Perching and floor laying by domestic hens: Experimental results and their commercial application

1. The effect of perching experience on use of ground level nest boxes was tested in medium hybrid hens. Twelve out of 14 hens (86%) reared without perches laid their first egg on the floor when isolated with ground level nests. Only 4 out of 19 hens (21%) reared with perches laid on the floor. Medium hybrids with experience of only one level apparently have difficulty even stepping up to another level.

2. The age at which perches should be introduced to minimise floor laying was investigated in a second experiment with medium hybrids. Five groups had perches provided at 4, 8, 12, 16 and 20 weeks respectively. Floor laying in the first group varied between 0 and 10%. The proportion of floor eggs laid by the other groups was between 31 and 100% initially, falling to between 23 and 43% by the end of the experiment. Provision of perches as early as possible is recommended.

3. In a commercial trial, perches were provided in a rearing pen of 2600 broiler grandparents. A control pen of 2130 birds had no perches during rearing. At 30 weeks old, floor laying in the experimental flock was 5% of total production, compared to 11% in the control flock. The effect of providing perches during rearing on subsequent floor laying may be of considerable commercial significance.     

Effect of production system and flock age on egg quality and total bacterial load in commercial laying hens

The shell of the egg is essential in providing shape to the egg and ensuring safe packaging of the internal contents; however, shell defects have been shown to increase the risk of microbial contamination of eggs. Eggs were collected from commercial cage and free-range flocks at the ages of 25, 35, 45, 55, 65, and 75 wk. From each collection per flock, 30 eggs were processed for the eggshell and egg internal quality determination, 30 eggs for cuticle estimation, 30 eggs for mammillary layer ultrastructural features scoring, and 60 eggs for egg microbial enumeration. Translucency score and shell reflectivity were significantly higher in free-range eggs and increased with flock age in both production systems. Egg weight, shell weight, percentage shell, shell thickness, albumen height, Haugh unit, and yolk color were higher for cage eggs. The amount of cuticle was higher in cage eggs and fluctuated with flock age in both production systems. For the mammillary layer ultrastructural variables, a significant effect of production system and flock age was observed for early fusion, Type A bodies, and Type B bodies, whereas aragonite, depression, erosion, and hole were rarely observed. Variability of mammillary cap size, the incidence of poor mammillary cap quality, incidence of late fusion, alignment, Type A bodies, Type B bodies, and cubic cone formation were greater in the free-range versus cage system and increased with flock age in both production systems. The incidence of confluence and early fusion were greater in cage eggs and decreased with age in both production systems. Significantly lower total microbial load was observed for cage compared with free-range eggs, but the overall bacterial load recorded in this study was low. It can be concluded that cage eggs were better in overall quality when directly compared with free-range eggs.     

Urinary tract cryptosporidiosis in commercial laying hens

Formalin-fixed kidney tissues from adult egg-laying chickens in two houses of an egg-production complex in the upper Midwest were submitted to Iowa State University for histopathologic examination. An increased incidence of visceral gout, average daily mortality 1%-2% higher than expected, and egg production within normal limits were observed in both houses. Numerous developing stages of Cryptosporidium were observed on the apical surface of epithelial cells lining renal collecting tubules and ureters. Scanning and transmission electron microscopy were used to visualize colonization of cryptosporidia, disruption of microvilli, and exfoliation of parasitized epithelial cells. Lymphoplasmacytic infiltration in the wall of ureters and hyperplasia of parasitized epithelial cells resulted in partial obstruction of ureters, which may have induced visceral gout in affected hens. This is the first report of urinary tract cryptosporidiosis occurring in adult hens in a modern commercial egg-production facility.     

商品蛋鸡绦虫病的诊治

绦虫病是鸡常见的一种寄生虫病，主要危害雏鸡，能引起雏鸡大批死亡，但引起成年蛋鸡发病的报道却很少。2003年10月，辽西地区，尤其是锦州周边地区的一些蛋鸡饲养户饲养的商品蛋鸡陆续发生绦虫病，造成鸡产蛋量下降及部分鸡死亡。现将发病及诊治情况报告如下。     

Space use at night and social relationship between roosting partners in a large flock of laying hens

1. Laying hens in two aviary flocks of 1250 females and 12 males were investigated to determine if hens used the same roosting site more often than expected by chance and whether hens that roost next to each other for two consecutive nights (close groups) had fewer agonistic interactions than hens roosting far away from each other (distant groups) when put into a new environment in groups of 4 birds.

2. Hens showed a significant preference for using the same roosting site on consecutive nights. There was no difference between close groups and distant groups in agonistic interactions. However, in close but not distant groups, a low or high level of interaction on day 1 predicted a low or high level on day 2 that might reflect established relationships in the close groups.

3. It was concluded that hens prefer the same roosting site in the short term but further research is needed to investigate whether hens roosting next to each other recognise roosting partners or not.     

