Detection of brucella antigen in bovine fetal stomach contents by agar gel precipitation and counter-immunoelectrophoresis

Among 21 fetuses from serologically positive dams soluble brucella antigen was detected in the stomach contents in 14 instances by agar gel precipitation test and in 19 by counterimmunoelectrophoresis. Brucella abortus biotype 3 was isolated from the fetal stomach contents in 15 of these cases. None of 20 fetuses from serologically negative dams revealed brucella antigen in the stomach contents in either test.     

Ultracentrifugal Studies of Sera from Cattle Vaccinated or Naturally Infected with Brucella Abortus

In conformity with the findings of previous investigators, it was shown by density gradient ultracentrifugation that the antibodies in sera collected from calves shortly after vaccination with Brucella abortus, strain 19, were entirely or mainly rapidly-sedimenting. These macroglobulin (19S or IgM) antibodies showed complement-fixing as well as agglutinative activity with Br. abortus antigen. In later bleedings from the same vaccinated calves, antibodies with an intermediate sedimentation rate, (IgG), were present, as well as IgM. Sera from 15 of 22 non-vaccinated, relatively recent field cases of brucellosis appeared to contain only the IgG class of antibodies. In one herd, however, two cows with IgM only and five with both IgM and IgA were found; all seven of these cattle had been serologically negative before their introduction into this known infected herd a few months earlier. The agglutinative activity of sera from four cases of brucellosis of long standing and from eight cows, 4 to 13 years of age, that had been vaccinated as calves, was confined to the IgG fraction.     

苜蓿黄萎病菌中国菌株生物学特性研究

为了解我国苜蓿黄萎病菌的生物学特性,于2007-2008年间对苜蓿黄萎病菌进行了分离、鉴定及生物学特性研究。采用常规组织分离法从新疆伊犁地区新源县苜蓿黄萎病标样中分离到一种真菌(VA001),依据Koch′s法则,并结合形态学、培养特性及ITS序列分析,鉴定为黑白轮枝菌(Verticillium albo-atrum Reinke et Berthold)。适合该菌生长的培养基有甜瓜培养基、马铃薯蔗糖培养基、马铃薯培养基,适合产孢的培养基有马铃薯葡萄糖培养基、甜瓜培养基、梅干培养基。在碳源和氮源中,麦芽糖(Maltose)、乳糖(Lactose)、甘露醇(Mannitolum)、赖氨酸(Lysine)、牛肉膏(Beef extract)、氨基乙酸(Aminoacetic acid)、组氨酸(Histidine)有利于病菌的生长;蔗糖(Sugar)、果糖(Fructose)、乳糖(Lactose)、硝酸钠(Sodium nitrate)、丙氨酸(Alanine)有利于病菌的产孢。苜蓿黄萎菌生长和产孢的适宜pH值为7.0-9.5,温度为25℃。     

Production of dialysable leukocytes extracts in cattle (author's transl)

Seven cows, one of which is negative control, have been immunized by a Measles' antigen and/or a brucella antigen.All of them have presented a specific immunization answer against one or both antigens used for their immunization and against those single antigens.The immunization control has been effected by some serological methods and by the inhibition of leukocyte migration test.The best immunization has been obtained by the injection of live Measles virus, Schwartz strain alone, or by the Brucella abortus B19 strain alone, when the administration of both strains showed a less intense immunization.In return, the simultaneous administration of the inactivated Schwartz strain and the live B19 strain has permitted the correct immunization of the animals, but only at the time of their second reimmunization.     

市售商品牛肉品质的比较分析

 为了分析市售商品牛的牛肉品质,随机选择108头市售商品牛,按体重分为401 kg以下、401～500 kg、501～600 kg、601 kg以上,共4组。结果表明,4组胴体重差异极显著（P＜0.01),但各组牛的屠宰率无显著差异(P＞0.05);体重越大,牛肉色越深,脂肪色越白;剪切力随年龄和体重增大剪切力越小(P＞0.05);不同体重组间大理石花纹没有明显趋势(P＞0.05);背膘厚度随体重增加而变厚,但401 kg以下和501～600 kg两组间差异显著(P＜0.05);体重越大眼肌面积越大,401 kg以下组与其他各组间差异极显著(P＜0.01);体重越大分割肉重越多(P＜0.01)。综合分析表明,市售商品牛体重越大,食用品质越好。     

