The intensity of resistance by mature Merino ewes against Haemonchus contortus and Tichostrongylus colubriformis in single-species and combined-species infection     

DB ADAMS  JJ LYNCH†  BH ANDERSON  LR FELL‡  GN HINCH§  RK MUNRO¶ 《Australian veterinary journal》1990,67(12):443-445

Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted.  相似文献   

Surveillance of dairy production holdings supplying raw milk to the farmhouse cheese sector for Escherichia coli O157, O26 and O111     

Murphy M  Buckley JF  Whyte P  O'Mahony M  Anderson W  Wall PG  Fanning S 《Zoonoses and public health》2007,54(9-10):358-365

Clinically healthy domestic animals can harbour Escherichia coli O157 and other verocytotoxigenic E. coli (VTEC) strains in their faeces. Milk filters can be used to microbiologically monitor direct milk secretion and environmental contamination for these pathogens. The aim of this study was to establish baseline data on the prevalence and characteristics of VTEC organisms in lactating animals (bovine, ovine and caprine) supplying milk to the farmhouse cheese sector, with particular emphasis on serogroups O157, O111 and O26. Fifty-six bovine, 13 caprine and 5 ovine herds/flocks, the majority of which supplying milk for farmhouse cheese production, were surveyed from May 2004 to July 2005. Milk filters were analysed by immunomagnetic separation followed by PCR, on a serogroup-specific basis for E. coli O157, O26 and O111. Positive isolates were examined using a multiplex PCR protocol, for their potential to produce verocytotoxins (vt1/vt2), the haemolysin-encoding gene (hlyA) and the gene encoding attaching and effacement (eae). Five verocytotoxigenic and 22 non-virulent E. coli O157 isolates were detected. Seventeen E. coli O26 isolates were also detected, four of which were verocytotoxigenic, seven isolates contained the eae gene only and six isolates were devoid of any of the virulence factors. The VTEC O157 and O26 isolates contained the hlyA and eae genes along with the verocytotoxin genes. No E. coli O111 isolates were detected. Some of the herds were positive on more than one occasion and multiple E. coli serogroups were isolated from the same milk filter sample. Although all food products tested were VTEC negative, routine surveillance for such pathogens in raw milk/raw milk products is of public health importance. Herd-level surveillance along with subsequent risk management action may be a cost-effective component of risk reduction strategies for food production, drinking water supplies and the protection of public health.  相似文献   

疑似碘酊致牛死亡一例     

何国新  刘金杰 《中国兽药杂志》2005,39(10):53-53

笔者在临床上曾遇到一疑似“碘酊”致牛死亡的病例,由于未曾见过碘酊致牛死亡的报道,查阅资料也终未得到答案.笔者将其整理如下,供同行探讨。  相似文献   

The effect of commercial steam pasteurization on the levels of Enterobacteriaceae and Escherichia coli on naturally contaminated beef carcasses     

Minihan D  Whyte P  O'Mahony M  Collins JD 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(7):352-356

The aim of the study was to assess the reduction achieved by steam pasteurization of beef carcasses of Escherichia coli, Enterobacteriaceae and total aerobic mesophilic plate counts (APCs). In total, 30 carcass halves were exposed to steam pasteurization (90 degrees C, 10 s exposure time) and the 30 corresponding carcass halves remained as untreated controls. The neck, midline and rump were sampled on each carcass half. Significant reductions in E. coli incidence (P < 0.05) and counts, 0.5 log10 CFU 1000 cm(-2) (P < 0.05), were observed on rump sites only. Significant reductions (>0.8 log10 CFU 1000 cm(-2)) of Enterobacteriaceae were observed at all carcass sites sampled (P < 0.05). Enterobacteriaceae reductions (>2 log10 CFU 1000 cm(-2)) were highly significant at the more contaminated sites (P < 0.001). Reductions in total APCs were inconsistent. Steam pasteurization significantly reduced the level of E. coli and Enterobacteriaceae at more contaminated sites, but did not result in complete decontamination. Therefore, steam pasteurization should be classed as an aid to hygienic beef processing, but not as a critical control point.  相似文献   

