces post prandial hypergly-caemia and may help to improve gylcaemic control in diabetes mellitus.     

Effects of the alpha-glucosidase inhibitor acarbose on postprandial serum glucose and insulin concentrations in healthy dogs.

OBJECTIVE: To determine effects of acarbose on baseline and postprandial serum glucose and insulin concentrations in healthy dogs, if effects of acarbose were dosage related, and if acarbose caused any short-term adverse effects. ANIMALS: 5 healthy dogs fed a high-fiber diet. PROCEDURE: A Latin-square design was used. During each 1-week treatment period, dogs were given a placebo or 25, 50, 100, or 200 mg of acarbose, PO, twice daily immediately prior to feeding. There was a 1-week interval between periods. At the end of each treatment period, serum glucose and insulin concentrations were measured prior to feeding and at 30- to 60-minute intervals for 6 hours after feeding. RESULTS: Baseline serum glucose and insulin concentrations, insulin peak response, and total glucose absorption were not significantly different following treatment with placebo and treatment with acarbose; however, total insulin secretion was significantly decreased when dogs were treated with 100 or 200 mg of acarbose. Four dogs developed soft to watery stools when treated with 200 mg of acarbose, and 2 dogs lost weight during the study. Results of CBC and serum biochemical analyses were within reference ranges throughout the study. CONCLUSIONS: Acarbose did not induce any serious adverse effects and was effective in healthy dogs in reducing total postprandial insulin secretion when administered immediately prior to meals. CLINICAL RELEVANCE: Results suggest that acarbose may help control hyperglycemia in dogs with insulin-dependent diabetes mellitus. Additional studies designed to evaluate the effect of acarbose on postprandial blood glucose concentrations in dogs with diabetes mellitus are indicated.     

Effects of six carbohydrate sources on diet digestibility and postprandial glucose and insulin responses in cats

The effects of diets with different starch sources on the total tract apparent digestibility and glucose and insulin responses in cats were investigated. Six experimental diets consisting of 35% starch were extruded, each containing one of the following ingredients: cassava flour, brewers rice, corn, sorghum, peas, or lentils. The experiment was carried out on 36 cats with 6 replications per diet in a completely randomized block design. The brewers rice diet offered greater DM, OM, and GE digestibility than the sorghum, corn, lentil, and pea diets (P < 0.05). For starch digestibility, the brewers rice diet had greater values (98.6%) than the sorghum (93.9%), lentil (95.2%), and pea (96.3%) diets (P < 0.05); however, starch digestibility was >93% for all the diets, proving that despite the low carbohydrate content of carnivorous diets, cats can efficiently digest this nutrient when it is properly processed into kibble. Mean and maximum glucose concentration and area under the glucose curve were greater for the corn-based diet than the cassava flour, sorghum, lentil, and pea diets (P < 0.05). The corn-based diets led to greater values for the mean glucose incremental concentration (10.2 mg/dL), maximum glucose incremental concentration (24.8 mg/dL), and area under the incremental glucose curve (185.5 mg.dL(-1).h(-1)) than the lentil diet (2.9 mg/dL, 3.1 mg/dL, and -40.4 mg.dL(-1).h(-1), respectively; P < 0.05). When compared with baseline values, only the corn diet stimulated an increase in the glucose response, occurring at 4 and 10 h postmeal (P < 0.05). The corn-based diet resulted in greater values for maximum incremental insulin concentration and area under the incremental insulin curve than the lentil-based diet (P < 0.05). However, plasma insulin concentrations rose in relation to the basal values for cats fed corn, sorghum, pea, and brewers rice diets (P < 0.05). Variations in diet digestibility and postprandial response can be explained by differences in the chemical composition of the starch source, including fiber content and granule structure, and also differences in the chemical compositions of the diets. The data suggest that starch has less of an effect on the cat postprandial glucose and insulin responses than on those of dogs and humans. This can be explained by the metabolic peculiarities of felines, which may slow and prolong starch digestion and absorption, leading to the delayed, less pronounced effects on their blood responses.     

