Assessment of the effects of feed restriction and amino acid supplementation on glucose tolerance in llamas

OBJECTIVE: To assess the effects of prolonged feed deprivation on glucose tolerance, insulin secretion, and lipid homeostasis in llamas. ANIMALS: 9 adult female llamas. PROCEDURE: On each of 2 consecutive days, food was withheld from the llamas for 8 hours. Blood samples were collected before and 5, 15, 30, 45, 60, 120, and 240 minutes after IV injection of dextrose (0.5 g/kg) for determination of plasma insulin and serum glucose, triglyceride, and nonesterified fatty acid concentrations. Between experimental periods, the llamas received supplemental amino acids IV (185 mg/kg in solution). The llamas were then fed a limited diet (grass hay, 0.25% of body weight daily) for 23 days, after which the experimental procedures were repeated. RESULTS: Feed restriction decreased glucose tolerance and had slight effects on insulin secretion in llamas. Basal lipid fractions were higher after feed restriction, but dextrose administration resulted in similar reductions in serum lipid concentrations with and without feed restriction. Insulin secretion was decreased on the second day of each study period, which lessened reduction of serum lipid concentrations but did not affect glucose tolerance. CONCLUSIONS AND CLINICAL RELEVANCE: Despite having a comparatively competent pancreatic response, feed-restricted llamas assimilated dextrose via an IV bolus more slowly than did llamas on full rations. However, repeated administration of dextrose reduced insulin secretion and could promote hyperglycemia and fat mobilization. These findings suggested that veterinarians should use alternative methods of supplying energy to camelids with long-term reduced feed intake or consider administering agents to improve the assimilation of glucose.     

Assessment of the effects of epinephrine and insulin on plasma and serum biochemical variables in llamas and alpacas

OBJECTIVE: To describe the metabolic effects of epinephrine administration in New World camelids and investigate whether these effects are influenced by administration of insulin. ANIMALS: 6 llamas and 8 alpacas (all adult castrated males). PROCEDURE: Prior to each experiment, food was withheld from camelids for 8 hours. On each of 2 consecutive days, alpacas were administered epinephrine (10 mg/kg, IM; time 0); alpacas were randomly assigned to receive regular insulin (0.2 U/kg, IV) immediately after epinephrine administration on one of those days. In llamas, the experiment was performed once after administration of epinephrine only. At 0, 30, 60, 90, 120, 150, 180, 210, and 240 minutes after treatment, blood samples were collected and several serum or plasma biochemical variables were assessed; in addition, plasma samples from llamas were assessed for insulin concentrations. Data were compared between days (alpacas only) and between time points. RESULTS: Administration of epinephrine induced mobilization of glucose, triglycerides, nonesterified fatty acids, and beta-hydroxybutyrate. A small increase in endogenous insulin concentration was detected in epinephrine-treated llamas, compared with baseline values. Overall, insulin administration decreased, negated, or delayed the epinephrine-associated increases in serum or plasma concentrations of circulating energy substrates, except that it augmented the epinephrine-associated increase in concentration of triglycerides. CONCLUSIONS AND CLINICAL RELEVANCE: Epinephrine appeared to mobilize energy substrates in camelids and hence may be involved in the pathogenesis of disorders of glucose and fat metabolism. Insulin appeared to antagonize most of these effects, and its administration may have therapeutic value in camelids.     

