Clearer understanding is needed of the premises underlying SI and how it relates to food-system priorities.

Genetics is key to the improvement of welfare in broiler chickens at both juvenile and adult (breeder) stages but progress is hampered currently by the seemingly conflicting demands of welfare, commercial production, food security and calls for increasing intensification to curb climate change. Animal welfare is therefore most likely to be improved on a commercial scale by future breeding programmes that incorporate multiple goals of different stakeholders as far as possible and give higher priority to animal welfare. These include: i) broilers with high welfare traits; ii) broiler breeders that do not need feed restriction; iii) birds that can be grown in an economically profitable way; iv) birds with low disease levels without the need for routine medication; v) chicken meat that is healthy and good for humans to eat; and (vi) broilers and breeders that thrive in systems that are environmentally sustainable. Progress towards achieving these goals is hampered currently by the assumptions that high juvenile growth rate is incompatible with good welfare and that feed restriction in adults is inevitable with fast-growing juveniles. We challenge these assumptions at both genetic and whole-animal level and argue that the conflict between good welfare and productivity can be reduced by making use of all available genetic variation from existing breeds and other sources and selecting birds in the range of environments they will encounter in commercial production.

Note to P. Lewis. A few general formatting points. Some phrases in bold, some et al.s not in italics. 1 The first para of "Statisitical analysis" contains several 'levels'-I try to encourage authors to avoid the 2 word-it's lazy and sometimes ambiguous-wherever possible it should be replaced by the actual 3 measure-concentration, intensity, number etc and sometimes it can even be deleted altogether. Think 4 about its use here. Some probability symbols are lowercase Roman. Ampersands in some text 5 references.

Rather than construct lists of many different welfare indicators and give each of them the same weight, I argue that the assessment of animal welfare should be directed at answering two key questions: I) Are the animals healthy? 2) Do they have what they want? Behaviour has a major role in answering both. Behaviour is currently used to help answer the first question through its use in the clinical and pre-clinical assessment of pain, injury and disease, and potentially could have an even greater role, particularly if used in conjunction with new technology. Behaviour is also of crucial importance in gauging what animals want, most obviously in the use of choice and preference tests, but also through other methods that are particularly suitable for on-farm welfare assessment. These include quantitative observations of the spatial distribution of animals and of behavioural ‘indicators’ of what animals want, such as vocalisations.

The effect of two different lactation environments on the development of pig behaviour was examined at weaning and on days 1, 8, 15 and 57 post weaning. Ten focal indoor-bred pigs and 10 focal outdoor-bred pigs were weaned and mixed together into a group of 60 to 80 mixed indoor- and outdoor-bred pigs. There were six replicate groups. Scans of all focal animals were made using time sampling with a 2-min interval, for 3·0 h immediately following weaning and from 06:00 to 11:00 h on days 1, 8, 15 and 57 post weaning. All pens were straw bedded with two different types of feeder system: one seven-space ad libitum hopper and two rooting-action feeders each accommodating up to four piglets at one time.From weaning to day 1 post weaning, outdoor-bred pigs were observed to feed more than were indoor-bred pigs (115·6 v. 97·0 observations per pen per day, P < 0·05, s.e.d. = 1·18). From days 8 to 57 post weaning, outdoor-bred pigs were observed to root more than were indoor-bred pigs (22·5 v. 14·7 observations per pen per day, P < 0·05, s.e.d. = 1·22). These findings support the hypothesis that the lactation environment has a significant effect on the behaviour of pigs in their subsequent growing environment. However, such effects appear not to lead to differences in carcass weights, rigor following dressing or carcass blemish at slaughter.

No abstract

Group level measures of welfare flocks have been criticized on the grounds that they give only average measures and overlook the welfare of individual animals. However, we here show that the group-level optical flow patterns made by broiler flocks can be used to deliver information not just about the flock averages but also about the proportion of individuals in different movement categories. Mean optical flow provides information about the average movement of the whole flock while the variance, skew and kurtosis quantify the variation between individuals. We correlated flock optical flow patterns with the behavior and welfare of a sample of 16 birds per flock in two runway tests and a water (latency-to-lie) test. In the runway tests, there was a positive correlation between the average time taken to complete the runway and the skew and kurtosis of optical flow on day 28 of flock life (on average slow individuals came from flocks with a high skew and kurtosis). In the water test, there was a positive correlation between the average length of time the birds remained standing and the mean and variance of flock optical flow (on average, the most mobile individuals came from flocks with the highest mean). Patterns at the flock level thus contain valuable information about the activity of different proportions of the individuals within a flock.

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.