Operant determination of the cage and feeder size preferences of the laying hen

The design of an apparatus which allows hens to work for feeder space or for cage size is described. Using this apparatus, it is shown that groups of 4 hens will only rarely work to obtain more than the 40-cm length of feed trough which is usually provided in Europe for a group of 4 medium hybrid hens in a deep battery cage. This implies that there is no requirement for a larger feeder.Given the opportunity, the hens chose to spend up to 50% of the day in a cage larger than their usual battery cage, but this effect was highly variable both between groups and from day to day. A more detailed study of which birds in a group work, and of what the birds do in the enlarged cage, is needed before firm conclusions about the cage-size requirements of laying hens can be made.     

Motivation to dust-bathe of laying hens housed in cages and in aviaries

New housing systems for commercial egg production, furnished cages and non-cage systems, should improve the welfare of laying hens. In particular, thanks to the presence of a litter area, these new housing systems are thought to satisfy the dust-bathing motivation of hens more than in conventional cages, in which no litter area is present. However, although apparently obvious, there is no concrete evidence that non-cage systems, particularly aviaries, satisfy hens' motivation to dust-bathe and thus improve hens' welfare in terms of dust-bathing behaviour. The aim of this study was to compare hens' dust-bathing motivation when housed for a long time under similar conditions to commercial conditions in laying aviaries (with litter) and in conventional cages (without litter). Three treatments were compared: hens reared in floor pens then housed in conventional cages, hens reared in furnished floor pens then housed in a laying aviary, and hens reared in rearing aviaries then housed in a laying aviary. All three treatments provided access to litter during the rearing period. After transfer to the laying systems, access to litter was maintained for the aviary hens but stopped for the cage hens. Twelve groups of four hens per treatment were tested 36 to 43 weeks after transfer. The hens were placed in sawdust-filled testing arenas, and latency to dust-bathe, duration and number of dust baths, and number of hens dust-bathing were recorded. Latency to dust-bathe was shorter, dust baths were longer and more numerous and more hens dust-bathed among cage hens than among aviary hens. Our results indicate that hens' motivation to dust-bathe was more satisfied in laying aviaries than in conventional cages. Thus, laying aviaries improve hens' welfare in term of dust-bathing behaviour compared with conventional cages.     

Testing resource value in group-housed animals: an investigation of cage height preference in laying hens

To avoid unpredictable social effects, animals' behavioural priorities are almost always tested using individuals housed singly, yet many species kept commercially are social animals housed in groups. Our aim was to develop a method of investigating environmental preference in group-housed laying hens, Gallus gallus domesticus, that maximised the external validity of our findings. In a simple test of preference, eight groups of ten hens were given free choice between furnished cages with minimum heights of 38 cm (low) and 45 cm (high). A preference for one cage height over the other would be evident as a shift from a binomial distribution of flock sizes in the two cages. No height preference was found as hens distributed evenly between the two cages more frequently than was expected. This suggests at high stocking densities maximising average inter-individual distance could be a priority over increased cage height. In a second experiment, to investigate the value that hens placed on a change in cage height; a 'cost' in the form of a narrow gap was imposed on movement from a low or high start cage to a high or low target cage, respectively. Cage height did not influence the latency of the first three hens to enter the target cage. However, latencies for subsequent hens were shorter and more hens worked to access a high target cage than a low target cage. We suggest that titrating animals' willingness to tolerate higher stocking densities against access to a resource could be an effective way to compare responses of group-housed animals to resources that are expected to satisfy the same motivational state.     

Do hens suffer in battery cages? environmental preferences and welfare

The question ‘Do hens suffer in battery cages?’ is difficult to answer because of the problem of objectively assessing suffering in animals. It is argued that preference tests may be one way of throwing light on this difficult problem. This paper describes some experiments on habitat preference in domestic hens. No preference was observed between a commercial battery cage and a large pen when hens were given continuous access to the two. A simultaneous choice between a battery cage and an outside hen-run showed a clear preference for the run, but choice was strongly influenced by prior experience. The strength of the run preference was investigated by ‘pitting’ the run against food and access to companions.     

Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens

This study was conducted to evaluate the effect of early rearing conditions on physiological, haematological and immunological responses relevant to adaptation and long-term stress in white Leghorn hens with intact beaks housed in furnished cages (FC) or conventional cages (CC) during the laying period. Pullets were cage reared (CR) or litter floor reared (FR). From 16 to 76 weeks of age, hens were housed in FC (eight hens per cage) or in CC (three hens per cage). As measures of long-term stress at the end of the laying period, adrenal reactivity was quantified by assessing corticosterone responses to adrenocorticotropin challenge, and immune response was assessed by measuring antibody responses after immunization with sheep red blood cells (SRBC) and keyhole limpet haemocyanin (KLH). Heterophil to lymphocyte (H/L) ratio was employed as an indicator of stress. Rearing conditions significantly affected anti-SRBC titres (P < 0.0001) and tended to affect H/L ratios (P = 0.07), with the highest values found in FR hens. Layer housing affected H/L ratio (P < 0.01); the highest ratio was found in FR birds housed in FC during the laying period. This study shows that early rearing environment affects immunological indicators that are widely used to assess stress in laying hens. However, while results on H/L ratio indicated that FR birds experienced more stress particularly when they were housed in FC during the laying period, the immune responses to SRBC in FR hens was improved, indicating the opposite. This contradiction suggests that the effects on immune response may have been associated with pathogenic load due to environmental complexity in FR and FC hens rather than stress due to rearing system or housing system per se.     

Non-exclusive spatial preference in the laying hen

Two experiments were performed to elucidate aspects of the spatial preference of domestic hens kept in battery cages.In the first experiment, 12 hens were given a choice between four cages differing in size and shape. The measure of preference used was the amount of time spent in each cage under free-access conditions. The results show that the hens spent most time in the cage with the largest floor area, but that substantial amounts of time were spent in the remaining three cages. Eight possible explanations for this non-exclusive choice are proposed: variation among hens; change of preference with time; mis-identification; constraints on decision-making; pacing; sampling; monitoring; genuine preference. The first six hypotheses are discussed with respect to this experiment.The second experiment, using 6 hens under similar conditions, was designed to distinguish between the latter two hypotheses. The results suggest there may be a monitoring component to the hens' behaviour in this apparatus, characterised by cage visits of short duration. In addition, the hens may continue to visit small cages in order to perform particular behaviour patterns. Nest-building behaviour is mentioned as one possibility.     

The European Union ban on conventional cages for laying hens: history and prospects

Since the publication of Animal Machines (Harrison, 1964), there has been widespread public pressure in Europe-supported by European institutions-to “ban the battery cage. ”The European Union (EU) and national governments (particularly in Northern Europe) funded research on noncage systems for egg production and enriched cages. In 1986, the EU passed a Directive specifying a minimum size for cages, but public opinion-again particularly in the North-continued to require more. A market sector emerged that would pay more for noncage eggs. Denmark, Sweden, and Switzerland passed more stringent legislation than the rest of Europe. A 1999 Directive with details based on advice from the EU's Scientific Veterinary Committee will phase out conventional laying cages but allow enriched cages. Implementation depends on various factors, including negotiations in the World Trade Organization. In the next 10 years, however, major changes to the housing of most laying hens in Europe almost certainly will occur. Similar changes in other countries will follow. As in Europe, change probably will be piecemeal, affected both by public pressure and by all sectors of society: producers, retailers, consumers, legislators, and the media.     

