Comb size, shape complexity and laterality of laying hens reared in environments varying in resource choice.

The comb is an ornament involved in signalling condition in domestic fowl. We hypothesised that comb size, comb shape complexity (i.e., rugosity, the comb perimeter jaggedness), and comb laterality of laying hens would be influenced by the degree of environmental enrichment experienced during juvenile development in the form of resource choice. We conducted a 2 × 2 factorial crossover experiment with pullets reared in pens containing four perches of equal length and four litter areas of equal size. Pullets were exposed to a single choice vs multiple choices of perch and litter types (i.e., all the same vs all different) during Weeks 1-4 (Period 1) and/or Weeks 5-15 (Period 2) of rearing (n = 4 pens/treatment combination) prior to transfer to standard adult laying pens for Weeks 16-27 (Period 3). In Week 27, combs were photographed, and comb laterality (hanging on left or right side) was noted. Using a custom-made image analysis programme, we captured comb area (mm2), perimeter length (mm), and rugosity ((perimeter length - horizontal length) / horizontal length) from comb photographs of 6-7 randomly selected hens/pen. We predicted that hens reared in the multi-choice environment during Periods 1 and 2 would have larger, more complex, and left-side-biased combs than those in the other treatment groups, reflecting lower allostatic load. The predicted comb side bias was based on a possible bias in head posture/movements associated with greater right eye/ear use and left-brain hemispheric dominance. Contrary to our predictions, we detected an overall right-side bias in comb laterality, and no associations between resource choice treatment in Period 1 or Period 2 and comb area, perimeter length, rugosity, or laterality of the adult hens. Thus, variation in allostatic load resulting from the rearing treatments was insufficient to modify the trajectory of comb morphological development, possibly due to a ceiling effect when comparing environmental treatments on the positive end of the welfare spectrum. We found that left-lopping combs had shorter perimeters than right-lopping combs. However, among hens with left-lopping combs, those with larger combs were heavier and had less feather damage, while among hens with right-lopping combs, those with longer-perimeter combs were heavier and tended to have less comb damage. In conclusion, comb characteristics were related to physical condition at the individual level but did not serve as sensitive integrated indicators of hen welfare in response to basic vs enhanced resource choice during rearing.

An epidemiological analysis of equine welfare data from regulatory inspections by the official competent authorities.

Determining welfare status in a population is the first step in efforts to improve welfare. The primary objective of this study was to explore a new epidemiological approach for analysis of data from official competent authorities that pertain to compliance with animal welfare legislation. We reviewed data already routinely collected as part of Swedish official animal welfare inspections for 2010-13, using a checklist containing 45 checkpoints (CPs). These covered animal-, resource- and management-based measures of equine welfare. The animal-based CPs were measures that directly related to the animal and included social contact, body condition, hoof condition and cleanliness. Non-compliance with one or more of the animal-based CPs was used as a binary outcome of poor equine welfare; 95% confidence intervals (CI) were estimated using the exact binomial distribution. Associations were determined using multivariable logistic regression, adjusting for clustering on premises. Resource- and management-based CPs (model inputs) were reduced by principal component analysis. Other input factors included premises characteristics (e.g. size, location) and inspection characteristics (e.g. type of inspection). There were 30 053 premises with horses from 21 counties registered by the Swedish Board of Agriculture. In total 13 321 inspections of premises were conducted at 28.4% (n=8532) of all registered premises. For random inspections, the premises-prevalence of poor equine welfare was 9.5% (95% CI 7.5, 11.9). Factors associated with poor equine welfare were non-compliance with requirements for supervision, care or feeding of horses, facility design, personnel, stable hygiene, pasture and exercise area maintenance, as well as the owner not being notified of the inspection, a previous complaint or deficiency, spring compared with autumn, and not operating as a professional equine business. Horses at premises compliant with stabling and shelter requirements had significantly better welfare if they also complied with documentation requirements. We present a novel approach for analysis of equine welfare data from regulatory inspections by the official competent authorities, and propose on-going analyses and benchmarking of trends in animal-based measures over time. We also suggest how such a database could be further improved to facilitate future epidemiological analyses of risk factors associated with poor equine welfare. The study has implications for other competent authorities and researchers collaborating in the area of animal welfare epidemiology.

Human-animal interactions and safety during dairy cattle handling--Comparing moving cows to milking and hoof trimming.

