Feed efficiency is an economically important trait in beef production. It can be measured as residual feed intake. This is the difference between actual feed intake recorded over a test period and the expected feed intake of an animal based on its size and growth rate. DNA-based marker-assisted selection would help beef breeders to accelerate genetic improvement for feed efficiency by reducing the generation interval and would obviate the high cost of measuring residual feed intake. Although numbers of quantitative trait loci and candidate genes have been identified with the advance of molecular genetics, our understanding of the physiological mechanisms and the nature of genes underlying residual feed intake is limited. The aim of the study was to use global gene expression profiling by microarray to identify genes that are differentially expressed in cattle, using lines genetically selected for low and high residual feed intake, and to uncover candidate genes for residual feed intake. A long-oligo microarray with 24 000 probes was used to profile the liver transcriptome of 44 cattle selected for high or low residual feed intake. One hundred and sixty-one unique genes were identified as being differentially expressed between animals with high and low residual feed intake. These genes were involved in seven gene networks affecting cellular growth and proliferation, cellular assembly and organization, cell signalling, drug metabolism, protein synthesis, lipid metabolism, and carbohydrate metabolism. Analysis of functional data using a transcriptional approach allows a better understanding of the underlying biological processes involved in residual feed intake and also allows the identification of candidate genes for marker-assisted selection.

A group of 1,623 ovine fecal samples recovered from 65 geographically distinct mutton sheep and prime lamb properties across New South Wales, Australia, were screened for the presence of Shiga toxin-producing Escherichia coli (STEC) virulence factors (stx 1 , stx 2 , eaeA, and ehxA). A subset was cultured for STEC isolates containing associated virulence factors (eaeA and/or ehxA), which were isolated from 17 of 20 (85%) and 19 of 20 (95%) tested prime lamb and mutton sheep properties, respectively. STEC isolates containing stx 1 , stx 2 , and ehxA were most commonly isolated (19 of 40 flocks; 47.5%), and this profile was observed for 10 different serotypes. Among 90 STEC isolates studied, the most common serotypes were O91:H Although isolates belonging to serogroup O157 are regarded as the most clinically significant Shiga toxin-producing Escherichia coli (STEC) strains, the number of non-O157 serotypes recovered from episodes of hemorrhagic colitis and hemolyticuremic syndrome (HUS) continues to increase. Currently over 160 serotypes of E. coli have been isolated from human sources (5,6,13,14,25). Ruminants, in particular (6,7,16,24), but also other domestic animals, including pigs, poultry, cats, and dogs (1,6,8), are natural reservoirs of STEC. Although more than 200 different STEC serotypes have been isolated from cattle (reference 13 and references therein), few studies have extensively examined the presence of STEC in sheep. Existing studies have been performed on comparatively small numbers of sheep or have focused intensively on a single flock or only examined the presence of O157 serotypes (3,12,16,17). Kudva et al. (17) investigated the presence of E. coli O157:H7 in a single flock over a 16-month period and described the presence of non-O157 STEC isolates of serotypes O128:NM, O5:NM, O6:H49, O88:NM, and O91:NM, with various combinations of the virulence-associated genes stx 1 , stx 2 , and eaeA. In Australia, one of the largest sheep-producing countries in the world, recent studies focusing primarily on the southeastern parts of Queensland have suggested that the prevalence of stx in fecal cultures ranges from 69 to 88% (12,22).In this study, we investigated the presence of STEC in fecal enrichment broths derived from 65 geographically diverse flocks of slaughter-age sheep (mutton sheep and prime lambs) in New South Wales, Australia, using a multiplex PCR which detects stx 1 , stx 2 , eaeA, and ehxA (11) and vancomycin-cefixime-cefsulodin blood agar (BVCCA) (18). Mutton sheep and prime lambs represent two different genetic lines of meatproducing animal and comprise sheep of different slaughter ages and production systems, parameters which have been reported to influence STEC colonization in ruminant species (26). Our aim was to isolate STEC strains that contained at least one other virulence factor (eaeA and/or ehxA). These STEC isolates were serotyped and examined for the ability to express Shiga toxins using Vero cell cultures. Commercial properties from 29 prime lamb and 36 mutton sheep flocks we...

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The virulence properties and serotypes of complex Shiga toxin-producing Escherichia coli (cSTEC) were determined in two studies of healthy cattle in eastern Australia. In the first, a snapshot study, 84 cSTEC isolates were recovered from 37 of 1,692 (2.2%) fecal samples collected from slaughter-age cattle from 72 commercial properties. The second, a longitudinal study of three feedlots and five pasture beef properties, resulted in the recovery of 118 cSTEC isolates from 104 animals. Of the 70 serotypes identified, 38 had not previously been reported.

Summary Of 61 horses with sarcoids treated with intralesional injection of a double emulsion incorporating inactivated bacillus Calmette Guérin organisms, 36 (59 per cent) showed complete regression and 11 (18 per cent) showed partial regression. The majority of cases required only one treatment. Not all sarcoids were responsive to this therapy; those not responding were usually large or on horses with multiple sarcoids.