Effects of separation of resources on behaviour of high-, medium- and low-ranked hens in furnished cages

In our previous studies, we demonstrated that dominant hens had priority in using the dust bath, resulted in increased competition for the resource. It seemed that the problem was that the resource was placed on one side of the cage (‘localised’). Therefore, we designed a medium-sized furnished cage with a dust bath and nest box on both sides of the cage (‘separated’, MFS). To evaluate the effects of separation of these resources, we compared the behaviour of high-, medium- and low-ranked hens in MFS cage with that in small (SF) and medium furnished (MFL) cages with a localised resource. In total, 150 White Leghorn layers were used. At the age of 17 weeks, the hens were randomly divided into three groups and moved to small furnished cages (SF, 90 cm wide; five birds per cage) and two types of medium furnished cages (180 cm wide; 10 birds per cage) with a nest box and dust bath on both sides (MFS) and a nest box and dust bath on one side of the cage (MFL). The total dust bath and nest box areas per hen were same for the three cages. The dominance hierarchy was determined by observing the aggressive interactions and by this high-, medium- and low-ranked hens in each cage were identified. The behaviour, use of facilities and physical condition of these hens were measured. Data were analysed by using repeated measure ANOVA. A significant interaction between social order and cage design was found in the proportions of time spent in the dust bath and on performing dust-bathing (both P < 0.001), and these proportions tended to be higher in higher-ranked hens in SF and MFL. Conversely, the MFS low-ranked hens tended to use the dust bath more than the SF and MFL low-ranked hens. Thus, hens from each rank used the dust bath equally in MFS, though the MFS high-ranked hens tended to use the resource less than the SF and MFL high-ranked hens. While the frequency of pre-laying sitting was lower among low-ranked hens (P < 0.05), the proportion of time in the nest box was higher among low- than high-ranked hens (P < 0.01). The low-ranked hens spent more time performing escaping, moving and standing in the nest box. In conclusion, it is suggested that separation of the dust bath to two locations would be an effective arrangement to promote more equal usage of the dust bath by hens from each rank in the furnished cages. It was also confirmed in the present study that nest boxes were not only used for laying eggs but also as a refuge by lower ranked hens.     

Competitive feeding behavior and social status in multiple-hen cages

The feasibility of using brief tests of competitive feeding behavior or observations of the displacement of one bird by another at the feeder to estimate the social status of hens in cages was evaluated. Data were gathered from 24 hens in six, 4-bird cages. Social status, determined from aggressive and submissive acts, was not found to be associated with success in gaining access to feed from a restricted-space feeder during the first 5 or 15 min, or with number of displacements of other hens from the feeder over 2-h periods, following 4 h feed deprivation.     

Furnished cages for laying hens: study of the effects of group size and litter provision on laying location, zootechnical performance and egg quality

The furnished cage is a new housing system for layers. A current trend in furnished cage design is to increase group size and replace the litter box with a mat provided with litter. An experiment was set up to determine the effects of group size and litter provision on laying performance and egg quality of beak-trimmed ISA Brown hens housed in large furnished cages with more than 12 hens. Six treatments, each of 18 furnished cages (768 cm(2)/hen including nest and litter area) were compared in a 3 × 2 experimental trial: three group sizes (S20 (20 hens per cage), S40 (40) and S60 (60)), with or without feed as litter distributed on the mat of the litter area. The provision of facilities per hen was equal in all treatments. Mortality, laying rate, mean egg weight, feed intake and feed conversion ratio were unaffected by group size over the 53-week laying period, and performance exceeded the ISA production standards. The overall percentage of eggs laid in the nest exceeded 95% except that it was slightly lower in group S20 (92.0% ± 6.4% v. S40: 96.0% ± 3.3% and S60: 96.2% ± 2.7%) leading to a higher proportion of dirty eggs (S20: 1.6% ± 2.2%, S40: 1.4% ± 1.5%, S60: 1.0% ± 1.0%). At 66 to 70 weeks, eggs laid outside the nest had a slightly higher count of mesophilic bacteria on the eggshell (5.0 log CFU/egg ± 0.4) than those laid in the nest (4.8 log CFU/egg ± 0.5) but no difference in contamination was observed between group sizes. Litter provision had no effect on mortality, egg weight or egg quality traits except for a higher proportion of broken eggs in cages with litter (5.3% ± 6.2% v. 4.6% ± 5.7%). Providing hens with feed for litter was associated with a higher laying rate (97.3% ± 3.2% v. 94.8% ± 4.4% at 23 weeks) and an apparent improvement in feed efficiency at the beginning of the laying period (feed conversion ratio based on feed consumption at the trough: 2.18 ± 0.06 with litter v. 2.28 ± 0.09 without litter at 25 weeks). The results of this study showed that a high level of productivity and good egg quality could be obtained in large furnished cages. Further research is needed to assess the impact on hens' welfare and performance of using more economically competitive substrates than feed for litter.     