Cattle handling is a dangerous activity on dairy farms, and cows are a major cause of injuries to livestock handlers. Even if dairy cows are generally tranquil and docile, when situations occur that they perceive or remember as aversive, they may become agitated and hazardous to handle. This study aimed to compare human-animal interactions, cow behavior, and handler safety when moving cows to daily milking and moving cows to more rarely occurring and possibly aversive hoof trimming. These processes were observed on 12 Swedish commercial dairy farms. The study included behavioral observations of handler and cows and cow heart rate recordings, as well as recording frequencies of situations and incidents related to an increased injury risk to the handler. At milking, cows were quite easily moved using few interactions. As expected, the cows showed no behavioral signs of stress, fear, or resistance and their heart rate only rose slightly from the baseline (i.e., the average heart rate during an undisturbed period before handling). Moving cows to hoof trimming involved more forceful and gentle interactions compared with moving cows to milking. Furthermore, the cows showed much higher frequencies of behaviors indicative of aversion and fear (e.g., freezing, balking, and resistance), as well as a higher increase in heart rate. The risk of injury to which handlers were exposed also increased when moving cows to hoof trimming rather than to routine milking. Some interactions (such as forceful tactile interactions with an object and pulling a neck strap or halter) appeared to be related to potentially dangerous incidents where the handler was being kicked, head-butted, or run over by a cow. In conclusion, moving cows to hoof trimming resulted in higher frequencies of behaviors indicating fear, more forceful interactions, and increased injury risks to the handler than moving cows to milking. Improving potentially stressful handling procedures (e.g., by better animal handling practices and preparation of cows to cope with such procedures) can increase handler safety, animal welfare, ease of handling, and efficiency.

Promoting positive states: the effect of early human handling on play and exploratory behaviour in pigs.

It is known that tactile stimulation (TS) during ontogeny modifies brain plasticity and enhances the motor and cognitive skills. Our hypothesis was that early handling including TS would increase play and exploratory behaviour in commercial pigs under standardized test conditions. Piglets from 13 litters were subjected to three handling treatments from 5 to 35 days of age: all the piglets were handled (H), none of the piglets were handled (NH) or half of the piglets in the litter were handled (50/50). At 42 days of age, the pigs' behaviour was observed in pairs in a novel pen with a 'toy' (tug rope). The main results were that more locomotor play was performed by pigs from litters where all or half of them had been handled, whereas social exploratory behaviour was more pronounced in pigs from litters where half of them had been handled. Although behaviour was affected by the interaction of treatment with sex or with weight category, we propose that the handling procedure does seem to have acted to increase locomotor skills and that handling half of the piglets in the litter may have triggered a series of socio-emotional interactions that were beneficial for the whole group.

A Nordic survey of management practices and owners' attitudes towards keeping horses in groups.

Keeping horses in groups is widely recommended but limited information is available about how this is implemented in practice. The aim of this survey was to describe how horses are kept in the Nordic countries in relation to sex, age, breed, and equestrian discipline and to assess owners' attitudes toward keeping horses in groups. Horse owners in Denmark, Finland, Norway, and Sweden were approached using a web-based questionnaire, which was translated into 4 languages and distributed online via equestrian forums, organizations, and social media. The number of respondents was 3,229, taking care of 17,248 horses. Only 8% of horses were never kept in groups, 47% were permanently grouped for 24 h/d, and 45% were stabled singly but grouped during turnout. Yearlings were most often permanently kept in groups (75%), mares and geldings more commonly during parts of the day (50 and 51%, respectively), and stallions were often kept alone (38%). Icelandic horses were more likely to be permanently kept in groups (36%) than warmbloods (16%) and ponies (15%). Twice as many competition horses (51%) were never grouped compared with horses used for breeding (20%) or leisure purposes (15%). The majority of respondents (86%) strongly agreed that group housing benefits horse welfare and that it is important for horses to have the company of conspecifics (92%). Nevertheless, not all horses were kept in groups, showing that attitudes toward group housing may not necessarily reflect current management. The risk of injury was a concern of many respondents (45%), as was introducing unfamiliar horses into already established groups (40%) and challenges in relation to feeding in groups (44%). Safety of people (23%) and difficulties handling group-kept horses (19%) were regarded as less problematic. Results suggest that the majority of horses have the possibility to freely interact with other horses, either as fulltime members of a group during 24 h/d or during turnout. Future research should address the extent to which being a part-time member of a group affects horse welfare. For permanent group housing to become more widespread, such as it is the case for most farm animals, future research could focus on solving some of the reoccurring problems perceived with keeping horses in groups. The dissemination of evidence-based information on all aspects around keeping horses in groups can ultimately stimulate further positive changes in the management of group-kept horses.