Letters to the Editor

Extract

Sir.—There has been some correspondence in the Velerinary Record recently concerning brucella abortion breakdowns in heifers vaccinated with Strain 19 Brucella abortus. This year we have been alarmed by the sudden occurrence of abortion storms in vaccinated heifers. Brucella abortus has been seen in large numbers in direct smears taken from cotyledons and foetal stomach contents stained by the modified Z-N technique, both in our own practice laboratory and at the Department of Agriculture laboratory. To remove any possible doubt as to the identity of the organism, it has been cultured. Blood samples have been taken from the heifers concerned and sent to the Department of Agriculture laboratory where agglutination titres to Br. abortus were observed at dilutions of up to 1 in 1,280. Our practice here serves 550 dairy farms in one of the most closely stocked areas in New, Zealand. In 18 herds more than 25% of the heifers have aborted owing to brucellosis.     

动物性食品中单核白细胞增多症李氏菌的检测

比较了4种增菌液和3种分离琼脂对动物性食品中单核白细胞增多症李氏菌的检测效果,以蛋白陈增菌液和胰蛋白陈琼脂为最佳.用这种方法检测了市售猪肉、分割鸡肉、鲜牛奶、奶皮、奶酪和奶豆腐中的单核白细胞增多症李氏菌,其检出率分别为6.7%,5.45%,5.0%,7.89%,27.03%和58.97%.     

Isolation and identification of anaerobic bacteria from ovine foot rot in Spain

A microbiological study was made of 125 Merino sheep showing clinical signs of foot rot. A total of 435 strictly anaerobic strains were isolated, belonging to the following genera: Bacteroides, Peptostreptococcus, Tissierella, Fusobacterium, Megasphaera, Eubacterium, Acidaminococcus, Clostridium, Peptococcus and Propionibacterium. Of the 35 species obtained, the following were found in more than 10 per cent of animals sampled: Bacteroides nodosus, B putredinis, B buccae, B ruminicola subspecies brevis, Tissierella praeacuta, Peptostreptococcus anaerobius and Megasphaera elsdenii. Six culture media were used for isolation. Agar brucella and agar brucella enriched with G-N anaerobe supplement proved to be the most efficient for isolating anaerobic bacteria.     

Identification of Yersinia enterocolitica in Minced Meat: A Comparative Analysis of API 20E,Yersinia Identification Kit and a 16S rRNA‐based PCR Method

The isolation and identification of Yersinia enterocolitica from minced meat on CIN agar medium is still one of the major problems in food microbiology because of the low selectivity of cefsulodin–irgasan–novobiocin (CIN) agar. A total of 198 minced meat samples were collected from commercial establishments (butcher shops and supermarkets) in seven German cities in order to investigate the sensitivity and specificity of three identification techniques suitable for the differentiation of Y. enterocolitica within the rich background flora on CIN agar plates. As expected isolation of Y. enterocolitica from minced meat on CIN agar medium after 72 h enrichment in peptone, sorbitol and bile salts (PSB) broth was difficult because all plates were abundantly covered with numerous ‘typical’Yersinia‐like colonies of bull's eye appearance as well as with atypical colonies. Based on the phenotype of the colonies it was possible to detect colonies showing Yersinia‐like growth on CIN agar in 52 samples (26%). For identification of Y. enterocolitica the API 20E system (bioMerieux, Nürtingen, Germany), the Yersinia identification kit (Merlin, Bornheim‐Hersel, Germany) and a 16S rRNA based PCR assay were compared. Only in one sample (0.5%) a Y. enterocolitica strain was detected by all methods. Of the three identification systems tested for routine laboratory diagnostics the API 20E system was found to be the most suitable tool to identify Y. enterocolitica colonies within the rich background flora from minced meat samples on CIN agar plates.     