The effect of a commercial high-fibre diet and an iso-malto-oligosaccharide-supplemented diet on post-prandial glucose concentrations in dogs

In order to evaluate the effect of insoluble and soluble fibre on the levels of post-prandial glycaemia, six healthy dogs were fed three different diets: a low-fibre control diet, a high-fibre diet (HF; mainly insoluble fibre) and the control diet with 10% iso-malto-oligosaccharides (IMO) added. The diets were fed for 2 days before the blood collections were started on the third day. Serial blood samples were taken 20, 60, 90, 150, 180, 240 and 360 min after feeding and one sample was taken just before the feeding after a fasting period of at least 20 h. There were no problems concerning the faecal consistency. The post-prandial glycaemia curve was significantly lower in the HF and IMO group in comparison with the control group. At 20 and 60 min the glucose concentration was significantly lower in the HF and IMO groups. At 90 and 150 min only the IMO group had a significantly lower glucose concentration. At 360 min there was a trend for a lower glucose concentration in the IMO group. The results show that both the HF and the IMO diets had a beneficial effect on post-prandial hyperglycaemia. Substitution of IMO may have the same or a slightly better effect, but this has to be confirmed in diabetic dogs and the effect may depend on the composition of the basal diet.     

Influence of type of starch and feeding management on glycaemic control in diabetic dogs

The present study evaluated the effects of two diets with different starch sources and two feeding methods on the glycaemic control in dogs with diabetes mellitus. The diets had similar nutrient contents (40% starch and 16% dietary fibre), one formulated with 46% of broken rice and the other with 42% sorghum and 10% lentils (as-fed). Ten client-owned diabetic dogs were fed with each diet for 2 months, in a crossover design. Five dogs received NPH human insulin and food every 12 h (feeding method 1), and the other five received insulin every 12 h but were fed three times a day (feeding method 2). In feeding method 2, morning insulin was higher than the evening dose and dogs received the second meal after 4 to 5 h of the morning insulin and meal. Parameters evaluated included insulin dosage, 12- and 8-h glycaemic curves, complete blood count, biochemical profile and urinalysis. Glycaemic curves were analysed by ANOVA with repeated measures. Glycaemic control parameters (fasting, mean, minimum and maximum glycaemia and serum fructosamine) and glucose area under the curve (AUC) were calculated and analysed by paired t test (p < 0.05). In feeding method 1, dogs fed the sorghum-based diet presented lower mean (p = 0.04) and minimum blood glucose concentrations (p = 0.03), and a tendency to lower maximum blood glucose (p = 0.06) and glucose AUC (p = 0.08) than when fed the rice-based diet. When food was provided twice a day, the ingestion of the rice-based diet resulted in higher post-prandial glucose response than the diet with sorghum and lentil. In feeding method 2, there was no effect of diet on the assessed parameters (p > 0.05). No differences in insulin dosage were observed between groups or feeding methods (p > 0.05). Providing two meals a day followed by insulin administration associated with the sorghum- and lentil-based diet improved glycaemic control in diabetic dogs.     

Influence of a high fibre diet on glycaemic control and quality of life in dogs with diabetes mellitus

A study was undertaken to evaluate a high fibre diet used in the management of 10 dogs with naturally occurring insulin-dependent diabetes mellitus. Following baseline measurements of health and glycaemic control, the dogs were fed a canned diet containing a blend of insoluble and soluble dietary fibres and were monitored during the ensuing four months. Switching to the high fibre diet was associated with significantly lower mean 24-hour and postprandial plasma glucose concentrations, which were maintained over the study period. The high fibre diet was also associated with significant reductions in plasma concentrations of fructosamine, glycated haemoglobin, free glycerol and cholesterol, and there were significant improvements in dog activity and demeanour. Bodyweight declined during the fourth month of feeding the diet, which is likely to have resulted from underfeeding relative to increased activity. The results indicate that a high fibre diet can significantly improve glycaemic control and quality of life in dogs with diabetes mellitus.     

Effects of dietary fiber supplementation on glycemic control in dogs with alloxan-induced diabetes mellitus.

The effect of a high insoluble-fiber (IF) diet containing 15% cellulose in dry matter, high soluble-fiber (SF) diet containing 15% pectin in dry matter, and low-fiber (LF) diet on glycemic control in 6 dogs with alloxan-induced insulin-dependent diabetes mellitus was evaluated. Each diet contained greater than 50% digestible carbohydrate in dry matter. A crossover study was used with each dog randomly assigned to a predetermined diet sequence. Each dog was fed each diet for 56 days. Caloric intake was adjusted weekly as needed to maintain each dog within 1.5 kg of its body weight measured prior to induction of diabetes mellitus. All dogs were given pork lente insulin and half of their daily caloric intake at 12-hour intervals. Mean (+/- SEM) daily caloric intake was significantly (P less than 0.05) less when dogs consumed the IF diet vs the SF and LF diets (66 +/- 3 kcal/kg, 81 +/- 5 kcal/kg, and 79 +/- 4 kcal/kg, respectively). Serum alkaline phosphatase activity was significantly (P less than 0.05) higher when dogs consumed the LF diet vs the IF and SF diets (182 +/- 37 IU/L, 131 +/- 24 IU/L, and 143 +/- 24 IU/L, respectively). Mean postprandial plasma glucose concentration measured every 2 hours for 24 hours, beginning at the time of the morning insulin injection, was significantly (P less than 0.05) lower at most blood sampling times in dogs fed IF and SF diets, compared with dogs fed the LF diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of insoluble and soluble dietary fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus

OBJECTIVE: To evaluate the effects of diets differing in type and quantity of fiber on glycemic control in dogs with naturally occurring insulin-dependent diabetes mellitus. DESIGN: Prospective randomized crossover controlled trial. ANIMALS: 7 dogs with well-regulated naturally occurring insulin-dependent diabetes mellitus. PROCEDURE: Dogs were fed 1 of 3 diets for 1 month each in 1 of 6 randomized diet sequences. Diets included a low-fiber diet (LF) and 2 high-fiber diets; 1 contained only insoluble fiber (HIF), and 1 contained soluble fiber in addition to insoluble fiber (HSF). Caloric intake was unchanged throughout the study. Glycemic control was assessed after each feeding trial by measuring serum fructosamine concentration and performing 5 serial measurements of blood glucose concentration every 2 hours after the morning feeding and insulin injection. RESULTS: Significant differences were not detected in body weight, required insulin dosage, or albumin concentration among dogs fed the HIF, HSF, and LF diets. Mean and maximum blood glucose concentrations and area under the blood glucose curve were significantly lower in dogs fed the HIF diet, compared with values in the same dogs fed the HSF or LF diet. Fructosamine concentration was significantly lower in dogs fed the HIF or HSF diet, compared with values in the same dogs fed the LF diet. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs with naturally occurring insulin-dependent diabetes mellitus, a dry, high insoluble-fiber diet may aid in glycemic control.     

Effects of high carbohydrate and high fat diet on plasma metabolite levels and on i.v. glucose tolerance test in intact and neutered male cats

To elucidate the impact of dietary influence on carbohydrate and lipid metabolism and on the development of diabetes mellitus in the carnivorous cat, a 3 weeks feeding trial was carried out on six sexually intact and six neutered adult male cats. The effects of two isonitrogenic diets, differing in carbohydrate and fat content, were investigated on plasma metabolite levels in a 24-h blood sampling trial. Plasma leptin concentrations were also determined at the beginning and at the end of the 24-h trial. Glucose and insulin response was measured in an i.v. glucose tolerance test. A 5 days long digestion trial was also performed, which revealed a high digestion capacity of both fat and carbohydrates in cats. The high fat diet induced a significant rise in the plasma triglyceride, FFA, beta-hydroxybutyrate and cholesterol concentration, while the elevation in the glucose level did not reach significance. In the glucose tolerance test no significant difference was found between the neutered and intact cats. However, independently of the sexual state, the cats on the high fat diet showed a slightly elongated glucose clearance and reduced acute insulin response to glucose administration. This is indicative of diminished pancreatic insulin secretion and/or beta-cell responsiveness to glucose. The results of this preliminary study may be the impetus for a long-term study to find out whether it is rather the fat rich ration than carbohydrate rich diet that is expected to impair glucose tolerance and thus might contribute to the development of diabetes mellitus in cats. Whether the alteration in glucose metabolism is due to altered leptin levels remains to be determined.     

Dynamic changes of postprandial plasma metabolites after intake of corn-soybean meal or casein-starch diets in growing pigs