Science-based management of livestock welfare in intensive systems: looking to the future.

As welfare is a multidimensional concept, its assessment should be a multidisciplinary process, providing a comprehensive assessment of animal welfare in any given system. The different measurable aspects of welfare may be turned into welfare indicators and assessed in a scientific manner. Assessment of welfare may combine different approaches that include the assessment of the production system and measurement of animal-based welfare indicators. With both approaches, however, risk managers face difficulties related to the availability of resources for implementing regulations and training staff. Most animal-based welfare indicators have the advantage that they can be measured whatever the production system; they relate to the animal's experience of its own state. It is essential to confirm the reliability of the measures and their robustness to ensure valid welfare assessment, especially for a science-based management approach. Many welfare indicators, even those measured at the individual level, are expressed at group level, as a proportion of the animals. This allows benchmarking and following of trends over time. The decision on what is or is not acceptable from a welfare point of view is an ethical or managerial one. The advantage of a graded welfare indicator is that it allows different thresholds to be set by different people, countries or organisations, depending on the purpose of the assessment. The development of a set of harmonised international welfare indicators for global trade is also discussed.

Using data from electronic feeders on visit frequency and feed consumption to indicate tail biting outbreaks in commercial pig production.

The long term aim with this study was to identify predictors or early indicators of tail biting outbreaks using registrations from electronic feeders. This study is based on information about daily frequency of feeder visits (DFV) and daily feed consumption (DFC) recorded in electronic feeders from 460 noncastrated boars in tail biting pens (TB pens, n = 21) and matched control pens (Con pens, n = 21) from 10 wk before to 10 wk after the first injured tail in the pen. The results showed lower average DFV among pigs in TB pens compared with pigs in Con pens 6 to 9 wk before the start of the tail biting outbreak (first treatment for tail damage due to tail biting; P ≤ 0.1, df = 487) but a greater DFV for tail biting victims 2 to 5 wk before the start of the tail biting outbreak compared both to other pigs in the TB pen and to pigs in the Con pen (P < 0.1, df = 6,500). Tail biting victims had decreased DFC during and after the tail biting outbreak [wk 0 to 2 after the tail biting outbreak (P < 0.1, df = 6,500)]. In conclusion, information from electronic feeders can be used for surveillance of tail biting outbreaks in pigs. Due to common casual factors, low feeding frequencies observed on the group level can predict future tail biting in the pen as early as 9 wk before the first tail injuries. Moreover, increased feeding frequencies for individual pigs in potential tail biting pens may predict which pigs will be become the victims in the tail biting outbreak. The results further support previous findings that pigs with tail injuries due to tail biting consume decreased amounts of feed.

Health parameters in tail biters and bitten pigs in a case-control study.

Health in relation to tail-biting behaviour was investigated on a problem farm. Quartets (n = 16) of age- and gender-matched fattening pigs including a tail biter (TB, n = 16), a victim (V, n = 16), a control in the same pen (Ctb, n = 10) and a control in a pen where no tail biting was observed (Cno, n = 14) were chosen by direct behavioural observation. Haematological and clinicochemical analyses, autopsy and histological examination of 16 different tissues were carried out. Tail lesion severity was evaluated both macroscopically, on the basis of inspection, and histologically, in the sagittally cut tail. Category effects were tested using Friedman's ANOVA by Ranks, Cochran's Q or a repeated-measure GLM and, if significant, pair-wise tests were conducted using Wilcoxon Signed Ranks or McNemar's Test. The number of received tail bites correlated better with histological than with macroscopic tail lesion scoring because of deep inflammation beneath healthy skin in some cases. Most individuals had mild inflammatory lesions in internal organs suggestive of generalized activation of the immune system, and 30% of the animals were anaemic, possibly because of systemic spread of infectious agents. V had more severe respiratory organ lesions and higher serum protein concentrations than all other categories of pigs. Liver- and muscle-specific enzymes (alanine aminotransferase, alkaline phosphatase and creatine kinase) differed between categories. In conclusion, most animals had signs of generalized activation of the immune system, possibly because of systemic spread of infectious agents. V pigs suffered from more severe inflammatory lesions than TB, Ctb or Cno. Deep infections may exist under healthy skin in the tail of bitten pigs.

