Renal energy excretion of horses depends on renal hippuric acid and nitrogen excretion

The prediction of renal energy excretion is crucial in a metabolizable energy system for horses. Phenolic acids from forage cell walls may affect renal energy losses by increasing hippuric acid excretion. Therefore, the relationships were investigated between renal energy, nitrogen (N) and hippuric acid excretion of four adult ponies (230–384 kg body weight (BW)) consuming diets based on fresh grass, grass silage, grass cobs (heat‐dried, finely chopped, pressed grass), alfalfa hay, straw, extruded straw and soybean meal. Feed intake was measured; urine and faeces were quantitatively collected for three days. Feed was analysed for crude nutrients, gross energy, amino acids and neutral‐detergent‐insoluble crude protein (CP); faeces were analysed for crude nutrients and cross energy; urine was analysed for N, hippuric acid, creatinine and gross energy. Renal energy excretion (y; kJ/kg BW^0.75) correlated with renal N excretion (x₁; g/kg BW^0.75) and renal hippuric acid excretion (x₂; g/kg BW^0.75): y = 14.4 + 30.2x₁+20.7x₂ (r = .95; n = 30; p < .05). Renal hippuric acid excretion was highest after intake of fresh grass and lowest after intake of soybean meal. The ratio of hippuric acid to creatinine in urine and the excretion of hippuric acid per gram of dry matter intake was significantly higher for fresh grass than for all other rations. There was no relationship between aromatic amino acid intake and renal hippuric acid excretion. The results of the present study and literature data suggest that feed can be categorized into four groups with regard to the energy losses per gram CP intake: (i) protein supplements (e.g., soybean meal): 4.2–4.9 kJ/g CP intake (ii) alfalfa hay, grains, dried sugar beet pulp: 6.4 kJ/g CP intake, (iii) hay, preserved grass products, straw: 5.2–12.3 kJ/g CP intake (mean 8) and (iv) fresh grass. For group (iii) a negative relationship was observed between renal energy losses per gram of CP and the content of CP or neutral‐detergent‐insoluble CP in dry matter.     

Phosphorus excretion by mares post-lactation

Across the equine literature, estimates of true P digestibility range from −23% to 79%. This large range cannot be explained by differences in P intake or phytate-P intake alone. However, differences in endogenous P secretion into the GI tract may explain the variation. In horses, excess absorbed P is not excreted in the urine but is re-secreted into the GI tract, increasing faecal P and leading to estimates of low P digestibility. Thus, accurate estimates of P digestibility can only be obtained if absorbed P is retained in the horse. The objective of this study was to examine P digestibility in post-lactational mares and control mares that were fed similar amounts of P. It was hypothesized that post-lactational mares would have greater P retention and higher apparent P digestibility than control mares. Prior to the study, four lactating and four non-lactating mares were fed a diet that provided 100% of the control mares’ P requirement, but only 55% of the lactating mares’ P requirement. During the study, both groups were fed P at the rate recommended for non-lactating mares. Post-lactational mares did not retain more P than control mares but tended to excrete more P than control mares (p = .082), presumably due to differences in endogenous P secretion into the GI tract. Metabolic changes occurring during mammary gland involution may have contributed to the increase in P excretion. However, faecal P excretion exceeded P intake in both groups (p = .08) and both groups lost weight during the study. Tissue mobilization during weight loss may have influenced P secretion into the GI tract.     

国产克洛素隆尿药排泄数据分析

应用Kromasil-C18色谱柱(250 mm×4.6 mm,5 μm),WatersTM480型可调波长紫外检测器,0.01M磷酸钾(pH=7):乙腈(3:1)为流动相,检测波长265 nm,含量测定采用标准曲线法,建立了RP-HPLC法检测绵羊尿中克洛素隆含量的方法.方法有效性评价结果表明,尿药含量在0.01～5.0μg/ml及5.0～30.0μg/ml范围呈良好线形关系(r=0.9993、0.9995),方法平均回收率99.32%,日内、日间变异系数分别为3.91%、6.28%.尿药最低检测限0.005μg/ml.试验绵羊以7 mg/kg单剂量经静脉、肌肉及口服三种途径给药后,尿中药物浓度分析表明,克洛素隆经体内处理后主要经肾脏排泄,给药96 h内,静注经尿排泄原药为81.76%,肌注为64.03%,口服为48.50%.     

Persistent excretion of rotavirus by pregnant cows

In a study of the epizootiology and prevalence of enteropathogens which may be involved in neonatal calf diarrhoea, 10 in-calf cows from a herd with a history of rotavirus-induced calf diarrhoea were monitored over a period of six to seven months. All the cows excreted rotavirus intermittently without showing any clinical signs, and 21.8 per cent of faecal samples contained rotavirus. Reoviruses were isolated from 87 per cent of the samples from the cows, and from all the 10 calves born to them. However, rotavirus was detected in only one calf, and diarrhoea developed only in this calf even though the calves were housed in communal pens. Campylobacter jejuni was isolated from six of the 10 dams and from five of the 10 calves, not including the calf with diarrhoea. Other potential enteropathogens such as cryptosporidium, salmonella, Clostridium difficile, coronavirus and other viruses were not found, but two cows and two calves shed enterotoxigenic Escherichia coli.     