Effects of hydrocortisone on substrates of energy metabolism in alpacas

OBJECTIVE: To evaluate effects of hydrocortisone administration, with and without concurrent administration of insulin, on intermediary metabolism in alpacas. ANIMALS: 8 adult castrated male alpacas. PROCEDURE: On each of 2 consecutive days, food was withheld from alpacas for 8 hours. Alpacas then were administered 1 mg of hydrocortisone sodium succinate/kg, IV (time 0). On 1 of the days, randomly assigned alpacas were also administered regular insulin (0.2 U/kg, IV) 120 minutes after hydrocortisone administration. Blood samples were collected at 0, 120, 135, 150, 165, 180, 210, 240, 300, and 360 minutes. Plasma concentrations of glucose and lactate and serum concentrations of triglycerides, cholesterol, nonesterified fatty acids, and beta-hydroxybutyrate were determined. Data were compared between days. Additionally, serum insulin concentrations before and after hydrocortisone administration were determined for selected samples. RESULTS: Hydrocortisone administration induced hyperglycemia, hyperinsulinemia, a reduction in concentrations of triglycerides and cholesterol, and a reduction in triglyceride-to-cholesterol ratio. Subsequent insulin administration temporarily negated the hyperglycemic effects of hydrocortisone, induced temporary hyperlactemia, and augmented the reduction in blood triglycerides. CONCLUSIONS AND CLINICAL RELEVANCE: A single dose of a short-acting corticosteroid does not increase blood lipid fractions in healthy alpacas, probably because of a competent endogenous insulin response. Corticosteroids may induce differing responses in camelids with depleted glycogen stores or an ineffective insulin response. Administration of insulin can effectively negate the hyperglycemic effects of hydrocortisone and augment lipoprotein clearance. Hence, insulin administration may be therapeutic for alpacas with hyperglycemia, hyperlipemia, or hyperketonemia.     

Glucose tolerance testing in llamas and alpacas

OBJECTIVE: To determine blood glucose clearance in 2 species of New World camelids after IV challenge and to examine mechanisms of this clearance. ANIMALS: 5 adult female llamas and 5 adult gelded alpacas. PROCEDURE: After food was withheld for 12 hours, camelids received 0.5 g of glucose/kg of body weight by rapid IV infusion. Serum concentrations of glucose, nonesterified fatty acids, cortisol, and insulin, and plasma concentrations of lactate were determined before and 0, 1, 2, 3, 4, 5, 15, 30, 60, 90, 120, 180, and 240 minutes after infusion. Ratios of insulin to glucose and insulin to cortisol were calculated for each time point. RESULTS: Postinfusion glucose concentrations were significantly higher in llamas than alpacas for the first 15 minutes and remained significantly higher than baseline values in both species for 180 minutes. Lactate and cortisol concentrations did not change significantly; nonesterified fatty acid concentrations decreased in both species 30 minutes after infusion. Baseline insulin concentrations were < 6 microU/ml in both species and increased only to 10.1 +/- 0.7 microU/ml in llamas. Insulin concentrations did not change significantly in alpacas. CONCLUSIONS AND CLINICAL RELEVANCE: Llamas and alpacas clear glucose more slowly than other domestic species after challenge, mainly because of a weak insulin response and slow cellular uptake. This response may impair the assimilation of exogenous glucose as well as make llamas and alpacas prone to diabetes-like disorders when an abundance of endogenous or exogenous glucogenic agents are present.     

Evaluation of glucose tolerance and insulin sensitivity in Ilama crias

OBJECTIVE: To investigate glucose tolerance and insulin sensitivity in llama crias. ANIMALS: 7 llamas (age range, 14 to 30 days). PROCEDURE: On each of 2 sequential days, crias were administered glucose (0.5 g/kg) via rapid i.v. injection. On 1 day (randomly determined for each cria), regular insulin (0.2 U/kg) or 0.9% NaCl solution (0.002 mL/kg) was administered i.v. 15 minutes after glucose administration. Blood samples were collected before (baseline) and at 5, 15, 30, 45, 60, 90, 120, 180, and 240 minutes after glucose administration for determination of plasma glucose and insulin concentrations; fractional turnover rates and plasma half-life of glucose were calculated. The data were compared over time and between days (ie, between glucose treatments with and without insulin administration). RESULTS: A peak plasma glucose concentration of 342 +/- 47 mg/dL was detected at 5 minutes after glucose administration and llamas cleared glucose from plasma within 60 minutes; at 15 minutes, plasma insulin concentration attained a peak value of 33 +/- 13 microU/mL (ie, triple the baseline value). During the 15- to 45-minute interval, fractional turnover rate of glucose was 1.10 +/- 0.24%/min and plasma half-life was 65.7 +/- 13.4 minutes. Insulin significantly increased glucose turnover and resulted in hypoglycemia within 75 minutes of administration. CONCLUSIONS AND CLINICAL RELEVANCE: Healthy immature llamas have glucose tolerance and insulin sensitivity superior to that of adults. However, whether sick crias retain the pancreatic sufficiency and tissue responsiveness that are likely responsible for the rapid glucose clearance in healthy individuals is not known.     

