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901.
权变理论是当前西方管理学中一种较流行的理论。在介绍了权变理论基本思想的基础上,探讨了权变理论在灌区产权制度改革、经营管理模式、水费计收、用水管理等领域的应用,强调灌区管理水平的高低取决于灌区管理与其外部环境和内部环境的适应性。 相似文献
902.
鸭病毒性肝炎鸭胚灭活疫苗的研究 总被引:6,自引:0,他引:6
以鸭病毒性肝炎病毒Ⅰ型ATCC毒株接种健康鸭胚,收集致死的全胚组织作制苗材料,用福尔马林灭活,以麸氨酸钠终止其作用。先后试制疫苗11批,在试验室免疫雏鸭71只,经强毒攻击后,总的保护率为90.4%。本疫苗免疫雏鸭3天后可产生较坚强的免疫力,在室温至少可保存11天,在4℃可保存254天。经在江苏、安徽、广东等省推广应用200000头剂,均安全有效,颇受用户欢迎,对控制鸭病毒性肝炎的流行起了重要作用。 相似文献
903.
1. From 1992 to 2003, selected (S) and control lines (C) of the laying Brown Tsaiya duck (Anas platyrhynchos) were simultaneously maintained under the same standardised conditions of feeding and management. 2. The selection objective was to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. From generations G1 to G11, 2452 and 2022 female ducks, in S and C lines, respectively, were measured and recorded. In the S line, the percentage selected varied between 20.2 and 34.3% in females and between 7.2 and 20.8% in males. 3. Selection for number of fertile eggs had a correlated effect of increasing the parameter tau of the logistic curves which fitted the daily variations (d 2 to 15) in fertility or hatchability on the basis of eggs set. The differences S-C for the estimates of the times of half maximal fertility and hatchability increased by 0.41 and 0.37 d per generation between G1 and G11, respectively. 4. The highest increases of fertility per day rates after a single AI were observed between d 5 and 11. Moreover, in the selected line, fertility rate was higher than, or equal to, 90% in d 2 from G8. The same tendencies were observed for the changes in the evolution of hatchability on the basis of eggs set. 5. Selection increased fertility and hatchability according to the egg set rates, especially for d 2 to 8 after AI. Hatchability of fertile eggs was not impaired, confirming that selection for one AI per week was possible in this strain of laying ducks. 相似文献
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908.
Wang H Gao Y Gong Y Chen X Liu C Zhou X Blackall PJ Zhang P Yang H 《Veterinary microbiology》2007,119(2-4):231-239
Avibacterium paragallinarum is the causative agent of infectious coryza. The protective antigens of this important pathogen have not yet been clearly identified. In this paper, we applied phage display technique to screen the immunodominant mimotopes of a serovar A strain of A. paragallinarum by using a random 12-peptide library, and evaluated the immunogenicity in chickens of the selected mimotope. Polyclonal antibody directed against A. paragallinarum strain 0083 (serovar A) was used as the target antibody and phage clones binding to this target were screened from the 12-mer random peptide library. More than 50% of the phage clones selected in the third round carried the consensus peptide motif sequence A-DP(M)L. The phage clones containing the peptide motif reacted with the target antibody and this interaction could be blocked, in a dose-dependent manner, by A. paragallinarum. One of the peptide sequences, YGLLAVDPLFKP, was selected and the corresponding oligonucleotide sequence was synthesized and then inserted into the expression vector pFliTrx. The recombinant plasmid was transferred into an expression host Escherichia coli GI826 by electroporation, resulting in a recombinant E. coli expressing the peptide on the bacterial surface. Intramuscular injection of the epitope-expressing recombinant bacteria into chickens induced a specific serological response to serovar A. A. paragallinarum. The chickens given the recombinant E. coli showed significant protection against challenge with A. paragallinarum 0083. These results indicated a potential for the use of the mimotope in the development of molecular vaccines for infectious coryza. 相似文献
909.
Wei Zhong Hanlu Liu Guoliang Luo Zhongjuan Chang Fenghua Liu Jingbo Zhao Danli Li Zhigang Yue Haihua Zhang Guangyu Li 《Animal Science Journal》2014,85(7):757-762
Copper has an essential role in normal fur pigmentation and fur quality. This study evaluated the effects of cupric citrate (CuCit) supplementation on growth, nutrients metabolism and pelt characteristics of the female silver fox (Vulpes fulva). Fifty age‐matched female silver foxes with similar body weights were randomly divided into five dietary groups for 58 days during the winter fur‐growing season. The basal diet contained 4.92 mg/kg copper. Groups I‐V were supplemented with 6, 30, 60, 90 or 150 mg Cu from CuCit per 1 kg dry matter basal diet. Serum alkaline phosphatase activity was significantly higher (P < 0.05) in those fed 90 mg/kg Cu than those fed 150 mg/kg Cu. Pelt total thickness was significantly higher (P < 0.05) in those fed 30 mg/kg Cu than foxes fed 6 mg/kg Cu supplemented diet, but were similar to the other groups. Length of guard hair was significantly lower (P < 0.05) in those fed 90 mg/kg Cu than fed 6 mg/kg Cu and 30 mg/kg Cu, but were similar to the other groups. Length of underhair was significantly higher (P < 0.05) in those fed 6 mg/kg Cu than those fed 90 mg/kg Cu, but was similar to the other groups. Considering decreasing environmental contamination and improving pelt performance, supplementing 30 mg/kg Cu from CuCit (actual copper 35 mg/kg dry matter) is appropriate for female silver fox. 相似文献
910.
X‐M Zhao J‐J Ren S‐J Zhao L‐S Cui H‐S Hao H‐Y Wang W‐H Du T Qin Y Liu D Wang H‐B Zhu 《Reproduction in domestic animals》2014,49(4):543-549
This study utilized three staining assays (Annexin V, mitochondrial membrane potential (JC‐1) and TUNEL) for flow cytometric analysis of apoptosis in sex‐sorted sperm from four different bulls (A, B, C and D). Correlations between sperm quality and IVF efficiency were then assessed to determine which assay provided the best prediction of IVF efficiency. The results of the Annexin V assays, as well as measures of viable sperm, early apoptosis, necrotic sperm and mitochondrial membrane potential (?ψm) showed that the sex‐sorted sperm collected from bull A significantly differed from those of the other three bulls (p < 0.05). In addition, the levels of DNA fragmentation in sex‐sorted sperm from bull A were significantly lower than those from bulls B and C (p < 0.05). The percentage of cells reaching the cleavage and blastocyst stages in sex‐sorted sperm from bull A were significantly greater than those from the other bulls (p < 0.05). A significant positive correlation was observed between viable sperm and the percentage of cells at the cleavage or blastocyst stages (p < 0.05). In contrast, a negative correlation was found between early apoptotic sperm and the percentage of cells at the cleavage or blastocyst stages (p < 0.05). In conclusion, these results indicated that the Annexin V assay was the most reliable technique for the prediction of the IVF success of sex‐sorted bovine sperm. 相似文献