HPLC法测定怀山药零余子尿囊素的含量

[目的]测定怀山药及零余子中尿囊素成分的含量。[方法]以尿囊素为标准对照品,采用HPLC法在波长224 nm处对怀山药及零余子的尿囊素成分进行含量测定。[结果]平均加标回收率为98.35%,RSD为1.29%;怀山药中尿囊素含量为0.533%,怀山药零余子中尿囊素含量为0.848%;零余子中尿囊素含量略高于怀山药。[结论]该方法简便、易行、准确度高,可用于怀山药零余子中尿囊素成分的含量测定。     

The effect of grain species, processing and time of feeding on the efficiency of feed utilization and microbial protein synthesis in sheep

This study investigated the effect of cereal grain species (sorghum, wheat, oats and barley), extent of processing (cracked barley, finely ground barley, and wet whole barley) and time of feeding (barley grain mixed with ryegrass hay or fed 2 h before hay was fed), on whole tract dry matter digestibility (WTDMD), and microbial protein synthesis (MPS), as a supplement to ryegrass hay when fed to rumen-cannulated sheep.Expected dry matter digestibility (EDMD) in mixtures of cereal grain and ryegrass hay was calculated by interpolation between in vitro dry matter digestibility (DMD) of each grain and the ryegrass hay. These were compared with measured actual WTDMD to detect positive or negative associative effects. Among grain species, the percentage difference in digestibility between actual WTDMD and EDMD was negative at − 6.6% units for wheat but positive at + 2.3%, + 4.3% and + 5.7% units for sorghum, oats, cracked or finely ground barley, respectively.As expected, the supplementation of sheep fed ryegrass hay with different sources of carbohydrates increased urinary allantoin output (as an indicator of MPS) when compared to sheep fed ryegrass hay alone. The concentration of urinary allantoin was significantly higher in sheep supplemented with sorghum (1916 mg/sheep/day) than wheat, oats or cracked barley ([mean ± S.E.M.] 1451 ± 24 mg/sheep/day) grain. There was a significantly higher urinary allantoin concentration in sheep fed cracked barley compared to finely ground barley or wet whole barley (1479 vs. 1095 vs. 1031 mg/sheep/day, respectively). There was no significant (P > 0.05) difference in urinary allantoin output, expressed as output/kg DM intake, when cracked barley was mixed and fed with the hay or fed 2 h before hay. However, in terms of total output of allantoin this was significantly higher (P < 0.05) (1479 vs. 1209 mg/sheep/day).In sacco degradability characteristics of organic matter and nitrogen for sorghum, oats, wheat, barley at different levels of processing and for ryegrass hay were also measured in the rumen of cannulated sheep.Among grain species, wheat had the highest effective organic matter degradability in the rumen (78.1%) while sorghum had the lowest. The effective degradability of protein of finely ground barley in the rumen was found to be higher than cracked barley or wet whole barley.Wheat grain, being highly degradable in the rumen, had a negative effect on WTDMD. In contrast, sorghum grain, being more slowly degradable in the rumen, would be expected to provide a substantially increased supply of energy to microbes over time in the rumen for MPS.Both cracked barley and finely ground barley also had a positive associative effect on WTDMD when fed with ryegrass increasing it by 5.7% units. The MPS was significantly higher (P < 0.05) in sheep fed cracked barley compared to finely ground barley or wet whole barley. This supports the hypothesis that slowly degrading carbohydrate sources synchronise more closely with available N from degradation of forage in the rumen.     

Molybdenum as an essential element for improving total yield in seawater-grown Salicornia europaea L.

The growth of crop plants on full-strength seawater constitutes a major challenge because of the high salt content and the limited availability of essential microelements such as molybdenum. For cultivation of the halophyte Salicornia as seawater-grown crop, the effect of molybdate application on total yield production and the activities of the two molybdenum containing enzymes, nitrate reductase (NR) and xanthine dehydrogenase (XDH) was investigated. Increasing molybdate levels in the growth medium supplemented with nitrate or ammonium enhanced yield during multiple shoot removal. Similarly, NR and XDH activities were enhanced with increasing molybdate, indicating that the activity of both enzymes may play an important role in facilitating yield accumulation. Notably, XDH activity in the roots was high and the levels of ureides were low, whereas in the shoot tips ureides were higher and XDH activity was lower. Considering that XDH is a key enzyme in the biosynthesis of the low C/N ratio ureides, these suggest a source–sink relationship between the roots and shoot tips for efficient transport of root-generated ureides to the young growing shoot tips. Our results imply that the supply of molybdenum to Salicornia grown in seawater enhances plant biomass accumulation by increasing the activities of NR and XDH, thereby stimulating a more efficient remobilization of ureides to the newly grown shoot tips after periodic shoot removal.     

