Diminution of Campylobacter colonization in neonatal pigs reared off-sow

Pigs may be a natural reservoir of Campylobacter and can be colonized as early as 24 h after birth. The purpose of the present study was to evaluate what effect early removal of piglets from Campylobacter-positive sows has on Campylobacter prevalence in neonates. In two trials, piglets were removed from sows within 24 h of birth and were reared in nurseries isolated from sows for 21 days. From the neonates rectal swabs were cultured for Campylobacter, and Campylobacter status of the isolated piglets was compared to that of littermates reared on sows. The nurseries consisted of wire-floored farrowing crates that were equipped with heaters and self-feeders. In trial I, the Campylobacter prevalence in nursery-reared piglets was 13 of 14 on day 2 and 0 of 14 on day 20. Campylobacter prevalence in the sow-reared piglets was 8 of 9 from days 2 to 20. In trial II, 12 of 29 on day 2, and 5 of 26 on day 20, of the nursery-reared piglets were culture positive for Campylobacter. For the sow-reared piglets, Campylobacter prevalence was 7 of 15 on day 1 and 15 of 15 (100%) on day 20. These data suggest that successful permanent colonization of the gut by Campylobacter is probably related to constant exposure of piglets to Campylobacter-positive feces. Campylobacter prevalence may be diminished in neonates that are reared off-sow in isolated nurseries.     

Investigation of Campylobacter in reared game birds

A total of 103 pooled samples of neck skin and meat from pigeons for the table and neck skin of pheasant were analyzed bacteriologically to determine the presence of Campylobacter. Colonies suspected of being Campylobacter were grown from 15.8% of pigeon neck skin samples, 12.5% of pigeon meat samples, and 50% of pheasant neck skin samples after culturing, and in 6.9% of pigeon neck skin samples (4 x 10(2) to 2 x 10(3) CFU/g) assessed quantitatively without preculturing. PCR confirmed the presence of Campylobacter spp. in 5.26 and 3.44% of samples of pigeon neck skin and meat, respectively. Species identified from pigeon neck skin samples by PCR were C. jejuni (3 of 3) and C. coli (1 of 3); no C. lari was identified. No species were identified by PCR in pheasant neck skin. We conclude that the small number of Campylobacter-positive pigeon samples presents a low risk of Campylobacter infection to Italian consumers, particularly since pigeon is always well cooked before consumption, although there is always the possibility of cross-contamination with raw or insufficiently cooked foods particularly during food preparation.     

Compensatory growth in slaughter pigs reared under organic conditions

BACKGROUND: Compensatory growth is the physiological process leading to accelerated growth following a period of growth retardation. This study assessed different feeding strategies that may induce compensatory growth. Pigs from two sire breeds, reared under organic conditions, were subjected to: (1) ad libitum feeding; (2) 0.7× ad libitum feeding; (3) 0.7× ad libitum feeding for 25 days followed by ad libitum feeding to slaughter; and (4) as (3) but finished with an energy‐ and vitamin E‐enriched diet. RESULTS: Compared to the performance of ad libitum fed pigs, re‐alimentation was not capable of fully compensating the effect of the imposed feed restriction either in the number of days used to reach the same slaughter weight (+4% to 7%) or in the slaughter weight achieved in the same number of feeding days (?0.5% to 2.0%, P = 0.65 and 0.11). CONCLUSION: It is reasonable to propose that although compensatory growth does occur by re‐alimentation after feed restriction, the compensation is far from always complete. The latter is a crucial aspect that has to be taken into account when considering the application of feeding strategies expected to lead to compensatory growth in organic pig production. The expectation of compensatory growth alone does not necessarily justify the application of these strategies. Copyright © 2009 Society of Chemical Industry     

Survival of Escherichia coli O157:H7 and Campylobacter jejuni in bottled purified drinking water under different storage conditions

Survival of Escherichia coli O157:H7 and Campylobacter jejuni that were separately inoculated into bottled purified drinking water was investigated during storage at 22, 4, and -18 °C for 5, 7, and 2 days, respectively. Two inoculation levels were used, 1 and 10 CFU/ml (10(2) and 10(3) CFU/100 ml). In samples inoculated with 10(2) CFU/100 ml, C. jejuni was not detectable (>2-log reduction) after storage under the conditions specified above. E. coli O157:H7 was detected on nonselective and selective media at log reductions of 1.08 to 1.25 after storage at 22 °C, 1.19 to 1.56 after storage at 4 °C, and 1.54 to 1.98 after storage at -18 °C. When the higher inoculation level of 10(3) CFU/100 ml was used, C. jejuni was able to survive at 22 and 4 °C, with 2.25- and 2.17-log reductions, respectively, observed on nonselective media. At these higher inoculation levels, E. coli O157:H7 was detectable at 22, 4, and -18 °C, with log reductions of 0.76, 0.97, and 1.21, respectively, achieved on nonselective media. Additionally, E. coli O157:H7 showed significant differences in culturability (P<0.05) on the nonselective and selective culture media under the different storage conditions, with storage at -18 °C for 2 days being the treatment most inhibiting. The percentage of sublethal injury of E. coli O157:H7 ranged from ～33 to 75%, indicating that microbial examination of bottled water must be done carefully, otherwise false-negative results or underestimation of bacterial numbers could pose a health risk when low levels of pathogens are present.     

