Contrafreeloading and foraging-related behavior in hens differing in laying performance and phylogenetic origin.

Different breeds of domestic and junglefowl differ in foraging strategies indicating that domestication resulted in modified energy saving behavioral strategies. In the present study we investigated foraging strategies and foraging-related behavior in 4 lines of laying hens differing in phylogenetic origin and laying performance to analyze a possible relationship between foraging and the level of egg production. High performing brown and white pure bred lines were compared with their low performing brown and white counterparts. To control possible effects on behavior other than genetic effects, all hens were reared and kept in an identical environment. A total of 72 hens from each line were kept in 6 compartments with 12 hens per compartment, respectively. Observations were done for 3 times during one laying period. Foraging strategy was tested by a contrafreeloading (CFL) paradigm. CFL describes a behavior in which animals prefer food that requires effort to obtain, although at the same time food is freely available. The hens were offered a commercial standard diet in one trough and a mixture of wood shavings and commercial standard diet in another trough. The behavior of hens was video recorded and the activity level of individual hens in the litter area was recorded by an antenna-transponder system. The high performing layers showed less CFL and foraging-related behavior compared with their low performing counterparts in both the white and brown layers. Despite differences in CFL, all hens showed a preference for the commercial standard diet compared to the mixture of wood-shavings. Our results show an association between foraging strategy and level of egg production. This suggests that a high level of egg production is accompanied by behaviors enabling the hens to satisfy their higher energy demand more efficiently. Saving energy by reduced activity probably allows them to reallocate energy into reproduction, that is, laying performance.

A Novel Model to Explain Extreme Feather Pecking Behavior in Laying Hens.

Feather pecking (FP) is a serious economic and welfare problem in the domestic fowl. It has recently been shown that the distribution of FP bouts within groups is heterogeneous and contains a sub-population of extreme feather peckers (EFP). The present study proposed a novel model to detect EFP hens. A mixture of two negative binomial distributions was fitted to FP data of a F2 cross of about 960 hens, and, based on the results, a calculation of the posterior probability for each hen belonging to the EFP subgroup (pEFP) was done. The fit of the mixture distribution revealed that the EFP subgroup made up a proportion of one third of the F2 cross. The EFP birds came more frequently into pecking mood and showed higher pecking intensities compared to the remaining birds. Tonic immobility and emerge box tests were conducted at juvenile and adult age of the hens to relate fearfulness to EFP. After dichotomization, all traits were analyzed in a multivariate threshold model and a genomewide association study was performed. The new trait pEFP has a medium heritability of 0.35 and is positively correlated with the fear traits. Breeding for this new trait could be an interesting option to reduce the proportion of extreme feather peckers. An index of fear related traits might serve as a proxy to breed indirectly for pEFP. GWAS revealed that all traits are typical quantitative traits with many genes and small effects contributing to the genetic variance.

Analysis of the influences on plumage condition in laying hens: How suitable is a whole body plumage score as an outcome?

An important indicator of the health and behavior of laying hens is their plumage condition. Various scoring systems are used, and various risk factors for feather damage have been described. Often, a summarized score of different body parts is used to describe the overall condition of the plumage of a bird. However, it has not yet been assessed whether such a whole body plumage score is a suitable outcome variable when analyzing the risk factors for plumage deterioration. Data collected within a German project on farms keeping laying hens in aviaries were analyzed to investigate whether and the extent to which information is lost when summarizing the scores of the separate body parts. Two models were fitted using multiblock redundancy analysis, in which the first model included the whole body score as one outcome variable, while the second model included the scores of the individual body parts as multiple outcome variables. Although basically similar influences could be discovered with both models, the investigation of the individual body parts allowed for consideration of the influences on each body part separately and for the identification of additional influences. Furthermore, ambivalent influences (a factor differently associated with 2 different outcomes) could be detected with this approach, and possible dilutive effects were avoided. We conclude that influences might be underestimated or even missed when modeling their explanatory power for an overall score only. Therefore, multivariate methods that allow for the consideration of individual body parts are an interesting option when investigating influences on plumage condition.

