用大肠杆菌K99和F41菌毛抗原检测牛血清抗体的琼脂扩散试验的研究

用含２ｍｏｌ／Ｌ尿素的磷酸盐缓冲液以热处理方法提取的Ｋ９９和Ｆ４１菌毛作为抗原,对琼脂扩散试验方法进行研究。结果表明本试验方法简便,特异性强,敏感性高,可用于血清抗体检测;所制备的抗原稳定、重复性好。     

采用“诱乳素”诱导空怀母牛泌乳的效果分析

试验选择6头500—800kg屡配不孕的荷斯坦母牛采用“诱乳素”进行诱导泌乳处理。结果表明,“诱乳素”在春季对母牛处理后开始出现泌乳的时间有差异,但到23天后,其产奶量可逐渐达到20kg。对体重大的母牛,虽然诱导泌乳处理时加大了药物的剂量,处理的时间延长,但开始出现泌乳的时间却推迟到8～9天,达到产奶高峰的时间也较晚。采用“诱乳素”处理除了对空怀母牛有明显的诱导泌乳作用外,对母牛的诱导发情亦有明显的作用。采用“诱乳素”处理空怀母牛,不仅可以在短期内达到诱导泌乳的效果,而且可以改善母牛的生殖功能,使不发情的母牛发情趋于正常,提高了其繁殖率。     

Serine-to-glycine ratios in low-protein diets regulate intramuscular fat by affecting lipid metabolism and myofiber type transition in the skeletal muscle of growing-finishing pigs

Serine and glycine are 2 of the first-affected nonessential amino acids in low crude protein (CP) diets for pigs. Therefore, we explored the effects of different dietary serine-to-glycine ratios on growth performance and lipid metabolism in growing-finishing pigs. A total of 160 crossbred healthy barrows, with a similar body weight of around 59.50 kg, were randomly allotted into 1 of 5 treatments (8 pens per treatment and 4 pigs per pen). The serine-to-glycine ratios of the 5 dietary treatments were as follows: diet A (NORMAL group), 1.18:1 (16% CP); diet B (LOW group), 1.2:1 (12% CP); diet C (S2G1 group), 2:1 (12% CP); diet D (S1G2 group), 1:2 (12% CP); and diet E (S1G1 group), 1:1 (12% CP).We found that the pigs fed a low CP diet (12% CP), when maintaining serine-to-glycine ratio at 1:2 and a total amount of 1.44%, had the same average daily gain as the pigs fed a normal CP diet (16% CP) (P > 0.05), but they had increased intramuscular fat (P < 0.05). Furthermore, they exhibited higher expression of genes involved in lipid oxidation (P < 0.05), which was regulated by modulating methylation levels in the promoters of acyl-CoA oxidase 1 (ACOX1) and acyl-CoA dehydrogenase medium chain (ACADM). When compared with the pigs fed a normal CP diet, these pigs had more oxidative myofibers (P < 0.05), which were regulated by AMPK-PGC-1α and Calcineurin-MEF2/NFAT pathways in a coordinated manner. Our findings suggested that a dietary serine-to-glycine ratio of 1:2 is beneficial for improving meat quality in pigs fed a low CP diet.     

PMSG提高初产母猪繁殖力的研究

７０头初产断奶母猪随机分为两组，试验组于断奶当日颈部肌肉注射１０００Ⅰ．Ｕ．ＰＭＳＧ；对照组只注射等容量生理盐水（注射用水），以观察初产母猪断奶后发情配种和２胎产仔的情况。结果表明：试验组母猪断奶发情配种的时间比对照组显著提前（Ｐ＜０．０１）；２胎产仔数增加（Ｐ＜０．０１）；而两组母猪发情配种的受胎率差异不显著（Ｐ＞０．０５）。     

经验学习对警犬技术成人培训的影响

所谓经验学习就是学习者通过对自己过去所掌握的知识和经验的深刻回顾与系统反思,结合需要学习的新知识、新内容,从中总结归纳并产生出新知识的过程。实践证明,经验学习对警犬技术专业成人培训的影响是巨大而深刻的,有时往往会超出人     

Dietary supplementation with sodium bicarbonate improves calcium absorption and eggshell quality of laying hens during peak production

1. The advantage of supplemental sodium bicarbonate (NaHCO₃) on eggshell quality in laying hens changes with age. Besides increasing calcium (Ca) secretion in the eggshell gland, it may improve Ca absorption in the intestine or kidney.

2. Hy-Line Brown layers (n = 384), 25 weeks of age, were allocated to two treatment groups in two experiments, each of which included 4 replicates of 24 hens. Hens were fed a basal diet (control) or the basal diet containing 3 g NaHCO₃ g/kg for 50 or 20 weeks in Experiment 1 or 2, respectively. A 24-h continuous lighting regimen was used to allow hens to consume the dietary supplements during the period of active eggshell formation.