Effect of Different Crossbred Combinations on Fatting Performance in Beef Cattle

This study was aimed to determine the effects of different crossbred combinations on fatting performance in beef cattle. Using single factor randomized block design, 30 bulls (health, similar weight and age) were chosen, Simmental cattle×Kerqin beef cattle (group A), Charolais cattle×Kerqin crossbred beef cattle (group B) and Kerqin beef cattle (group C) were divided into three groups with 10 bulls per group. After 95 d, the body weight, slaughter performance, meat quality and the economic benefits of fattening were measured. The results showed that there were no significant influence on dry matter intake among trials (P>0.05). The F/G, ethanolic extract (EE) of muscle in crossbred groups (groups A and B) were significant lower than group C (P<0.05). The weight of carcass, weight of meat, rate of carcass, and the weight of shank, plate, chine and rump in crossbred groups were significant higher than group C (P<0.05). There were no significant difference in content of amino acids among groups (P>0.05),and it had difference in the content of palmitoleic acid (PAA),stearic acid(SA) and linoleic acid (LA). In this trial, it had better fattening performance and the economic benefits in crossbred cattle groups than Kerqin beef group cattle, but the ethanolic extract and unsaturated fatty acids of muscle in Kerqin beef cattle were higher than the crossbred groups, and it had better fattening performance by crossbred.     

Application of a whole-blood lymphocyte stimulation test in detection of Brucella infection in an outbreak

A whole-blood lymphocyte stimulation test (WBLST), the standard plate and tube agglutination tests, the Brucella buffered antigen test, the 2-mercaptoethanol agglutination test, the Rivanol plate precipitation test and bacteriological isolation were utilized in a brucellosis outbreak investigation in a beef herd. Three of the animals were classified as not infected serologically. However, these 3 animals were classified as infected on the WBLST, andBrucella abortus biotype 1 (not strain 19) was isolated from their lymph nodes. The WBLST exhibited significant sensitivity in this investigation and more observations of this nature might strengthen the application of this assay in similar situations.     

Feeding of Ferrets with the Raw Meat and Liver of Chickens Chronically Poisoned with Toxic Groundnut Meal

Chickens were fed a ration containing 30 per cent of toxic groundnut meal for up to six weeks. The concentration of aflatoxin (toxic metabolites of Aspergillus flavus) in the above ration was 3.06 p.p.m. At the end of 2nd, 4th or 6th week the birds were killed. The meat was removed from the bones and put through a meat grinder. The livers of three groups were pooled together. Three control groups of birds kept on commercial pellets were treated similarly.

Female ferrets, two years of age, were used in the present study. They were divided into four groups. The first three groups were given for one month meat from chickens fed the toxic ration for 2, 4, and 6 weeks, respectively. Each of these three groups contained one control ferret that was fed with the meat of chickens fed a commercial ration for a similar period of time. One half of the 4th group was fed pooled liver from intoxicated birds and one half was fed liver from control birds.

No significant changes in the ferret tissues were observed as a consequence of feeding them with the meat or liver from the chickens chronically poisoned with toxic groundnut meal.

     

Identification of Yersinia enterocolitica in minced meat: a comparative analysis of API 20E, Yersinia identification kit and a 16S rRNA-based PCR method

The isolation and identification of Yersinia enterocolitica from minced meat on CIN agar medium is still one of the major problems in food microbiology because of the low selectivity of cefsulodin-irgasan-novobiocin (CIN) agar. A total of 198 minced meat samples were collected from commercial establishments (butcher shops and supermarkets) in seven German cities in order to investigate the sensitivity and specificity of three identification techniques suitable for the differentiation of Y. enterocolitica within the rich background flora on CIN agar plates. As expected isolation of Y. enterocolitica from minced meat on CIN agar medium after 72 h enrichment in peptone, sorbitol and bile salts (PSB) broth was difficult because all plates were abundantly covered with numerous 'typical'Yersinia-like colonies of bull's eye appearance as well as with atypical colonies. Based on the phenotype of the colonies it was possible to detect colonies showing Yersinia-like growth on CIN agar in 52 samples (26%). For identification of Y. enterocolitica the API 20E system (bioMerieux, Nürtingen, Germany), the Yersinia identification kit (Merlin, Bornheim-Hersel, Germany) and a 16S rRNA based PCR assay were compared. Only in one sample (0.5%) a Y. enterocolitica strain was detected by all methods. Of the three identification systems tested for routine laboratory diagnostics the API 20E system was found to be the most suitable tool to identify Y. enterocolitica colonies within the rich background flora from minced meat samples on CIN agar plates.     