Characterization of hypertriglyceridemia and response to treatment with insulin in llamas and alpacas: 31 cases (1995-2005)

OBJECTIVE: To evaluate camelids with hypertriglyceridemia with regard to signalment, clinical features of disease, and response to treatment with insulin. DESIGN: Retrospective case series. ANIMALS: 23 alpacas and 8 llamas with hypertriglyceridemia. PROCEDURES: For analysis of medical record data, 20 hypertriglyceridemic camelids with multiple recorded measurements of serum or plasma triglycerides concentration were classified as follows: those with an initial triglycerides concentration > 60 to > or = 500 mg/dL that were or were not treated with insulin (HT-I and HT-N camelids, respectively) and those with an initial triglycerides concentration > 500 mg/dL that were treated with insulin (lipemic [LIP-I] camelids). Only 1 recorded triglycerides concentration was available for an additional 11 hypertriglyceridemic camelids; data from those records were included in the characterization of signalment and clinical features of disease. RESULTS: Compared with the general population of hospitalized camelids, hypertriglyceridemic camelids did not differ significantly with respect to age or sex. Of 22 female camelids, only 7 were lactating or pregnant. Serum or plasma triglycerides concentrations in HT-N and HT-I camelids did not differ significantly at admission, but triglycerides concentrations in HT-I camelids decreased significantly after insulin treatment. Posttreatment triglycerides concentrations in HT-I camelids were significantly lower than those in HT-N camelids. During the period of hospitalization, triglycerides concentrations in HT-N camelids increased, whereas those in LIP-I camelids decreased significantly. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that hypertriglyceridemia affects llamas and alpacas of all ages and both sexes. Insulin treatment may reduce serum or plasma triglycerides concentrations in camelids with hypertriglyceridemia.     

Effect of withholding feed on concentration and composition of plasma very low density lipoprotein and serum nonesterified fatty acids in horses

OBJECTIVE: To measure and compare the concentration and composition of very low-density lipoprotein (VLDL) in plasma and selected lipids in serum of horses fed mixed grass hay ad libitum or denied feed for 36 hours. ANIMALS: 4 healthy adult mares. PROCEDURE: Mares were either fed mixed grass hay ad libitum or denied feed for 36 hours beginning at 8:00 AM. Blood samples were collected every 2 hours during the study period and analyzed for nonesterified fatty acid (NEFA), triglyceride (TG), VLDL, and glucose concentrations and composition of VLDL. RESULTS: Withholding feed significantly increased mean serum concentrations of NEFA. By 36 hours, a 16-fold increase in mean serum NEFA concentration and 2-fold increase in mean plasma VLDL concentration, compared with baseline values, were detected. Mean plasma TG concentrations significantly increased with time in feed-deprived horses. Significantly lower overall mean plasma glucose concentrations were detected in feed-deprived horses. Mean percentage of protein in VLDL was significantly lower in feed-deprived horses. Plasma VLDL concentrations varied widely among horses in response to withholding feed. Plasma TG and VLDL concentrations remained unaltered in 2 horses. CONCLUSIONS AND CLINICAL RELEVANCE: Withholding feed significantly increases blood lipid concentrations in horses, but individual horses respond differently. Serum NEFA concentrations were increased in all 4 horses denied feed, indicating mobilization of tissue triglyceride stores. Variation in plasma VLDL concentration in response to withholding feed suggests that its metabolism is strongly influenced by other, as yet undetermined, factors in horses. Differences in the plasma VLDL concentrations among horses in response to withholding feed may be used as an indication of susceptibility to the hyperlipemic syndrome of Equidae.     

