兽药使用环节存在的问题及对策

经过对兽药生产厂家和经营企业几年的整治,尤其是新<兽药管理条例>和<兽药标签和说明书管理办法>出台后,又经过GMP认证,兽药生产经营市场秩序和经营行为得到了一定的规范.但兽药使用环节中却存在诸多的问题,如:违法使用人用药品;违法使用禁用兽药;不执行休药期规定;未建立台帐等等.这些问题的存在,直接导致了动物产品的安全性问题.对此,笔者分析了兽药使用环节存在问题的原因,并对解决这些问题提出了个人观点.     

应用绵羊粪便的近红外光谱方程评定其日粮的可消化有机物

利用近红外光谱法 (NIRS)对绵羊粪便的扫描值和日粮的体内测定值来建立定标方程式。以绵羊为试验动物 ,日粮主要由各种牧草、作物秸秆和棉花籽壳组成 ,试验动物日粮设计了 78个蛋白水平。在 2 0 0 2年和 2 0 0 3年分别用 15只和 2 0只成熟母羊 (体重为 5 5± 2 .4kg)进行了为期 7周的实验。体内收粪法测定出的日粮可消化有机物(DOM)水平为 5 2 .4 %至 75 .8% ,日粮的可消化有机物的定标方程式决定系数r2 =0 .80 ,定标标准误差SEC =1.5 1。随机选取 2 0 0 3年试验第 3周第 7d的 10个粪便样品利用可消化有机物定标方程预测其日粮的可消化有机物 ,其结果是决定系数r2 =0 .94 5 ,预测标准误差SEP =0 .5 5 2 ,斜率Slope =1.0 83,表明利用近红外光谱法 (NIRS)对粪便的扫描值可以有效预测绵羊日粮的可消化有机物     

正交试验法优化普抗合剂制备工艺

以干浸膏得率和黄芩苷提取率为考核指标,采用正交试验法对普抗合剂水提取醇沉淀制备工艺进行考察.普抗合剂最佳制备工艺方案为加水量10倍,提取2次,每次1 h,55%的乙醇沉淀杂质 .该工艺科学合理,适合于大规模工业生产.     

C型肉毒梭菌肉毒毒素的提取与鉴定

[目的]通过对C型肉毒梭菌肉毒毒素的提取与鉴定,为类毒素和抗毒素的制备及抗原性分析奠定基础.[方法]将分离鉴定得到的C型肉毒梭菌通过扩大培养、产毒培养后将产生的肉毒毒素采用除菌过滤、硫酸铵盐盐析、离心、透析、浓缩的方法从产毒培养基中分离提取出来.再将提取的肉毒毒素通过SDS-PAGE鉴定毒素蛋白的分子量.[结果]分离出来的毒素蛋白重链和轻链分别在98和53 KDa左右,与C型肉毒毒素的理论分子量相符.[结论]提取的肉毒毒素是C型肉毒毒素.     

Effect of Previous Experience on Grazing Patterns and Diet Selection of Brangus Cows in the Chihuahuan Desert

The ability to adapt to different environments is critical when livestock are moved because of drought or other management considerations. The impact of previous experience on grazing patterns and diet selection of Brangus cows in desert conditions was evaluated. Cows originating from a humid-subtropical environment (Leona, Texas) were brought to the Chihuahuan Desert (naïve) and evaluated against cows that spent their life in the Chihuahuan Desert (native) and cows that were born and raised in the Chihuahuan Desert but were moved to Leona, Texas during the preceding 3 yr (tourist). In addition, native cows with recent experience in desert conditions were compared with naïve cows and tourist cows that had not been in the Chihuahuan Desert for at least 3 yr. All cows were mature and had similar pedigrees (n = 21). Cows from the three groups were tracked in three extensive pastures (> 1 000 ha) for three 8–10-d periods during winter, early summer, and later summer. Cows never grazed in the experimental pastures before the study, but native and tourist cows had grazed adjacent pastures. Fecal near-infrared spectroscopy was used to estimate diet quality. Naïve cows used 335 ha ± 83 standard error (SE) less area (P = 0.06) and were 479 m ± 105 SE closer to water (P = 0.03) than cows born and raised in the Chihuahuan Desert (native and tourist cows pooled) when first evaluated in winter. After pooling all data, native cows were farther (P = 0.06) from water (730 m ± 283 SE) and spent less time at water (10.53% ± 3.93 SE) than cows that did not spend their entire life in the desert (naïve and tourist pooled). During winter and early summer (drought conditions), naïve cows selected diets with lower (P < 0.05) crude protein (CP) than cows born in the desert, but during late summer after abundant precipitation naïve cows selected a diet with higher (P = 0.07) CP. Although Brangus cows are highly adaptable, animals raised in nearby pastures appear to have advantages over naïve animals when grazing Chihuahuan Desert rangeland.     