The efficacy of three commercial Mycoplasma gallisepticum vaccines in laying hens

The efficacy of three commercial Mycoplasma gallisepticum (MG) immunizing agents-a bacterin, a recombinant fowlpox-MG vaccine, and a live F-strain vaccine-was compared in specific-pathogen-free hens in egg production. Three groups of 25 chickens were vaccinated with one of the vaccines at 10 wk of age and 25 birds were not vaccinated. At 25 wk of age (and approximately 50% egg production), 20 birds from each of the three vaccinated groups and 15 nonvaccinated controls were challenged with virulent R-strain via aerosol; the birds were necropsied and evaluated at 10 days post-challenge. The MG bacterin and live F-strain vaccinations were both protective and resulted in significant differences in air sac lesions, tracheal lesions, and ovarian regression compared to the nonvaccinated controls and the recombinant fowlpox-MG vaccine (P < or = 0.05). The evaluation of ovarian regression is a useful method of testing the efficacy of MG vaccines in laying hens.     

Nesting,dust bathing and perching by laying hens in cages: Effects of design on behaviour and welfare

1. Laying hens (192 ISA Brown medium hybrids) were housed from 18 to 72 weeks as groups of 4 in conventional or experimental cages. The main area of all cages provided 675 cmVhen. All experimental cages had perches, dust baths and nest boxes, which were of three types: litter (L), artificial turf (A) or plastic rollaway (P). These facilities provided an additional 375 to 480 cm²/hen. The nest boxes and dust baths occupied either high or low positions. Behaviour, physical condition and production of the birds were regularly recorded.

2. Mortality was low (1.6% overall) and egg production very good in all treatments. The proportion of cracked and dirty eggs was slightly (but not significantly) higher in the experimental cages. In the experimental cages 90% of eggs were laid overall in the nest boxes and 3% in the dust baths. The proportion laid in the nest boxes was lower early in the laying cycle and increased with time, reaching 99% in A.

3. The facilities were heavily used. Birds spent about 25% of day time on the perches and 10–15% in or near the nest box and dust bath. At night, the majority of birds (90 to 94%) roosted on perches, but most of the remainder were on the lips of the nest box or dust bath, fouling the interiors.

4. Pre‐laying behaviour was much more settled in the experimental cages (45 min spent in the eventual laying position) than in the conventional ones (20 min) and total duration varied from 68 min in A to 87 min in P. The number of nest entries varied from 3.0 (A and P) to 4.3 (L); disturbance to sitting birds was correspondingly greater in L.

5. Dust bathing in the experimental cages generally took place during the afternoon in a single bout of about 5 min duration, whereas in the conventional cages it was brief and fragmented (3 bouts of 10 s each). The dust bath was also used for foraging behaviour (pecking and scratching). The treatments with small dust baths (A and P) caused problems for the birds.

6. Feather, foot and claw damage all tended to be less in the experimental than in the conventional cages, though only in the last case was the difference significant. Keel bone depressions appeared to be associated with perches; they were present in 43% of hens in the experimental cages but only 4% in conventional cages. There were no significant differences in body weight or in tibial or humerus strength between birds in the various treatments.

7. This study confirms that experimental cages with nest boxes, dust baths and perches offer appreciable benefits for welfare, with few production problems. The most successful treatment (A) could, with relatively minor modifications, form the basis of a practical design for large-scale commercial production.     

Effects of commercial enzyme preparations on egg and eggshell quality in laying hens

1. Four different commercial enzyme products were added to standard commercial layer diets, based on barley, wheat or triticale. 2. Diets were fed to 4 different strains of commercial laying hen: ISA Brown, Hy-Line CB, Tegel SB2 and Tegel HiSex. 3. Diets were given for 5 weeks prior to measurements of egg and eggshell quality. 4. The inclusion of commercial enzyme products in the diets had no effect on egg weight. 5. Positive effects of the enzymes were: improved eggshell breaking strength, shell weight, percentage shell and shell thickness for the barley-based diet and increased eggshell breaking strength for two of the enzymes with the wheat-based diets. 6. Negative effects of the enzyme products were slightly lighter coloured eggshells and reduced albumen quality for the barley-based diet and for two enzymes with the wheat-based diet. 7. The addition of commercial enzyme preparations had no main effect on egg and eggshell quality for the triticale-based diet, except for effects on yolk colour. 8. Yolk colour was lower than control for enzyme 3 in all diets and for enzyme 4 with the barley- and wheat-based diets. 9. Further investigation is required to elucidate the specific enzyme components that influence egg quality.     

