The amino acid taurine--physiology and pathophysiology]

In this review, the main aspects of our knowledge of the physiology and pathophysiology of the beta-amino sulfonic acid taurine will be summarized. After shortly considering the chemistry, the occurrence and the metabolism of taurine, the biological functions of taurine in the mammalian organism will be dealt with. With respect to taurine deficiency, this review will be limited to the cat since taurine is an essential nutrient for this species.     

Effects of chronic ingestion of ochratoxin a on blood levels and excretion of the mycotoxin in sheep

Ruminants are relatively resistant to the acutely toxic effects of ochratoxin A, due to extensive degradation of ochratoxin A to its less toxic metabolite ochratoxin alpha by rumen microorganisms. However, most estimates of the degradation capacity for ochratoxin A in ruminants are based on in vitro studies. In the current study, the metabolism of ochratoxin A was investigated over a period of 29 days, feeding various doses of the mycotoxin (0, 9.5, 19.0, and 28.5 mug ochratoxin A/kg body weight) to sheep. Animals were fed diets consisting of 70% concentrates and 30% grass silage. Significant concentrations of undegraded ochratoxin A were detected in serum of sheep at all levels of ochratoxin A tested. Serum concentrations of ochratoxin A slightly accumulated with time of exposure and were linearly dependent on the administered dose of ochratoxin A. Furthermore, a constant proportion (6-8%) of the dose was excreted in the urine. The results of this study indicate that even at moderate to low levels of ochratoxin A in the diet, considerable amounts of the mycotoxin are absorbed by ruminants and may accumulate in tissues. Therefore, feeding of ochratoxin A-contaminated feedstuffs to ruminants does not seem to be a reliable means for using these feedstuffs.     

Oral Bioavailability of Quercetin in Horses

Quercetin, one of the most abundant flavonoids in plants, is discussed with respect to health-promoting effects like antioxidative and anti-inflammatory properties. Although most claims regarding biological effects of flavonoids are based on in vitro and ex vivo studies, the use of flavonoid-containing supplements in humans and companion animals has increased in recent years. Flavonoid-containing supplements are also offered for pet and livestock nutrition. However, any systemic effect of a substance within a living subject depends on its bioavailability. Therefore, the aim of the present study was to gain information on the oral bioavailability of quercetin in horses. Four Icelandic horses with a mean body weight (BW) of 315 ± 25 kg (mean ± standard error [SEM]) were fed a test meal (crimped oats 1 g/kg BW) with the addition of quercetin (20 mg/kg BW). Blood samples were collected directly from the jugular vein before and after ingestion of the test meal for 24 hours, and flavonoid content was analyzed by high-performance liquid chromatography. Quercetin was the main metabolite in plasma with intact flavonol structure after β-glucuronidase/sulfatase treatment of blood samples. The area under the plasma concentration–time curve of quercetin accounted for 88% of total flavonols. Forty-seven percent of the quercetin detected in plasma after ingestion of the test meal was not conjugated. In addition to quercetin, the quercetin derivatives isorhamnetin (methylated) and kaempferol were detected in plasma. Although quercetin is orally bioavailable in horses, similar to other monogastric species, the plasma metabolite pattern differs from those found in species investigated previously (rat, dog, pig, and human).     

Plant Extracts of Winter Savory, Purple Coneflower, Buckwheat and Black Elder Activate PPAR-γ in COS-1 Cells but do not Lower Blood Glucose in Db/db Mice In vivo

