首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
After domestication of wild yak and utilization of its frozen semen was successful in 1983, frozen semen of wild yak was used to improve domestic yak and local yellow cattle by artificial insemination(AI). Hybrid vigor of their F1 was obvious, i. e. , productive performance of F1 was significantly increased. Their offspring did not only have significant heterosis in performance but also can rejuvenate effectively their adaptability and survival, and can use alpine grassland more efficiently. This resulted in significant social and economic benefits.Compared with dairy cattle, beef cattle and yellow cattle, AI of yak was more difficult. Using AI to improve yak performance was difficult and significant in yak production areas of our country. It is necessary to invest more technique and fund to extend AI.  相似文献   

3.
4.
1. Open pores were a notable feature of the shell of hens' eggs which were naturally devoid of cuticle.

2. In contrast with normal eggs, the surface of the cuticle‐less shell was irregularly contoured and, in many instances, deeply fissured.  相似文献   


5.
In a series of investigations from 1965 to 1970 on the Transvaal Highveld it was found that trie elevation of shoot apices of two ecotypes of Themeda triandra was affected by season, ecotype and treatment. The absence of defoliation increased the susceptibility of the ecotypes to defoliation, whereas the shorter the defoliation the greater the subsequent resistance to grazing. The most important finding was that general application of earlier research findings from Natal was not possible in this case.  相似文献   

6.
The effects of mixed soda saline-alkali (NaHCO3:Na2CO3=9:1) at different concentrations (10,20,30,40 and 50 mmol·L-1) on the germination of five Longmu alfalfa seeds were studied. The results showed that the germination rate,germination potential,germination index,vigor index,dry weight,fresh weight,water content,embryo length,radicle length of alfalfa seeds showed different trends under different mixed soda saline-alkali concentrations. Through principal component analysis of nine indicators,GR,GP,GI,VI,FW,WC and EL indicators were screened out to be related to salt and alkali tolerance of Longmu alfalfa varieties. According to the analysis of membership function,weight coefficient and D value of comprehensive evaluation,the salt and alkali tolerance of five longmu alfalfa varieties were in the order of LM 807 > LM 808 > LM 806 > LM 803 > LM 801. © 2019 Journal of Refrigeration. All rights reserved.  相似文献   

7.
Beginning in July 2000 legislation in Lower Saxony restricted the keeping of bull terriers, American Staffordshire terriers, pit bull terriers, and 11 other breeds. Exemption was possible after attending an especially developed test. The tests analyzed for breed predisposition for excessively aggressive signaling or aggressive behavior in inappropriate situations, differences in behavior between breeds, and factors differentiating biting from nonbiting dogs.The test results of 415 dogs were analyzed. The test consisted of a veterinary examination; a learning test; situations of dog-human, dog-environment, and dog-dog contact; and obedience. Escalation in aggressive behavior was scored using a scale of 1-7. No aggressive behavior (1 on the scale) was shown by 38.07% of the dogs, 61.69% showed aggressive behavior scored as 2 to 5 on the scale, and 0.24% bit without previous threatening signals (6 on the scale).Concerning a score of 1 on the scale, pairwise comparison (chi-square test) showed significant differences between bull terriers and American Staffordshire terriers (P = 0.004), pit bull terriers (P = 0.01), Doberman pinschers (P = 0.003), and rottweilers (P = 0.009). Concerning scores of 2 to 7 on the scale,, no significant differences were found.Ninety-five percent of the animals reacted appropriately in the test situation. Five percent displayed excessive aggressive signaling or aggressive behavior in inappropriate situations. These displays were associated with unusual movements and the dogs' apparent apprehension. Correlation between test results and owners jerking on the leash or misinterpreting their dogs' behavior and dogs trying to elude physical manipulation was found. No significant difference in behavior between breeds was detected.The results show no indication of dangerousness in specific breeds. Justification for specific breed lists in the legislation was not shown.  相似文献   

8.
1. The cause of the sticky droppings and poor performance that can occur when barley is fed to poultry was investigated.

2. The problems could be overcome by water‐treatment of the barley or by addition of β‐glucanase.

3. The problems appear to be caused by a viscous factor, which is hydrolysed by β‐glucanase. Water‐treatment allows hydrolysis by enzymes in the barley.