Characterization of bovine pyruvate carboxylase promoter 1 responsiveness to serum from control and feed-restricted cows

Pyruvate carboxylase (PC; EC 6.4.1.1) is critical in gluconeogenesis from lactate and maintenance of tricarboxylic acid cycle intermediates. Whereas increases in PC mRNA have been observed during feed restriction, the mechanism of regulation is unknown; however, coinciding increases in circulating NEFA concentrations suggests that fatty acids may contribute to regulation of gene expression during feed restriction. The objective of this study was to examine the direct effect of exposure to serum from full-fed control cows with serum from cows that were restricted to 50% of ad libitum intake for 5 d on PC expression in vitro. Rat hepatoma (H4IIE) cells were transiently transfected with bovine promoter-luciferase constructs containing bovine PC promoter 1 and treated with serum from control cows, serum from feed-restricted cows, or modified serum. Modified serum pools were generated by supplemented serum from control cows with C14:0, C16:0, C18:0, C18:1n-9 cis, C18:2n-6 cis, and C18:3n-3 cis to match the total NEFA in serum from feed-restricted cows (1.3 mM) in the relative proportion found in serum from control or feed-restricted cows. Exposure of cells to serum from feed-restricted cows increased (P < 0.05) PC promoter 1 activity 2.2-fold compared with cells exposed to control cow serum. Exposure to serum from control cows with fatty acids added to a NEFA concentration of 1.3 mM to reflect the fatty acid profile of control and feed-restricted cows increased (P < 0.05) promoter 1 activity 2.1- and 2.5-fold, respectively, compared with cells incubated with control cow serum. There was no difference (P ≥ 0.05) in promoter 1 activity in cells treated with modified serum compared with serum from feed-restricted cows. These data indicate that promoter 1 is activated by fatty acids found in serum of feed-restricted cows. These data suggest a role of NEFA to regulate expression of bovine PC mRNA through specific activation of PC promoter 1.     

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.     

围产期奶牛血清代谢物和相关激素水平的变化规律研究

试验旨在揭示围产期奶牛血清代谢物和相关激素水平的动态变化规律,选取临床健康经产奶牛 20 头,分别于产前 14、7 d 及产后 0、7、14 d 采血并分离血清,检测血清葡萄糖、甘油三酯、非酯化脂肪酸、β-羟丁酸等代谢物浓度和胰岛素、生长激素、脂联素和瘦素等激素水平,并根据相应公式计算胰岛素敏感指数。结果表明:奶牛分娩当天的血糖浓度较高,而后逐步恢复至产前水平;奶牛分娩后甘油三酯浓度下降,非酯化脂肪酸和β-羟丁酸浓度升高;胰岛素浓度在产前 14 d 至产后 7 d 各时间点无显著变化;产前 7 d 时的生长激素浓度高于其他时间点(P<0.01);脂联素浓度在整个试验期无显著变化;瘦素水平在产前 7 d 和产后 0 d升高(P<0.01),但产后 7 d 时下降(P<0.01);胰岛素敏感性指数在分娩当天显著降低,随后逐步恢复。结果表明,奶牛产后体脂动员明显,可能与生长激素、瘦素等激素的调控有关。     

Effect of omega-3 polyunsaturated fatty acids and body condition on serum concentrations of adipokines in healthy dogs