Brain gene expression differences are associated with abnormal tail biting behavior in pigs.

Knowledge about gene expression in animals involved in abnormal behaviors can contribute to the understanding of underlying biological mechanisms. This study aimed to explore the motivational background to tail biting, an abnormal injurious behavior and severe welfare problem in pig production. Affymetrix microarrays were used to investigate gene expression differences in the hypothalamus and prefrontal cortex of pigs performing tail biting, pigs receiving bites to the tail and neutral pigs who were not involved in the behavior. In the hypothalamus, 32 transcripts were differentially expressed (P < 0.05) when tail biters were compared with neutral pigs, 130 when comparing receiver pigs with neutrals, and two when tail biters were compared with receivers. In the prefrontal cortex, seven transcripts were differently expressed in tail biters when compared with neutrals, seven in receivers vs. neutrals and none in the tail biters vs. receivers. In total, 19 genes showed a different expression pattern in neutral pigs when compared with both performers and receivers. This implies that the functions of these may provide knowledge about why the neutral pigs are not involved in tail biting behavior as performers or receivers. Among these 19 transcripts were genes associated with production traits in pigs (PDK4), sociality in humans and mice (GTF2I) and novelty seeking in humans (EGF). These are in line with hypotheses linking tail biting with reduced back fat thickness and explorative behavior.

Feather pecking behavior in laying hens: hypothalamic gene expression in birds performing and receiving pecks.

Feather pecking (FP) is a welfare and economic problem in the egg production sector. Beak trimming, the current method used to reduce FP, is also criticized. The present study used gene expression to explore the biological mechanisms underlying this behavior, which could lead to a greater understanding of the cause and a tool to mitigate the problem. White Leghorn hens performing and receiving FP, as well as neutral control birds, were identified on a commercial farm. Hypothalamic RNA from 11 peckers, 10 victims, and 10 controls was hybridized onto GeneChip Chicken Genome Arrays (Affymetrix Inc., Santa Clara, CA) to compare gene expression profiles in the different groups. Eleven transcripts corresponding to 10 genes differed significantly between the 3 groups (adjusted P < 0.05). Eight of these transcripts differed in the peckers compared with the controls, 1 was upregulated in the victims compared with the controls, and 6 differed significantly in the peckers compared with the victims. Additionally, 5 transcripts showed a trend (adjusted P < 0.1) to differ in the pecker-victim comparison. Some of the products of the differently expressed genes are involved in disorders, such as intestinal inflammation and insulin resistance, which fit well with the previously proposed hypothesis that FP is an abnormal foraging behavior. Other findings may also support the proposal that FP is linked to immune mechanisms and may serve as an animal model for obsessive compulsive disorder in humans. In conclusion, this study provides a gene list that may be useful in further research on the mechanisms behind FP.

Training young horses to social separation: effect of a companion horse on training efficiency.

REASONS FOR PERFORMING STUDY: The intensity with which a horse responds to separation from its group and subsequently to being alone is relevant for both horse and handler safety. Identification of training methods that may reduce responses to separation would be useful in practice. OBJECTIVES: To investigate whether the initial presence of a familiar companion horse modifies responses to separation from the group, lowers stress levels (as measured by heart rate) and increases training efficiency. HYPOTHESIS: Habituation to separation proceeds more quickly if the horse is first trained with a companion, and heart rate is lower when the horse is subsequently trained alone, compared to control horses trained individually from the start. METHODS: Young mares (n = 32), kept in groups of 4 were exposed to social separation: 2 horses of the group were trained singly (S1, n = 16) and the remaining 2 horses (n = 16) were trained first with a companion (P2) and then alone (P1). The training comprised 3 steps whereby distance from the group was gradually increased. The final learning criterion was met when a horse fed calmly alone inside a test arena (Step 3). Horses that were trained in a pair had to succeed in Step 3 together before they repeated the steps alone. Feeding behaviour and heart rate were recorded. RESULTS: There were no significant differences between S1 and P1 horses, indicating that the initial pair-training did not reduce responses in P1 horses. However, heart rate was significantly lower when horses were trained in pairs (P2) compared to when the same horses were subsequently trained alone (P1). CONCLUSIONS AND POTENTIAL RELEVANCE: It may not be efficient to habituate naïve young horses to social separation initially with a partner as these horses appear to have to relearn being in the test situation alone when switching to the individual training.