Is the Production of Embryos in Small‐Scale Farming an Economically Feasible Enterprise?          下载免费PDF全文

Z Sánchez  MA Lammoglia  MA Alarcón  JJ Romero  CS Galina 《Reproduction in domestic animals》2015,50(4):574-579

The present assay attempts to evaluate the feasibility of using embryo transfer in small community farmers by in vivo study and by modelling the results obtained. From the total of 59 donor cows, 62.7% responded to treatment, with a significant difference (p = 0.002) in the percentage of the response between breeds, being 90.5% (19/21) in Holstein and 47.4% (18/38) in Brahman. A total of 283 embryos were graded as transferable, while 141 as non‐transferable, without difference in the percentage of transferable embryo by breed (p = 0.18). The mean of transferable embryos graded as class I and II was not different between Holstein and Brahman (p = 0.96 and p = 0.92, respectively); besides, no differences were observed in the other grades (non‐transferable). The highest difference in costs, regardless of its quality by breed, was seen in the lower levels of probable fertility of the embryo transferred, even reaching several hundred dollars. When modelling the expected costs for embryo produced and transferred, values can reach nearly $2000.00 when the probable fertility is only 10%. However, when the probable fertility was 60%, embryo cost was close to $300.00. This technology seems to be viable on average or high‐scale systems, having a superovulatory response between 60 and 80% with 4–6 transferrable embryos. Yet, in small‐scale farming, due to the reduced number of donors and/or recipients, the costs surpass the economical feasibility of the technique.  相似文献   

Percentage of Ubiquitinated Spermatozoa does not Correlate with Fertilizing Capacity of Thawed Bovine Semen     

I Rodríguez‐Lozano  A Ávalos‐Rodríguez  H Castillo‐Juárez  F Borderas‐Tordesillas  JJ Roa‐Vidal  AM Rosales‐Torres 《Reproduction in domestic animals》2014,49(1):27-31

In the spermatozoa of some species, the ubiquitin–proteasome system detects altered proteins and tags them for elimination by the proteasome. In some species' ejaculates, a high proportion of ubiquitinated spermatozoa (i.e. those having ubiquitin bound to the altered or damaged membrane proteins) has been related to infertility. The aim of this study was to assess whether the percentage of ubiquitinated spermatozoa relates to fertility of dairy bulls and whether ubiquitination increases during protein remodelling that occurs during in vitro spermatic capacitation. Thirty‐two frozen semen straws from four high‐fertility (ReproMax^®) and four normal‐fertility (Normal) Holstein‐Friesian sires were evaluated. Ubiquitinated and capacitated spermatozoa were quantified by sperm ubiquitin tag immunoassay and chlortetracycline stain, respectively. Fertilizing capacity of sires was assessed by in vitro fertilization. No differences were found between Normal and ReproMax^® sires with regard to the observed percentage of ubiquitinated spermatozoa (42.97 ± 3.69% and 49.68 ± 9.27%, respectively; p > 0.05). Additionally, no differences were found in the percentage of ubiquitinated spermatozoa as a consequence of spermatic capacitation in either Normal (42.97 ± 3.69% before capacitation vs 44.67 ± 7.5% after; p > 0.05) or ReproMax^® sires (49.68 ± 9.27% before vs 45.05 ± 7.51% after; p > 0.05). The percentage of ubiquitinated spermatozoa in a thawed sperm samples did not correlate with its in vitro fertilizing capacity; thus, this assay does not prove useful to detect in vivo fertility differences between sires. Additionally, protein degradation occurring during remodelling of the spermatozoon plasma membrane during the capacitation process does not seem to involve the ubiquitin–proteasome system.  相似文献   

Microbial origin of the abdominal swelling affecting farmed larvae of gilt-head seabream, Sparus aurata L.     