Objective-To determine associations between serum concentrations of omega-3 polyunsaturated fatty acids or body condition and serum concentrations of adiponectin, leptin, insulin, glucose, or triglyceride in healthy dogs. Animals-62 healthy adult client-owned dogs. Procedures-Body condition score and percentage of body fat were determined. Blood samples were collected after food was withheld for 12 hours. Serum was harvested for total lipid determination, fatty acid analysis, and measurement of serum concentrations of adiponectin, leptin, insulin, glucose, and triglyceride. Associations between the outcome variables (adiponectin, leptin, insulin, glucose, and triglyceride concentrations) and each of several variables (age, sex, percentage of body fat, and concentrations of total lipid, α-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid) were determined. Results-Serum concentrations of docosapentaenoic acid were significantly positively associated with concentrations of adiponectin and leptin and negatively associated with concentrations of triglyceride. Serum concentrations of α-linolenic acid were significantly positively associated with concentrations of triglyceride. No significant associations were detected between serum concentrations of eicosapentaenoic acid or docosahexaenoic acid and any of the outcome variables. Percentage of body fat was significantly positively associated with concentrations of leptin, insulin, and triglyceride but was not significantly associated with adiponectin concentration. Age was positively associated with concentrations of leptin, insulin, and triglyceride and negatively associated with concentrations of adiponectin. Sex did not significantly affect serum concentrations for any of the outcome variables. Conclusions and Clinical Relevance-Docosapentaenoic acid may increase serum concentrations of adiponectin and leptin and decrease serum triglyceride concentration in healthy dogs.     

Endocrine responses in mares undergoing abrupt changes in nutritional management

Leptin, a protein hormone secreted by adipocytes, plays an important role in energy homeostasis and regulation of body composition. We previously observed that acute feed restriction resulted in a rapid decline in concentrations of leptin in obese pony mares. This acute response prompted us to characterize the temporal changes in concentrations of leptin, GH, and insulin in obese pony mares during the transition between fed and feed-restricted conditions. Nine obese pony mares of mixed breed, previously maintained on fescue pasture, were randomly allotted to 2 groups. Treatments consisted of a 48-h feed restriction, a 48-h refeeding, and a 24-h feed restriction (RFR; n = 4), or 48 h of alfalfa hay ad libitum, a 48-h feed restriction, and a 24-h refeeding (FRF; n = 5). Blood samples were taken every 15 min during restriction and feeding transitions (0600 to 1400 on d 2 and 4), and every 30 min thereafter until 0830 of the following days (d 3 and 5). In the FRF treatment, plasma concentrations of leptin declined precipitously 6 h after the removal of feed (sample by treatment interaction; P < 0.01), and remained low and unresponsive to refeeding. Similarly, in the RFR group, plasma concentrations of leptin were initially low, and did not respond to feeding during the second (refeeding) sampling period. After feed restriction in each of the 2 treatment sequences, plasma insulin decreased and GH mean concentration, pulse frequency, pulse amplitude, and area under the curve increased (P < 0.05). Refeeding reversed these effects on insulin and GH. These data provide evidence that peripheral concentrations of insulin and GH are dynamically responsive to feed removal (decrease in insulin; increase in GH) and replacement (increase in insulin; decrease in GH), whereas leptin decreases in response to feed restriction but is slow to recover from a transient nutritional insult.     

Effect of darglitazone on glucose clearance and lipid metabolism in obese cats

OBJECTIVE: To examine the effect of darglitazone, a compound of the thiazolidinedione class, on glucose clearance and lipid metabolism in obese cats. ANIMALS: 18 obese and 4 lean adult neutered female cats. PROCEDURE: IV glucose tolerance tests with measurements of glucose, insulin, and nonesterified fatty acid (NEFA) concentrations were performed before and 42 days after daily administration of darglitazone (9 obese cats) or placebo (9 obese and 4 lean cats). Additionally, cholesterol, triglyceride, leptin, and glycosylated hemoglobin concentrations were measured. RESULTS: Darglitazone-treated cats had significantly lower cholesterol, triglyceride, and leptin concentrations, compared with placebo-treated obese cats. A significant decrease in the area under the curve for NEFAs, glucose, and insulin during an i.v. glucose tolerance test was seen in darglitazone-treated cats. The drug was well tolerated. CONCLUSION AND CLINICAL RELEVANCE: The response of obese cats to darglitazone was similar to the response to thiazolidinediones in obese humans and rodents Darglitazone was effective in improving insulin sensitivity and glucose and lipid metabolism in obese cats.     

