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

Plasma estradiol-17β, cortisol, and insulin concentrations and serum biochemical parameters surrounding puberty in Japanese Black beef bulls with normal and abnormal semen

The associations of semen abnormalities with circulating hormones (estrogens, glucocorticoid, insulin) and common biochemical parameters are unclear in beef bulls. We compared plasma concentrations of estradiol-17β, cortisol, and insulin and serum biochemical parameters surrounding puberty in Japanese Black beef bulls (n = 96) with normal post-thaw or abnormal semen (fresh and frozen). Blood samples were collected monthly from 4 to 24 months of age (n = 50) for the assays of plasma estradiol, cortisol, and insulin and every 3 months from 6 to 21 months of age (n = 92) for the serum biochemical analyses. Semen was collected weekly from 12 months until at least 18 months of age. Fresh semen was evaluated for semen volume, sperm progressive motility, concentrations, and morphological defects. The normal fresh semen was frozen by a standard method and examined for post-thaw sperm motility and fertility, which were evaluated for rates of transferable embryos. Bulls were classified as having either normal fresh semen or abnormal fresh semen (when at least one of the above test items was abnormal for 6 months). The normal fresh semen was categorized as having either normal post-thaw semen or low fertility post-thaw semen. The abnormal fresh semen was categorized as having sperm morphological defects, low motility, or morphological defects plus low motility. Plasma cortisol concentrations in the abnormal fresh semen group were higher than those of the normal fresh semen group (p < 0.0001). Plasma estradiol-17β and insulin concentrations in the low-fertility post-thaw semen group were lower than those of the normal post-thaw semen group (p < 0.0001). Serum aspartate aminotransferase and magnesium concentrations were greater for the abnormal fresh semen group vs. the normal fresh semen group (p < 0.005). These results suggest that fresh semen abnormality in pubertal beef bulls might be associated with increased circulating aspartate aminotransferase, magnesium and cortisol. Low-fertility post-thaw semen could have been involved with the lower peripheral estradiol and insulin levels in beef bulls.

Effect of ursodeoxycholic acid on glycemic markers: A systematic review and meta-analysis of clinical trials

Ursodeoxycholic acid (UDCA) is widely used to treat liver diseases; however, its potential effect on metabolic parameters has been poorly investigated. Additionally, owing to divergent data, the objective of this meta-analysis was to evaluate the effect of UDCA on glycemic parameters in clinical trials. Clinical trials investigating the impact of UDCA treatment on glycemic markers were searched in PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases (from inception to April 16, 2018). A random-effects model and generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. A weighted random-effects meta-regression was performed to evaluate the impact of potential confounders on glycemic parameters. Meta-analysis of seven studies comprising eight treatment arms revealed a significant reduction of fasting glucose levels following UDCA therapy (WMD: -3.30 mg/dL, 95% CI: -6.36, -0.24, p = 0.034; I² = 28.95%). Also, meta-analysis of two treatment arms indicated a significant reduction of glycated hemoglobin (HbA1c) concentrations (WMD: -0.41% mg/dL, 95% CI: -0.81, -0.01, p = 0.042; I² = 0%). Additionally, meta-analysis of four treatment arms also revealed a significant reduction in plasma insulin levels (WMD: -1.50 mg/dL, 95% CI: -2.81, -0.19, p = 0.025; I² = 67.90%) but not significant effect HOMA-IR (WMD: -0.20 mg/dL, 95% CI: -0.42, 0.01, p = 0.057; I² = 85.34%). Results of this meta-analysis showed that UDCA significantly reduces fasting plasma glucose, HbA1c, and insulin concentrations suggesting a positive impact on glucose homeostasis.

Serum blood metabolite response and evaluation of select organ weight, histology, and cardiac morphology of beef heifers exposed to a dual corticotropin-releasing hormone and vasopressin challenge following supplementation of zilpaterol hydrochloride