The presence of extreme feather peckers in groups of laying hens.

Feather pecking is a serious economic and welfare problem in laying hens. Feather damage occurs mainly through severe feather pecking (SFP). Selection experiments have proved that this behavior is heritable and lines have been divergently selected for high (HFP) and low feather pecking (LFP). The number of bouts of SFP per hen follows a Poisson distribution with a maximum nearby 0. A few studies indicate that the distribution within flocks is not homogenous but contains sub-groups of birds showing extremely high levels of feather pecking (EFP). It was the aim of the current study to re-analyze data on SFP of lines selected for HFP/LFP and their F2 cross so as to uncover hidden sub-populations of EFP birds. Data of seven selection generations of HFP and LFP selection lines as well as their F2 cross have been used. We fitted a two-component mixture of Poisson distributions in order to separate the sub-group of EFP from the remaining birds. HFP and LFP lines differed mainly in mean bouts per bird. The proportion of EFP was only marginal in the LFP as compared with the HFP and the F2 population. Selection for LFP did not result in total elimination of EFP. The presence of even small proportions of EFP may play an important role in initiating outbreaks of feather pecking in large flocks. Further studies on feather pecking should pay special attention to the occurrence of EFP sub-groups.

Quantitative genetic analysis of causal relationships among feather pecking, feather eating, and general locomotor activity in laying hens using structural equation models.

The objective of this research was to analyze the relationship between feather pecking (FP) and feather eating (FE) as well as general locomotor activity (GLA) using structural equation models, which allow that one trait can be treated as an explanatory variable of another trait. This provides an opportunity to infer putative causal links among the traits. For the analysis, 897 F2-hens set up from 2 lines divergently selected for high and low FP were available. The FP observations were Box-Cox transformed, and FE and GLA observations were log and square root transformed, respectively. The estimated heritabilities of FE, GLA, and FP were 0.36, 0.29, and 0.20, respectively. The genetic correlation between FP and FE (GLA) was 0.17 (0.04). A high genetic correlation of 0.47 was estimated between FE and GLA. The recursive effect from FE to FP was [Formula: see text], and from GLA to FP [Formula: see text] These results imply that an increase of FE leads to an increased FP behavior and that an increase in GLA results in a higher FP value. Furthermore, the study showed that the genetic correlation among the traits is mainly caused by indirect effects.

A pilot study of the genetic variation of phosphorus utilization in young Japanese quail (Coturnix japonica).

This study estimated the genetic variance components of P utilization in Japanese quail. A parental generation was assembled from an unselected random-bred Japanese fattening quail line. Seven sires and 14 dams were randomly selected, and each sire was paired with 2 dams to produce full and half sibs. A total of 200 unsexed 1-d-old quail with known pedigree were wing-banded and raised during the first 4 d posthatch in groups in floor pens on wood shavings and fed a preexperimental diet that was adequate in all nutrients. Starting on d 5, quail were individually housed in metabolic compartments on P-free filter paper. This started a balance trial with 5 d of adaption and 5 d of total excreta collection. During this balance period, all quail were fed a low-P (3.9 g/kg of DM) corn-soybean meal-based diet with a Ca:P ratio of 1.6:1.0. Phosphorus and Ca utilization were determined individually using the difference in P or Ca intake and the total P or Ca excretion. The average P utilization was 72% and the average Ca utilization was 63%, each with very high variation. Heritabilities were estimated to be 0.09 (SE = 0.09) for P utilization and 0.09 (SE = 0.09) for Ca utilization. Heritabilities were close to the values reported in the literature for broilers and suggest that quail are suitable as a model animal. The SE of the heritability estimates were large. This implies that further studies with a larger sample size are needed to identify genetic and physiological mechanisms that influence P and Ca utilization in Japanese quail.

