Effect of low light and high noise on behavioural activity, physiological indicators of stress and production in laying hens

The Effects of Mild Disturbances on Sleep Behaviour in Laying Hens

The positive welfare of commercial animals presents many benefits, making the accurate assessment of welfare important. Assessments frequently use behaviour to determine welfare state; however, nighttime behaviours are often ignored. Sleep behaviour may offer new insights into welfare assessments. This study aimed to establish a baseline for sleep behaviour in laying hens and to then apply mild short-term disturbances and observe the subsequent effects. Twelve laying hens were divided into four batches and were surgically implanted with electroencephalogram (EEG) devices to record their brain activity. The batches were subjected to undisturbed, disturbed and recovery types of nights. Disturbed nights consisted of systematic sequences of disturbance application (wind, 90 dB noise or 20 lux light) applied one at a time for 5 min every 30 min from 21:00 to 03:00 (lights off period: 19:00-05:00). Sleep state was scored using EEG data and behaviour data from infrared cameras. Over all the types of night hens engaged in both SWS (58%) and REM sleep (18%) during lights off. When applied, the disturbances were effective at altering the amounts of wakefulness and SWS (Time × Type of Night, p < 0.001, p = 0.017, respectively), whereas REM sleep was unaltered (p = 0.540). There was no evidence of carry-over effects over the following day or night. Laying hens may be resilient to short-term sleep disruption by compensating for this in the same night, suggesting that these disturbances do not impact their long-term welfare (i.e., over days). Sleep behaviour potentially offers a unique means of assessing an aspect of animal welfare that, to date, has been poorly studied.

Determination and Evaluation of Noise Pollution in Layer Hen House: A Bursa Case Study

Both animals and employees need to improve the indoor conditions in livestock barns and keep them at an optimum level. With the development of automation systems for increased productivity and mechanisation, more systematic production occurs within the poultry houses and the need for a workforce is reduced. However, the increase in industrialisation and herd size can cause noise pollution problems in the poultry house. In this study, noise levels were measured and statistically evaluated in a laying hen farm operating in a battery-type cage in the Bursa region. It is aimed to be assessed according to environmental pollution and animal welfare. It was measured in the corridors between the rows of cages and on the cage floors with the studied facility's noise meter (EXTECH SDL600). The obtained noise data were determined by the SPSS statistical program, the variance analysis of the differences between the corridors and the relationship between the layer hen house environmental factors (temperature, humidity and wind speed) and the regression analysis. According to the results measured throughout the year in the investigated enterprise, the maximum noise intensity was measured as 80.6 dB, and the minimum noise intensity was measured as 76.3 dB. The differences between the noise values measured in the aisles and floors of the cage rows are statistically significant.

Effects of blue-green LED lights with two perceived illuminance (human and poultry) on immune performance and skeletal development of layer chickens

Light is one of the essential environmental factors in the production process of laying hens, which can directly affect their behavior, growth and development, and production performance. The spectral sensitivity of humans is different from that of poultry, and the perceived illuminance units of human and poultry are lux and clux, respectively. If the light management of laying hen production is carried out according to human perceived illuminance, the growth and development of laying hens during pullet rearing may be adversely affected due to the discomfort of the perceived illuminance. Preliminary research has found that blue-green LED light can improve the immune function of laying hens during the brooding and rearing periods. However, the differences of the effects caused by blue-green light on the immune performance and bone development of laying hens during pullet rearing are still unclear for the 2 spectral sensitivities. A total of 120 Jinghong layer chickens were raised from 1 d to 13 wk of age in one of three groups with a white LED light (light intensity unit lux, WL) group, a blue-green LED light (light intensity unit lux, HBGL) group, and blue-green LED light (light intensity unit clux, PBGL) group, and unlimited feed and water were provided during the whole experiment. At 7 and 13 wk of age, the immune performance, bone parameters, and related gene expression were investigated. The results showed that compared with the WL groups, HBGL and PBGL increased the immunoglobulin A (IgA) content at 13 wk of age and the IgM content at 7 wk of age (P < 0.05). The bone mineral density (BMD) at 7 and 13 wk of age and tibial strength (TS) at 13 wk of age of the pullets in the WL group were significantly higher than those in the HBGL and PBGL group (P < 0.05). Osteoclastogenesis inhibitory factor gene (OPG mRNA) expression was increased in the layer chickens at the age of 7 and 13 wk for the WL group (P < 0.05). Compared with the WL group and PBGL group, the melanopsin gene (OPN4 mRNA) transcription level of hypothalamus and pineal gland of the chickens under HBGL significantly increased at 7 and 13 wk of age (P < 0.05). In conclusion, blue-green LED light with two perceived illuminance (human and poultry) can increase the Ig content and the immune performance of layer chickens, and blue-green LED light (light intensity unit lux) can promote the expression of OPN4 gene in the hypothalamus and pineal gland. In addition, white LED light can enhance bone quality by increasing tibia OPG gene expression.