3. In Experiment 1, particularly from 25 to 50 weeks of age, and in Experiment 2, NaHCO₃ supplementation favoured hen-d egg production at the expense of lower egg weight. The increased eggshell thickness should have nothing to do with the additional eggshell formation, because of the unchanged egg mass and daily eggshell calcification.

4. At 35 weeks of age in both experiments, NaHCO₃ supplementation increased duodenal expression of calbindin-d28k (CaBP-D28k) protein, contributing to higher Ca retention and balance.

5. From 50 to 75 weeks of age in Experiment 1, the hens had little response to NaHCO₃ supplementation and showed a negative trend on eggshell thickness and strength.

6. It is concluded that dietary supplementation with 3 g NaHCO₃ g/kg improves Ca absorption and eggshell quality of laying hens during the peak but not late production period, with the introduction of continuous lighting.

     

Identification and molecular characterization of a novel flavivirus isolated from Pekin ducklings in China

A flavivirus-associated disease of egg-laying ducks was observed in eastern China in 2010, and a novel mosquito-borne flavivirus, Tembusu virus (TMUV), was isolated (Cao et al., 2011). Following up on the earlier study, a virus similar to TMUV was isolated recently from ducklings and characterized. We report that (1) the recently isolated virus, TMUV ZJ-6, replicated in vertebrate cells (DF-1, BHK-21) as well as in mosquito cells (C6/36) and caused cytopathic effect (CPE) in the cell lines tested; (2) extracellular viral particles examined by electron microscopy were approximately 45 nm in diameter and enveloped; (3) the full-length genome of the virus was determined, showing that the TMUV ZJ-6 is more closely related to the Ntaya group of viruses than other members of the Flaviviridae based on the data of phylogenetic analyses. Most importantly, the disease of ducklings was reproducible after administration of plaque-purified virus by intracerebral (i.c.), subcutaneous (s.c.) or intranasal (i.n.) inoculation. This is the first report that TMUV infects not only egg-laying ducks but also 3-21 days-old ducklings. The findings extend our understanding of how the virus spreads and causes disease.     

Chemical composition and microstructure of uroliths and urinary sediment crystals associated with the feeding of high-level cottonseed meal diet to water buffalo calves

The chemical composition and microstructure of seven uroliths and four urinary sediment samples associated with the feeding of high-level cottonseed meal diet to buffalo calves were examined by chemical qualitative analyses, scanning electron microscopy ( ), X-ray diffraction, and X-ray energy dispersive spectrometry ( ). Struvite was a major component of kidney stones and of some bladder stones. The kidney stone sample appeared cracked under low power under , aggregated into tiny balls under high power, and as a bladelike structure under even higher power. The bladder stone samples appeared finely granular or granular with various forms of prismatic crystals. The urinary sediments were prismatic crystals, with granules. The newly found prismatic crystals, which were rich in potassium and similar to struvite in crystal structure, were identified as potassium magnesium phosphate (KMgPO₄ · 6H₂O) in some bladder stones and urinary sediments. However, crystals which contained Mg and P only, which had been used for struvite identification, were not found by examination in urinary sediments from fresh urine samples of buffalo calves fed the high-level cottonseed meal diet.     

益生菌发酵饲料对猪的生长和肉质的影响

应用益生菌发酵饲料喂猪,能提高饲料中粗蛋白含量,明显降低猪粪臭味,促进生长、降低料肉比和提高猪肉品质。     

Pharmacokinetics and bioavailability of valnemulin in broiler chickens

Wang, R., Yuan, L.G., He, L.M., Zhu, L.X., Luo, X.Y., Zhang, C.Y., Yu, J.J., Fang, B.H., Liu, Y.H. Pharmacokinetics and bioavailability of valnemulin in broiler chickens. J. vet. Pharmacol. Therap. 34 , 247–251. The objective of this study was to investigate the pharmacokinetics and bioavailability of valnemulin in broiler chickens after intravenous (i.v.), intramuscular (i.m.) and oral administrations of 10 mg/kg body weight (bw). Plasma samples were analyzed by high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS). Pharmacokinetic characterization was performed by non‐compartmental analysis using WinNonlin program. After intravenous administration, distribution was wide with the volume of distribution based on terminal phase(V_z) of 4.27 ± 0.99 L /kg. Mean valnemulin t_1/2β(h), Cl_β(L /h /kg), V_ss (L /kg) and AUC_(0–∞)(μg·h /mL) values were 2.85, 0.99, 2.72 and 10.34, respectively. After intramuscular administration, valnemulin was rapidly absorbed with a C_max of 2.2 μg/mL achieved at 0.43 h (t_max), and the absolute bioavailability (F) was 88.81%; and for the oral route the same parameters were 0.66 ± 0.15 μg/mL, 1.54 ± 0.27 h and 74.42%. A multiple‐peak phenomenon was present after oral administration. The plasma profile of valnemulin exhibited a secondary peak during 2–6 h and a tertiary peak at 32 h. The favorable PK behavior, such as the wide distribution, slow elimination and acceptable bioavailability indicated that it is likely to be effective in chickens.