Sj Pope

Leg disorders in broiler chickens: prevalence, risk factors and prevention.

Broiler (meat) chickens have been subjected to intense genetic selection. In the past 50 years, broiler growth rates have increased by over 300% (from 25 g per day to 100 g per day). There is growing societal concern that many broiler chickens have impaired locomotion or are even unable to walk. Here we present the results of a comprehensive survey of commercial flocks which quantifies the risk factors for poor locomotion in broiler chickens. We assessed the walking ability of 51,000 birds, representing 4.8 million birds within 176 flocks. We also obtained information on approximately 150 different management factors associated with each flock. At a mean age of 40 days, over 27.6% of birds in our study showed poor locomotion and 3.3% were almost unable to walk. The high prevalence of poor locomotion occurred despite culling policies designed to remove severely lame birds from flocks. We show that the primary risk factors associated with impaired locomotion and poor leg health are those specifically associated with rate of growth. Factors significantly associated with high gait score included the age of the bird (older birds), visit (second visit to same flock), bird genotype, not feeding whole wheat, a shorter dark period during the day, higher stocking density at the time of assessment, no use of antibiotic, and the use of intact feed pellets. The welfare implications are profound. Worldwide approximately 2×1010 broilers are reared within similar husbandry systems. We identify a range of management factors that could be altered to reduce leg health problems, but implementation of these changes would be likely to reduce growth rate and production. A debate on the sustainability of current practice in the production of this important food source is required.

Effects of stocking density, flock size and management on the welfare of laying hens in single-tier aviaries

1. Management practices, stocking rate and flock size may affect laying hen welfare but there have been few replicated studies in commercial non-cage systems that investigate this. This study used a broad range of physical and physiological indicators to assess the welfare of hens in 36 commercial flocks. 2. Six laying period treatments were examined with each treatment replicated 6 times. It was not possible to randomly allocate treatments to houses, so treatment and house were largely confounded. 3. Three stocking rates were compared: 7 birds/m2 (n = 2450), 9 birds/m2 (n = 3150) and 12 birds/m2 in either small (n = 2450) or large (n = 4200) flocks. In addition, at 12 birds/m2, in both small and large flocks, birds were subjected to either standard (SM) or modified (MM) management. MM flocks had nipple drinkers and no nest-box lights. 4. Bone strength, fracture incidence, heterophil:lympocyte (H:L) ratio, live weight, organ weights, serum creatine, serum osmolality, muscle pH and faecal corticosterone were measured on samples of birds at the end of the rearing period and at the end of lay. During the laying period, mortality, production and integument condition were recorded at regular intervals. 5 Birds housed at 9 birds/m2 had higher mortality than birds housed at 12 birds/m2 by the end of lay, but not higher than birds housed at 7 birds/m2. Birds housed at 7 and 9 birds/m2 had lower percent liver weight, and worse plumage condition than most of the 12 bird/m2 treatments. Modified management tended to improve plumage condition. There were no clear effects of flock size on the welfare indicators recorded. 6. At the end of the rearing period fracture incidence was almost negligible and H:L ratio was within a normal range. 7. By the end of lay fracture incidence was 60% and H:L ratio was high, with no treatment effect for either measure. This, together with information on faecal corticosterone, feather loss and mortality, suggests that the welfare of birds in all treatments was relatively poor by the end of lay.

Social learning in sibling pigs

Abstract Three experiments were designed to assess the extent to which pigs can acquire information from their siblings. In Experiment 1, pigs were pre-exposed to the sight and smell of a novel diet, or to a sibling demonstrator eating the novel diet, or to a sibling demon-strator eating a familiar diet. In subsequent individual feeding trials, pigs from the first two treatment groups showed an enhanced preference for the novel diet relative to the third (control) group, but did not differ significantly from each other. In Experiment 2, food was hidden in three distinctly coloured and positioned troughs. Individual pigs observed a sibling demonstrator feed from one trough. In subsequent tests, ten out of 24 individuals discovered that food was available in the test room. Eight of these ten made their initial discovery of food in the same trough that their demonstrator had used. Thus, some combination of cues resulted in a significant bias in food searching behaviour towards a site where a demonstrator had previously eaten. In Experiment 3, pigs observed a trained sibling demonstrator press one of two panels for food reward during ten daily sessions. Control groups observed untrained siblings in the same apparatus. In subsequent tests, there were no significant effects of observation experience on rewarded panel pressing, but pigs that had observed demonstrators spent significantly more time facing the operant panels and directed more non-rewarded presses at the operant panels than controls. They also showed a significant discrimination for making non-rewarded presses at a panel of the same colour/position as that used by their demonstrator. Visual cues appeared to be more important than residual olfactory cues in attracting non-rewarded panel presses.

Estimating the body temperature of groups of pigs by thermal imaging

Measurements on 28 pens of pigs containing 384 animals to be slaughtered at a commercial abattoir showed that the mean ear temperatures of the pigs in each pen, measured with a thermal imaging camera, were significantly correlated (r=0·71, P<0·001) with the mean temperature of the blood the pigs lost at exsanguination. In measurements on 220 pigs in 16 of the 28 pens, the mean activity of serum creatine kinase was positively correlated with the mean ear temperature (r=0·55, P<0·05) and the mean concentration of serum cortisol was positively correlated with the mean blood temperature (r=0·50, P<0·05), suggesting that the hotter pigs were suffering from a higher level of stress.

Comparison of the effects of fan-assisted and natural ventilation of vehicles on the welfare of pigs being transported to slaughter

A total of 417 pigs with an estimated average liveweight of 91 kg were transported to slaughter in three journeys, carried out in late June, each consisting of a three-hour drive followed by a one-hour holding period at the slaughter plant before they were unloaded. The pigs were accommodated on the lower two decks of a three-deck articulated lorry, each deck having five equal-sized pens; half were kept in naturally ventilated pens and half in pens with fan-assisted ventilation. The pigs’ body temperature was recorded as the temperature of the blood lost at exsanguination, and as the temperature of the inner surface of the ear measured by thermal imaging. The pigs carried on the upper deck were hotter than those carried on the lower deck, and the pigs carried at the front of the vehicle were hotter than those at the back. There were small differences between the temperatures of the pigs in the different pens, but overall the temperatures of the pigs kept in pens with fan-assisted ventilation were no lower than those of the pigs kept in pens with natural ventilation. The higher temperature of the pigs transported in the front of the vehicle was associated with significantly higher serum concentrations of cortisol and activities of creatine kinase, and a tendency to higher albumin concentrations and osmolality, suggesting that they may have been exposed to more physical and psychological stress, and were possibly slightly more dehydrated, than the pigs in the rearmost pens. The type of ventilation had no effect on the blood composition of the pigs.