The aim of this study was to investigate possible blood glucose-lowering effects of plant extracts in vivo for which prior to this a peroxisome proliferator-activated receptor-γ activity in vitro was observed. The ability of extracts of winter savory, purple coneflower, buckwheat and black elder to dose-dependently activate peroxisome proliferator-activated receptor-γ was determined in a reporter gene assay in COS-1 cells. For evaluation of glucose-lowering effects in vivo, db/db mice were fed a diet containing either rosiglitazone (0.02 g/kg diet, positive control) or one of the plant extracts (0.1 and 1 g/kg diet) for four weeks. Apart from glucose, insulin, triacylglycerols, non-esterified fatty acids, cholesterol and adiponectin were determined in plasma. All plant extracts showed a dose-dependent peroxisome proliferator-activated receptor-γ-activating effect in vitro. In db/db mice none of the plant extracts exerted glucose-lowering effects at the used dosages compared to rosiglitazone. Non-esterified fatty acids, triacylglycerols, cholesterol, insulin and adiponectin in plasma were not altered by the plant extracts as well. Although dose-dependent peroxisome proliferator-activated receptor-γ activity could be shown in COS-1 cells, the experiments in db/db mice lacked to confirm any anti-diabetic effect of the plant extracts in vivo and emphasizes the importance of verifying cell culture data using an appropriate in vivo model.     

Dietary green tea polyphenols do not affect vitamin E status,antioxidant capacity and meat quality of growing pigs

Supplementation of pigs with vitamin E, the most important lipid-soluble antioxidant, has been shown to improve meat quality and animal health. Previous studies in cultured cells and laboratory animals indicate synergistic effects between polyphenols and vitamin E. The present feeding trial was undertaken to investigate the effects of dietary green tea polyphenols (GTP) on vitamin E status, antioxidative capacity and parameters of meat quality in growing pigs. Eighteen castrated, crossbred, male pigs received a flavonoid-poor diet based on corn starch, caseinate and rapeseed oil with a total vitamin E content of 17 IU/kg diet over a period of 5 weeks. This basal diet was supplemented with green tea extract to provide daily doses of 0 (control), 10 and 100 mg GTP/kg body weight. Dietary supplementation of growing pigs with GTP did not affect serum, liver, lung and muscle vitamin E (α- and γ-tocopherol) concentrations, plasma antioxidant capacity (ferric reducing ability of plasma, trolox equivalent antioxidant capacity) or parameters of meat quality including meat temperature, pH, conductivity, colour and drip loss. In conclusion, supplementation of pig diets with green tea catechins is not associated with improved antioxidant status and meat quality under practice-oriented conditions.     

Selenium deficiency in humans and animals--a short review]

This brief review is concerned with the main aspects of our knowledge of a deficiency of the trace element selenium in man and animals. After an introduction about the history of the discovery of selenium as an essential trace element in man and animals a short definition of the term "essential" is given. The following chapters are concerned with the etiology of selenium deficiency, the measurement of selenium status and the biological functions of selenium in mammals. Finally selenium deficiency diseases in man and animals will be discussed.     

Metabolism and excretion of ochratoxin A fed to sheep.

Hydrolysis of the mycotoxin ochratoxin A (OA) to ochratoxin alpha (Oalpha) by microorganisms within the gastrointestinal tract leads to the excretion of OA as the nontoxic alpha form. The Oalpha form is the principal means for the detoxification of OA. In the current experiment, three groups of four sheep were fed diets consisting of 70% concentrates and 30% hay (dry matter basis, energy to supply 1.1 times the requirement for maintenance) for 4 wk with three dietary concentrations of OA (0, 2, or 5 mg/kg of concentrate feed). The OA content did not affect feed intake or nutrient digestibility. In a preliminary experiment, an OA dose of 20 mg/kg of concentrate feed greatly reduced feed intake. After 1, 2, 3, and 4 wk of the trial, significant concentrations of OA were detected in the serum of the animals fed 2 or 5 mg of OA/kg feed. This suggested that even at a dosage of 2 mg of OA/kg of concentrate feed, considerable amounts of OA were not degraded by ruminal and intestinal microorganisms. The analysis of the feces and urine samples reflected these findings; OA and Oalpha were found in significant concentrations, escaping fermentation in the rumen and in the hindgut. The current experiment demonstrates that OA hydrolysis in the gastrointestinal tract of sheep is substantially less than previously described, especially if OA is ingested in combination with concentrate-rich diets.