Influence of obesity on plasma lipid and lipoprotein concentrations in dogs

OBJECTIVE: To determine effects of obesity and diet in dogs on plasma lipid and lipoprotein concentrations by assaying plasma leptin and ghrelin concentrations and determining total plasma cholesterol and triglyceride concentrations as well as the concentrations of cholesterol and triglycerides in various lipoprotein classes (ie, very-low-density, low-density, and high-density lipoproteins). ANIMALS: 24 Beagles; 12 lean (mean [+/- SEM] body weight, 12.7 +/- 0.7 kg) and 12 chronically obese (21.9 +/- 0.8 kg) dogs of both sexes, between 1 and 9 years old. PROCEDURES: Total plasma cholesterol and triglyceride concentrations; lipoprotein cholesterol and triglyceride concentrations; and plasma ghrelin, leptin, free fatty acids, insulin, and glucose concentrations were measured and compared between lean and obese dogs, both of which were fed a complete and balanced maintenance diet. Chronically obese dogs were subsequently fed a high-protein low-energy diet to evaluate effects of diet composition on plasma lipid and lipoprotein measurements. RESULTS: Chronic obesity resulted in a significant decrease in plasma ghrelin concentration and a significant increase in plasma leptin, cholesterol, and triglyceride concentrations in dogs. High total plasma cholesterol and triglyceride concentrations resulted from increased cholesterol and triglyceride concentrations in all lipoprotein fractions. In obese dogs, modification of diet composition resulted in beneficial effects on plasma lipid and leptin concentrations, even before weight loss was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Correlations exist between obesity and plasma measurements (ie, lipoproteins, leptin, insulin, and ghrelin) commonly associated with obesity. Modification of diet composition to control energy intake improves plasma lipid and leptin concentrations in obese dogs.     

Influence of nutritional deprivation on insulin-like growth factor I, somatotropin, and metabolic hormones in swine

Although growth hormone (GH) is a primary stimulus for the synthesis of insulin-like growth factor I (IGF-I), other factors such as nutritional status, insulin, and thyroid hormones are important modulators of circulating IGF-I levels. Thus, the effects of feed restriction and subsequent refeeding on plasma levels of IGF-I, GH, insulin, and thyroid hormones were studied in swine. Despite an elevation in plasma GH levels after 48 h of feed restriction, circulating IGF-I levels were decreased by 53% (P less than .05). Plasma triiodothyronine (T3) and insulin were lower (P less than .05) within 24 h after the feed restriction began, whereas thyroxine (T4) did not decrease until 48 h after removal of feed. Blood glucose levels remained unchanged throughout the experiment. Refeeding after the 48-h fast was associated with a decline (P less than .05) in circulating GH levels within 2 h, concomitant with an elevation (P less than .05) in plasma insulin and T3. Refeeding fasted pigs was associated with an increase (P less than .05) in plasma IGF-I; however, levels still had not returned to prefast concentrations within 24 h after refeeding. These data indicate that the GH-IGF-I axis becomes uncoupled during nutritional restriction in swine and that inadequate nutrient supply may limit the expression of the anabolic effects of GH.     

Metabolic changes and induction of hepatic lipidosis during feed restriction in llamas.

OBJECTIVES: To determine whether feed restriction induces hepatic lipidosis (HL) in llamas and to evaluate the metabolic changes that develop during feed restriction. ANIMALS: 8 healthy adult female llamas. PROCEDURE: Llamas were fed grass hay at a rate of 0.25% of their body weight per day for 13 to 28 days. Llamas were monitored by use of clinical observation, serum biochemical analyses, and ultrasound-guided liver biopsies. RESULTS: All 8 llamas lost weight and mobilized fat. Five llamas developed HL, including 4 that were nursing crias. During the period of feed restriction, mean serum concentration of bile acids and activities of aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), and gamma-glutamyl transferase (GGT) were significantly higher in llamas that developed HL, compared with llamas that did not. Mean insulin-to-cortisol concentration ratios were lower in llamas with HL before and up to 7 days of feed restriction, compared with those that did not develop HL. CONCLUSIONS AND CLINICAL RELEVANCE: HL in llamas may be induced by severe feed restriction, particularly in the face of increased energy demand. Llamas with weight loss attributable to inadequate dietary intake may develop biochemical evidence of hepatopathy and HL. Increases in serum concentration of bile acids and activities of GGT, AST, and SDH may indicate the development of HL in llamas and identify affected animals for aggressive therapeutic intervention.     

