Detrimental effects on villus form during conventional oral rehydration therapy for diarrhoea in calves; alleviation by a nutrient oral rehydration solution containing glutamine

Metabolism and Nutrition of L-Glutamate and L-Glutamine in Ruminants

Although both L-glutamate (Glu) and L-glutamine (Gln) have long been considered nutritionally nonessential in ruminants, these two amino acids have enormous nutritional and physiological importance. Results of recent studies revealed that extracellular Gln is extensively degraded by ruminal microbes, but extracellular Glu undergoes little catabolism by these cells due to the near absence of its uptake. Ruminal bacteria hydrolyze Gln to Glu plus ammonia and, intracellularly, use both amino acids for protein synthesis. Microbial proteins and dietary Glu enter the small intestine in ruminants. Both Glu and Gln are the major metabolic fuels and building blocks of proteins, as well as substrates for the syntheses of glutathione and amino acids (alanine, ornithine, citrulline, arginine, proline, and aspartate) in the intestinal mucosa. In addition, Gln and aspartate are essential for purine and pyrimidine syntheses, whereas arginine and proline are necessary for the production of nitric oxide (a major vasodilator) and collagen (the most abundant protein in the body), respectively. Under normal feeding conditions, all diet- and rumen-derived Glu and Gln are extensively utilized by the small intestine and do not enter the portal circulation. Thus, de novo synthesis (e.g., from branched-chain amino acids and α-ketoglutarate) plays a crucial role in the homeostasis of Glu and Gln in the whole body but may be insufficient for maximal growth performance, production (e.g., lactation and pregnancy), and optimal health (particularly intestinal health) in ruminants. This applies to all types of feeding systems used around the world (e.g., rearing on a milk replacer before weaning, pasture-based production, and total mixed rations). Dietary supplementation with the appropriate doses of Glu or Gln [e.g., 0.5 or 1 g/kg body weight (BW)/day, respectively] can safely improve the digestive, endocrine, and reproduction functions of ruminants to enhance their productivity. Both Glu and Gln are truly functional amino acids in the nutrition of ruminants and hold great promise for improving their health and productivity.

Effect of parenteral administration of glutamine on autophagy of liver cell and immune responses in weaned calves

The objectives of this study were to determine the effects of an increased jugular supply of L-Gln on post-weaning growth, immune responses, intestinal morphology and autophagy of weaned calves. At 35 days of age, 24 Holstein calves (initial 50 ± 1.5 kg; 35 ± 2 day of age) were randomly allocated to four treatments, and each treatment included five male and one female calves. Holstein calves were assigned to treatments of (i) i.v. infusion of 2 l of 0.85% NaCl, Control group [C]; (ii) i.v. infusion of 8 g/day of L-Gln mixed with 2 l of 0.85% NaCl solution [L]; (iii) i.v. infusion of 16 g/day of L-Gln mixed with 2 l of 0.85% NaCl solution [M]; and (iv) i.v. infusion of 32 g/day of L-Gln mixed with 2 l of 0.85% NaCl [H]; The infusion was 2 h/day for each of 14 consecutive days starting on day 1 after weaning. Feed and water were freely available to all calves. All calves were killed on the 14th day post-weaning for measurements of autophagy of liver cell and intestinal morphology. Gln has no effect on dry matter intake (DMI) and average daily gain (ADG). Gln infusion increased quadratically the abundance of CD4+, monocyte and the ratio of CD4+/CD8+. The urea N, Gln and Glucose in plasma increased linearly with increasing Gln loads. Gln infusion increased quadratically villus height and crypt depth of intestine. The autophagy level of liver cell was improved with the Gln infusion dose increased.

Treatment of calf diarrhea: antimicrobial and ancillary treatments

Adjunct treatment of diarrhea should be routinely undertaken in all calves with systemic signs of illness, manifest as fever, inappetance, or lethargy. Ancillary treatments with documented efficacy in undifferentiated calf diarrhea include parenteral administration of antimicrobials with a predominantly gram negative spectrum of activity, parenteral administration of non-steroidal anti-inflammatory agents such as meloxicam and flunixin meglumine, and continued feeding of cow's milk. Halofuginone and azithromycin have efficacy in calves with diarrhea due to Cryptosporidium parvum, and their administration should be considered in calves documented or suspected to have cryptosporidiosis.

Supplementation of 1% l-Glutamine to Milk Replacer Does Not Overcome the Growth Depression in Calves Caused by Soy Protein Concentrate

Glutamine, an important fuel and biosynthetic precursor in intestinal epithelial cells, helps maintain intestinal integrity and function when supplemented to the diet of many species. The hypothesis tested here was that glutamine supplementation would overcome the decreased average daily gain (ADG) and altered intestinal morphology caused by milk replacer containing soy protein concentrate (SPC). Holstein calves (9 male and 1 freemartin female per treatment) were assigned to diets of 1) all-milk-protein (from whey proteins) milk replacer, 2) milk replacer with 60% milk protein replacement from SPC, and 3) SPC milk replacer as in diet 2 plus 1% (dry basis) l-glutamine. Milk replacers were reconstituted to 12.5% solids and were fed at 10% of body weight from d 3 to 10 of age, and at 12% of body weight (adjusted weekly) from d 10 through 4 wk of age. No dry feed (starter) was fed, but water was freely available. Glutamine was added at each feeding to reconstituted milk replacer. Five calves from each treatment were slaughtered at the end of wk 4 for measurements of intestinal morphology. The ADG was greater for calves fed the all-milk control than for those fed SPC; glutamine did not improve ADG (0.344, 0.281, and 0.282 kg/d for diets 1 to 3, respectively). Intake of protein was adequate for all groups and did not explain the lower growth for calves fed SPC. Villus height and crypt depth did not differ among treatments in the duodenum. In the jejunum, villus height (713, 506, and 464 mum, for diets 1 to 3, respectively) and crypt depth (300, 209, and 229 mum, respectively) were greater for calves fed all milk protein than for either SPC group. In the ileum, villus height was greater for calves fed all milk than for either soy group (532, 458, and 456 mum), whereas crypt depth tended to be greater (352, 301, and 383 mum for diets 1 to 3, respectively), and the villus to crypt ratio was lower for calves supplemented with glutamine than for those fed SPC alone. Urea N concentration in plasma was greater for calves supplemented with glutamine than for those fed SPC alone, indicating that glutamine was at least partially catabolized. Supplemental l-glutamine did not improve growth or intestinal morphology of calves fed milk replacer containing SPC.