4. Heat‐treatment of barley denatures hydrolytic enzymes and prevents reduction in viscosity.  相似文献   


9.
The observation of body height and weight of 10 captured wild yak shows the body height and weight of the wild yak at three and four months old were similar with that of domestic yak. At their 24 months old, the body height and weight were higher by 26.9 % and 62.5 % than that of the domestic ones. The results indicate that, once adapted to the half-shed and half-grazing conditions, the tamed Kunlun type of wild yak with superior genetics would grow and develop faster than the domestic yak at elder ages.  相似文献   

10.
Even though occidental food production and control systems guarantee a reasonable level of safety for consumers, western countries are facing a growing phenomenon of immigration from all over the world. With this enrichment and the shuffling of cultures and customs in the same places, even alimentary habits undergo an unavoidable evolution, also influencing the commercial trends of society. The growing demand for ethnic products, often of uncertain provenance, composition and manufacturing, has motivated the appearance of illegal trade and markets or improper local productions besides the legal ones, implying a rise in hygienic risks for the consumers. These underground realities, together with the unfilled gap that still exists between different cultures and customs cause significant difficulties in carrying out efficient controls to guarantee sanitary safety for consumers. For this reason, the risks associated with this increasing globalization must be faced with proper information and a decisive formative strategy must be divided, in order to allow the operator of the whole system and control employees to be acquainted about different raw materials, manufacturing systems, alimentary habits, languages for communication and commercial dynamics which stand beyond the new alimentary trends.  相似文献   

11.
Chronic non-progressive pneumonia (CNP) is a common disease which affects lambs in New Zealand during late summer and autumn. Mycoplasma ovipneumoniae can be recovered from a high proportion of lesions but it is also present in some normal lungs. Bacteria, especially Pasteurella haemolytica, can also be recovered from more than half the lungs of affected animals.

Isolates of M. ovipneumoniae are genetically heterogeneous, as demonstrated by examination of their DNA or total cellular proteins, and are serologically heterogeneous as shown by metabolic inhibition tests. The number of strains present in New Zealand is large and several distinguishable strains can be recovered from each affected lung. Mycoplasma ovipneumoniae has pathogenic potential as indicated by its ability to produce hydrogen peroxide, cause ciliostasis and by its possession of a capsule.

Chronic non-progressive pneumonia can be transmitted consistently to over 50% of lambs by inoculation of pooled pneumonic lung homogenate and transmission can be suppressed by broad spectrum antibiotics. In contrast, penicillin does not prevent the development of lesions but diminishes their severity. Pooled lung homogenate treated with digitonin, which inactivates mycoplasmas, has failed to transmit CNP. Pure cultures of M. ovipneumoniae produce only mild lesions in some animals, whereas inoculation with pooled lung homogenate (from which no viruses were isolated) containing mixed strains of M. ovipneumoniae and free from bacteria, is more effective in producing lesions.

Research work to date suggests that CNP may be initiated by colonisation of the lung by M. ovipneumoniae which causes ciliostasis and elicits an exudate allowing colonisation of the lungs by bacteria especially P. haemolytica and by other strains of M. ovipneumoniae. The immune response to the initial strain of M. ovipneumoniae may inhibit its replication but would be less effective in inhibiting heterologous strains of the organism allowing their sequential replication. Eventually production of a broad immune response to M. ovipneumoniae would lead to its elimination which in turn would facilitate the elimination of other microorganisms and the resolution of lesions. As natural immunity to CNP occurs within the first year, it may be possible to develop an effective and useful vaccine. Such a vaccine may need to include multiple strains of M. ovipneumoniae.  相似文献   

12.
13.
1. Three methods of restricting the growth rate of pullets from 8 to 20 weeks of age were compared. They were: quantitative food restriction, a diet low in lysine and arginine and a low protein diet.

2. Food consumption up to 20 weeks of age was significantly reduced by all three treatments; mortality was increased and sexual maturity was delayed.

3. Greatest uniformity was observed amongst pullets fed on the low protein and the low lysine diets

4. By 70 weeks there were no significant differences in food conversion based on food consumed between 20 and 70 weeks of age, but based on consumption between 8 and 70 weeks the quantitatively restricted birds converted food most efficiently.

5. The most favourable method of restriction appeared to be the feeding of a low lysine or low protein diet, since rearing costs were low, and the performance of the pullets on these treatments was high.  相似文献   


14.
1. The effects of egg turning upon the formation of sub‐embryonic fluid (SEF), and albumen weight and composition are described up to day 8 of incubation.

2. The density of albumen increased, and the density of yolk sac contents decreased, during the first 5 d of incubation. Failure to turn eggs diminished these changes.

3. The rate of formation of SEF and its maximum weight were lower if eggs were not turned, as was the rate of decrease in albumen weight.

4. The concentration of sodium and chloride, as well as osmolality, were higher in SEF than in thin albumen, and were affected by a failure to turn eggs.