D-lactate production and excretion in diarrheic calves

The origin of D-lactate, the most important acid contributing to metabolic acidosis in the diarrheic calf, is unknown. We hypothesized that because D-lactate is produced only by microbes, gastrointestinal fermentation is the source. The objective of this study was to determine whether D-lactate production occurs in the rumen, colon, or both, and to measure D- and L-lactate concentrations in urine. Fecal, rumen, blood, and urine samples were obtained from 16 diarrheic and 11 healthy calves. Serum electrolyte concentrations were measured in both groups, and blood gas analyses were performed for diarrheic calves. All samples were analyzed for D- and L-lactate by high performance liquid chromatography (HPLC). Diarrheic calves were generally hyperkalemic with high serum anion gap, depressed serum bicarbonate, and low blood pH. L-lactate was markedly higher in rumen contents (22.7 mmol/ L [median]) and feces (8.6 mmol/L) of diarrheic calves than healthy calves (0.5 mmol/L and 5.1 mmol/L, respectively), but not different in serum or urine. Rumen, fecal, serum, and urine D-lactate concentrations were all significantly higher (P < .05) in diarrheic calves (17.0, 25.4, 13.9, and 19.2 mmol/L, respectively) than in healthy calves (0.5, 9.1, 1.4, and 0.5 mmol/L, respectively). Higher D-lactate concentrations in the rumen and feces of diarrheic calves suggests these sites as the source of D-lactate in blood and urine.     

Urinary pseudouridine excretion in lactating dairy cows

Introduction   A number of systems based on metabolizable protein, such as that adopted in the UK (A gricultural and F ood R esearch C ouncil 1992) have been developed to improve the accuracy of protein rationing for ruminants. Quantification of microbial protein synthesis in the rumen is a fundamental requirement of all such systems. In the UK system, microbial protein supply is predicted from an estimate of fermentable metabolizable energy intake, using a correction for the effects of level of feeding on the energetic efficiency of microbial protein synthesis. Use of such an approach is however subject to considerable error due to large variations in the energetic efficiency of microbial protein synthesis (A gricultural R esearch C ouncil 1984). Consequently there is an urgent requirement for an on-farm diagnostic marker of microbial protein supply as a basis for adjusting diets to maximize efficiency of dietary nitrogen utilization by dairy cows (D ewhurst et al. 1996). Urinary purine derivative excretion has been proposed as a noninvasive index of microbial protein supply in ruminant animals (T opps and E lliot 1965). Use of this microbial marker is based on the assumption that purines entering the duodenum are essentially microbial in origin (M c A llan 1982), and that following metabolism, their derivatives are quantitatively recovered in the urine (C hen et al. 1990; V erbic et al. 1990). Purine metabolites excreted in ruminant urine are primarily derived from the metabolism of absorbed purines, but as a consequence of tissue adenosine triphosphate and nucleic acid turnover, a proportion of purine bases are not salvaged and re-utilized, but enter catabolic pathways, constituting an endogenous loss.     

Campylobacter infection and Campylobacter excretion in turkeys

Five turkey poults at an age of 27 days were infected with Campylobacter jejuni strain. Additional five poults were infected by contact. Turkeys infected by contact and artificially were necropsied 1 and 3 months later, respectively. The histological examination of the liver revealed degenerative changes in contact birds and a proliferation of the connective tissue and bile-ducts in two of the oral infected poults. Campylobacter spp. were excreted daily during the first two weeks and afterwards with interruptions of several days. The excretion lasted until the end of the experiment between day 86 and 98. The excretion period, which is prolonged compared with that of chickens may be of particular importance under aspects of epizootiology and food hygiene.     

Biliverdin and bilirubin excretion in the turkey.

Mean endogenous bile flow in 11 turkeys was 0.81 plus or minus 0.52 mul/g of the liver per minute (10.4 plus or minus 5.3 mul/Kg of body weight per minute). Endogenous biliverdin and bilirubin excretory rates were 0.59 plus or minus 0.31 and 0.058 plus or minus 0.018 mug/g of liver per minute (7.6 plus or minus 3.6 and 0.76 plus or minus 0.23 mug/Kg of body weight per minute), respectively. Mean concentrations of biliverdin and bilirubin in endogenous bile were 92 plus or minus 55 and 8.9 plus or minus 5.2 mg/100 ml, respectively. Livers constituted 1.36 plus or minus 0.22 percent of the body weight. Thin layer chromatographic studies revealed a heterogeneity of bilirubin conjugates in bile.     

Renal and mammary excretion of sulfadimidine in buffaloes

The renal and mammary excretion of sulfadimidine was investigated in 8 lactating buffaloes after intravenous administration. The results showed that sulfadimidine was bound to the proteins in plasma (39--59 per cent) and milk (5.5 per cent). The renal handling of sulfadimidine was influenced by the variations in the urinary pH and the concentration of non-protein-bound drug. From the results it is concluded that glomerular filtration, back diffusion and active tubular secretion are involved in the renal handling of sulfadimidine in buffaloes. The results of mammary excretion showed that sulfadimidine is excreted into milk of buffaloes in concentration lower than in plasma. The ratio between the concentration of sulfadimidine in milk and plasma increases when the pH of milk increases. The results are consistant with the theory that drugs are excreted through the mammary gland by passive diffusion.