Why has oral rehydration for calves and children diverged: direct vs. indirect criteria of efficacy

Oral rehydration therapy (ORT) for acute diarrhoea has advanced in contrary directions in humans and animals; the unresolved question is whether this reflects species differences or a divergence in scientific outlook. This review suggests that the explanation lies in the fact that developments in veterinary ORT have the advantage of utilising more reliable criteria than those available from human patients. The dilemma for human ORT is that the validity of systematic reviews and meta-analyses are undermined when the underlying data only reflect crucial variables indirectly and unreliably. It is therefore possible that the approaches currently used to treat calves, which are radically different from those used by paediatricians, could potentially benefit children and the necessary additional research should be initiated. At a time when the value of animal models of human disease is frequently questioned, the benefits of being able to utilise disease models in the target species for clinical research deserve to be emphasised.

Comparative clinical science: The medicine of the future

This review explores the emergence of Comparative Medicine in the late 19th Century as 'the medicine of the future', its failure to realise these expectations during the 20th century as it became increasingly equated with laboratory animal models of human disease, and explains why there is now an unprecedented opportunity for this latent potential to be fully realised. Comparative medicine no longer rests on apparent similarities between disease mechanisms in different species but on the rapidly maturing ability to relate these similarities to a remarkably rich shared genetic heritage. In the United Kingdom, the creation of the new Medical Research Council Comparative Clinical Science Panel, once securely funded, will provide the infrastructure and strategic focus to foster comparative clinical research, encouraging collaboration between veterinary and human medicine and between investigators in institutes and in practice. This will generate the necessary evidence base for veterinary practice, raise the standard of veterinary research, broaden the horizons of human medicine and create real opportunities for veterinary surgeons to reconcile research with practice. The review explores the broad scope of the science which will flourish in this new environment and examines specific areas in greater depth as examples, notably multifactorial disease such as hypertension and diarrhoea, also aspects of comparative endocrinology and oncology, with emphasis on the growing power conferred by comparative molecular genetics.

Alanyl-glutamine hastens morphologic recovery from 5-fluorouracil-induced mucositis in mice

OBJECTIVE

In this study, we postulated the beneficial role of oral alanyl-glutamine, a more stable glutamine derivative to decrease 5-fluorouracil (5-FU)-induced mucositis in mice.

METHODS

We measured different morphologic parameters to assess structural changes over time in the small bowel, including crypt depth, villus height, villus area, mitotic and apoptotic indices at the crypt level using terminal deoxyuridine triphosphate nick end labeling, and hematoxylin-eosin staining of ileal tissue. In addition, we analyzed the effect of different alanyl-glutamine concentrations on animal weight curves after 5-FU treatment.

RESULTS

Neither glutamine nor alanyl- glutamine prevented the 5-FU intestinal structural damage or apoptosis in crypt enterocytes at 24 h after 5-FU challenge. However, we found that alanyl-glutamine, but not glutamine, speeds intestinal recovery when compared with 5-FU-treated controls (P < 0.05), predominantly by enhancing mitotic activity and crypt length.

CONCLUSION

Our findings provide important data to support clinical studies of oral alanyl-glutamine in 5-FU-induced mucositis.

Glutamine and the gastrointestinal tract

The amino acid glutamine has become one of the most intensively studied nutrients in the field of nutrition and metabolic support. A variety of studies in cell culture systems, animal models of gut mucosal atrophy, injury/repair and adaptation and a limited number of clinical trials demonstrate trophic and cytoprotective effects of glutamine in small bowel and colonic mucosal cells. Although the routine clinical use of glutamine-enriched parenteral and enteral nutrient solutions remains controversial, available data demonstrate both the safety and metabolic and clinical efficacy of glutamine treatment in selected patient groups. Basic investigations are elucidating underlying mechanisms of glutamine action in intestinal cells. These will inform preclinical and clinical investigations designed to determine glutamine efficacy in selected gastrointestinal disorders. Emerging clinical trials will further define the utility of adjunctive glutamine supplementation as a component of specialized nutrition support in gastrointestinal disease.

Oral rehydration solution therapy in the management of children with rotavirus diarrhea

Rotavirus infections are the most common cause of gastroenteritis among children younger than 3 years of age and are associated with sporadic outbreaks of diarrhea in elderly and immunocompromised patients. Oral rehydration solutions (ORS) are formulated to correct dehydration and acidosis. Currently, ORS do not promote intestinal healing; however, investigators are examining the role of nutrition in promoting intestinal healing. This article reviews the composition of several ORS in human medicine and summarizes our current knowledge of the nutritional treatment of rotavirus diarrhea and intestinal healing.

Oral electrolyte therapy

Diarrhea is a common condition in neonatal calves and can be caused by a wide variety of infections and noxious agents. Oral electrolyte therapy is a simple and economical method of treating diarrheic calves. Oral electrolyte solutions can correct dehydration and acidosis, and they may also have a role in preventing or alleviating mucosal damage. Indications, the principles of administration, and choosing an electrolyte product are discussed with examples.