The Effect of Music on Livestock: Cattle, Poultry and Pigs

Simple Summary

In times of intensified livestock production, the search for methods that reduce stress, which has an adverse impact on the health and welfare of their animals, has become a challenge for breeders and producers. Therefore, the possibility of using various musical genres to alleviate stress in chickens, cattle or pigs was considered. It has turned out that choosing a musical item is extremely important, as it can positively affect the health and production performance of animals by increasing the feeling of relaxation. The time of exposure to sounds and their intensity are important as well, and some authors propose to also pay attention to the frequency of sound waves. Music therapy, which was previously more widely deployed among humans, is increasingly used for farm animals as an element of enriching their living environment. Current research shows the importance of sound waves’ influence in animal production. Proper selection of the music genre, music intensity and tempo can reduce the adverse effects of noise and, thus, reduce the level of stress. It should be remembered, however, that silence is equally important and necessary for the welfare of animals. The paper presents literature findings regarding the influence of music on cattle, poultry and pigs.

Abstract

The welfare of animals, especially those kept in intensive production systems, is a priority for modern agriculture. This stems from the desire to keep animals healthy, to obtain a good-quality final product, and to meet the demands of today’s consumers, who have been increasingly persuaded to buy organic products. As a result, new sound-based methods have been pursued to reduce external stress in livestock. Music therapy has been known for thousands of years, and sounds were believed to improve both body and spirit. Today, they are mostly used to distract patients from their pain, as well as to treat depression and cardiovascular disorders. However, recent studies have suggested that appropriately selected music can confer some health benefits, e.g., by increasing the level and activity of natural killer cells. For use in livestock, the choice of genre, the loudness of the music and the tempo are all important factors. Some music tracks promote relaxation (thus improving yields), while others have the opposite effect. However, there is no doubt that enriching the animals’ environment with music improves their welfare and may also convince consumers to buy products from intensively farmed animals. The present paper explores the effects of music on livestock (cattle, poultry and pigs) on the basis of the available literature.

The Effect of Light Intensity, Strain, and Age on the Behavior, Jumping Frequency and Success, and Welfare of Egg-Strain Pullets Reared in Perchery Systems

The effects of light intensity (L) are not well studied in pullets. Our research objective was to study the effect of L on navigational success, behavior, and welfare of two pullet strains (S). In two repeated trials, a 3 × 2 × 4 factorial arrangement tested three L (10, 30, 50 lux) and two S (Lohmann Brown-Lite (LB), LSL-Lite (LW)) at four ages. One thousand eight hundred pullets/S (0-16 wk) were randomly assigned to floor pens within light-tight rooms (three pens/S/room, four rooms/L) containing four parallel perches and a ramp. Data collection included jumping frequency and success (24h continuous sampling), novel object tests (fear), heterophil to lymphocyte (H/L) ratios (stress), and behavior (instantaneous scan sampling) during photoperiods. L did not affect injurious behavior, fear, or H/L. Pullets reared at 50 lux spent more time preening than at 10 lux. Pullets reared at 10 lux spent more time wall pecking than at 50 lux. Time spent standing and preening and total number and accuracy of jumping increased with age. Pullets reared at 30 lux had higher jumping frequency than at 10 lux; accuracy was not affected. LW jumped more than LB, but with similar success. LB spent more time exploring and scored higher in the fear and stress assessments, suggesting S differences.