Effects of zilpaterol hydrochloride on retail yields of subprimals from beef and calf-fed Holstein steers

Retail cutting tests were conducted on subprimals from cattle fed zilpaterol hydrochloride (ZH) to determine if the improved carcass composition and red meat yield resulting from ZH feeding would translate into increased retail yields of ready-to-cook products. As part of a 3-phase study, selection of carcasses from Holstein steers was done once (fall 2008), followed by the collection of carcasses from beef-type steers on 2 separate occasions (beef study I: summer 2009; beef study II: spring 2010). Each of the 3 groups of steers was assigned previously to 1 of 2 treatments, treated (fed 8.3 mg/kg of ZH for 20 d) or control (not fed ZH). All steers were slaughtered and carcasses were fabricated in commercial beef-processing establishments. Only those carcasses grading USDA Choice or higher were used. Five subprimals were used for both the calf-fed Holstein study (n = 546 subprimals) and beef study I (n = 576 subprimals): beef chuck, chuck roll; beef chuck, shoulder clod; beef round, sirloin tip (knuckle), peeled; beef round, top round; and beef round, outside round (flat). Seven subprimals were used in beef study II (n = 138 subprimals): beef chuck, chuck roll; beef round, sirloin tip (knuckle), peeled; beef round, top round; beef round, eye of round; beef loin, strip loin, boneless; beef loin, top sirloin butt, boneless; and beef loin, tenderloin. A simulated retail market environment was created, and 3 retail meat merchandisers prepared retail cuts from each subprimal so salable yields and processing times could be obtained. Differences in salable yields were found for the calf-fed Holstein steer chuck rolls (96.54% for ZH vs. 95.71% for control; P = 0.0045) and calf-fed Holstein steer top rounds (91.30% for ZH vs. 90.18% for control; P = 0.0469). However, other than heavier subprimals and an increased number of retail cuts obtained, total salable yields measured on a percentage basis and processing times were mostly unaffected by ZH. Cutability advantages of feeding ZH are achieved primarily in the carcass-to-subprimal conversion rather than in the subprimal-to-retail conversion.     

Prevalence and molecular identification of Chlamydia abortus in commercial dairy goat farms in a hot region in Mexico

The aim of this study was to determine the seroprevalence and presence of Chlamydia abortus in Saanen breed female goats from commercial dairy goat farms under intensive production in the municipality of Guanajuato, Mexico. Sera were collected to determine the prevalence of anti-C. abortus IgG antibodies using recombinant enzyme-linked immunosorbent assay (rELISA) and cell culture. Polymerase chain reaction (PCR) was used to prove the presence of the pathogen in swab samples collected from the vagina and rectum of selected animals. Additionally, foetal tissue samples from a sudden abortion were collected. C. abortus prevalence in female goats of commercial milking farms sampled in Guanajuato, Mexico, was 4.87 % (n?=?246). Seropositive animals were found in six out of nine (66.6 %) dairy goat farms sampled, and prevalence among animals in individual farms ranged between 3.44 and 13.51 %. C. abortus was detected using PCR in spleen tissue from the aborted foetus. PCR-based detection, as well as isolation from vaginal and rectal swabs, was not possible in the present study. Isolation through cell culture was also unsuccessful from aborted foetal tissue samples. In conclusion, the results from rELISA and PCR show that C. abortus is present in dairy goat farms in the state of Guanajuato, Mexico.     

Serological response of cattle after vaccination and challenge with Brucella abortus

New and currently used serological procedures were evaluated using sera from cattle that were challenged with B. abortus S544 (S544) after vaccination with either B. abortus S19 (S19) or B. abortus 45/20 (S45/20) as calves or adults. In animals vaccinated with S19, titres to the indirect haemolysis test (IHLT) rose more slowly, declined more rapidly and involved fewer animals than did titres to the complement fixation test (CFT). In animals vaccinated with S45/20 the rough antigen complement fixation test (RCFT) showed persistent titres. At slaughter the IHLT and CFT were found to be more specific and more sensitive than the Rose Bengal Plate Test (RBPT) and Serum Agglutination Test (SAT) in the detection of cattle infected with B. abortus.     