Genetic parameters for feather pecking and aggressive behavior in a large F2-cross of laying hens using generalized linear mixed models.

Feather pecking and aggressive pecking is a well-known problem in egg production. In the present study, genetic parameters for 4 feather-pecking-related traits were estimated using generalized linear mixed models. The traits were bouts of feather pecking delivered (FPD), bouts of feather pecking received (FPR), bouts of aggressive pecking delivered (APD), and bouts of aggressive pecking received (APR). An F2-design was established from 2 divergent selected founder lines. The lines were selected for low or high feather pecking for 10 generations. The number of F2 hens was 910. They were housed in pens with around 40 birds. Each pen was observed in 21 sessions of 20 min, distributed over 3 consecutive days. An animal model was applied that treated the bouts observed within 20 min as repeated observations. An over-dispersed Poisson distribution was assumed for observed counts and the link function was a log link. The model included a random animal effect, a random permanent environment effect, and a random day-by-hen effect. Residual variance was approximated on the link scale by the delta method. The results showed a heritability around 0.10 on the link scale for FPD and APD and of 0.04 for APR. The heritability of FPR was zero. For all behavior traits, substantial permanent environmental effects were observed. The approximate genetic correlation between FPD and APD (FPD and APR) was 0.81 (0.54). Egg production and feather eating records were collected on the same hens as well and were analyzed with a generalized linear mixed model, assuming a binomial distribution and using a probit link function. The heritability on the link scale for egg production was 0.40 and for feather eating 0.57. The approximate genetic correlation between FPD and egg production was 0.50 and between FPD and feather eating 0.73. Selection might help to reduce feather pecking, but this might result in an unfavorable correlated selection response reducing egg production. Feather eating and feather pecking are genetically correlated and this needs further investigation.

Comparison and evaluation of bone measurements for the assessment of mineral phosphorus sources in broilers.

The main objective of this study was to compare different bone measurements in response to supplements of mineral P sources. Comparisons were also made with P retention and digestibility responses determined in a companion study and with blood inorganic phosphate (P(i)) responses. A corn-soybean meal-based basal diet was used (0.35% total P on DM basis). Anhydrous monosodium phosphate (MSP(a)) or anhydrous dibasic calcium phosphate (DCP(a)) was supplemented to increment the P concentration by 0.08%, 0.16%, or 0.24%. Each of the 7 diets was fed for 10 d starting 11 d (period 1) or 25 d posthatch (period 2). Bone ash and P were determined, and density criteria were measured using quantitative computed tomography. Responses were evaluated and compared based on linear regression analysis. In general, responses to MSP(a) had a greater slope than DCP(a) for all criteria studied. In period 1, differences between the slopes were significant (P < 0.05) for almost all bone criteria. In period 2, the slopes significantly differed for the amounts of ash and P of all bones studied, for tibia, tarsometatarus, and foot ash percentage, for total and cortical density of tibiae, but not for the other criteria. For the different bones, the ratio of slopes for MSP(a) and DCP(a) was very similar based on the amount of ash in both periods. Foot ash proved to be as sensitive as tibia ash for evaluation of mineral P sources in both periods. Ninety-four percent of the variance of the corticalis content based on quantitative computed tomography measurements could be explained by the amount of tibia ash in period 1. Blood serum P(i) and BW gain were not suitable for P evaluation. We concluded that the ranking of mineral P sources based on bone criteria differed from the ranking that was based on P retention or prececal digestibility. This underlines the need for developing a standard protocol of determination of available P in poultry.

The preference for high-fiber feed in laying hens divergently selected on feather pecking.