Stocking density effects on broiler welfare: identifying sensitive ranges for different indicators.

Although stocking density is perceived as a topic of major importance, no consensus has been reached on what density would allow for good welfare. In the present study, the welfare of 4 replicates of birds stocked at 8, 19, 29, 40, 45, 51, 61, and 72 broilers per pen (or 6, 15, 23, 33, 35, 41, 47, and 56 kg actually achieved BW/m(2)) was studied using 6 welfare indicators. Density did not affect bursa weight, mortality, or concentrations of corticosterone metabolites in droppings but did influence leg health (P = 0.015) and footpad and hock dermatitis (P < 0.001) and tended to influence fearfulness (P = 0.078). However, not every increase in density or group size, or both, led to poorer welfare for the affected indicators: leg health and fearfulness showed unexpected peaks at intermediate densities. Furthermore, the indicators were influenced at different densities: leg strength showed a steep decrease from 6 to 23 kg/m(2), hock dermatitis rose from 35 to 56 kg/m(2), and footpad dermatitis and fearfulness were only significantly higher at the highest density of 56 kg/m(2). No threshold stocking density above which all aspects of welfare were suddenly altered was found in this study. Instead, different aspects of welfare were influenced at different densities or group sizes, or both. Thus, evaluating the effects of stocking density on welfare as a whole would require either identification of acceptable levels for each separate indicator or a weighting of the indicators in an integrated welfare score. A tentative attempt to such an integration, made using equal weights for all parameters, showed a decrease in welfare as density increased (P < 0.001). The lowest 2 densities (6 and 15 kg/m(2)) scored better than most middle densities (23, 33, 35, and 47 kg/m(2)), whereas all densities scored better than the highest density (56 kg/m(2)).

The combination of amlodipine/valsartan 5/160 mg produces less peripheral oedema than amlodipine 10 mg in hypertensive patients not adequately controlled with amlodipine 5 mg.

AIMS: To demonstrate the benefit of the combination amlodipine/valsartan 5/160 mg over amlodipine 10 mg, in producing a lower incidence of peripheral oedema for a comparable mean sitting systolic blood pressure (MSSBP) reduction. METHODS: After a 4-week amlodipine 5 mg run-in phase, inadequately controlled hypertension patients (aged > or = 55 years, MSSBP > or = 130 and < or = 160 mmHg) were randomised to receive amlodipine/valsartan 5/160 mg or amlodipine 10 mg for 8 weeks, followed by amlodipine/valsartan 5/160 mg for 4 weeks for all patients. Primary variables were MSSBP change from baseline to week 8 and incidence of peripheral oedema reported as an AE. Resolution of peripheral oedema was assessed 4 weeks after switching patients from amlodipine 10 mg to amlodipine/ valsartan 5/160 mg. RESULTS: At week 8, MSSBP showed greater reduction with amlodipine/valsartan 5/160 mg than amlodipine 10 mg (least square mean: -8.01 vs.-5.95 mmHg, p < 0.001 for non-inferiority and p = 0.002 for superiority). Systolic control, overall BP control and systolic response rate at week 8 were significantly higher with combination than amlodipine 10 mg (34 vs. 26%; 57 vs. 50%; 36.57 vs. 27.77%, respectively). Incidence of peripheral oedema was significantly lower with the combination than amlodipine 10 mg (6.6 vs. 31.1%, p < 0.001). Peripheral oedema resolved in 56% patients who switched from amlodipine 10 mg to the combination, without the loss of effect on BP reduction. CONCLUSION: In non-responders to amlodipine 5 mg, treatment with amlodipine/valsartan 5/160 mg induced significantly less peripheral oedema than amlodipine 10 mg for similar BP reduction. Peripheral oedema resolved in > 50% patients switching from amlodipine 10 mg to the combination.

Effects of a calm companion on fear reactions in naive test horses.

