Yersinia ruckeri—A threat not only to rainbow trout

Yersinia ruckeri (Y. ruckeri) can cause mortalities that are contributing to substantial economic losses in the rainbow trout (Oncorhynchus mykiss) aquaculture sector. Because of its most characteristic clinical signs, the disease in rainbow trout caused by this pathogen is called enteric redmouth disease. Although it is considered to affect mainly salmonids, there are reports in the available literature of isolating this bacterium from other fish species, both clinically healthy and diseased. The aim of this study was to analyse the available data concerning yersiniosis in non‐salmonid fish. The analysed data indicate that Y. ruckeri is a threat not only to rainbow trout. Some of the affected species have high commercial importance and mortalities may contribute to high economic losses. The disease symptoms may not be specific and can be different from those characteristic for enteric redmouth in trout, which may lead to misdiagnosis. Collected information indicates that infection with Y. ruckeri should be taken into account in the diagnostic procedures not only in salmonids.     

肉鸡发育障碍与矮小综合征

肉鸡发育障碍与矮小综合征是一种包括肠道损害等多症状的传染性疾病，目前已遍布世界各地，在蛋鸡、珍珠鸡和火鸡中均有发生，是一个严重威胁现代养禽业的重大问题。论文从肉鸡发育障碍与矮小综合征的临床症状、病理变化和病原学对其进行了综述，以期为本病的诊断和预防提供参考。     

奶牛场温室气体排放与减排措施

奶牛养殖在产能提升的同时也排放了大量温室气体。本文梳理了奶牛养殖场温室气体排放的重点环节,主要分为奶牛养殖活动温室气体排放以及牛场日常运行耗能两个方面;结合奶牛养殖肠道发酵和粪污管理的温室气体核算方法,归类整理了主要的减排措施,包括进行提高饲料质量和转化效率、粪污高效管理、清洁能源替代等方式,助力奶牛养殖实现低碳乃至零碳排放。     

The use of a real-time PCR primer/probe set to observe infectivity of Yersinia ruckeri in Chinook salmon, Oncorhynchus tshawytscha (Walbaum), and steelhead trout, Oncorhynchus mykiss (Walbaum)

Yersinia ruckeri is the causative agent of enteric redmouth disease (ERM), a common pathogen affecting aquaculture facilities and implicated in large losses of cultured fish. Fisheries scientists continue to gain a greater understanding of the disease and the pathogen by investigating methods of identification and pre- and post-infection treatment. In this study, a real-time PCR probe set for Y. ruckeri was developed to detect daily changes in the bacterial load during pathogen challenges. Two species of fish, Chinook salmon, Oncorhynchus tshawytscha, and steelhead trout, Oncorhynchus mykiss, were exposed to two strains of Y. ruckeri (Hag and SC) during bath challenges. A subset of fish was killed daily for 14 days, and the kidney tissue was biopsied to enumerate copies of pathogen DNA per gram of tissue. While Chinook exposed to either the Hag or SC strains exhibited similar pathogen loads, those exposed to the Hag strain displayed higher mortality (～66%) than fish exposed to the SC strain (～24% mortality). Steelhead exposed to the Hag strain exhibited a greater pathogen load and higher mortality (～42%) than those exposed to the SC strain (<1% mortality). Steelhead challenged with either strain showed lower pathogen loads than Chinook. The study illustrates the efficacy of the probe set to enumerate Y. ruckeri bacterial growth in the kidneys of fish. Also, strains of Y. ruckeri display species-specific growth patterns that result in differential mortality and pathogen load.     

Digestive physiology,metabolism and methane production of captive Linné's two‐toed sloths (Choloepus didactylus)