Fear responses of individually-caged laying hens as a function of cage level and aisle

Chickens kept under intensive conditions are often housed in multi-deck battery cage systems. The effects on egg production of housing birds at different cage levels have been extensively studied, but little is known of the behavioural consequences of this. The present study examined the responses of individually-caged adult laying hens from each tier of a 3-tier battery system in a number of situations intended to elicit fear. Birds housed in the top tier showed (a) longer durations of tonic immobility, (b) greater avoidance of a novel rod placed at the front of the cage, and (c) lower levels of approach and greater inhibition when placed in a pen containing either a human being or one of two novel, inanimate objects, than did those from middle and bottom tiers. The latter birds behaved remarkably similarly. The consistently higher fear scores recorded by hens from the top tier are considered likely to reflect differences in general fearfulness as a function of cage level, and may be a consequence of long-term exposure to different degrees of environmental stimulation.     

Effect of simple and low-cost enrichment items on behavioral,clinical, and productive variables of caged laying hens

Housing layers in battery cages is a practice still used by many countries but it has been criticized because of its influence on behavioral repertoire of birds. We investigated whether simple and affordable enrichment devices alone impact behavior, foot condition and performance of laying hens housed in conventional cages. Hens were divided into plain cages (CON), cages with perches (PER), and cages with tassels and scratch-pads (ENR), and parameters were evaluated before and after enrichment placement. After perch placement inactivity, drinking and competition for space reduced 35.6%, 40.8% and 70.3%, respectively, whereas social interaction increased 19.3%. Both modifications decreased locomotion (75.0% and 42.4% for PER and ENR respectively) and abnormal behaviors (62.5% and 43.9.4% for PER and ENR respectively). None of the performance variables were affected by ENR or PER. Thermography was more efficient than visual inspection in detecting subclinical bumblefoot, and it confirmed that PER reduced subclinical and clinical cases. Our findings indicate that perches increased welfare-related behaviors and foot health of hens, supporting the use of these inexpensive and highly adaptable alternatives for the enrichment of battery cages.     

Animal Welfare Issues in the Poultry Industry: Is There a Lesson to Be Learned?

Many of the conditions in which poultry live and the procedures to which they are subjected compromise their welfare. This article describes these welfare problems in the hope that they may serve as warnings to the rest of animal agriculture, which then might take steps to avoid the same pitfalls. The article discusses poultry welfare problems under the headings of battery cages for laying hens, forced molting, disposal of spent laying hens, fast growth problems in meat poultry, catching and transportation, food restriction of broiler breeders, hyperaggressiveness in broiler breeder males, elective surgeries, and water-bath stunning.     

Responses of adult laying hens to abstract video images presented repeatedly outside the home cage