Proportions of potatoes and fodder beets selected by dairy cows and the effects of feed choice on nitrogen metabolism

Twenty-three lactating dairy cows were switched from a standard diet to a ration of alfalfa/grass silage and 1 kg rapeseed cake supplemented with raw potatoes and fodder beets allowed on a semi-restricted basis. The effects of feed choice on urinary markers for nitrogen metabolism were evaluated by the Stepwise regression technique. Each kilogram dry matter of potatoes and fodder beets lowered milk urea concentration and also the urinary ratio urea/creatinine to a similar extent, but allantoin and fecal results suggested larger hindgut fermentation and hence lower ruminal microbial protein production with potatoes than with fodder beets. The variation for concentration of urinary constituents associated with animal, sampling day and sampling time suggests multiple sampling within a day as preferable for spot sampling. It is concluded that the reluctance to potatoes by some cows may cause initial difficulties when fed to high yielding cows naïve to the feed.     

Urinary purine derivates excretion as an indicator of in vivo microbial N flow in cattle: A review

Microbial protein flow to the duodenum may be regarded as the most important and sensitive indicator to optimise rumen metabolism in high-yielding dairy cows. In this review, the methodology and the sources of variation to estimate the duodenal microbial N flow with urinary excretion of purine derivatives (PD) as a non-invasive method is discussed. The urinary PD excretion was linearly related with the amount of purine bases (PB) infused in the abomasum or duodenum, but the recovery of PB in urine differed between experiments. The main sources of variation in the relationship between microbial N flow and urinary PD excretion are dietary contribution of nucleic acids to duodenal flow, varying N:purine ratio in duodenal digesta, differences in intestinal digestibility of nucleic acids and infused PB, and endogenous contribution of PD to urinary excretion. The recycling of PD to the rumen is negligible, and does not explain the incomplete urinary recovery of PD. A large proportion of the total PD is excreted as allantoin in urine. In some experiments this proportion was constant, whereas in others it varied with diet or physiological state of the animal. The excretion of PD in milk is not a suitable indicator of microbial N flow, due to mammary purine catabolism to uric acid and due to the strong positive correlation between milk allantoin excretion and milk yield. Instead of total urine collection, the molar ratio between urinary PD and creatinine can be used to estimate microbial N flow. However, a substantial between-animal variation in this ratio was found, and effects of changes in energy balance of dairy cows on urinary creatinine excretion should be determined. The urinary excretion of total PD and of allantoin provided lower estimates of duodenal microbial N flow than with measurements in the omasum or duodenum, but they closely reflected the changes observed with these measurements.     

盐生肉苁蓉中2种水溶性成分的薄层色谱鉴别

[目的]建立盐生肉苁蓉药材中2种水溶性成分尿囊素和半乳糖醇的薄层色谱分析方法。[方法]采用硅胶G薄层板,分别对乙酸乙酯∶丙酮∶甲酸、氯仿∶异丙醇∶乙酸等6种不同的展开剂及25%对二氨基苯甲醛、10%硫酸乙醇、3%酸性高锰酸钾溶液、10%香草醛浓硫酸4种不同的显色剂进行考察,确定盐生肉苁蓉提取物中尿囊素、半乳糖醇的最佳薄层分析条件,并对不同产地盐生肉苁蓉中的2种成分进行鉴定。[结果]尿囊素的展开剂为乙酸乙酯∶丙酮∶甲酸(8∶1∶3),显色剂为25%对二氨基苯甲醛溶液;半乳糖醇的展开剂为乙酸乙酯∶异丙醇∶水∶甲酸(3∶4∶2∶1),显色剂为3%酸性高锰酸钾溶液。不同产地盐生肉苁蓉中均含有尿囊素和半乳糖醇。[结论]该方法快速简便、专属性强、重现性好,可快速鉴别肉苁蓉药材,是全面控制和评价盐生肉苁蓉药材质量的重要补充。     

尿囊素对小麦幼苗光合功能的影响

小麦种子经尿囊素浸种处理,幼苗气孔增多,开度增大;叶绿体变宽基础片层间隙增大。悄囊素处理提高幼苗光合色素含量和净化合率,增强ＲｕＢｐ强化酶活性。尿囊素对非环式光合磷酸化和电子传递活力有促进作用;但对Ｍｇ＾２＋－ＡＴＰ酶水解ＡＴＰ活性有抑制作用,对环式光合磷酸化无影响。