Background: Postprandial nutrients utilization and metabolism of a certain diet is a complicated process. The metabolic feature of pigs after intake of corn-soybean meal or casein-starch diets are largely unknown. Therefore,this study was conducted to investigate the dynamic postprandial changes of plasma metabolic profile using growing pigs using metabolomics.Methods: Twenty-four growing pigs with average initial body weight(BW) about 30 kg were placed in metabolic cages and then fitted with precaval vein catheters. Pigs were fed daily 4% of initial body weight. Two experimental diets were included:(i) a starch-casein based purified diet(PD) and(ii) a common corn-soybean meal diet(CD).Plasma was collected before feeding and 0.5 h, 1 h, 2 h, 4 h, 8 h after feeding.Results: In both diets, compared to prior to feeding, the concentrations of glucose, most amino acids, metabolites such as 5-aminopentanoic acid, pipecolic acid, ornithine and 5-hydroxy-L-tryptophan were significantly increased in plasma during the first hour, whereas the concentrations of plasma triglycerides, glutamate, glycine, palmitelaidic acid, 13-HODE and oleic acid were decreased in the first hour. Compared with PD group, concentration of plasma leucine and isoleucine declined at 30 min in CD group. Plasma linoleic acid, sphingosine and many dipeptides were significantly higher in pigs fed CD.Conclusion: Most significant metabolic changes occurred during the first hour after feeding and then became relatively stable after 2 h in both diets. These results show a broad scope picture of postprandial changes in plasma metabolites after intake of PD and CD and could be a reference for further nutrition intervention as well as the design of nutritional studies.     

High versus low protein diets to mink--postprandial plasma urea and creatinine response, osmotic load and pattern of nitrogen and electrolyte excretion.

Nitrogen balance, pattern of excretion of nitrogenous end-products, endogenous urinary N excretion, postprandial plasma urea and creatinine, osmotic load, urinary electrolyte excretion and water intake/output relationships were studied in 12 adult female mink fed a high protein diet (HP; n = 6) providing about 155 g protein/kg or a low protein diet (LP; n = 6) providing about 95 g protein/kg. Two balance periods of each 3 d were used and diets were fed raw or cooked. After the last balance period followed a 48 h fasting period. Postprandial plasma urea and creatinine were studied for 48 h following a test meal given after an overnight fast. Osmotic load was determined based on collection of non-acidified urine carried out during 48 h. Level of protein supply did not affect N balance, being close to zero, whereas slightly negative balances were achieved for fasting animals. Protein supply was clearly reflected in excretion of urinary urea and allantoin but not in creatinine and uric acid. Endogenous urinary N excretion was estimated by a second order regression equation giving an intercept of 280 mg/kg0.75. Post-prandial plasma urea concentrations were strongly influenced by protein supply, HP animals having substantially higher peaks than LP animals, but values returned to fasting values within 24 h after the test meal. Plasma creatinine followed a biphasic pattern with a peak about 2 h after feeding and a nadir approximately 6 h after feeding. Physical form of diet influenced postprandial urea, animals fed raw diets having a higher peak, but not creatinine. The HP diet provided almost the double osmotic load of the LP diet and a corresponding increase in urine volume. The resulting water balances were identical irrespective of diet, showing that water intake/output relationships are very accurately regulated.     

Influence of a high-protein diet on energy balance in obese cats allowed ad libitum access to food

The influence of a high-protein [HP, 47% of metabolizable energy (ME)] diet on energy balance was evaluated in obese cats allowed ad libitum access to food. Energy intake, body weight, body composition, energy expenditure, and concentrations of hormones and metabolites associated with carbohydrate and lipid metabolism (glucose, insulin, free fatty acids, triglycerides and leptin) were measured in cats after consuming either a moderate protein (MP, 27% of ME) or HP diet for 4 months. Indirect respiration calorimetry showed that resting and total energy expenditure (kJ/day) adjusted for either body weight or lean body mass was increased in cats consuming the HP in relation to MP diets. However, voluntary energy intake also was increased in the HP treatment and, thus, there was no difference in body weight between animals consuming the two diets. Body composition measurements using deuterium oxide dilution showed that dietary protein content did not alter amounts of either lean body mass or fat mass. No significant differences (p > 0.05) were observed between the two treatment groups for blood glucose, free fatty acid or leptin concentrations, although there was a trend (p = 0.054) towards an increase of serum insulin concentrations in the cats eating the HP diet. This study showed that short-term ad libitum feeding of an HP diet did not reduce food intake or promote weight loss in obese cats. However, energy expenditure was increased in the HP diet group and it is possible that this effect of HP might help promote weight loss when energy intake is restricted.     

The effects of diet on blood glucose, insulin, gastrin and the serum tryptophan: large neutral amino acid ratio in foals

High carbohydrate diets can affect the health and behaviour of foals, but the mechanisms are not always fully understood. The objective of this study was to compare the effects of feeding a starch and sugar (SS), or a fat (oil) and fibre (FF) rich diet to two groups of eight foals. Diets were fed from 4 to 42 weeks of age, alongside ad libitum forage. Faecal pH levels did not differ significantly between groups and endoscopic examination showed that the gastric mucosa was healthy in both groups at 25 and 42 weeks of age. At 40 weeks of age, SS foals had significantly higher total blood glucose and lower total blood gastrin than FF foals during the 6h period following ingestion of their respective diets, but insulin levels did not differ significantly. The ratio between serum tryptophan and other large neutral amino acids showed a trend towards an interaction between diet and sampling time. The results provide preliminary information about the effects of diet on the physiology of young horses.     