Assessment of the influence of fatty acids on indices of insulin sensitivity and myocellular lipid content by use of magnetic resonance spectroscopy in cats

OBJECTIVE: To determine whether dietary fatty acids affect indicators of insulin sensitivity, plasma insulin and lipid concentrations, and lipid accumulation in muscle cells in lean and obese cats. ANIMALS: 28 neutered adult cats. PROCEDURE: IV glucose tolerance tests and magnetic resonance imaging were performed before (lean phase) and after 21 weeks of ad libitum intake of either a diet high in omega-3 polyunsaturated fatty acids (3-PUFAs; n = 14) or high in saturated fatty acids (SFAs; 14). RESULTS: Compared with the lean phase, ad libitum food intake resulted in increased weight, body mass index, girth, and percentage fat in both groups. Baseline plasma glucose or insulin concentrations and glucose area under the curve (AUC) were unaffected by diet. Insulin AUC values for obese and lean cats fed 3-PUFAs did not differ, but values were higher in obese cats fed SFAs, compared with values for lean cats fed SFAs and obese cats fed 3-PUFAs. Nineteen cats that became glucose intolerant when obese had altered insulin secretion and decreased glucose clearance when lean. Plasma cholesterol, triglyceride, and non-esterified fatty acid concentrations were unaffected by diet. Ad libitum intake of either diet resulted in an increase in both intra- and extramyocellular lipid. Obese cats fed SFAs had higher glycosylated hemoglobin concentration than obese cats fed 3-PUFAs. CONCLUSION AND CLINICAL RELEVANCE: In obese cats, a diet high in 3-PUFAs appeared to improve long-term glucose control and decrease plasma insulin concentration. Obesity resulted in intra- and extramyocellular lipid accumulations (regardless of diet) that likely modulate insulin sensitivity.     

Effects of low feed intake and hot environment on plasma profiles of glucose, nonesterified fatty acids, insulin, glucagon, and IGF-I in lactating sows

This experiment was designed to compare the effects of high ambient temperature and of feed restriction on plasma hormones and metabolites in primiparous lactating sows. Females were exposed to a constant thermoneutral (20 degrees C) or hot environment (30 degrees C) during lactation. Sows housed at 30 degrees C were given free access to feed (30AL: n = 12), whereas those housed at 20 degrees C were either pair-fed with those at 30 degrees C (20RF: n = 6) or were fed ad libitum (20AL: n = 6). A jugular vein catheter was surgically inserted in all sows at 100 d of gestation. Absorption of nutrients during the meal induced significant increases in plasma glucose, insulin, and glucagon, and a decrease in nonesterified fatty acids on Day 19 of lactation and Day 1 postweaning (P < 0.05). On Day 19, feed restriction at 20 degrees C was associated with higher plasma glucagon before the meal, lower plasma insulin after the meal and a lower insulin-to-glucagon ratio (I/GA) before and after the meal (P < 0.05). On Day 19, mean plasma concentrations measured in 30AL females were between those measured in 20AL and 20RF sows for nonesterified fatty acids and glucagon before feeding, and for glucose, nonesterified fatty acids, insulin, and glucagon after feeding. None of the differences between the 30AL and the 20RF groups was significant (P < 0.1). On Day 19, the only significant differences between the 30AL and 20AL groups were observed after the meal for plasma insulin and I/GA. Plasma insulin-like growth factor-I increased after farrowing in 20AL and 30AL sows only (P < 0.05). It was higher in 20AL than in 20RF and 30AL sows on Days 4 and 19 of lactation (P < 0.05). Overall, underfeeding at 20 degrees C induced changes in plasma insulin, glucagon, I/GA, and insulin-like growth factor-I, which would favor gluconeogenesis and body-reserve mobilization during lactation. Differences in glucagon and I/GA before the meal between well-fed sows at 20 degrees C and heat-exposed sows were attenuated, which could have detrimental consequences on glucose availability to the mammary gland and hence on milk production at 30 degrees C.     