Impact of male-female cohabitation period on behavioral aspects, fertility, hatchability, and hormonal estimates of Japanese quail

To evaluate the impact of male-female cohabitation period on the fertility, hatchability, injuries response, and some hormonal estimates in Japanese quails. A total of 288 mature Japanese quails were equally divided into 3 groups (3 groups × 8 replicates × 12 birds), with 1 Male: 2 Females sex ratio. In the first group (control), male and female quails were reared continuously together, while the males in the second and third groups were reared together with females once or twice/wk times (24 h/ time), respectively throughout the experiment. The obtained results showed that final body weight (FBW/g), fertility (%), and hatchability (%) in the second and third groups significantly (P ≤ 0.01) increased compared with the control group. Laying quails in the second and third groups significantly (P ≤ 0.01) produced more and heavier eggs, while the feed consumption and feed conversion ratio were significantly (P ≤ 0.01) decreased compared with the control group. The injuries response for both sex in the second and third groups significantly (P ≤ 0.01) decreased compared with the control group. The cloacal size (mm²) for quails in the third group significantly (P ≤ 0.01) increased than those of the first and second groups, while the testes (%) were not affected. The testosterone hormone concentration for male chickens in the second and third groups significantly (P < 0.01) decreased, while the female progesterone hormone concentration (ng/mL) significantly (P < 0.01) increased compared with the control group. The means of red blood cells (RBC/106), white blood cells (WBC/103), and hemoglobin (g/dL) for quails in the second and third groups significantly (P < 0.01) increased, while heterophil/lymphocyte (H/L ratio) significantly (P < 0.01) decreased compared with the control group. Thus, it could be concluded that the reduction male-female cohabitation period of quails is recommended for improving the fertility and hatchability percentages as well as and some hormonal estimates.

Effect of light intensity and stocking density on the performance, egg quality, and feather condition of laying hens reared in a battery cage system over the first laying period

The present study aimed to determine the effects of varying light intensity (high 121.8, medium 57.4 and low 11.9 lux) and stocking density (high 552.3, medium 736.3, and low 1104.5 cm² cage floor area per hen) treatments on the performance, egg quality, and certain feather condition traits of Lohmann-Brown hens reared in a battery cage system between 20 and 40 weeks of age. Body weight was determined individually at 19 weeks and at 50% yield age (sexual maturity). Feed intake, egg yield, egg weight, and feed conversion ratio were determined weekly. Feather condition was also evaluated individually at 40 weeks of age. Hens reared under high light intensity and low stocking density reached sexual maturity and peak yield earlier than others. The highest body weight was determined for hens reared under high light intensity (1536.6 g), while the lowest in the medium light intensity group (1461.2 g). Hens reared under high and medium light intensity showed higher egg yield than those reared in low intensity (120.5, 120.0 and 112.8 eggs, respectively). In addition, hens reared at low and medium stocking density had higher egg yield than high density (119.7, 120.7, and 112.9 eggs, respectively). Hens reared under low (61.6 g) and medium (61.0 g) light intensity produced heavier eggs than hens in high light intensity (59.6 g). While feed intake was not affected in any treatment, hens reared at low and medium stocking density had a better feed conversion ratio than hens at high density (2.19, 2.20, and 2.40, respectively). Our study results showed that a sustainable production is possible by maintaining the welfare-performance balance when 50-60 lux light intensity and 700-800 cm² cage floor area per hen are provided.