Effect of dry, soft moist, and canned dog foods on postprandial blood glucose and insulin concentrations in healthy dogs

The effect of dry, soft moist, and canned dog foods on immediate postprandial plasma glucose and insulin concentrations was evaluated in clinically normal dogs. Dogs were fed either dry (10 dogs; group I), soft moist (10 dogs; group II), or canned (8 dogs; group III) dog food for 5 consecutive days. On the fifth day, plasma glucose and insulin concentrations were determined in each dog prior to, during, and at 5, 10, 15, 30, 45, 60, 90, 120, 180, and 240 minutes after ingestion of the food. The alterations in plasma glucose concentrations were not significantly different from prefeeding values until 240 and 180 minutes after feeding for groups I and III, respectively. In contrast, the increments in plasma glucose were significantly (P less than 0.01) increased from basal concentrations at 30 and 45 minutes after feeding in group-II dogs. The maximal mean postprandial plasma glucose concentration was significantly (P less than 0.0001) less for group III, compared with concentrations for groups I and II, but there was no significant difference between concentrations for groups I and II. Although a biphasic insulin secretory response was found in all 3 groups of dogs, the patterns of phase-2 insulin secretion and the total amount of insulin secreted during the study were significantly different. There was a rapid increase in the plasma insulin concentration immediately after phase 1 in group II, with maximal plasma insulin concentrations occurring 30 minutes after feeding, followed by a gradual decrease in concentrations throughout the remainder of the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of processing barley on its digestion by horses

Four horses were randomly fed a diet containing rolled, micronised or extruded barley; the barley intake was adjusted to supply 2 g starch/kg bodyweight per day. During a 10-day acclimatisation period the horses were also fed 1 kg grass hay/100 kg bodyweight per day. Samples of blood and breath were collected at the end of each period after the test meal of barley had been fed after a 12-hour overnight fast. The glycaemic and insulinaemic responses of the horses were measured as an indication of the pre-caecal digestibility of starch, and postprandial breath hydrogen and methane were measured to detect microbial fermentation of starch. The highest peak serum glucose and serum insulin concentrations were observed after feeding the extruded barley, lower concentrations were observed after feeding the micronised barley and the lowest concentrations were observed after feeding the rolled barley. Breath hydrogen increased within four hours of feeding all the barley diets, and the mean (sd) peak hydrogen concentrations were 98.3 (55.2) ppm for rolled barley, 59.3 (31.5) ppm for micronised barley and 96.1 (51.9) ppm for extruded barley. There were wide variations within individual horses but these concentrations were not significantly different. Breath methane concentrations were very variable and, although there were no significant differences, there was a trend for higher methane concentrations after the feeding of rolled barley.     

Effects of excess caloric fat feeding on the lipid metabolism in Shetland ponies

To investigate the influence of overweight and dietary fat supplementation on lipid and insulin glucose metabolism of Shetland ponies, eight Shetland pony geldings were fed a hypercaloric (30 MJ DE/150 kg bwt. and day) fat diet (10% fat as soybean oil) or a carbohydrate control diet for nine months until ponies gained an overweight of 15%. Afterwards oral glucose tolerance tests (oGTT; 5, 6 mmol/kg bwt.) were performed after a 12 hour fast and after a fast which led to an increase of plasma triglyceride concentrations to a threshold of 3 mmol/l (36-65 hrs.). Plasma concentrations of glucose, insulin, triglycerides and non esterified fatty acids (NEFA) were determined for 480 minutes after the glucose load. Ponys having had received the control diet tended to a higher insulin secretion in case of both oGTTs, whereas the glucose tolerance was similar in both groups but lower than in ponies of normal weight. During the oGTTs after fasting leading to the plasma triglyceride threshold, triglyceride concentrations decreased significantly (p < 0.05) faster and stronger in fat fed ponies. Additionally, fat fed pony showed significantly (p < 0.05) lower NEFA levels. The results of this study demonstrate a positive effect of fat feeding on the triglyceride clearance of overweight Shetland ponies.