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The objective of this study was to examine the relationship of DMI fluctuation, feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics in Nellore cattle classified by residual feed intake (RFI). One experiment was conducted in 2 consecutive years using individual pens (1.0 x 7.0 m) at the São Paulo State University feedlot, Dracena campus, Brazil. The experiment in year 1 started in June of 2012 with forty-eight 20-mo-old Nellore yearling bulls with an initial BW of 358.2 ± 19.4 kg. The experiment in year 2 started in January of 2013 with sixty 20-mo-old Nellore yearling bulls with an initial BW of 402.5 ± 33.0 kg. Experiments in years 1 and 2 lasted 94 and 84 d, respectively. All yearling bulls were categorized as high RFI (>0.5 SD above the mean, n = 25), medium RFI (±0.5 SD from the mean, n = 56), and low RFI (<0.5 SD below the mean, n = 27). Visual appraisal to collect behavior data was made on d 40 (finishing period) of both years. Yearling bulls were harvested when average across treatment groups achieved a fat thickness of 4 mm at the 12th rib. Low-RFI yearling bulls had lower daily DMI, expressed either in kilograms (P < 0.01) or as percentage of BW (P < 0.01), and improved G:F (P < 0.01) when compared to high-RFI animals. No differences were observed (P > 0.10) for ADG, final BW, or HCW among RFI groups. Also, low-RFI yearling bulls had thinner final 12th rib (P < 0.01) and biceps femoris (P8) fat thickness (P < 0.01). Low-RFI yearling bulls were slower to consume (P = 0.03) and ruminate (P < 0.01) 1 kg of either DM or NDF. No significant (P > 0.10) RFI effect was observed for any ruminal morphometrics variables evaluated, with the exception of papillae area, in which low-RFI Nellore yearling bulls tended to have smaller (P = 0.07) papillae area than medium-RFI animals. In general, low-RFI Nellore yearling bulls consumed more particles larger than 19 and 8 mm and had a similar performance when compared to both medium- and high-RFI bulls; however, carcass fat composition was negatively impacted. [ABSTRACT FROM AUTHOR]

Aims: Agrobacterium vitis is the causal agent of crown gall of grapevine. Surface motility (swarming), an important mechanism for bacterial colonization of new environments and a previously unknown behaviour of Ag. vitis, was demonstrated. Methods: Surface motility assays were performed on half-strength potato dextrose agar (Difco) containing 0·75% agar. To test for surfactant production, a drop-collapse test was used. Quorum-sensing (QS) negative and complemented mutants were tested for swarming activity. Results: Ninety-one Agrobacterium strains representing – Agrobacterium tumefaciens (17 strains), Agrobacterium rhizogenes (14 strains) and Ag. vitis (60 strains) were tested for swarming and production of surfactant. All Ag. vitis strains expressed a surface-related motility. In contrast, none of 17 strains of Ag. tumefaciens or 14 strains of Ag. rhizogenes exhibited this behaviour. Surface motility in Ag. vitis was associated with surfactant secretion; both of which are regulated by a QS system previously associated with induction of a hypersensitive response on tobacco and necrosis on grape. An aviR (belongs to luxR family) mutant was surface motility negative and did not produce surfactant. An avsI mutant (autoinducer synthase) was also surface motility negative and was complemented with an Ag. tumefaciens clone expressing avsI. Conclusions: Agrobacterium vitis is able to produce a characteristic swarming phenotype that is regulated by a complex QS system. Significance and Impact of the Study: Swarming activity is unique to Ag. vitis among Agrobacterium sp. and may be associated with the ability of the pathogen to colonize grapevines. [ABSTRACT FROM AUTHOR]

Aims: The antagonistic activity of the Escherichia coli strain H22 against enteric bacteria was studied both in vitro and in vivo. Methods and Results: In vitro, bacterial strains belonging to seven of nine genera of the family Enterobacteriaceae ( Enterobacter, Escherichia, Klebsiella, Morganella, Salmonella, Shigella and Yersinia) were inhibited by the strain H22. Six days after simultaneous oral inoculation in germ-free mice, E. coli strain H22 reduced the faecal population of Shigella flexneri 4 to undetectable levels ( P < 0·05). In ex vivo assay, inhibitory zones against Sh. flexneri 4 were observed around faecal samples from mice inoculated with E. coli strain H22. The in vitro inhibition of Sh. flexneri 4 was shown to be mediated by microcin C7. In addition to microcin C7, strain H22 was shown to produce aerobactin, new variants of colicins E1 and Ib, and bacteriophage particles with morphology similar to the phages of the family Myoviridae. Conclusions: Altogether, the properties of E. coli H22, observed both under in vitro and in vivo conditions, suggest its potential use as a probiotic strain for livestock and humans. Significance and Impact of the Study: The strain H22 was shown to produce several antimicrobial compounds with inhibitory capabilities against pathogenic or potentially pathogenic enterobacteria. [ABSTRACT FROM AUTHOR]