Causes of feather pecking and subsequent welfare issues for the laying hen: a review

When feather-pecking behaviour by hens becomes repetitive, plumage damage often results for the recipient of the pecks. The forceful removal of feathers and vigorous pecks directed at the skin may also cause pain, fear and even wounds. ‘Outbreaks’ of pecking behaviour have been reported in all housing systems in which poultry are managed. Pecking may progress to cannibalism and death, thus constituting significant hen welfare and farm economy problems. Farmers apply preventative management practices to minimise the risk of outbreaks. However, outbreaks are unpredictable and, once in progress, are difficult to control, especially in non-cage housing systems. For more than a century, research has been directed at trying to identify the causal factors underlying this problem, without success. The problem is multi-factorial and different studies often identify contradictory findings, such as, for example, in relation to the effects of adding forage to increase environmental enrichment, among others. The present review aims to provide background information about severe feather-pecking behaviour in laying hens, with mention of the resultant issues from repeated performance, such as, for example, on feather cover over the life of the laying hen. On-farm surveys, epidemiological studies and experimental trials have generated much information that has improved our general understanding of the significance of the problem, even though studies have typically been inconclusive due to its multi-factorial causes. While ‘Good Practice Guides’ are available and provide relevant advice for farmers to manage flocks to minimise the risk of outbreaks, we suggest significant progress towards identifying the root-cause(s) of the problem will more likely be achieved through controlled experimental trials using research models than through survey approaches. For example, using a stress-induction model, researchers should first focus on the impact of cumulative stressors in the flock that seem to predispose a hen to either become a feather pecker, or be the victim of pecking. Subsequent research should then investigate the affected hens for altered behavioural or (neuro-) physiological states, or physical stimuli on the skin and feathers, that may increase the motivation of hens to become feather peckers.

Behavioral responses of turkeys subjected to different climatic conditions

I was evaluated the effect of seven different combinations of temperature, air velocity, and relative air humidity on the frequency and duration of eating, drinking, resting, cannibalism, dust bathing, scratching, ground pecking, shivering, and stretching behaviors of turkeys at three different ages. The combinations tested of temperature, relative air humidity, and air velocity were, respectively: 1 (22 °C, 50%, 1 m/s); 2 (26.2 °C, 73.2%, 0.45 m/s); 3 (26.6 °C, 71.2%, 1 m/s); 4 (28.9 °C, 72%, 1.4 m/s); 5 (31.1 °C, 85%, 0.45 m/s); 6 (34.1 °C, 82.1%, 1 m/s); and 7 (34.4 °C, 82.1%, 1.4 m/s) for three ages of birds (61, 96, and 131 days of age). Seven birds were housed per pen, at a density of 3 males/m², totaling 147 birds in the entire experiment. Each combination was applied for 5 days. The data were analyzed considering the number of times the bird performed the behavior and the time it performed (in seconds). Each pen was considered a repetition. A comparison of the medians was used to compare the treatments by each age. The results showed that young birds were more likely to suffer from the combination of low temperature and high air velocity, reducing their frequency of normal behaviors. Increased humidity at a low temperature raised the frequency of scratching, shivering, and cannibalism behaviors leading to poorer bird welfare. It is recommended that the temperature, relative air humidity, and air velocity combination of 26.6 °C; 71.2%; and 1 m/s, respectively, for young birds, and 22 °C; 50%; and 1 m/s, respectively, for older birds should be used.