Earlier studies in laying hens have demonstrated a negative correlation between feather pecking and the dietary fiber content of the feed. However, the factors underlying this relationship are not fully understood. In the present experiment, we hypothesized that birds prone to feather pecking would prefer a diet supplemented with dietary fiber. Thus, the aim was to investigate the voluntary consumption of a wheat-soy control diet (CON) and a diet supplemented with 8% spelt hulls (FIB) on the expense of wheat in 20 individually caged hens selected for high feather pecking (HFP) behavior and 20 individually caged hens selected for low feather pecking (LFP) behavior. The proportional intake of FIB was 0.39 and significantly different from 0.50 (P<0.001). As hypothesized, HFP had higher proportional intake of FIB (0.43) than LFP hens (0.36; P<0.05). The HFP hens had inferior plumage condition (P<0.001), higher BW (P<0.001), and higher feed intake (P<0.01) than LFP. The HFP hens plucked more feathers from a simple inanimate feather-pecking model, but the number of feathers being pulled out did not correlate with the proportional intake of FIB. It was concluded that the preference for feed supplemented with spelt hulls was different between hens displaying different feather-pecking behavior. The underlying reason for such a difference needs further investigation.

Dietary inclusion of feathers affects intestinal microbiota and microbial metabolites in growing Leghorn-type chickens.

Feather pecking in laying hens is a serious behavioral problem that is often associated with feather eating. The intake of feathers may influence the gut microbiota and its metabolism. The aim of this study was to determine the effect of 2 different diets, with or without 5% ground feathers, on the gut microbiota and the resulting microbial fermentation products and to identify keratin-degrading bacteria in chicken digesta. One-day-old Lohmann-Selected Leghorn chicks were divided into 3 feeding groups: group A (control), B (5% ground feathers in the diet), and C, in which the control diet was fed until wk 12 and then switched to the 5% feather diet to study the effect of time of first feather ingestion. The gut microbiota was analyzed by cultivation and denaturing gradient gel electrophoresis of ileum and cecum digesta. Short-chain fatty acids, ammonia, and lactate concentrations were measured as microbial metabolites. The concentration of keratinolytic bacteria increased after feather ingestion in the ileum (P < 0.001) and cecum (P = 0.033). Bacterial species that hydrolyzed keratin were identified as Enterococcus faecium, Lactobacillus crispatus, Lactobacillus reuteri-like species (97% sequence homology), and Lactobacillus salivarius-like species (97% sequence homology). Molecular analysis of cecal DNA extracts showed that the feather diet lowered the bacterial diversity indicated by a reduced richness (P < 0.001) and shannon (P = 0.012) index. The pattern of microbial metabolites indicated some changes, especially in the cecum. This study showed that feather intake induced an adaptation of the intestinal microbiota in chickens. It remains unclear to what extent the changed metabolism of the microbiota reflects the feather intake and could have an effect on the behavior of the hens.

Feather-pecking response of laying hens to feather and cellulose-based rations fed during rearing.

Recent studies in laying hens have shown that feather peckers eat more feathers than nonpeckers. We hypothesized that food pellets containing feathers would decrease the birds' appetite for feathers and thereby also decrease feather pecking. To separate the effect of feathers from that of insoluble fiber per se, additional control groups were fed pellets containing similar amounts of cellulose. Sixty (experiment 1) and 180 (experiment 2) 1-d-old Lohmann-Selected Leghorn birds were divided into 12 groups of 5 (experiment 1) and 15 (experiment 2) birds, respectively, and kept on slatted floors. During the rearing period, 4 groups each had ad libitum access to either a commercial pelleted diet, a pelleted diet containing 5% (experiment 1) or 10% (experiment 2) of chopped feathers, respectively, or a pelleted diet containing 5% (experiment 1) or 10% (experiment 2) of cellulose, respectively. In the consecutive laying period, all groups received a commercial pelleted diet. In experiment 1, feather pecking was recorded weekly from wk 5 to wk 16. In the laying period, observations were made in wk 18, 20, 22, 23, 24, 25, 26, 27, 28, and 30. In experiment 2, feather pecking was recorded weekly from wk 5 to 11, in wk 16 to wk 18, and in wk 20 and 21. At the end of the rearing period, plumage condition per individual hen was scored. Scores from 1 (denuded) to 4 (intact) were given for each of 6 body parts. The addition of 10% of feathers to the diet reduced the number of severe feather-pecking bouts (P < 0.0129) and improved plumage condition of the back area (P < 0.001) significantly compared with control diets. The relationship between feather pecking/eating and the gastrointestinal consequences thereof, which alter feather pecking-behavior, are unclear. Understanding this relationship might be crucial for understanding the causation of feather pecking in laying hens.