Previous studies reported that domestic chicks showed progressively greater attraction towards biologically neutral video images (screensavers) with repeated exposure [Jones, R.B., Carmichael, N., Williams, C., 1998. Social housing and domestic chicks' responses to symbolic video images. Appl. Anim. Behav. Sci. 56, 231-243; Jones, R.B., Larkins, C., Hughes, B.O., 1996. Approach/avoidance responses of domestic chicks to familiar and unfamiliar video images of biologically neutral stimuli. Appl. Anim. Behav. Sci. 48, 81-98]. The potential existence of an adult parallel was examined here by studying the responses of laying hens to similar screensaver videos when these were presented repeatedly in front of their home cage. In Experiment 1, individually housed, 31-week-old laying hens were exposed to either the video image of a computer screensaver (SS) programme (Fish), a blank but illuminated television monitor (B), or a black plastic hide (H) presented approximately 50 cm in front of their home cages for 10 min/day on each of 5 consecutive days. The bird's position in the cage and the orientation of its head were recorded every 15 s during the-10 min exposure period in order to assess approach and interest, respectively. Interest was scored by summing the numbers of observations at which the hen was either facing the front or had its head out of the cage. Birds in the B and H treatment groups showed few deviations from neutrality in their approach or interest. Conversely, although SS birds avoided the video stimulus on the first day their responses had reached neutrality (neither approach nor avoidance) by the third day and they showed significantly more approach than would be expected by chance at the fifth presentation. They also showed significantly more interest than chance on each test day; this score increased progressively and showed no sign of waning even at the fifth presentation. To determine whether or not such interest would be maintained indefinitely, the responses of previously untested hens were examined when the same video (Fish) was presented for 10 min/day on each of 20 consecutive days (Experiment 2). A blank, lit television (B) was again used a control. An unfamiliar video (Doodles) was presented to the SS birds on day 21 to determine the effects of stimulus change. After avoiding the stimuli upon their first presentation, both SS and B birds achieved neutrality by day 3. Approach scores then fell in B birds but rarely deviated from neutrality in SS ones. The SS video attracted markedly more interest than did the blank screen. On this occasion, SS hens showed significantly greater interest than would be expected by chance as early as the third presentation and this was still evident upon the eighth presentation; thereafter it waned gradually. However, interest was reinstated fully when the unfamiliar SS image was shown on day 21. The present findings clearly demonstrate that abstract video images, presented in front of the home cage for 10 min on consecutive days, reliably attracted and sustained the interest of individually housed laying hens for as long as 8 days. These results are consistent with those obtained when chicks were repeatedly exposed to similar screensaver videos, i.e., this phenomenon is not dependent on the stage of development. Our results also confirm the importance of considering the environment outside as well as inside the cage in future environmental enrichment programmes.     

温室白粉虱自动计数技术研究初报

应用计算机视觉技术对温室白粉虱自动计数技术进行了研究。采用胶卷照相机和家用摄像机对田间温室白粉虱等生的叶片进行拍摄,以获得其数字图象,对白粉虱图象的分割采用Ｊohannsen基于熵的分割算法,对分割后的二值图象利用区域标记算法得到白粉虱个体的数量。对叶片挨在一起的白粉虱个体采用数学形态学算法进行了分离。用１９个虫叶片样本的统计结果表明,直接利用分割图象进行白粉虱个体计数的累积准确率达９１．９９％,而分离处理的算法则需要改进,因此,这一技术具有进一步在生态研究和ＩＰＭ实践中推广的可能性,这将使田间微小昆虫的种群数量监测和测查的工作量大幅度降低,而铉得到显著提高。     

Moving GIS Research Indoors: Spatiotemporal Analysis of Agricultural Animals

A proof of concept applying wildlife ecology techniques to animal welfare science in intensive agricultural environments was conducted using non-cage laying hens. Studies of wildlife ecology regularly use Geographic Information Systems (GIS) to assess wild animal movement and behavior within environments with relatively unlimited space and finite resources. However, rather than depicting landscapes, a GIS could be developed in animal production environments to provide insight into animal behavior as an indicator of animal welfare. We developed a GIS-based approach for studying agricultural animal behavior in an environment with finite space and unlimited resources. Concurrent data from wireless body-worn location tracking sensor and video-recording systems, which depicted spatially-explicit behavior of hens (135 hens/room) in two identical indoor enclosures, were collected. The spatial configuration of specific hen behaviors, variation in home range patterns, and variation in home range overlap show that individual hens respond to the same environment differently. Such information could catalyze management practice adjustments (e.g., modifying feeder design and/or location). Genetically-similar hens exhibited diverse behavioral and spatial patterns via a proof of concept approach enabling detailed examinations of individual non-cage laying hen behavior and welfare.     

Do Laying Hens with Keel Bone Fractures Experience Pain?