The effect of linear lighting systems on the productive performance and egg quality of laying hens

The low uniformity in light distribution provided by conventional lighting systems installed in laying poultry can compromise the productive performance and egg quality of laying hens. Thus, the aim of the current study is to evaluate the effect of a linear lighting system with light-emitting diode (LED strip) on the productive performance and egg quality of laying hens, by comparing it to the conventional LED lamp lighting system. The study used Hy-Line Brown hens from a commercial production unit. Hen-day egg production (%), mortality rate (%), egg weight (g), albumen height (mm), Haugh unit, eggshell thickness, eggshell strength, and thermal-environment conditions were evaluated from the 19th to the 48th wk of age. The results have shown that LED strips were capable of improving egg production (P < 0.05) in comparison to LED lamps. Egg quality was not affected (P > 0.05) by the evaluated lighting systems throughout the experimental period. Results of the current study indicate that the homogeneous illuminance distribution provided by the linear LED strip lighting system at different cage floors improved egg production in comparison to the conventional LED lamp lighting system.

Does light intensity affect the behavior, welfare, performance, meat quality, amino acid profile, and egg quality of Japanese quails?

The current study aimed to explore the impact of different light intensities on behavior, welfare, performance, meat quality, amino acid content, and egg quality of Japanese quails. A total of 600 1-day-old Japanese quail chicks were used (300/batch). Chicks were homogeneously classified into 3 groups (each of 100); low (10 lux), moderate (50 lux). and high light intensity (250 lux) groups. There was a significant effect (P < 0.05) of light intensity in most of the Japanese quails' behaviors. Quails reared on low light intensity showed the lowest behavior of feeding, drinking, flying, and feather picking, while the highest behaviors were preening, dust bathing, leg and wing stretching, and body shaking when compared with the other groups. Moreover, they had the better welfare (lowest H/L ratio and corticosterone levels). Quails of low light intensity groups possessed the heaviest body weight (145.17 g, P = 0.000) with the lowest daily feed intake (14.17 g) but with the best feed conversion ratio (3.39%, P = 0.000). Moreover, they had the heaviest slaughter (132.47 g, P = 0.000) and carcass weight (109.29 g, P = 0.000) and carcass yield (75.37%, P = 0.000) when compared with the others groups. Muscles of quails (both of pectoral and thigh) kept under low light intensity revealed the highest percentage of lightness, yellowness, and water-holding capacity with the lowest percentage of cooking loss, thiobarbituric acid reactive substances, and some amino acids. They also had the heaviest egg weight (11.24 g, P = 0.000) with the best external and internal egg-quality grades (P < 0.05). Consequently, low light intensity is suggested for improving quail's welfare, performance, and reproduction, while the high light intensity had a detrimental effect on both welfare and performance.

The Human-Animal Relationship in Australian Caged Laying Hens

Simple Summary

Stockperson behaviour can influence fear of humans and welfare of farm animals. This study observed the human-animal relationship (HAR) in 19 Australian caged laying hen flocks to determine whether stockperson behaviour was associated with behavioural indicators of fear of humans and stress in caged laying hens. The average avoidance response of each flock toward an approaching human was assessed using two behavioural tests, and stress was measured using the concentration of corticosterone in an egg sample collected immediately prior to these observations. Stockperson behaviour was observed for 2 days in each flock and compared to hen fear. Unexpectedly, no relationships were found between the observed stockperson behaviour and avoidance of humans in the hens, but flocks were more productive when they showed less avoidance of humans, and when stockpeople made less noise in the laying house. This suggests that stockperson behaviour and hen fear may influence productivity, but there was no evidence that any effect of fear on productivity was caused by stockperson behaviour. Unexpectedly, the most fearful flocks also had the lowest stress levels. These results clearly need further research to be fully understood but could not confirm the existence of the HAR on caged egg farms in Australia.

Abstract

Studies on farm animals have shown relationships between stockperson attitudes and behaviour and farm animal fear, stress and productivity. This study investigated how the avoidance behaviour of Australian commercial caged laying hens may be related to stockperson behaviour, albumen corticosterone, and the number of weeks producing within 5% of peak egg production. Nineteen laying houses were assessed over 3 days. Fear of humans in hens, based on their avoidance response to an unfamiliar human, was assessed using two behavioural tests. Albumen corticosterone concentrations were measured from egg samples collected immediately prior to behavioural testing. Stockperson attitudes were assessed using a questionnaire and stockperson behaviour was observed over 2 days. Productivity records for each laying house were also obtained. The duration of peak production was negatively related to both noise made by the stockperson and hen avoidance. No relationship between stockperson behaviour or attitudes and hen avoidance was found, but stockpeople with negative attitudes made more noise. In conclusion, this study could not confirm a relationship between stockperson behaviour and hen avoidance behaviour for Australian caged laying hens. However, this study did confirm a relationship between hen avoidance behaviour, albumen corticosterone concentration, and the duration of peak egg production.