不同条件下蔬菜中亚硝酸盐含量的变化

研究8种蔬菜在室温下(20～25℃)、低温下(4℃)贮藏后水浸泡和不用水浸泡情况下亚硝酸盐含量的变化.试验结果表明:室温条件下贮藏的蔬菜亚硝酸盐含量在1～2 d内会达到高峰,然后出现下降,随着时间继续延长,亚硝酸盐含量会逐渐升高.亚硝酸盐含量低温条件下较室温下低.不论室温下还是低温下贮藏的蔬菜,用水浸泡1 h后,其亚硝酸盐含量都会比不浸泡低.     

不同处理条件对乳铁蛋白抑菌性的影响

对不同处理条件下乳铁蛋白(Lactoferrin LF)的抑菌性进行了研究.结论表明:LF经过70 ℃以下的巴氏杀菌,不会影响到其抑菌活性.LF在弱碱性的条件下抑菌效果最好,环境pH值的变化时,LF针对金黄色葡萄球菌的抑菌活性变化较大,在pH值为6～10之间,LF对沙门氏菌有抑菌效果.LF在人工胃液中抑菌效果明显增加.     

Sources and spread of thermophilic Campylobacter spp. during partial depopulation of broiler chicken flocks

The practice of partial depopulation or thinning (early removal of a portion of birds from a commercial broiler flock) is a reported risk factor for Campylobacter colonization of residual birds because of the difficulty in maintaining biosecurity during the thinning process. The effect of this practice was studied in detail for 51 target flocks, each at a different growing farm belonging to one of seven major poultry companies throughout the United Kingdom. On 21 of these farms, the target flock was already colonized by Campylobacter, and at slaughter all cecal samples examined were positive, with a mean of 8 log CFU/g. An additional 27 flocks became positive within 2 to 6 days of the start of thinning and had similarly high levels of cecal carriage at slaughter. Just before the thinning process, Campylobacter was isolated frequently from the farm driveways, transport vehicles, equipment, and personnel. Strains from seven farms on which flocks became colonized after thinning were examined by pulsed-field gel electrophoresis typing. An association was found between strains occurring at specific sampling sites and those isolated subsequently from the thinned flocks. The results indicated that particular strains had spread from one farm to another when the farms were jointly owned by the same company and employed the same bird-catching teams and/or vehicles. These results highlight the need for better hygiene control in relation to catching equipment and personnel and more effective cleaning and disinfection of vehicles and bird-transport crates.     

Oxidative and lipolytic deterioration of different muscles from free-range reared Iberian pigs under refrigerated storage

Three different type of muscles, two glicolytic (Serratus ventralis and Longissimus dorsi) and one oxidative (Masseter) were displayed under refrigeration at +4?°C during 10 days to evaluate differences in lipolytic and oxidative changes of different muscles with different metabolic pattern. Thiobarbituric acid reactive substances (TBARS), phospholipid content, hexanal content and fatty acid profiles of neutral and polar lipid fractions were analysed at day 0 and day 10. Phospholipid content (g phospholipids/g intramuscular fat) significantly (P<0.035) decreased from day 0 to day 10 in m. Masseter (0.33 vs. 0.25, respectively), but not in m. L. dorsi (0.12 vs. 0.09, respectively) and m. S. ventralis (0.19 vs. 0.14, respectively). Changes in fatty acid profiles of neutral and polar lipids significantly differed among muscles after storage. Slight differences were found in neutral lipids from m. L. dorsi and m. S. ventralis, while neutral lipids from m. Masseter were highly altered. Great changes affected fatty acid profiles from polar lipids in the three muscles. m. Masseter muscle showed significantly higher (P<0.000) TBARS values (1.13, 0.65 and 0.60 mg MDA/kg meat, respectively) and hexanal content (689.2, 241.2 and 355.8 μg/g meat, respectively) than m. L. dorsi and m. S. ventralis. In conclusion, oxidative meat is more prone to oxidative and lipolytic deterioration than glycolytic muscles during refrigerated storage and as a consequence of that a lower shelf-life.     