Effects of short- or long-term infusions of acetate or propionate on luteinizing hormone, insulin, and metabolite concentrations in beef heifers

Two trials were conducted to evaluate the effects of short- (Trial 1) or long-term (Trial 2) intraruminal isocaloric infusions of acetate or propionate on secretion of LH, insulin, and selected metabolites in short- or long-term energy-restricted beef heifers. In Trial 1, 16 Angus heifers were assigned on d 6 to 12 of a synchronized estrous cycle (estrus = d 0) to a body weight-maintenance (BWM; n = 4) or an energy-restricted, body weight-loss (BWL; n = 12) treatment. On d 12 of a synchronized estrous cycle, heifers received PGF2alpha to synchronize estrus, and 12 h later BWL heifers received intraruminal, isocaloric infusions of acetate, propionate, or vehicle for 6 h and BWM heifers received vehicle concurrently. Mean plasma LH and LH pulse frequencies and amplitudes were not affected by treatment (P > .05). In contrast, infusion of propionate increased plasma insulin (P < .05) and reduced plasma concentration of NEFA (P < .05). In Trial 2, six ovariectomized Angus heifers were energy-restricted for 30 d. On d 14 and 26 of restriction, heifers began receiving intraruminal isocaloric infusions of acetate or propionate for 96 h in a switchback approach. Intraruminal infusions of vehicle for 6 h preceded infusions of acetate or propionate. Jugular blood was collected at 12-min intervals during infusions of vehicle and during the last 6 h of infusion of acetate or propionate. Mean concentration of LH and amplitude of pulses of LH were lower during acetate vs propionate or vehicle infusion (P < .05). Infusion of propionate increased insulin relative to acetate or vehicle infusion (P < .05). Plasma NEFA were reduced by infusion of propionate (P < .05) and increased by infusion of acetate (P < .05).     

Assessment of an intradermal test for the detection of bovine brucellosis

Forty-eight cattle were sensitised toBrucella antigens either by vaccination withBrucella abortus strain 19 (S19) orB. abortus 45/20 (S45/20) and 24 of these and 12 unvaccinated cattle were subsequently challenged with virulentB. abortus strain 544 (S544). All these cattle (n=60), together with 12 control cattle which were neither vaccinated nor challenged, were subsequently subjected to an intradermal test using a S45/20 protein antigen. Reactions were interpreted subjectively by observation and palpation and were measured to the nearest mm with calipers at 48 and 72 hours after injection of protein antigen. Ten weeks later the cattle were slaughtered and tissues cultured for the presence ofB. abortus. Two of the 48 vaccinated cattle died, 40 of the remaining 46 gave a positive response to the intradermal test at 48 hours and 36 were positive at 72 hours. In the controls any increase in the skin thickness had disappeared by 72 hours. An increase in skin thickness was still present at 72 hours in all other cattle except those vaccinated with S19 only. The intradermal test was found to be sensitive but not specific in detecting infected cattle and both sensitive and highly specific if used (with the exception of S19) to detect exposure toBrucella antigen.     

A study on the effect of Pseudomonas aeruginosa in semen on bovine fertility.

Two experiments were done to demonstrate whether the presence of Pseudomonas aeruginosa in bovine semen could affect fertilization and/or early embryonic development. In the first experiment, superovulated heifers were inseminated with semen naturally contaminated with P. aeruginosa (ADRI 102) or clean semen and seven day-old embryos were collected nonsurgically. The endometrium of treated heifers appeared more sensitive to the flush procedures. In experiment 2, heifers were inseminated at synchronized estrus with semen experimentally contaminated with P. aeruginosa (ADRI 102) and processed in the same way as commercial semen with antibiotics (gentamicin, lincomycin, spectinomycin and tylosin) or processed without antibiotics added. Embryos were recovered at slaughter seven days later. In general, there was no significant reduction in fertility or development of embryos in vitro as a result of relatively high numbers of P. aeruginosa in bovine semen.     

The capacity of various fractions of Pasteurella haemolytica to stimulate protective immunity in mice and hamsters

Cells of a pathogenic strain of Pasteurella haemolytica isolated from cattle were grown on solid as well as in liquid media. The harvested cells were subjected to various fractionation methods. The capacity of 15 different preparations to stimulate protective immunity was examined in mice and hamsters. It was found that extraction of cells, grown on blood agar, with an aqueous solution of potassium thiocyanate (KSCN) yielded the fraction that was most immunogenic (55 to 100% protection), in both species of animals. A saline extract of the capsular antigen gave less protection (30 to 40%) than the KSCN extract. Bacterins obtained from the same cell population used for the KSCN extract gave only 20 to 60% protection. The results indicate that the immunogenic factors present in the intact cells may not be able to induce as much protection as when these are freed from the cells. The percentage survival of immunized animals against a challenge dose was always higher in hamsters than in mice, which may represent an inherent resistance of this species of animals to the challenge organism. The deduction could also be made that hamsters are more responsive to immunization than mice.