Electrical waterbath stunning: influence of different waveform and voltage settings on the induction of unconsciousness and death in male and female broiler chickens.

Stunning effectiveness of male and female broiler chickens was analyzed in response to different waveforms at 3 constant voltage levels. In total, 180 male and female broiler chickens were stunned using a sine wave alternating current (AC) of 50 Hz, rectangular AC of 70 Hz, and pulsed direct current (DC) of 70 Hz (duty-cycle 1:1) with a constant voltage of 60, 80, or 120 V, respectively. In each stunning group, 10 male and 10 female birds were stunned for 4 s. The current obtained by every bird was recorded. For stunning efficiency, the electroencephalogram (EEG) and physical reflexes were recorded and analyzed. The EEG was recorded for 120 s poststun. Simultaneously, the occurrence of spontaneous eye blinking, wing flapping, and breathing was assessed, and the corneal reflex was tested every 20 s poststun. The EEG was analyzed regarding the occurrence of a profound suppression to less than 10% of the prestun level in the 2 to 30 Hz and 13 to 30 Hz bands. Female broilers obtained a significantly lower stunning current compared with that of the males. This resulted in a lower stunning efficiency for females, when the same constant voltage was applied to males and females. The waveforms required different amounts of currents to achieve a 90% stunning efficiency. A minimum necessary stunning current of 70, 90, and 130 mA could be established for sine wave AC, rectangular AC, and pulsed DC, respectively. The low stunning efficiency of pulsed DC might be caused by the short stunning time of 4 s. This effect should be further investigated for DC stunning. Very few birds stunned with AC resumed breathing following stunning, indicating stun to kill. Pulsed DC stunning showed a lower effect on the induction of death. The level of wing flapping, indicating convulsions and possible meat quality defects, was higher for the AC treatments.

Electroencephalograms and physical reflexes of broilers after electrical waterbath stunning using an alternating current.

Stunning efficiency of broilers after electrical waterbath stunning with an alternating current was assessed using electroencephalograms (EEG) and physical reflexes. Four hundred eighty-nine broilers (246 males and 243 females) were stunned in an electrical waterbath with a rectangular alternating stunning current of 60, 80, 100, 120, and 150 mA and frequencies of 70, 100, 200, 400, 800, and 1,500 Hz. Stunning time was 10 s. The EEG was recorded for 120 s poststun. Occurrence of spontaneous breathing, eye blinking, and wing flapping and the corneal reflex were recorded. The EEG was analyzed regarding the occurrence of a profound suppression to less than 10% of the prestun level in the 2 to 30-Hz band and 13 to 30-Hz band. The occurrence of epileptiform patterns was assessed and the occurrence of clonic-tonic convulsions was recorded. Statistical analysis showed a highly significant effect of stunning frequency and stunning current for all groups in the EEG analysis. Stunning frequencies above 400 Hz or below 100 mA did not result in profound suppression of brain power to less than 10% of the prestun level in more than 90% of the broilers and can therefore not be recommended. More than 80% of the birds stunned with 70 or 100 Hz at 100 mA or 70, 100, and 200 Hz with 120 and 150 mA did not recover from stunning. The occurrence of epileptiform activity could only be observed in a few birds. It is assumed that this is due to the long stunning time of 10 s and epileptiform activity could have occurred just before EEG recording started. A maximum of 30% of birds with corneal reflexes and spontaneous eye blinking should not be exceeded, whereas at 15 s poststun, not more than 15% of birds should show spontaneous eye blinking. Wing flapping occurred in at least 50% of birds with adequate stunning results. This seems to be related to convulsions and could cause meat quality defects.