Sophisticated Fowl: The Complex Behaviour and Cognitive Skills of Chickens and Red Junglefowl

The world’s most numerous bird, the domestic chicken, and their wild ancestor, the red junglefowl, have long been used as model species for animal behaviour research. Recently, this research has advanced our understanding of the social behaviour, personality, and cognition of fowl, and demonstrated their sophisticated behaviour and cognitive skills. Here, we overview some of this research, starting with describing research investigating the well-developed senses of fowl, before presenting how socially and cognitively complex they can be. The realisation that domestic chickens, our most abundant production animal, are behaviourally and cognitively sophisticated should encourage an increase in general appraise and fascination towards them. In turn, this should inspire increased use of them as both research and hobby animals, as well as improvements in their unfortunately often poor welfare.

Effects of Dark Brooders on Behavior and Fearfulness in Layers

Chicks require heat to maintain body temperature during the first weeks after hatch. This may be provided by dark brooders; i.e. , horizontal heating elements equipped with curtains. The objective was to test effects of rearing layer chicks with dark brooders on time budget and fearfulness. Behavioral observations were performed during the first six weeks of age. Three different fear tests were conducted when the birds were age 3-6, 14-15 and 26-28 weeks. During the first four days, brooder chicks rested more than control chicks whereas they spent less time drinking, feather pecking and on locomotion ( p ≤ 0.009). On days 16, 23, 30 and 42, brooder chicks spent less time on feather pecking, locomotion and fleeing ( p ≤ 0.01) whereas foraging and dust bathing occurred more often on day 42 ( p ≤ 0.032). Brooder birds had shorter durations of tonic immobility at all ages ( p = 0.0032), moved closer to the novel object at age 15 weeks ( p < 0.0001), and had shorter latencies to initiate locomotion in the open-field test at age 28 weeks ( p < 0.0001). Results support the suggestion that dark brooders can be a successful method of reducing or preventing fear and feather pecking in layers.

Assessment of welfare and egg production of laying hens moravia ssl in small-scale breeding