Thermal inactivation of ricin using infant formula as a food matrix

Ricin is a potent protein toxin found in the seeds of the castor bean plant, Ricinus communis. Ricin specifically and irreversibly inactivates ribosomes, promoting cell death by inhibiting protein synthesis. It is composed of a ribosome-inactivating enzyme (A-chain) linked to a lectin (B-chain) by a single disulfide bond. Several reports indicate that ricin can be detoxified by thermal treatment; however, the conditions required for inactivation are not well characterized. In addition, little information exists on the thermal stability of ricin added to foods. The objective of this work was to determine the effects of heat treatments on the detection and toxicity of ricin added to milk- and soy-based infant formulas. Reconstituted infant formula powders containing 100 mug of ricin/mL were heated at 60-90 degrees C for up to 5 h. The heat-treated formulas were analyzed by ELISA to determine levels of ricin. The residual cytotoxicity of ricin-containing infant formula after heat treatments was determined using RAW264.7 mouse macrophage cells. The ELISA and the cytotoxicity assay indicated that ricin detection and toxicity decreased with increasing heating times and temperatures. Minimal losses in detection and toxicity were found for ricin heated at 60 degrees C for 2 h. The half-lives of ricin cytoxic activity in a milk-based infant formula at 60, 70, 75, 80, 85, and 90 degrees C were >100, 9.8 +/- 0.5, 5.8 +/- 0.9, 5.1 +/- 0.7, 3.1 +/- 0.4, and 1.8 +/- 0.2 min, respectively; the comparable values for a soy-based infant formula were >100, 16 +/- 1.6, 8.7 +/- 1.2, 6.9 +/- 1.1, 3.0 +/- 0.4, and 2.0 +/- 0.3 min. ELISA detection was a good indicator of the cytotoxicity of heat-treated ricin. The results indicate that ricin is a relatively heat stable protein and may remain toxic under some food processing conditions.     

Expression of Occludin in Testis and Epididymis of Wild Rabbits, Lepus sinensis coreanus

Tight junctions (TJs) in inter-Sertoli junctional areas and epididymal epithelia build up the blood–testis barrier (BTB) and the blood–epididymal barrier (BEB), respectively. In this study, the expression of occludin, an integral member of the TJs, was examined in testis and different regions of epididymis of Lepus sinensis coreanus , an Korean wild rabbit species. In testis, intense occludin immunoreactivity was found in the basally located inter-Sertoli junctional area together with diffused immunoreactivity of occludin in the cytoplasm of Sertoli cells. It can be suggested that occludin is one of the robust elements of BTB in seminiferous tubules of rabbit testis. In proximal and distal caput epididymis, occludin immunoreactivity was found in the lateral as well as apical contacts of epithelial cells. In corpus epididymis, intense occludin immunoreactivity was found in the basolateral as well as apical contacts of epithelial cells together with cytoplasmic signal. In cauda epididymis, occludin immunoreactivity in luminal epithelia was relatively strong but largely found in the cytoplasm. This suggests that intriguing regulatory mechanisms differentially recruit occludin to the TJ in the different regions of epididymal epithelia. The differences in the subcellular localization as well as expression levels of occludin among the epididymal segments may reflect differential paracellular permeability of epithelia along the epididymal tubules and be correlated with sperm maturation in rabbit. In Western blot, a major form of occludin was MW 62 kDa together with small fragments of MW 34–39 kDa in testis and epididymis, suggesting the peptide cleavage of occludin. This is the first report on the molecular nature of TJs in a wild rabbit testis and epididymis.     

Comparison of bite size, biting rate and grazing time of beef heifers from herds distinguished by mature size and rate of maturity

Sixteen-month-old heifers from herds having known genetic growth patterns were compared for differences in grazing behavior in a 3-yr study. Treatments were heifers from four size-maturity groups defined by the mature size and maturing rate of cow herds in which they originated. Average growth curve parameters indicating mature BW and rate of maturing in these cow herds were 387 kg and .19%/d for treatment Group I; 413 kg and .18%/d for Group II; 468 kg and .15%/d for Group III; and 589 kg and .16%/d for treatment Group IV. Data were from three heifers per treatment group grazing Midland bermudagrass during June and July observation periods. With the exception of the Group II vs Group III comparison, bite size increased with current or mature BW. Biting rate values were similar for all treatment groups but lower than those previously reported on other grass swards. Grazing time increased (P less than .01) in treatment groups defined by larger mature BW. Differences in grazing time for Group IV vs the other treatments and Group I vs Group II and Group III were observed repeatedly; the Group II vs Group III comparison was significant in one period during each of the 3 yr. Diurnal variations in grazing patterns among the treatments were observed. Period of observation affected (P less than .001) bite size and grazing time. These effects were not associated with month but could best be explained by differences in forage height and total mass. Forage availability had a direct influence on bite size, and a compensating effect of longer grazing time with smaller bite size was demonstrated as a regulator of intake. Differences in ingestive behavior were associated with genetic growth patterns in cattle.