不同温度条件下玉米穗红外干燥试验研究

针对玉米收获后由于气候原因导致霉变发芽、公路晾晒造成严重污染,或采用“先脱粒后干燥”工艺导致籽粒破碎严重等问题,按照“玉米穗干燥→脱粒→玉米籽粒干燥”分段干燥工艺设计了一种玉米穗红外干燥试验台.试验结果表明,采用等温干燥时,较佳的干燥温度为58℃左右;采用变温干燥时,宜选用“先低后高”的变温方式,且在保证干玉米品质的前提下,应尽量选用较高的起始干燥温度;无论采用等温干燥还是变温干燥,其干燥温度均不得高于60℃.该玉米穗红外干燥试验台干燥均匀性好、设备的空间利用率高,解决了收获期玉米霉变或采用“先脱粒后干燥”工艺而导致的籽粒破碎率严重等问题,为玉米穗红外干燥机的研制提供了参考.     

香蕉在不同冻结条件下的品质变化

探讨了香蕉分别经复合护色剂和热烫预处理后其在不同冻结温度分别为(-15、-25、-35、-45、-55、-70℃)条件下的冻结状态及其品质变化。复合护色剂与热烫预处理相比,随着冻结温度下降,香蕉在冻结过程其可溶性固形物、L值、p H值变化趋势及对细胞组织结构保护效果均优于热烫处理,结合光学显微镜观察香蕉组织切片,-35、-45、-55、-70℃时,冻结温度对香蕉细胞机械破坏程度无明显差异,综合考虑设备、成本等因素,采用复合护色剂预处理和-35℃温度条件冻结较适宜。     

不同照明条件下烟叶的视觉反映

  目的  为考察初烤烟叶在不同照明条件下的视觉反映, 以期为烟叶评级准确性和自动化提供参考。  方法  运用感官分析技术, 分析了烟叶在3个自然光处理和11个人工照明处理环境中的视效。  结果  ①在自然光条件下, 即便色温的变化较大, 烟叶的视觉反映却无明显差异; ②在人工照明条件下: 当相关色温为5000~5100 K、一般显色指数大于90、照度大于400 lx时, 烟叶的黄色、青色、平滑、褪色、灰色和红色等外观特性的视觉反映接近自然呈现; 当相关色温或一般显色指数超出该区间时, 烟叶部分外观特性的视觉反映将被明显强化或弱化; 当照度低于400 lx时, 视效模糊, 烟叶的光泽度和对比度被弱化。  结论  烟叶评级活动若在人工照明条件下进行, 相关色温应为5000~5100 K, 一般显色指数应大于90, 照度应大于400 lx。      

对米根霉在不同条件下产酸情况的研究

乳酸是目前世界上公认的3大有机酸之一,其广泛应用于食品、医药、化工、制革、纺织、环保和农业等诸多领域。用微生物发酵法生产L-乳酸可以达到较高的纯度要求。根霉属中的米根霉(Rhizopus oryzae)是目前发酵生产L-乳酸的重要菌株,本课题研究的是从自然界选取的米根霉在不同条件下的产酸情况。采用分析方法包括还原糖的测定,pH测定,NaOH滴定确定乳酸产量。通过对不同条件下产酸情况的分析,可以优化产酸条件,提高产酸率。最终确定出在葡萄糖浓度为130g/L,氯化铵作为氮源,其浓度在2.0g/L的条件下,实验室菌株的最佳产酸量是44.2g/L,葡萄糖的转化率是40.1%。     

不同交联条件的棉纤维微隙结构

采用N-羟甲基酰胺超低甲醛化合物作交联剂,对棉织物进行易护理整理,测定了不同交联程度(浸轧液中交联剂用量分别为289 g/L和120 g/L)和发生交联反应时棉纤维含湿不同(轧烘焙交联法和汽蒸交联法)织物的物理机械性能和纤维微观孔穴结构;通过测定,分析了织物物理机械性能和纤维微隙结构之间的关系.研究结果表明,生成的交联"分隔"了孔穴,使孔穴朝小尺寸方向移动;较大孔径孔穴的减少,与织物交联后断裂强力和断裂延伸度的降低有对应关系;在交联程度相当的条件下,汽蒸交联法棉织物的断裂强力和断裂延伸度优于焙烘交联法.     