The purpose of this study was to investigate the welfare of laying hens Moravia SSL housed in small-scale hen house with free range, behavior, egg production and selected physical indicators of eggs and chemical indicators of egg mass. The laying hens were kept in a hen house on deep litter. Breeding facility of hen house was within the meaning of recommendation for applying the principles of welfare, i.e. the space and breeding facility within the meaning of enriched breeding environment. Stocking density of the laying hens corresponded with recommendations for unrestricted movement and implementing natural activities. The hen house was equipped with the perch, nest, feeder and drinker. The commercial feed mixture was used for feeding, which is intended for laying hens. The kitchen remains were added to feed mixture, as are wet bread, the non-edible remains of foodstuffs. A feed mixture was served to laying hens 825 g per day. The laying hens had free access to drinking water, grazing, ground pecking, ground scratching and dust-bathing and in the free range. We focused investigation of on the egg laying intensity, selected parameters of physical egg quality and chemical egg contents. Time to relax of laying hens was adjusted according to the summer and winter breeding seasons. The main activities of free-range hens are grazing, ground pecking, ground scratching and dust-bathing. The main activities of free-range hens are grazing, ground pecking, ground scratching and dust-bathing. These activities were investigated in laying hens too in dependent of year period, more in the summer. Housing of the hens was equipped with the perch. The laying hens regularly used a perch. A beginning of occupation the perch was at the time of time growing dark, at the end of the light day. A nesting material was selected regular, monthly exchange. It was meadow hay of excellent quality for the collection of high quality and safe eggs from nests in the hen house. The laying hens had unlimited access to feed and water. The commercial feed mixture was available ad libitum and fresh kitchen remnants were added in a small amount, provided that they fed in the short term, so that not subject to harmful degradation process. The management of our experiment was scheduled at age of laying hens 30 to 90 weeks. The egg laying intensity was observed 50% in a moment of the experimental 1st week (age of laying hens 30 weeks). High egg laying intensity of laying hens was at their age between 39 to 63 weeks. At the end of the experiment, at age of laying hens 90 weeks was decreased egg laying intensity at 26.19%, which represents almost half of egg laying intensity recorded at the beginning of the experiment. An indicator of egg production in the our experiment was studied under defined conditions for small-scale breeding, i.e. in alternative production system with free range, under defined conditions of nutrition and timing of investigation more than one year, from the end of October to the end of December of the following year. The results of our experiment can be related to the season, months of the year. The laying hens laid the eggs by individual weeks 33-90 weeks of age about average weight from 57.5 to 75.0 g. The fat content of an egg mass was 11.3 g.100-1 and protein 12.39.g.100-1. The table eggs from conditions of small-scale breeding are an important source of foodstuffs for the population, especially in rural areas. It must be given to this source of table eggs for human nutrition the highest quality and health safety too.

The effect of keel fractures on egg production, feed and water consumption in individual laying hens

The impact of keel bone fractures on egg production, egg weight and feed and water consumption in individual laying hens. A total of 165 Lohmann brown laying hens were obtained from a commercial farm that consisted of 105 with keel fractures and 60 without keel fractures. 2. After a 4-d period of acclimatisation, hens were individually housed and provided with ad libitum food and water for a 24-h period. The number of eggs laid, egg weight, feed and water consumption during this period were recorded. Keel bone strength was also assessed. 3. Hens free from keel fractures laid more eggs (91.7% vs. 84.9%) of significantly heavier weight (61.9 g vs. 60.2 g), ate less feed (139 g vs. 151 g) and drank less water (212 ml vs. 237 ml) than hens with fractures. 4. There was a significant positive association between keel fracture severity and water consumption, and a significant negative association between keel fracture severity and egg weight and keel bone strength. 5. This small-scale study on individual birds shows that keel bone fractures may have an impact on the economics of egg production.

Immune alterations induced by chronic noise exposure: comparison with restraint stress in BALB/c and C57Bl/6 mice

Exposure to loud noise levels represents a problem in all regions of the world. Noise exposure is known to affect auditory structures in living organisms. However, it should not be ignored that many of the effects of noise are extra-auditory. In particular, it has been proposed that noise could affect immune system similarly to other stressors. Nevertheless, only a few studies so far have investigated the effects of noise on the immune function. The aim of the present work was to investigate the effect of chronic (2 weeks) noise (95-97 dBA) exposure on immune responses in BALB/c and C57 mice. To ascertain if the effect of noise is similar to other psychological stressors, the effect of chronic restraint--applied for the same time--on immune response was also analyzed. It was found that chronic noise impaired immune-related end-points in vivo and ex vivo depending on the strain used. Noise, but not restraint, affected C57Bl/6 mouse T-cell-dependent antibody production and ex vivo stimulated T-cell proliferation, but had no effect on these parameters in BALB/c mice or their cells. In fact, none of the stressors altered T-cell responses associated with the BALB/c mice. Further, noise exposure induced a decrease in corticosterone and catecholamines levels in BALB/c mice. In contrast, no differences were seen in these parameters for those BALB/c mice under restraint or for that matter C57Bl/6 mice exposed to restraint or noise. The results of these studies indicate that noise could seriously affect immune responses in susceptible individuals. In addition, it may also be concluded that noise possibility should not be considered a classic stressor.