Effects of waterbath stunning on the electroencephalograms and physical reflexes of broilers using a pulsed direct current.

Stunning efficiency of a pulsed direct current was assessed regarding the effect on the electroencephalogram (EEG) and physical reflexes. Four hundred sixty-seven broilers (males and females) were stunned in an electrified waterbath with 60, 80, 100, 120, and 150 mA at frequencies of 70, 100, 200, 400, 800, and 1,500 Hz. Stunning time was 10 s. The EEG recordings lasted for 120 s poststun and simultaneously the occurrence of breathing, spontaneous eye blinking, corneal reflex, and wing flapping was recorded. The EEG records were assessed regarding a profound suppression to less than 10% of the prestun brain power in 2 brain frequency bands, 2 to 30 Hz and 13 to 30 Hz. The EEG results showed a significant effect of stunning frequency for all analyzed parameters. Stunning frequencies of 800 and 1,500 Hz did not achieve adequate stunning results. With a minimum stunning current of 120 mA at frequencies of 70 or 100 Hz or 150 mA at 200 Hz, more than 80% of the animals did not resume breathing. Currents of 80 and 100 mA at 70 or 100 Hz achieved unconsciousness in more than 90% of the birds and birds recovered within 30 to 40 s poststun. Epileptiform activity was found in a relatively low proportion of EEG traces. This could be explained by the long stunning time of 10 s, in which epileptiform activity might have occurred already before the start of EEG recording. Direct current stunning causes less cardiac arrest during stunning, but occurrence of breathing seems more related to cardiac function than to consciousness. A maximum of 30% corneal reflexes and spontaneous eye blinking seems acceptable with a maximum of 15% spontaneous blinking at 15 s poststun. Fourty percent of wing flapping occurred in all effectively stunned groups. Direct current seems to have a different effect on male and female broilers because significantly more male broilers showed reflexes, whereas simultaneously the likelihood of profound EEG suppression was higher. Further investigation of this effect is necessary.

Laying hens learn to avoid feathers.

Previous work demonstrated an association between feather pecking and feather eating in laying hens. This raised the question if digestive feedback affects feather eating or feather pecking in laying hens. We hypothesized that feathers enriched with sugar form a positive feedback and feathers enriched with quinine sulfate form a negative feedback. Forty-eight laying hens were kept in individual cages and fed a pelleted diet ad libitum. Twenty-four birds were offered feathers on a daily basis; 12 of these birds were offered feathers soaked in 4% quinine sulfate solution (Q), and the other 12 were offered feathers soaked in 4% sucrose solution (S). The other 24 birds were kept as a control (C) without access to feathers. After a 10-d feather feeding period, 3 groups of 4 S and 4 C birds each and 3 groups of 4 Q and 4 C birds each were assembled. Feather-pecking behavior was recorded over a period of 8 d. The number of Q feathers eaten was significantly lower than the number of S feathers. Birds that were offered Q feathers in the feather feeding phase showed significantly less severe feather pecking than S and C birds. The results clearly show that Q as an unpalatable substance was the signal the animal used to avoid damaging the feather cover in laying hens.

Recording of individual feed intake and feeding behavior of pekin ducks kept in groups.