不同储存条件下核桃油的氧化稳定性研究

为了研究合适的核桃油储存方式,以温度、光照、氧气、水分四个因素为自变量,酸价、过氧化值为指标研究氧化规律。Rancimat法和60℃烘箱加速氧化法预测货架期,以常温储存核桃油为对照组,比较两种方法的可靠性。结果表明:效果最好为冷藏组,储存超过60 d,最短为敞口组和摇晃组,不足14 d,添加0. 1%～0.3%水分组,21 d开始酸败,避光组储存期为49 d。Rancimat法预测货架期为212 d,烘箱加速法预测为48～80 d。常温储存49 d酸败,烘箱加速法预测货架期更可靠。建议核桃油低温储存,同时可避光存放,尽量选用与空气接触面积小的储油容器,并减少油的重复使用。     

不同冻结条件下罗非鱼片的质构分析

对不同条件(-7,-21,-31℃)下冻结的罗非鱼片进行质地剖面分析(TPA)。研究罗非鱼片的硬度、内聚性、弹性、胶着性、咀嚼性的参数变化;分析罗非鱼片的干耗、汁液流失率的品质变化特征。结果表明,随着冻结温度的降低,弹性呈下降趋势;硬度、内聚性、胶着性、咀嚼性呈上升趋势;干耗、汁液流失率也呈现明显下降趋势,说明低温快速冻结条件比缓冻条件抑制罗非鱼体内酶活性更有效,减少蛋白质分解变性,从而保持鱼片的风味和品质。     

不同培养条件下酿酒酵母菌的转录组差异分析

从组学水平分析富硒条件下酿酒酵母菌(Saccharomyces cerevisiae)内在分子机制,为酿酒酵母菌富硒研究及富硒基因的挖掘利用提供理论依据。该研究以不加硒培养的酿酒酵母菌作为对照组Kb,以加20μg/mL硒培养的酿酒酵母菌为实验组Se,利用Illumina高通量测序平台对两组进行转录组测序,通过生物信息学方法对数据进行分析处理。结果表明,转录组测序共获得6 445个Unigenes,分别有1 401个(21.74%)、3 665个(56.87%)、5 630个(87.35%)、6 112个(94.83%)、6 077个(94.29%)、5 059个(78.49%) Unigenes被注释到GO、KEGG、COG、NR、Swiss Prot和Pfam数据库,共有6 150个(95.42%) Unigenes得到注释。在GO功能注释中,共得到41个GO功能小类,在KEGG代谢通路分析时,获得了113条KEGG通路。该转录组测序数据质量高,结果覆盖面广,为酿酒酵母菌富硒基因挖掘和研究提供了一定的理论参考。     

Carcass and meat quality characteristics of the progeny of two swine sire lines reared under differing environmental conditions

The objective of this study was to compare the carcass and meat quality of pigs of two sire lines (A vs B) reared in either a spacious or crowded environment. A total of 128 pigs (barrows and gilts) were used in the study. Animals were slaughtered at 120 kg live weight. Dressing percentage was greater for line A in the spacious but not the crowded environment and line A had a greater loin eye area than line B. Compared to line B, the longissimus from line A had lower pH, higher L* and b* values, and was judged to be paler and softer with a lower marbling fat content. Longissimus L* values were lower for pigs reared in the crowded compared to the spacious environment. Longissimus drip loss was greater for line A compared to line B in the spacious but not the crowded environment. This study highlights genetic differences in pork quality and suggests rearing environment effects that warrant further study.     

Pre-harvest surveillance of Campylobacter and Salmonella in Danish broiler flocks: a 2-year study.

In national surveillance programmes of broiler flocks carried out in Denmark during 1998 and 1999, 89,110 samples for Campylobacter representing 8911 broiler flocks were taken at 10 different abattoirs, and 44,550 samples for Salmonella were taken from the same flocks in the broiler houses at the farms. Of the swabs, 42.5% were Campylobacter positive. Most positive samples were found during July, August and September, while the lowest number of positive samples were found during January, February, March and April. Of the flocks, 5.5% were Salmonella positive, but no seasonal variation was observed. For each flock, the presence of Campylobacter and Salmonella was recorded in order to estimate the possible correlation between colonisation with the two pathogens. In conclusion, no significant effects on intensive cleaning and disinfection procedures on Campylobacter occurrence could be demonstrated, and no significant correlation between occurrence of Campylobacter and Salmonella infections in Danish broilers could be demonstrated which is in contrast to previous observations on concurrent colonisation of broilers with these two zoonotic pathogens.     

Evaluation of the Labeled Hedonic Scale under different experimental conditions

The present study explored the performance, psychophysical properties, and potential limitations of the Labeled Hedonic Scale (LHS) in two different test conditions. The LHS was first compared against the 9-point hedonic scale in a psychophysical laboratory setting by having subjects evaluate two sets of taste stimuli with different size of hedonic ranges. Both scales showed equal discrimination power, but the LHS was more resistant to ceiling effects and its data satisfied the normality assumption for statistical analysis. In the second experiment, subjects with different levels of prior experience with the 9-point scale were recruited to evaluate juice samples and food item names in a large-scale consumer test, after receiving either common written instructions or detailed instructions emphasizing the use of the LHS. Improper use of the LHS (e.g. categorical ratings) was evident for those who received written instructions, especially among subjects who had previous experience with the 9-point scale. The present results support the efficacy of the LHS in various test settings, while highlighting the importance of providing adequate instructions to subjects to fully utilize its advantages.