Watering cattle (young bulls) with brackish water--a hazard due to its salt content?

OBJECTIVE: The aim of this experimental study was primarily to test the effects and reactions of cattle offered salty water as the only source of drinking water. MATERIAL AND METHODS: Mineral balance studies were carried out on three bull, continuously fed a ration based on hay, hay cobs, barley, soybean meal and a vitamin/mineral supplement. The salt content of the drinking water varied between the trials (trials I/II/III: 0.10/5.00/10.0 g/l; town water supplemented by different amounts of an additive containing 95.4% sodium chloride and 4.6% potassium chloride). RESULTS: Rising salt concentration of the drinking water led to significantly higher sodium, potassium and chloride intake (sodium: trial I/II/III = 5.42/59.5/ 157 g/day; potassium: trials I/II/III = 108/117/121 g/day; chloride: trials I/II/III = 22.8/112/266 g/day) mainly caused by a significantly higher water intake (trials I/II/III: 21.8 ± 2.03/30.4 ± 3.08/41.5 ± 5.89 kg/day). Amounts of urine increased significantly (trials I/II/III: 3.99 ± 0.46/ 9.66 ± 1.34/20.2 ± 3.14 kg/day). The concentrations of minerals in the urine (sodium: trials I/II/III = 123/3729/6705 mg/kg; potassium: trials I/II/III = 17345/9996/ 5496 mg/kg; chloride: trials I/II/III = 2020/ 9672/11870 mg/kg) and faeces (sodium: trials I/II/III = 1299/6544/ 7653 mg/kg; potassium: trials I/II/III = 6343/3719/3490 mg/kg; chloride: trials I/II/III = 3851/4580/4693 mg/kg) also changed significantly over time. Serum values of sodium tended to decrease (trials I/II/III: 142/137/137 mmol/l) within the physiological range, whereas those of chloride increased (trials I/II/III: 91.5/95.6/97.5 mmol/l) at higher salt concentrations in drinking water. The haematocrit, pH-value as well as urea content in blood were not affected by the higher salt intake. In balance trial III (highest salt load: 10.0 g/l), sodium intake of the bulls reached 0.57 ± 0.03 g/kg BW (~22.1 ± 0.9 g sodium/kg dry matter feed). CONCLUSION AND CLINICAL RELEVANCE: An increase of salinity in drinking water up to 10 g/l--with otherwise harmless water quality--had no measurable negative effects on animal health in the investigation period and subsequent periods (total of 58 days with more than 5.00 g of salt per litre drinking water).

The pyruvate dehydrogenase complex from thermophilic organisms: thermal stability and re-association from the enzyme components.

Examples of pyruvate dehydrogenase complexes, and of its probable precursors, the pyruvate ferredoxin oxidoreductases, both isolated from thermophilic organisms, are described. The pyruvate ferredoxin oxidoreductases are mostly characterized from thermophilic archaea like Sulfolobus solfataricus and Pyrococcus furiosus. They retain their catalytic activity up to 60 and 90 degreesC, respectively. Characteristic for the thermophilic nature is a biphasic temperature behavior, reflecting a more stable low temperature and a metastable high temperature form. Another feature is the strong binding of the cofactor thiamin diphosphate. Detailed analysis of thermostable pyruvate dehydrogenase complexes so far only exist for the enzymes from Bacillus stearothermophilus and Thermus flavus. In most respects, especially in the structural features, the enzyme complex from B. stearothermophilus resembles its mesophilic counterparts and only an elevated temperature maximum for the catalytic activity reveals the thermophilic nature. In contrast to this, the more thermostable enzyme complex from T. flavus shows a quite distinct behavior. One single protein chain (Mr=100 kDa) instead of an alpha2beta2 aggregate was found for the pyruvate dehydrogenase (E1) subunits of this enzyme complex. Its catalytic activity is controlled by allosteric regulation, while the enzyme complex from B. stearothermophilus shows no such regulation. Reversible phosphorylation as a regulatory principle of pyruvate dehydrogenase complexes from higher organisms does not take place in the thermophilic enzyme complexes. The overall activity of the enzyme complex from B. stearothermophilus remains stable at 60 degreesC for 50 min while that from T. flavus is active up to 83 degreesC. Thermophilic pyruvate dehydrogenase complexes do not spontaneously renature from their separated enzyme components. However, chaperonins from Thermus thermophilus stimulate the reactivation of the enzyme complex from T. flavus.