Metabolic and hormonal alterations in cats with hepatic lipidosis

Hepatic lipidosis in cats is a commonly diagnosed hepatobiliary disease of unknown cause. The purpose of this prospective study was to characterize the blood hormone and lipid status of cats with hepatic lipidosis, and to compare this status to that of cats with other types of liver disease and to control cats. Twenty-three cats with hepatic disease were assigned to 1 of 2 groups on the basis of cytopathologic or histopathologic examination of the liver: group 1, hepatic lipidosis (n = 18); or group 2, cholangiohepatitis (n = 5). Ten healthy young adult cats were used as controls. Food was withheld from control animals for 24 hours before blood collection. Concentrations of plasma glucagon and serum insulin, cortisol, thyroxine, triglycerides, cholesterol, phospholipids, and nonesterified fatty acids (NEFAs) were determined in all cats, in addition to routine hematologic and serum biochemical testing. Cats with hepatic lipidosis had higher serum NEFA concentrations than cats with cholangiohepatitis or control cats (P < .05). Cats with cholangiohepatitis had higher serum cholesterol and phospholipid concentrations than those of cats with lipidosis or control cats (P < .05); their plasma glucagon concentrations were higher than those of control cats (P < .05), but were not different from those of cats with hepatic lipidosis. Serum insulin concentrations were significantly higher in control cats than in diseased cats (P < .05), but neither serum insulin nor the insulin to glucagon ratio was significantly different among the cats with hepatic disease. The high concentration of NEFAs in cats with hepatic lipidosis suggests that at least 1 factor in the pathogenesis of this syndrome may involve the regulation of hormone-sensitive lipase.     

Effects of calcium salts of long-chain fatty acids and rumen-protected methionine on plasma concentrations of ghrelin, glucagon-like peptide-1 (7 to 36) amide and pancreatic hormones in lactating cows

Our objective was to determine the effects of calcium salts of long-chain fatty acids (CLFAs) and rumen-protected methionine (RPM) on plasma concentrations of ghrelin, glucagon-like peptide-1 (7 to 36) amide, and pancreatic hormones in lactating cows. Four Holstein cows in midlactation were used in a 4 by 4 Latin square experiment in each 2-wk period. Cows were fed corn silage-based diets with supplements of CLFAs (1.5% added on dry matter basis), RPM (20 g/d), CLFAs plus RPM, and without supplement. Jugular blood samples were taken from 1 h before to 2 h after morning feeding at 10-min intervals on day 12 of each period. CLFAs decreased dry matter intake, but RPM did not affect dry matter intake. Both supplements of CLFAs and RPM did not affect metabolizable energy intake and milk yield and composition. Plasma concentrations of NEFAs, triglyceride (TG), and total cholesterol (T-Cho) were increased with CLFAs alone, but increases of plasma concentrations of TG and T-Cho were moderated by CLFAs plus RPM. Calcium salts of long-chain fatty acids increased plasma ghrelin concentration, and the ghrelin concentration with CLFAs plus RPM was the highest among the treatments. Plasma concentrations of glucagon-like peptide-1, glucagon, and insulin were decreased with CLFAs, whereas adding RPM moderated the decrease of plasma glucagon concentration by CLFAs. These results indicate that the addition of methionine to cows given CLFAs increases plasma concentrations of ghrelin and glucagon associated with the decrease in plasma concentrations of TG and T-Cho.