The objectives of this study were 1) to determine if supplementation of zilpaterol hydrochloride (ZH) altered select organ weights, histology, and cardiac anatomical features at harvest and 2) to determine if administration of a corticotropin-releasing hormone (CRH) and vasopressin (VP) challenge following 20 d of ZH supplementation altered the blood chemistry profile in cattle. Crossbred heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), without ZH, and 2) zilpaterol (ZIL; ZH at 8.33 mg/kg [DM basis] for 20 d). On d 20 of supplementation, heifers were fitted with indwelling jugular catheters. On d 24, starting at 0800 h and continuing until 1600 h, blood samples were collected at 60-min intervals. At 1000 h, heifers received an i.v. bolus of CRH (0.3 µg/kg BW) and VP (1.0 µg/kg BW) to activate the stress axis. Serum was separated and stored at -80°C until analyzed for a large-animal chemistry panel. Following the CRH/VP challenge, heifers were harvested on d 25, 26, and 27 (5, 6, and 7 d after ZH supplementation); BW, HCW, select organ weights, and histology were measured, and a total heart necropsy was performed. A treatment effect ( ≤ 0.02) was observed for Ca, K, creatinine, alkaline phosphatase, and sorbitol dehydrogenase. Zilpaterol-fed heifers had decreased ( ≤ 0.02) concentrations of Ca and K and increased concentrations ( 0.01) of creatinine ( = 0.02) during the CRH/VP challenge when compared to control heifers. Control heifers had greater ( ≤ 0.05) alkaline phosphatase and sorbitol dehydrogenase concentrations when compared with ZIL heifers. A treatment × time interaction ( = 0.02) was observed for P; concentrations were similar between treatments from -2 to 6 h postchallenge, and 7 h postchallenge CON heifers had decreased P. Liver ( = 0.06) and kidney ( = 0.08) weights as a percentage of BW tended ( ≤ 0.08) to be reduced in ZIL heifers. Gross liver weights tended ( = 0.08) to be lower in ZIL heifers. Other organ (heart, lung, adrenals) to BW ratios remained similar ( ≥ 0.41). These data suggest that there are some variations observed between treatments in terms of response to ZH supplementation and the CRH/VP challenge; however, in the environmental conditions of this study, limited variation in blood metabolic responses and organ weights suggests that the supplementation of ZH did not detrimentally alter the physiology of cattle.

Atypical Coccidiosis in South American Camelids

Reported clinical signs of coccidiosis in South American camelids include anorexia of a few days duration, sudden death, and diarrhea. Antemortem diagnosis of clinical coccidiosis is usually based on clinical signs and supported by detection of coccidial oocysts in feces. This report describes 2 atypical cases of coccidiosis in South American camelids that had no coccidial oocysts detected on antemortem fecal flotation, prolonged weight loss, and normal fecal consistency.

Evaluation of insulin secretion and action in New World camelids

OBJECTIVE

To measure and compare insulin secretion and sensitivity in healthy alpacas and llamas via glucose clamping techniques.

ANIMALS

8 llamas and 8 alpacas.

PROCEDURES

Hyperinsulinemic euglycemic clamping (HEC) and hyperglycemic clamping (HGC) were performed on each camelid in a crossover design with a minimum 48-hour washout period between clamping procedures. The HEC technique was performed to measure insulin sensitivity. Insulin was infused IV at 6 mU/min/kg for 4 hours, and an IV infusion of glucose was adjusted to maintain blood glucose concentration at 150 mg/dL. Concentrations of blood glucose and plasma insulin were determined throughout. The HGC technique was performed to assess insulin secretion in response to exogenous glucose infusion. An IV infusion of glucose was administered to maintain blood glucose concentration at 320 mg/dL for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout.

RESULTS

Alpacas and llamas were not significantly different with respect to whole-body insulin sensitivity during HEC or in pancreatic β-cell response during HGC. Alpacas and llamas had markedly lower insulin sensitivity during HEC and markedly lower pancreatic β-cell response during HGC, in comparison with many other species.

CONCLUSIONS AND CLINICAL RELEVANCE

New World camelids had lower glucose-induced insulin secretion and marked insulin resistance in comparison with other species. This likely contributes to the disorders of fat and glucose metabolism that are common to camelids.

Hepatic encephalopathy associated with hepatic lipidosis in llamas (Lama glama)

Hepatic encephalopathy has been listed as a differential for llamas displaying neurologic signs, but it has not been histopathologically described. This report details the neurologic histopathologic findings associated with 3 cases of hepatic lipidosis with concurrent neurologic signs and compares them to 3 cases of hepatic lipidosis in the absence of neurologic signs and 3 cases without hepatic lipidosis. Brain from all 3 llamas displaying neurologic signs contained Alzheimer type II cells, which were not detected in either subset of llamas without neurologic signs. Astrocytic immunohistochemical staining intensity for glial fibrillary acid protein was decreased in llamas with neurologic signs as compared to 2 of 3 llamas with hepatic lipidosis and without neurologic signs and to 2 of 3 llamas without hepatic lipidosis. Immunohistochemical staining for S100 did not vary between groups. These findings suggest that hepatic encephalopathy may be associated with hepatic lipidosis in llamas.