The temporal pattern of feed intake for individual ducks kept in groups was studied using a radio frequency identification system, to enable the continuous recording of feeding characteristics for a large numbers of animals over long periods. A total of 50 male ducks were used in experiment 1 and 480 male and female ducks in experiment 2. The bird:feeder ratio was 10:1 for both experiments. The birds were fed with a commercial pelleted duck grower ad libitum. For experiment 1, the BW, the amount and duration of feed intake, the number of meals, meal size, and feeding rate were recorded for ages from 3 to 7 wk and from 4 to 6(1/2) weeks for experiment 2. On the basis of the number of meals per day, the birds were assigned to 3 meal categories: high (H), low (L), and intermediate (I). The L-type ducks showed a higher feed consumption, BW, and meal size than I- and H-type ducks. The pattern of meal type and the interrelations among meal type, BW, feed intake, and other characteristics of feed intake were consistent for both experiments, throughout the experimental period. The relative frequency of pauses between feeding was plotted against the duration of the pauses for the H- and L-type ducks. The H-type birds showed a high number of pauses of less than 30 min in duration. The frequency of short meals declined with age for both meal types, whereas the frequency of larger meals increased.

The effect of feather eating on feed passage in laying hens.

Previous work has demonstrated an association between feather pecking and feather eating in laying hens. This raised the question of the dietary effect of feathers. We hypothesized that feathers, as indigestible components, have similar effects as insoluble fiber, i.e., speeding up feed passage. Twenty-four adult laying hens each of a high (H) and a low (L) feather pecking line were kept in individual cages and fed a commercial pelleted diet ad libitum. One-half of each line was offered downy feathers (HF; LF) of the same genetic line. The other half of the birds were kept as control without access to feathers (H0; L0). After a 6-wk feeding period, 5 birds of each group were selected for determination of feed passage. The HF birds with the highest number of feathers eaten and the LF birds with the lowest number of feathers eaten were used. Selection of L0 and H0 birds was carried out at random. Feed passage was determined over 48 h using titanium dioxide as a marker. The number of feathers eaten was significantly higher in HF birds than in LF birds before (P < 0.001) and during 48 h of marker excretion (P < 0.02). The time when 50% of the plateau level of excretion of the TiO2 was reached differed significantly among all groups; the shortest time was observed for the HF group (P < 0.05). The results clearly show that feathers increase the speed of feed passage and, in this regard, show similar effects as insoluble fiber. The dietary effect of feathers may be a crucial factor in the development of feather pecking and the related damages to the feather cover in laying hens.

Gait analysis in laying hens and broilers with and without leg disorders.

Selection of broiler strains for high body weight has changed the anatomical characteristics and in connection to that, the pattern of locomotion. In addition, rapid growing broilers show a high incidence of leg disorders which compromise the walking ability of the birds. Differences in the patterns of locomotion between laying hens and broilers and between broilers with and without leg disorders can be demonstrated and quantified by gait analysis. The gait pattern was recorded by videotracking. Three points of the body - the cloacal region and both feet joints - were marked by small patches of reflecting foils. The vertical and horizontal movements of the marked points were recorded by a camera in posterior position, while the bird was walking on a treadmill The camera was connected with a PC-operated videotracking system. The vertical and horizontal movements of the 3 marked points were recorded simultaneously and plotted against the time axis. Kinetograms show clearly the differences in the walking pattern between broilers and layers. Layers place the legs directly under the centre of gravity and, therefore, the body moves in a straight line. Broilers, in contrast, move the centre of gravity step by step laterally towards the position of the supporting leg. This pattern may be caused by the anatomical characteristics of broilers. Limping in broilers with leg problems can be measured by differences in the lateral and vertical movements of the right and left leg.

Aspects of "fear" in Japanese quail chicks (coturnix coturnix Japonica) genetically selected for different levels of locomotor activity.

Domestic chicks selected for high and low locomotor activity in a novel environment have low and high levels of fearfulness, respectively. Using four commonly employed methods of estimating fear, namely emergence, open-field, response to a bell and tonic immobility tests, we found a similar effect in lines of Japanese quail selected for high and low locomotor activity, i.e. the active line appeared the least fearful. The present findings demonstrate that this effect is common to two gallinaceous species and two selection procedures.