Sloths are renowned for their low metabolic rate, low food intake and low defecation frequency. We investigated factors of digestive physiology and energy metabolism in four captive individuals (mean body mass 10.0 ± SD 3.7 kg) of a hitherto mostly unstudied sloth species, Linné's two‐toed sloth (Choloepus didactylus), in a 2‐week digestion recording and 23‐h respiration experiment on animals fed a standard zoo diet of vegetables and starchy components. Dry matter intake, defecation frequency and particle mean retention time (MRT) in the gastrointestinal tract (GIT) were 12 ± 3 g/(kg^0.75 day), once every 5 days and >140 h in three individuals, but 53 g/(kg^0.75 day), daily and 82 h in one individual that was apparently compensating for a period of weight loss prior to the experiment. In all animals, solute marker was eliminated at a faster rate than the particle marker, indicating ‘digesta washing’ in the sloths’ GIT. The overall metabolic rate calculated from oxygen consumption matched the metabolisable energy intake in three individuals [173 ± 22 vs. 168 ± 44 kJ/(kg^0.75 day)] but not in the fourth one [225 vs. 698 kJ/(kg^0.75 day)], supporting the interpretation that this animal was replenishing body stores. In spite of the low food intake and the low‐fibre diet (209 ± 26 g neutral detergent fibre/kg dry matter), methane production was rather high accounting for 9.4 ± 0.8% of gross energy intake (2.7% in the fourth individual), which exceeded literature data for ruminants on forage‐only diets. These results corroborate literature reports on low intake, low defecation frequency, low metabolic rate and long MRT in other sloth species. The long MRT is probably responsible for the comparatively high methane production, providing more opportunity for methanogenic archaea than in other non‐ruminant mammals to produce significant amounts of methane.     

Molecular detection and characterization of unclassified bovine enteric caliciviruses in South Korea

The unclassified bovine enteric calicivirus (BEC) is a new bovine enteric calicivirus that is different from bovine norovirus, and causes diarrhea and pathologies in the small intestine of calves. This virus includes Nebraska (NB)- and Newbury agent 1 (NA1)-like strains. The prevalence of this BEC and its genetic characterization has only been reported in the UK and the USA. This study examined the prevalence and genetic diversity of these BECs in diarrheic calves in South Korea. Among a total of 645 diarrheic fecal specimens obtained from 629 cattle herds, these unclassified BECs were detected in 59 (9.1%) diarrheic fecal samples from 57 herds (9.3%) by either RT-PCR or nested PCR. Sequence and phylogenetic analyses of the partial RdRp gene showed that all the Korean BECs clustered together and were closely related to the NB-like viruses (80.9-88.1% nucleotide and 84.5-98.4% amino acid) but not to the NA1-like viruses (75.8-78.4% nucleotide and 79.7-82.8% amino acid). Although these viruses could not be classified into NA1- and NB-like viruses from the sequence and phylogenetic data of the entire capsid gene, all the Korean BECs clustered together on a branch separate from the other known BECs. These results show that these BEC infections are endemic in diarrheic calves in South Korea. The infecting strains are genetically closer to the NB-like viruses but have a distinct evolutionary pathway.     

Black tea reduces diarrhoea prevalence but decreases growth performance in enterotoxigenic Escherichia coli-infected post-weaning piglets

Enterotoxigenic Escherichia coli (ETEC) is a main cause of diarrhoea in humans and piglets. In vitro, black tea extract (BTE) has anti-pathogenic properties. Anti-diarrhoeal properties of BTE were assessed in a pig model of gastrointestinal infection. At weaning (day 0), piglets (n = 96) were randomly assigned to a diet containing 0% (control), 0.4% or 0.8% (wt/wt) BTE during 27 days. Piglets were orally infected with 6.4 × 10(6) cfu of ETEC on day 6. Faecal consistency, feed intake and body weight were measured. In a sub-study (n = 30 piglets), the effect of BTE palatability on feed intake was assessed. Additionally, the effect of BTE on ETEC growth in the presence or absence of iron was studied in vitro. The 0.8% BTE diet reduced diarrhoea prevalence by 20% but also decreased feed intake by 16% and feed efficiency by 12% over the total period. The 0.4% BTE diet decreased feed efficiency and weight gain from day 13 onwards. The palatability study demonstrated that piglets preferred the control to the BTE diets. In vitro, BTE delayed ETEC exponential growth, which was reversed by iron addition. Although BTE had anti-diarrhoeal properties, this effect was accompanied by impaired performance. The absence of a correlation between diarrhoea prevalence and feed intake suggests that reduced diarrhoea directly results from BTE rather than from reduced feed intake caused by BTE astringency.     

