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221.
222.
随着分子生物学技术的发展,抗病育种的重要性越来越显现出来。本文简要介绍了抗病育种的必要性、抗病育种的遗传基础、抗病育种的方法,最后对抗病育种将来的发展进行了展望。  相似文献   
223.
试验结果表明,不同地区的黑豆其表观代谢能(AME)值不同。将粗纤维、粗蛋白、有机物分别与AME建立一元、二元,三元回归方程并进行X~2检验。得出的结论是:用一元回归方程推算AME值既简单又较精确。  相似文献   
224.
畜禽粪便等固体废弃物及土壤中磷的形态分析对于管理固体废弃物、提高磷素利用率、减少磷素流失风险具有重要意义。自20世纪初以来,已提出多种固体废弃物及土壤中磷素形态分析的方法,包括化学分级、酶水解法、红外光谱(FT-IR)、X射线衍射(XRD)、31P核磁共振(31P NMR)、X射线吸收近边结构(XANES)等。本文系统总结了一些固体废弃物及土壤中磷素形态分析的方法,比较了其特点,指出只靠单一的方法并不能很好的鉴定固体废弃物及土壤中磷素的形态,必须综合考虑运用多种方法,从而为磷素形态分析提供方法选择的依据,同时为进一步发展固体废弃物及土壤中磷素形态分析新技术奠定基础。  相似文献   
225.
Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.  相似文献   
226.
维生素C在家禽抗应激中的作用研究进展   总被引:20,自引:0,他引:20  
本文就应激状态下家禽体内Vc的合成;应激状态下家禽机体对Vc的吸收、分布和利用效率;日粮中添加Vc对家禽抗应激及生产性能的影响;Vc在家禽抗应激作用研究的衡量指标及其测试手段和方法;抗应激中Vc与其他抗应激剂的互作;日粮Vc对家禽抗应激影响机理等六部分系统综述了Vc在家禽抗应激中的作用的研究进展。  相似文献   
227.
非淀粉多糖及其对家禽的抗营养作用   总被引:21,自引:2,他引:21  
本文综述了谷物饲料中非淀粉多糖的分类、含量、结构及理化性质,非淀粉多糖对家禽的抗营养作用及机制,应用酶制剂等消除非淀粉多糖的抗营养作用、提高谷物饲粮营养价值的原理和方法。  相似文献   
228.
An eight-week feeding trial was conducted to examine the possibility of replacing fish meal with poultry by-product meal (PBM) at high inclusion levels in the diets of the humpback grouper, Cromileptes altivelis, a carnivorous marine tropical fish. Six isolipidic (12%) and isoproteic (50%), experimental diets were formulated to contain graded levels of PBM. Fish meal protein was replaced with a feed-grade PBM at 50, 75 or 100% level (FPBM50, FPBM75, FPBM100, respectively), or a pet food grade PBM at 75 or 100% replacement level (PPBM75 and PPBM100, respectively). The control diet contained Danish fish meal as the sole protein source. The experimental diets were fed close to apparent satiation, twice a day to triplicate groups of humpback grouper fingerlings (12.4 ± 0.2 g). The grouper fingerlings were randomly distributed into groups of 15 fish in cylindrical cages (61 cm depth and 43 cm diameter) and placed in a 150-ton seawater polyethylene tank. Except for fish fed the FPBM100 diet, growth performance, survival, and feed utilization efficiency for fish fed PBM-based diets were not significantly lower (P > 0.05) compared to fish fed the control diet. The PBM source and dietary level did not significantly affect (P > 0.05) the hepato- and visero-somatic indices or the condition factor of fish. Dry matter and protein apparent digestibility coefficients (ADC) of the diets decreased with increasing dietary PBM, and ranged from 64.3-71.5% and 86.2 to 91.2%, respectively. High values (91.7 to 96.7%) for lipid ADC were observed in all diets, with no significant differences among dietary treatments. Whole-body moisture and lipid contents of the fish were not affected by the inclusion of PBM in the diets. With the exception of fish fed the FPBM100 diet, whole-body protein of fish fed the PBM-based diets was slightly higher than that of fish fed the control diet. There was a trend of increased whole-body ash with the increase in dietary levels of PBM. The results from this study indicate that good quality terrestrial PBM can successfully replace more than half the protein from marine fish meal in the diets for humpback grouper. However, total replacement of fish meal with PBM might be constrained by lowered nutrient digestibility and limiting essential amino acids, especially lysine and methionine.  相似文献   
229.
This systematic review considers the relationship between arthropods commonly found in and around livestock premises and zoonotic bacteria. The principal focus is upon insects and arachnids on poultry units, where houses, litter and manure provide good conditions for the growth, multiplication and protection of flies, beetles and mites, and where zoonotic pathogens such as Salmonella and Campylobacter are prevalent. Other members of the Enterobacteriaceae and the taxa Clostridium, Helicobacter, Erysipelas and Chlamydiaceae are also discussed. Salmonella is widely distributed in the flies of affected livestock units and is detectable to a lesser degree in beetles and mites. Persistent carriage appears to be common and there is some field and experimental evidence to support arthropod‐mediated transmission between poultry flocks, particularly carry‐over from one flock to the next. Campylobacter may readily be isolated from arthropods in contact with affected poultry flocks, although carriage is short‐lived. There appears to be a role for flies, at least, in the breaching of biosecurity around Campylobacter‐negative flocks. The carriage of other zoonotic bacteria by arthropods has been documented, but the duration and significance of such associations remain uncertain in the context of livestock production.  相似文献   
230.
Experiments were conducted to determine the effects of advanced vaccination and Chinese herbal adjuvants (CHA), containing astragalus polysaccharides (APS) and ginsenosides (GS) on the immune response to rabbit hemorrhagic disease (RHD) vaccine in young rabbits. In experiment 1, 5 New Zealand rabbits of each group at 30, 35, 40, or 45 days of age were injected with 2 mL of inactivated RHD vaccine, respectively. The dynamic changes of antibody titers were tested by the hemagglutination inhibition (HI) method. In experiment 2, 30 New Zealand rabbits at 35 days of age were randomly assigned to 5 treatment groups, representing inoculation with 3 mL of non-adjuvant RHD vaccine, CHA-RHD vaccine, CHA-HA vaccine (half dose antigen), aluminium adjuvant-RHD vaccine, and PBS, respectively. The dynamic changes of peripheral lymphocyte proliferation and serum antibody titers were tested by the MTT method and the HI method. The results showed that the titer of maternal HI antibody in the 35-day-old rabbits was lower than the protective level of 3 log2, while on days 7 to 49 after the vaccination, the antibody titers were higher than 3 log2. The CHA promoted the lymphocyte proliferation and enhanced the serum antibody titer (P〈 0.05). These findings from the two experiments suggested that advanced vaccination and Chinese herbal adjuvants significantly enhanced the immune response to vaccine against RHD, and effectively protected the young rabbits against RHD challenge.  相似文献   
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