Potential use of characterised hyper-colonising strain(s) of Campylobacter jejuni to reduce circulation of environmental strains in commercial poultry     

Calderón-Gómez LI  Hartley LE  McCormack A  Ringoir DD  Korolik V 《Veterinary microbiology》2009,134(3-4):353-361

Sixty-two persistently colonising Campylobacter jejuni strains were tested for their ability to dominate colonisation of the chicken gastrointestinal tract in competition with each other leading to selection of dominant or "hyper-colonising"Campylobacter strains, which are able to displace others in the chicken intestinal tract. One such strain was shown to be a hyper-efficient coloniser of chickens, as it was able to displace other colonising strains, as well as maintain itself in the chicken intestinal tract for the duration of the 56-day broiler production cycle. Once colonisation was established, this hyper-colonising C. jejuni strain, 331, could not be displaced by other colonising or hyper-colonising strains. We proposed that a defined, hyper-colonising strain, or a cocktail of defined strains with a similar phenotype, could form the basis for biological control of unknown/uncharacterised Campylobacter strains from the environment that continuously colonise chicken flocks. To validate this approach, three different chicken infection trials were carried out. These trials demonstrated that the dominant strain of C. jejuni was able to colonise broiler chickens consistently and for the entire life of the birds irrespective of the day of inoculation and antimicrobial agents used in the feed to control other pathogenic micro-organisms. In addition, we have shown that the bio-control strain was able to replace other colonising strains at various points of a 56-day broiler production cycle irrespective of time and type of inoculation. This strain was also capable of re-establishing itself following the challenge with other strains, with and without re-challenge. This work represents a "proof of principle" that a defined C. jejuni strain could be used to biologically control circulation of uncharacterised environmental strains in commercial poultry flocks.  相似文献   

Incidence, pathology and prevention of keel bone deformities in the laying hen   总被引：2，自引：1，他引：1  

Fleming RH  McCormack HA  McTeir L  Whitehead CC 《British poultry science》2004,45(3):320-330

1. As a baseline study of the nature and incidence of keel deformities in laying hens, keel condition was examined in three different strains of hen from a total of 4 different caged environments (two commercial farms and two experimental farms). Incidence of keel deformity on farms in end of lay hens ranged from 2.6 to 16.7%. Only 0.8% of younger 15-week-old pullets had deformed keels. 2. Incidence of keel deformities was unchanged in 100 birds sampled from a free-range system compared to conventional caged siblings at the same farm. 3. Keel condition was also examined in 5 selected generations of a study involving the use of a body-weight-restricted selection index for skeletal improvement. Divergent selection for skeletal characteristics decreased incidence of keel deformity and improved radiographic density (RD) in high bone index (BI) hens compared to low BI hens in all selected generations. Male high BI keels were also improved compared to low BI. Shear strength measured in normal keels in generation 6 (G6) of the genetic study was improved in high BI hens compared to low BI hens. For all hens in the genetic study, those with normal keels had stronger tibiotarsus and humerus breaking strengths than hens with deformed keels. 4. Histopathology of keels representative of different deformities showed the presence of fracture callus material and new bone in all cases. This establishes that deformities are a result of trauma and are not developmental in origin. 5. Ash contents of keels, tibiae and humeri showed no differences between hens with normal and deformed keels. There were no differences in indicators of collagen cross-linkage in other bones between hens with normal keels and those with deformed keels. 6. It is concluded that lack of bone mass is the underlying cause of keel fracture and deformity in laying hens, rather than qualitative changes in bone, and that genetic selection can improve keel quality and prevent deformity.  相似文献   

Alternate medical approaches to treatment in veterinary science     

McCormack PF 《Australian veterinary journal》2003,81(10):599

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Defective down syndrome in chicks is not caused by riboflavin deficiency in breeders     

C. C. Whitehead  J. S. Rennie  H. A. McCormack  P. M. Hocking 《British poultry science》1993,34(3):619-623

1. Riboflavin‐deficient practical and semi‐purified diets were fed to broiler breeder hens.

2. Yolk and albumen riboflavin concentrations were depressed by the deficient diets and cases of curled toes were seen in the chicks.

3. The few instances of defective down did not resemble cases seen in field outbreaks of a condition involving depressed hatchability and a defective down syndrome.

4. It is concluded from observations in this experiment and in the field outbreaks that there is a condition in breeding chickens causing depressed hatchability and defective down that is not attributable to riboflavin deficiency.  相似文献   

Carcinogen in rock fern (Cheilanthes sieberi) from New Zealand and Australia     

BL SMITH  PP EMBLING  DR LAUREN  MP AGNEW  AD ROSS  PL GREENTREE 《Australian veterinary journal》1989,66(5):154-155

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Abortion caused by neosporosis in cattle   总被引：2，自引：0，他引：2  

DL OBENDORF  N MURRAY  G VELDHUIS  BL MUNDAY  JP DUBEY 《Australian veterinary journal》1995,72(3):117-118

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Mycobacteriosis in young freshwater crocodiles (Crocodylus johnstoni)     

E. ARIEL  PW LADDS  BL ROBERTS 《Australian veterinary journal》1997,75(11):831-833

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Inheritance of bone characteristics affecting osteoporosis in laying hens   总被引：6，自引：0，他引：6  

Bishop SC  Fleming RH  McCormack HA  Flock DK  Whitehead CC 《British poultry science》2000,41(1):33-40

1. Heritabilities of a range of morphometric, radiological and strength characteristics were measured in the bones of end-of-lay hens. 2. Tibial strength (TSTR), humeral strength (HSTR) and keel radiographic density (KRD) were moderately to strongly inherited and were combined in a Bone Index which was used as a basis for selection. Data are available on 6 generations/cohorts of hens (n=1306), the last 3 of which are the progeny of divergently selected birds. 3. All bone characteristics used in the Bone Index responded rapidly to divergent selection and were strongly correlated with each other. In the last generation, the lines differed by 25% for TSTR, 13% for HSTR and 19% for KRD. The heritability of the index was 0.40. 4. There were no apparent genotype by environment interactions between birds housed at 2 different locations. 5. The incidence of bone fractures was significantly decreased in the line selected for high bone strength compared to the line selected for low bone strength. Humerus fracture incidence differed by a factor of 6 between the lines in the last generation. There was a strong quadratic relationship between tibia strength and overall fracture incidence (r2=0.92, P<0.01). 6. The results imply that selection for enhanced bone strength can be used as a long-term strategy for alleviating the problems of osteoporosis in laying hens.  相似文献   

Thousandfold change in resistivity in magnetoresistive la-ca-mn-o films   总被引：1，自引：0，他引：1  

Jin S  Tiefel TH  McCormack M  Fastnacht RA  Ramesh R  Chen LH 《Science (New York, N.Y.)》1994,264(5157):413-415

A negative isotropic magnetoresistance effect more than three orders of magnitude larger than the typical giant magnetoresistance of some superlattice films has been observed in thin oxide films of perovskite-like La(0.67)Ca(0.33)MnOx. Epitaxial films that are grown on LaAIO(3) substrates by laser ablation and suitably heat treated exhibit magnetoresistance values as high as 127,000 percent near 77 kelvin and approximately 1300 percent near room temperature. Such a phenomenon could be useful for various magnetic and electric device applications if the observed effects of material processing are optimized. Possible mechanisms for the observed effect are discussed.  相似文献   

AIDS. Turning the tide against HIV     

Shattock RJ  Warren M  McCormack S  Hankins CA 《Science (New York, N.Y.)》2011,333(6038):42-43

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