Characterization of Interstitial Cells of Cajal in Bowel of Cattle (Bos taurus)

Interstitial cells of Cajal (ICC) have been described in the gastrointestinal tract of different mammals including humans, horses, pigs, rats, dogs, mice and guinea-pigs. In the present study, ICC were identified in the jejunum of Bos taurus using polyclonal anti-c-Kit antibodies in immunohistochemical assays. Vimentin and desmin intermediate filaments were also determined using monoclonal antibodies. ICC were found in the tunica muscularis either in a palisade distribution pattern between the outer longitudinal and the inner circular layers (ICC-MP) or freely distributed in clusters in the longitudinal layer (ICC-LM). Morphometric studies determined that ICC have a fusiform shape presenting cytoplasmic prolongations. ICC were positive to c-Kit and vimentin antigens but negative to desmin. We have observed and described for the first time the presence of ICC in a ruminant. As observed in the aforementioned mammals, bovine ICC were associated with the myenteric plexus. Nevertheless, the presence of widespread ICC in the longitudinal muscular layer of the jejunum differs from previously described studies of other mammals.     

基于IPCC方法的新疆畜禽温室气体排放时空分析

在IPCC方法的基础上,对1980-2016年新疆畜禽温室气体排放的时空变化特征进行了研究。结果表明:新疆畜禽温室气体从1980年的1224.01×10^4 tCO2-eq波动升高至2016年的2032.80×10^4 tCO2-eq,增幅为66.08%,年均增长1.41%;畜禽肠道发酵甲烷排放是新疆畜禽温室气体的主要贡献者,占温室气体排放总量的84%,其次是畜禽粪便管理氧化亚氮和甲烷的排放;而主要畜禽温室气体排放以牛和羊为主,其次是马、驴、猪、骆驼和骡;最后通过对2015年新疆畜禽温室气体排放空间变化分析可知,伊犁州直属县(市)温室气体排放量最大,为456.78×10^4 tCO2-eq,而温室气体排放量最小的克拉玛依市仅有4.37×10^4 tCO2-eq,说明新疆畜禽温室气体排放空间差异性较大。     

植物乳杆菌对致病性肠炎沙门氏菌感染蛋鸡的生产性能及其蛋、粪含菌量的影响

试验旨在研究植物乳杆菌（Lactobacillus plantarum,LP）对致病性肠炎沙门氏菌（Salmonella enteric,SE）感染蛋鸡的生产性能和鸡蛋、粪中病菌残留的影响。选用144只50周龄农大3号蛋鸡,分4个组,每组4个重复,每个重复9只鸡。空白对照组和阳性对照组饲喂基础日粮;土霉素组在基础日粮中添加5 mg/kg土霉素;乳杆菌组在基础日粮中添加10⁹ CFU/kg植物乳杆菌。阳性对照组、土霉素组和乳杆菌组蛋鸡在试验第22和24天口腔接种1 mL沙门氏菌（10⁹CFU/mL）,试验期50 d。结果显示：攻毒前,各组生产性能指标无显著差异（P>0.05）;攻毒后,与空白对照组相比,感染前期阳性对照组平均蛋重显著降低（P < 0.05）,料蛋比显著升高（P < 0.05）,鸡蛋中沙门氏菌带菌率和粪中沙门氏菌含菌量显著升高（P < 0.05）。与阳性对照组相比,感染前期土霉素组和乳杆菌组蛋鸡平均蛋重分别提高5.43%（P < 0.05）、9.64%（P < 0.05）,料蛋比分别降低11.51%（P < 0.05）、5.16%（P > 0.05）;感染后期乳杆菌组料蛋比降低9.96%（P < 0.05）,乳杆菌组鸡蛋中沙门氏菌带菌率和粪中沙门氏菌含菌量分别比阳性对照组降低43.17%、23.93%（P < 0.05）。空白对照组、乳杆菌组和土霉素组间生产性能和鸡蛋大肠杆菌、沙门氏菌带菌率均无显著差异（P > 0.05）。以上结果表明,日粮中添加植物乳杆菌和土霉素均可改善沙门氏菌感染蛋鸡的生产性能,降低鸡蛋和粪中的沙门氏菌含量,提高家禽抗感染能力。植物乳杆菌具有无污染、无残留的特点,可作为家禽养殖中理想的抗生素替代品。