REASON FOR PERFORMING STUDY: In fear-eliciting situations, horses tend to show flight reactions that can be dangerous for both horse and man. Finding appropriate methods for reducing fearfulness in horses has important practical implications. OBJECTIVES: To investigate whether the presence of a calm companion horse influences fear reactions in naive subject horses. HYPOTHESES: The presence of a habituated (calm) companion horse in a fear-eliciting situation can reduce fear reactions in naive subject horses, compared to subject horses with a nonhabituated companion (control). METHODS: Minimally handled (n = 36), 2-year-old stallions were used, 18 as subjects and 18 as companions. Companion horses (n = 9) were habituated to an otherwise frightening, standardised test stimulus (calm companions), whereas the rest (n = 9) of the companion horses remained nonhabituated (control companions). During the test, unique pairs of companion and subject horses were exposed to the test stimulus while heart rate and behavioural responses were registered. Subsequently, subject horses were exposed to the stimulus on their own (post test). RESULTS: Subject horses, paired with a calm companion horse, showed less fear-related behaviour and lower heart rate responses compared to subject horses with control companions. Results from the post test suggest that the difference between treatment groups remained in the subsequent absence of companion horses. CONCLUSIONS AND POTENTIAL RELEVANCE: It appears possible to reduce fear reactions in young, naive horses by allowing them to interact with a calm companion horse in fear-eliciting situations.

Feather pecking in chickens is genetically related to behavioural and developmental traits.

Feather pecking (FP) is a detrimental behaviour in chickens, which is performed by only some individuals in a flock. FP was studied in 54 red junglefowl (ancestor of domestic chickens), 36 White Leghorn laying hens, and 762 birds from an F(2)-intercross between these two lines. From all F(2)-birds, growth and feed consumption were measured. Age at sexual maturity and egg production in females, and corticosterone levels in males were also measured. From 333 F(2)-birds of both sexes, and 20 parental birds, body composition with respect to bone mineral content, muscle and fat was obtained by post-mortem examinations using Dual X-Ray Absorptiometry (DXA). In femurs of the same birds, the bone density and structure were analysed using DXA and Peripheral Quantitative Computerized Tomography (pQCT), and a biomechanical analysis of bone strength was performed. Furthermore, plumage condition was determined in all birds as a measure of being exposed to feather pecking. Using 105 DNA-markers in all F(2)-birds, a genome-wide scan for Quantitative Trait Loci (QTL), associated with the behaviour in the F(2)-generation was performed. FP was at least as frequent in the red junglefowl as in the White Leghorn strain studied here, and significantly more common among females both in the parental strains and in the F(2)-generation. In the F(2)-birds, FP was phenotypically linked to early sexual maturation, fast growth, weak bones, and, in males, also high fat accumulation, indicating that feather peckers have a different resource allocation pattern. Behaviourally, F(2) feather peckers were more active in an open field test, in a novel food/novel object test, and in a restraint test, indicating that feather pecking might be genetically linked to a proactive coping strategy. Only one suggestive QTL with a low explanatory value was found on chromosome 3, showing that many genes, each with a small effect, are probably involved in the causation of feather pecking. There were significant effects of sire and dam on the risk of being a victim of feather pecking, and victims grew faster pre- and post-hatching, had lower corticosterone levels and were less active in a restraint test. Hence, a wide array of behavioural and developmental traits were genetically linked to FP.

Individual production differences do not explain cannibalistic behaviour in laying hens.

1. Sixty-three laying hens were collected from 5 commercial farms experiencing outbreaks of cannibalism. It is known that cannibalistic behaviour varies strongly between hybrids and between individuals of the same hybrid. The aim of this study was to test specific hypotheses about the causation of cannibalism by comparing matched individuals varying in their cannibalistic behaviour. 2. To investigate feed efficiency, egg production and feed consumption, data were collected over 30 d. Nutrient deficiencies have been associated with outbreaks of cannibalism and we hypothesised that cannibals are more feed efficient than their flock mates and, therefore, more susceptible to transient nutrient deficiencies or imbalances that trigger cannibalistic behaviour. 3. Video recordings were made of victims of cloacal cannibalism and their matched controls during oviposition. Victims were expected to have longer oviposition durations and a higher incidence of short-term cloacal prolapses than controls, because the starting point for cannibalism is often suggested to be pecking at the red mucosa of the victim during, or just after, oviposition. 4. Oviduct swab samples were taken from surviving victims of cloacal cannibalism and their matched controls 4 weeks after the cannibalistic attack. If peck wounds provide a route for subsequent bacterial invasion of the reproductive tract, victims would be expected to have greater bacterial colonisation of the oviduct. 5. Mortality within each matched trio was recorded over a 23-month period after the cannibalistic attack. Victims that survived a cannibalistic attack were expected to have reduced longevity compared to controls and cannibals. This could occur if they developed secondary infections as a result of the cannibalistic attack, or if they had poorer health even before the attack. 6. No significant differences were found between cannibals, victims and controls in feed efficiency or any of the production variables measured. Victims of cloacal cannibalism did not expose their cloacal mucosa more, or for longer, than matched control hens during oviposition, and had no more bacteria in their oviduct. Victims tended to die sooner than their matched cannibals or cannibals during a 23-month period after a cannibalistic attack.