Disorders of carbohydrate or lipid metabolism in camelids

Camelids develop a number of disturbances related to energy metabolism. Some are similar to disorders seen in other species, but most relate to camelids' unusual characteristics of poor glucose tolerance, partial insulin resistance, and low concentrations of circulating insulin. Camelids are especially prone to abnormalities related to stimuli that inhibit insulin release or activity, or that promote activities normally antagonized by insulin. These include stimuli that mobilize glycogen or fat stores, or inhibit glucose uptake or intravascular glycolysis. These stimuli are generally more important than negative energy balance in triggering these disorders. Treatment must concentrate on the hormonal aspects, and not just provision of energy. Treatments related to hormonal aspects include those to decrease catecholamine release and to provide exogenous insulin until the camelid is again able to maintain appropriate energy substrate homeostasis.

Nutritional requirements and assessing nutritional status in camelids

It has been nearly 30 years since the first imported llamas and alpacas have been commercially raised in the United States. Nutritional requirements for these animals have not been well understood and most feeding practices were based on extrapolated and experiential information. Only recently has a National Research Council committee reviewed the available published information relative to nutrient requirements of llamas and alpacas. This article summarizes current nutrient requirement recommendations and provides some practical feeding recommendations and methods to assess nutritional status.

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.

Pharmacokinetics of intravenously administered caffeine in healthy alpacas (Lama pacos) and llamas (Lama glama)

OBJECTIVE

To determine the pharmacokinetic disposition of IV administered caffeine in healthy Lama spp camelids.

ANIMALS

4 adult male alpacas and 4 adult female llamas.

PROCEDURES

Caffeine (3 mg/kg) was administered as an IV bolus. Plasma caffeine concentrations were determined by use of high-performance liquid chromatography in 6 animals and by use of liquid chromatography-mass spectrometry in 2 llamas.

RESULTS

Median elimination half-life was 11 hours (range, 9.3 to 29.8 hours) in alpacas and 16 hours (range, 5.4 to 17 hours) in llamas. The volume of distribution at steady state was 0.60 L/kg (range, 0.45 to 0.93 L/kg) in alpacas and 0.75 L/kg (range, 0.68 to 1.15 L/kg) in llamas. Total plasma clearance was 44 mL/h/kg (range, 24 to 56 mL/h/kg) in alpacas and 42 mL/h/kg (range, 30 to 109 mL/h/kg) in llamas.

CONCLUSIONS AND CLINICAL RELEVANCE

High-performance liquid chromatography and liquid chromatography-mass spectrometry were suitable methods for determination of plasma caffeine concentrations in alpacas and llamas. Plasma caffeine concentration-time curves were best described by a 2-compartment model. Elimination half-lives, plasma clearance, volume of distribution at steady state, and mean residence time were not significantly different between alpacas and llamas. Intravenous administration of caffeine at a dose of 3 mg/kg did not induce clinical signs of excitement.

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.

Assessment of the metabolic effects of hydrocortisone on llamas before and after feed restriction

OBJECTIVE

To evaluate the effects of administration of hydrocortisone on plasma concentration of insulin and serum concentrations of glucose, triglyceride, and nonesterified fatty acids (NEFAs) in llamas before and after feed restriction.

ANIMALS

9 adult female llamas.

PROCEDURE

Feed was withheld from llamas for 8 hours. Blood samples were collected before (0 minutes) and 120, 180, 240, and 300 minutes after IV injection of hydrocortisone sodium succinate (1 mg/kg) for determination of plasma insulin concentration and serum concentrations of glucose, triglyceride, and NEFAs. The llamas were then fed a limited diet (grass hay, 0.25% of body weight daily) for 21 days, after which the experimental procedures were repeated.

RESULTS

Compared with llamas that were not feed-restricted, llamas after feed restriction had significantly higher plasma insulin concentration and serum concentrations of triglycerides and NEFAs. Feed-restricted llamas after hydrocortisone injection had a significantly smaller increase in serum glucose concentration, a decrease (rather than an increase) in serum concentration of NEFAs, and no change in blood concentrations of insulin or triglycerides.

CONCLUSIONS AND CLINICAL RELEVANCE

Short-acting glucocorticoid hormones did not appear to increase blood lipid concentrations in healthy llamas, regardless of ongoing fat mobilization. Thus, these hormones appear unlikely to be major direct contributors to diseases such as hepatic lipidosis or hyperlipemia. Although administration of hydrocortisone reduced serum concentration of fatty acids in feed-restricted llamas, its use has not been evaluated in sick camelids and cannot be considered therapeutically useful.

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.

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.