Parallel sequencing reveals Campylobacter in commercial meat chickens less than 8 days old.

Campylobacter from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent in outcome. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, where Campylobacter is generally not detectable until birds are at least 21 days old. Using parallel sequence based bacterial 16S profiling analysis and targeted sequencing of the porA gene, Campylobacter was identified at very low levels in all commercial flocks at less than 8 days old that were tested from the UK, Switzerland, and France. These young chicks exhibited a much greater diversity of porA types than older birds testing positive for Campylobacter by culture or qPCR. This suggests that, as the bacteria multiply sufficiently to be detected by culture methods, one or two variants, as indicated by porA type, dominate the infection. The findings that: (i) most young chicks carry some Campylobacter and (ii) not all flocks become Campylobacter positive by culture, suggest that efforts to control infection, and therefore avoid contamination of poultry meat, should concentrate on how to limit Campylobacter to low levels by the prevention of the overgrowth of single strains. Importance: Our results demonstrate the presence of Campylobacter DNA amongst faecal samples from a range of commercially reared meat chicks that are less than 8 days of age, consistent across 3 European countries. The recently developed, sensitive detection method indicates that infection occurs on commercial farms much earlier and more widely than previously thought, which opens-up new opportunities to control Campylobacter contamination at the start of the food-chain, and reduce the unacceptably high levels of human disease.

Young chicks rely on symmetry/asymmetry in perceptual grouping to discriminate sets of elements

Grouping sets of elements into smaller, equal-sized, subsets constitutes a perceptual strategy employed by humans and other animals to enhance cognitive performance. Here, we show that day-old chicks can solve extremely complex numerical discriminations (Exp.1), and that their performance can be enhanced by the presence of symmetrical/asymmetrical colour grouping (Exp.2 versus Exp.3). Newborn chicks were habituated for 1 h to even numerosities (sets of elements presented on a screen) and then tested for their spontaneous choice among what for humans would be considered a prime and a non-prime odd numerosity. Chicks discriminated and preferred the prime over the composite set of elements irrespective of its relative magnitude (i.e. 7 versus 9 and 11 versus 9). We discuss this result in terms of novelty preference. By employing a more complex contrast (i.e. 13 versus 15), we investigated the limits of such a mechanism and showed that induced grouping positively affects chicks' performance. Our results suggest the existence of a spontaneous mechanism that enables chicks to create symmetrical (i.e. same-sized) subgroups of sets of elements. Chicks preferentially inspected numerosities for which same-sized grouping is never possible (i.e. the prime numerosity) rather than numerosities allowing for symmetrical grouping (i.e. composite).

Phylogenomic Characterization of a Novel Corynebacterium Species Associated with Fatal Diphtheritic Stomatitis in Endangered Yellow-Eyed Penguins

Yellow-eyed penguins, Megadyptes antipodes , are endangered species with a sharp decline in the numbers of breeding pairs over last 2 decades. Diphtheritic stomatitis, characterized by a thick fibrinopurulent exudate in the oral cavities and symptoms, including inanition and significant weight loss, is responsible for significant mortality among the young chicks.

Young chicks rely on perceptual grouping to discriminate prime numbers

Grouping sets of elements into smaller, equal-sized, subsets constitutes a perceptual strategy employed by humans and other animals to enhance cognitive performance. We hypothesized that asymmetrical grouping, a characteristic of prime numbers, could provide visual cues enabling discrimination of prime from non-prime numerosities. Newborn chicks were habituated to even numerosities (as sets of elements presented on a screen), and then tested for their spontaneous choice among a prime and a non-prime odd numerosity. Chicks discriminated and preferred the prime over the composite set of elements. We discuss this result in terms of novelty preference. By employing different contrasts (i.e., 7vs.9, 11vs.9, and 13vs.15) we investigated the limits of such mechanism showing that induced grouping positively affects chicks' performance.

Young chicks quickly lose their spontaneous preference to aggregate with females

It is not clear when and how animals start to discriminate between male and female conspecifics and how this distinction drives their social behaviour. A recent study on pheasants found that one-week-old chicks (Phasianus colchicus) preferentially aggregated with same-sex peers and this trend became more pronounced through development, suggesting that sexual segregation increases during ontogeny. However, it remains unclear whether this ability depends on experience or develops spontaneously. Using a similar experimental protocol, we investigated whether sex discrimination is present at birth in domestic chickens (Gallus gallus) by testing the aggregation preferences of young chicks with clutch mates. We measured the amount of time spent close to male and female conspecifics in visually inexperienced chicks. Soon after hatching, both males and females preferentially aggregated with females. To clarify whether the experience with conspecifics modifies the initial preference for females we used an imprinting procedure. We exposed chicks to conspecifics of the same sex, different sex or both sexes for three days and then tested their preferences to aggregate with males or females. No sex preference was observed after three days of imprinting exposure. The disappearance of the initial sex preference shows that, although chicks can discriminate between conspecifics of different sex, sex segregation does not influence aggregation in the first week of life. We suggest that the absence of sexual assortment in the first week of age can enhance the social cohesion of the flock.