Preen gland function in layer fowls: factors affecting preen oil fatty acid composition.

1. Preen oil derived from the preen gland has previously been shown to differ in its composition between birds of different ages, sex and diet. As a part of a larger study on preening behaviour and its components, the relative percentages of fatty acids in preen oil were examined in laying hens that differed in age, beak trimmed status, feather pecking status (pecker and pecked) and method of sampling (either direct from the preen gland or from lipid extracted from feathers). 2. Five experiments are described. Fatty acids extracted from lipid were analysed by gas chromatography (GC). Fatty acid composition was affected by age, by whether or not a bird was feather pecked (but not if it was a feather pecker) and by lipid source. 3. Changes in preen oil composition with age (shown here) may be due to changes in circulating concentrations of hormones. Differences in preen oil composition between feather pecked and non-pecked birds may influence plumage odour and therefore taste, making the plumage of some birds more attractive to pecking than others. 4. The proportions of some fatty acids derived from feathers differed to those extracted from the preen gland. Lipid found on feathers is most likely a combination of that from the preen gland and from sebaceous secretions from the skin.

Production-related traits of layers reared in different sized flocks: the concept of problematic intermediate group sizes.

Laying hens were reared from 1 d of age in four replicates each of four different group sizes: 15, 30, 60, and 120 birds. To maintain stocking density at a constant 5 birds/m2, they were housed in litter floor pens of 3, 6, 12, and 24 m2, respectively. The allocation of feeder space, drinker nipples, and perch space was also constant per bird, irrespective of group size, as was the arrangement of resources in the pens. Birds were individually weighed at 3, 7, 12, 15, and 18 wk of age, and comb length and height were measured with calipers. At 24 and 39 wk, a sample of 30 eggs from each pen was weighed to determine mean egg weight. Results show a significant effect of group size on BW, with birds in the groups of 30 and 120 being lighter than birds in groups of 15 and 60. Eggs from birds in groups of 30 were significantly smaller than those from birds in the other group sizes. Comb size was unaffected by group size. We propose that these results support the theory that the hierarchical social structure based on individual recognition in small groups breaks down in large groups as birds become less aggressive and more tolerant. The results suggest that this transition occurs at a group size of around 30 birds, and that this 'intermediate' group size presents social problems for birds which, in turn, has consequences for production. The practical implication of this research is to avoid keeping birds in flocks of this size.

Pecking at other birds and at string enrichment devices by adult laying hens.

1. Bunches of white string (polypropylene twine) are particularly attractive pecking stimuli for both chicks and adult laying hens. Furthermore, these devices can retain the birds' interest over lengthy periods. It has also been demonstrated that birds with trimmed feathers elicit feather pecking. The present study was designed to determine whether string devices would retain their attractiveness in the presence of a competing stimulus: a trimmed hen. 2. Lohmann Brown hens were reared in 20 groups of 5 in floor pens with perches from 17 weeks of age. They were exposed to one of two treatments when they were 23 weeks old. One hen was removed from every pen and the feathers on her rump were trimmed. Immediately before her return two string devices were suspended from a perch in treatment 1 whereas no devices were included in treatment 2. Pecking behaviours were immediately observed for 30 min; this procedure was repeated later that day. The devices remained in the pens used in treatment 1 and these birds were observed again for 15 min after 14 d. 3. The string devices were pecked earlier and more than either the trimmed or untrimmed hens. Furthermore, the devices were still being pecked 2 weeks after their introduction. 4. The virtual absence of severe feather pecking and of aggressive head pecks precluded test of our hypothesis that the devices would divert potentially injurious pecking away from other birds. However, the fact that the birds showed sustained interest in the devices, even in the presence of a competing stimulus, supports our proposal that string may represent a practicable and effective form of environmental enrichment.