The European ban on battery cages has forced a change towards the use of non-cage or furnished cage systems, but unexpectedly this has been associated with an increased prevalence of keel bone fractures in laying hens. Bone fractures are acutely painful in mammals, but the effect of fractures on bird welfare is unclear. We recently reported that keel bone fractures have an effect on bird mobility. One possible explanation for this is that flying becomes mechanically impaired. However it is also possible that if birds have a capacity to feel pain, then ongoing pain resulting from the fracture could contribute to decreased mobility. The aim was to provide proof of concept that administration of appropriate analgesic drugs improves mobility in birds with keel fracture; thereby contributing to the debate about the capacity of birds to experience pain and whether fractures are associated with pain in laying hens. In hens with keel fractures, butorphanol decreased the latency to land from perches compared with latencies recorded for these hens following saline (mean (SEM) landing time (seconds) birds with keel fractures treated with butorphanol and saline from the 50, 100 and 150 cm perch heights respectively 1.7 (0.3), 2.2 (0.3), p = 0.05, 50 cm; 12.5 (6.6), 16.9 (6.7), p = 0.03, 100 cm; 20.6 (7.4), 26.3 (7.6), p = 0.02 150 cm). Mobility indices were largely unchanged in birds without keel fractures following butorphanol. Critically, butorphanol can be considered analgesic in our study because it improved the ability of birds to perform a complex behaviour that requires both motivation and higher cognitive processing. This is the first study to provide a solid evidential base that birds with keel fractures experience pain, a finding that has significant implications for the welfare of laying hens that are housed in non-cage or furnished caged systems.     

The impacts of fermented feed on laying performance,egg quality,immune function,intestinal morphology and microbiota of laying hens in the late laying cycle

Fermented feed has the potential to improve poultry gastrointestinal microecological environment, health condition and production performance. Thus, the present study was undertaken to explore the effects of fermented feed on the laying performance, egg quality, immune function, intestinal morphology and microbiota of laying hens in the late laying cycle. A total of 360 healthy Hy-Line Brown laying hens aged 80 weeks were used to conduct a 56-day study. All hens were randomly separated into two treatment groups, with five replicates of 36 hens each as follows: basal diet containing 0.0% fermented feed (CON) and 20% fermented feed (FF). Subsequent analyses revealed that fermented feed supplementation was associated with significant increases in laying rates together with reduced broken egg rates and feed conversion ratio for hens in FF group (P < 0.05). There were additionally significant increases in both albumen height and Haugh unit values in hens following fermented feed supplementation (P < 0.05). Fermented feed was also associated with increases in duodenal, jejunal and ileac villus height (P < 0.05). Laying hens fed fermented feed had higher immune globulin (Ig)A, IgG, IgM levels (P < 0.01,) and higher interleukin 2, interleukin 6, tumour necrosis factor α and interferon γ (P < 0.05) concentrations than CON. Analysis of the microbiota in these laying hens revealed the alpha diversity was not significantly affected by fermented feed supplementation. Firmicutes abundance was reduced in caecal samples from FF hens relative to those from CON hens (30.61 vs 35.12%, P < 0.05). At the genus level, fermented feed was associated with improvements in relative Lactobacillus, Megasphaera and Peptococcus abundance and decreased Campylobacter abundance in laying hens. These results suggest that fermented feed supplementation may be beneficial to the laying performance, egg quality, immunological function, intestinal villus growth and caecal microecological environment of laying hens at the end of the laying cycle.     

Agonistic behaviour in domestic hens: the influence of housing method and group size

The incidence of agonistic behaviour was recorded over 1 year in laying hens of two strains, housed either in battery cages or in deep-litter pens in groups of either three or six birds. Aggressive head-pecking was more frequent in pens than in cages and in groups of six than in groups of three. Threats were more frequent in pens and in groups of six light-hybrids. Other pecking at the plumage was more common in cages in groups of six and in the light-hybrid than in the medium-hybrid strain. Observations showed that hens occupy a considerable area when engaging in threat displays: this suggests that the physical restraint of crowding may play an important part in limiting this behaviour. Two reasons for the reduction of aggressive head pecking in caged birds were suggested: firstly, inhibition of the subordinate hens' behaviour because they were constantly in the sphere of influence of the dominant bird and secondly, because agonistic encounters may be triggered only by the entry of other birds into an individual's 'personal space' and not by continuous proximity.