5. Static incubation altered the concentrations of yolk nutrients in SEF.

6. It is concluded that the formation of SEF is primarily dependent upon the transfer of sodium and chloride from albumen to SEF so creating an osmotic force for water movement in the same direction. Turning the eggs promotes this process by ensuring an adequate supply of ions in thin albumen adjacent to the blastoderm.  相似文献   


15.
A study was designed aimed at comparing the assessment of performance of animal health care delivery systems in peri-urban Ghana by livestock and poultry keepers in 4 locations. 889 respondents were interviewed using a questionnaire. A higher proportion of respondents in Location 1 met their needs for animal health by themselves, while in Location 3 these needs were met mainly by veterinarians. The mean distances to veterinary clinics, veterinary technicians or to purchase medicine were significantly higher in Location 1. Higher proportions in 3 locations perceived effectiveness of service delivery to be good. However, equity was poor in all 4 locations. Higher proportions in Locations 2, 3 and 4 said services were unaffordable. Client needs were perceived to have been met by higher proportions in Locations 3 and 4 but not in Locations 1 and 2. Staff attitude and technical competence were good in all 4 locations. The study concluded that the differences reported in the quality of service indicators in the 4 locations were not critical enough to recommend location-specific delivery systems.  相似文献   

16.
17.
The flat-end surfaces of dinosaur vertebral centra led to the presumption that intervertebral discs occupied the space between their vertebrae. A set of fused hadrosaur vertebrae allowed that hypothesis to be tested. The Tyrannosaurus rex responsible for this pathology did not escape unscathed. It left behind a tooth crown that had fractured. Fragments of that tooth were scattered through the intervertebral space, evidencing that there was no solid structure to impede its movement. That eliminates the possibility of an intervertebral disc and instead proves the presence of an articular space, similar to that in modern reptiles, but at variance to what is noted in birds. While avian cervical vertebral centra appear to be separated by diarthrodial joints, the preponderance of their thoracic vertebral centra is not separated by synovial joints.  相似文献   

18.
1. The aim was to investigate the effect of grain type (barley or rye) and exogenous enzymes (β-glucanase or xylanase) on the composition of chicken caecal microbiota as examined by classical culturing and molecular techniques (fluorescent in-situ hybridisation (FISH) and terminal-restriction fragment-length polymorphism (T-RFLP)). 2. Plate counting revealed higher total numbers of anaerobic bacteria, lactic acid bacteria and yeasts in caecal contents of birds fed with rye-based diets than in birds fed with barley-based diets. 3. As assessed by FISH analysis, the most abundant bacterial groups in the broiler caeca were Clostridium coccoides-Eubacterium rectale followed by Bacteroides sp., Lactobacillus sp./Enterococcus sp., Bifidobacterium sp. and Enterobacteriaceae. For both cereal types, the enzyme supplementation significantly decreased the relative amount of Enterobacteriaceae. 4. The T-RFLP profiles indicated that the caecal microbiota of birds receiving rye-based diets was more diverse than that of birds fed on barley-based diets. 5. Irrespective of the method applied, the results indicate that the cereal type as well as the exogenous enzyme supplementation influence the microbiota in broiler chicken caeca, and may have the effect of reducing potentially pathogenic Enterobacteriaceae populations.  相似文献   

19.
20.
A pigeon paramyxovirus serotypeⅠ(PPMV-1) isolate was recovered from samples collected from dead pigeons and initial isolation of the virus was performed in 9-day-old specific-pathogen-free (SPF) chicken embryos.The isolate was identified by the hemagglutination (HA) test,hemagglutination-inhibition (HI) assays,RT-PCR,sequencing and analysis of partial of F gene of the virus.The virulence and pathogenicity of the isolate were determined by mean death time (MDT),intracerebral pathogenicity index (ICPI) in 1-day-old chicks and animal regression experiment.The results indicated that one PPMV-1 was isolated from dead pigeon and named as GXP120012.The F gene sequence analysis of PPMV-1 GXP120012 strain showed that the cleavage sites of the virus was 112R-R-Q-K-R-F117 motif in accordance with characteristic of velogenic strains;The nucleotide sequence homologies of F gene between strain GXP120012 and PPMV-1 reference strain pi/CH/LLN/110713 were high and reached 98.9%.They located the same branch on phylogenetic tree and fell into genotype Ⅵ.The MDT and ICPI values of isolate were 102 h and 0,respectively.The results of animal regression experiment showed that GXP120012 isolate was virulent for pigeons and avirulent for chickens.The present study provided useful material and theoretical basis for the study of molecular epidemiology and prevention and control of Newcastle disease in pigeon in future.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号