J Sedano  I Zorrilla  MA Moriñigo  MC Balebona  A Vidaurreta  MA Bordas  JJ Borrego 《Aquaculture Research》1996,27(5):323-333

The aetiological agents of the abdominal swelling affecting farmed larvae of gilt-head seabream, Sparus aurata L., were studied. Four Vibrio strains were isolated from larvae of S. aurata affected by this disease, and all strains reproduced the disease in healthy larvae under controlled infection experiments, producing a significant increase of the mortality rates compared to the control (non-inoculated larvae). Several enzymatic properties, which can act as .virulence factors, were demonstrated both in the extracellular products (ECPs) and In live cells of the strains tested. Histopathological examinations of the infected fish larvae revealed important changes of the anterior intestine and liver characterized by a marked hyperthrophy of the intestinal epithelium and hepatocytes, and by a separation of the mucosal and submucosal layers in the digestive tube. These histological alterations were associated with the constant presence of cocobacillar bacteria in the anterior intestine and in the liver. However, the precise pathogenic mechanisms of the strains tested have not been completely elucidated yet.  相似文献   

Factors responsible for the introduction and spread of Campylobacter jejuni infection in commercial poultry production   总被引：4，自引：0，他引：4  

R R Kazwala  J D Collins  J Hannan  R A Crinion  H O'Mahony 《The Veterinary record》1990,126(13):305-306

Campylobacter jejuni and related thermophilic campylobacters were not found in a hatchery or in chicks aged less than seven days. However, an increasing proportion of chicks aged two weeks and older shed campylobacters in their droppings. It was shown that a likely source of C jejuni for young chicks was the environment in the immediate vicinity of the rearing houses, and that infection could readily be introduced on the footwear and clothing of farm staff. Thermophilic campylobacters were found in the air, litter and drinking water containers in the rearing and finishing houses.  相似文献   

Assessment of Suitable Porcine Semen for Freezing,According to the Ejaculate Characteristics in the Iberico × Landrace Breed     

LF Goslvez  JJ Valdelvira  A Vidal  JMR Alvario 《Reproduction in domestic animals》2002,37(5):282-284

A total of 35 ejaculates were studied in order to assess the suitability of porcine semen for freezing according to the ejaculate characteristics. The effects of the freezing procedure were identified; a decrease in motility and acrosome quality was found after thawing. The best results on motility were linked to the ejaculates with a volume of less than 100 ml of the sperm‐rich fraction, a concentration lower than 450 × 10⁶ spermatozoa/ml and an agglutination score below 2. However, the best normal apical ridge (NAR) was found when the volume of the sperm‐rich fraction was greater than 150 ml. For this reason, an intermediate volume of the sperm‐rich fraction of the ejaculate for the best motility and the best NAR, a concentration lower than 450 × 10⁶ spermatozoa/ml and a rate of agglutination below 2 should provide the best quality after freezing. This study also attempted to determine whether a positive effect of ejaculate selection on the overall freezing performance might be expected.  相似文献   

Stabilizing Lead-Salt Diode Lasers: Understanding and Controlling Chaotic Frequency Emission     

G Chin  LR Senesac  WE Blass  JJ Hillman 《Science (New York, N.Y.)》1996,274(5292):1498-1501

Lead-salt tunable diode lasers (TDLs) are the only devices currently available that can generate tunable monochromatic radiation at arbitrary wavelengths between 3 and 30 micrometers and are particularly useful for high-resolution spectroscopy over a wide range of spectral regimes. Detailed observations of TDLs show that the observed instrumental linewidth is actually a temporal average of many narrow (less than 0.5 megahertz) emission "modes." The time scale characteristic of these "modes," which appear to be of relatively constant intensity, is of the order of a microsecond. The laser's behavior is highly suggestive of a chaotic process, that is, seemingly random excursions of a dynamic variable (frequency) within a bounded range. This report shows experimentally that TDL emissions are indeed chaotic. Furthermore, in a simple and robust fashion, this chaotic behavior has been successfully controlled with the use of recent techniques that take advantage of chaos to produce a narrow band laser output.  相似文献