Decreased egg production in commercial laying hens fed zearalenone- and deoxynivalenol-contaminated grain sorghum

In an experiment to determine the effect of corn vs. grain sorghum on performance of laying hens, egg production decreased significantly in the grain sorghum-fed hens in each of two trials starting 24 weeks after the trials began. Necropsy of chickens fed both diets revealed buccal ulceration at the ventral aspect of the oral cavity and squamous metaplasia of the esophageal glands and submaxillary salivary glands. Lesions were much more severe in the sorghum-fed birds than in the corn-fed birds. Analysis of the grain sorghum and corn revealed the presence of mycotoxins. Zearalenone and deoxynivalenol were present in the grain sorghum, and a lower amount of deoxynivalenol and a trace of aflatoxin B1 were found in the corn. Although mycotoxin levels were low, interaction between these mycotoxins and others may have decreased egg production.     

Characterization of Escherichia coli isolates from peritonitis lesions in commercial laying hens

Five clinically normal chickens from three farms (farm A, farm B, and farm C), for a total of 15 clinically normal chickens, were examined bacteriologically. In a similar manner, five dead chickens with lesions of peritonitis from each of the same three commercial egg-laying operations were selected for bacterial culturing. Escherichia coli were isolated from the cloaca in 14 of 15 healthy chickens and from all 15 chickens with peritonitis. Oviducts of normal chickens did not contain E. coli (0/15) whereas oviducts from 13 of 15 hens with peritonitis were positive for this pathogen. No lesions and no E. coli (0/15) were found in the peritoneal cavity of healthy hens, but peritonitis lesions from 13 of 15 dead chickens yielded E. coli. On farm A and farm B, a flock consisted of all chickens within a single house and all chickens in each flock were of the same age and same genetic strain. In flock 1 from farm A, all five E. coli isolates from the oviduct and all five isolates from the peritoneal cavity were serogrouped as O78; contained the virulence genes iroN, sitA, iutA, tsh, and iss; and belonged to phylogenetic group A. In flock 2 from farm B, all four E. coli isolates from the oviduct and all four isolates from the peritoneal cavity were serogrouped as O111; contained virulence genes iroN, sitA, iutA, traT, iss, and ompT; and belonged to phylogenetic group D. These data suggest that all chickens with peritonitis in a single flock on farms A and B were likely infected by the same E. coli strain. Escherichia coli isolates from the magnum and peritoneum had the same serogroup, virulence genotype, and phylogenetic group, which is consistent with an ascending infection from the oviduct to the peritoneal cavity.     

Behavioural responses to different floor space allowances in small groups of laying hens

Under Council Directive 1999/74/EC, minimum space allowances per laying hen range from 550 cm(2) in unfurnished cages to 1111 cm(2) in alternative housing, and to 40,000 cm(2) outdoors for free-range hens. In official reports on the welfare of laying hens, there is recognition that knowledge of their space requirements is inadequate. This experiment studied expression of behaviour, including spacing, in five groups of six and one group of five ISA Brown hens aged 21-33 weeks in an adjustable test pen providing 600, 2400, 4800, 7200, 9600, and 12,000 cm(2) floor area per hen. Each group was tested with every treatment. Home pens provided 2400 cm(2) per hen. The main aim was to identify a hypothetical point at which mutual repulsion equals mutual attraction (a 'broken stick' response). Sequencing of treatments was according to a Latin square design, daytime tests lasted 2 h and had no feeder or drinker present, and overnight tests were done with 2400, 7200 and 12,000 cm(2) per hen with a feeder and drinker present. Groups were video-recorded from above to allow repeated measurements of spacing and other behaviours. In daytime tests, the relationship between mean distance to nearest neighbour and floor space allowance was asymptotic, rather than a 'broken stick'. The steepest part of the response was between 600 and 4800 cm(2) per hen. Changes in other behaviours were greatest between 600 and 2400 cm(2), and there was no significant change above 7200 cm(2). Spacing behaviour responses at night were the same as by day. It is concluded that any space allowance of less than about 5000 cm(2) per hen imposes at least some constraint on free expression of behaviour, and that hens would benefit from any increase above the current minimum 1111 cm(2) usable area in alternative housing.     

Isolation and characterization of a 6/85-like Mycoplasma gallisepticum from commercial laying hens

Eighty-three-week-old table egg layers with swollen sinuses were presented with a history of increased mortality. Serology revealed positive titers to Mycoplasma gallisepticum (MG). The birds were part of a flock in which some birds had been vaccinated with 6/85 live MG vaccine at 18 wk of age. Tracheal cultures were obtained from both vaccinated and unvaccinated birds within the flock. The cultures were indistinguishable from 6/85 vaccine by both random amplified polymorphic DNA analysis and DNA sequence analysis. Challenge studies were performed to compare the field isolates with 6/85 vaccine and the R strain of MG. The field isolates produced a greater antibody response by serum plate agglutination than did the 6/85 vaccine. The isolates effectively colonized the trachea without increasing the tracheal mucosal thickness; however, they did not extensively colonize the air sacs or cause airsacculitis in the experimental birds.     

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

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

Fear of humans and its relationships with productivity in laying hens at commercial farms.

1. The relationship between the behavioural responses of laying hens to humans and productivity was determined at 16 commercial sheds from 14 farms. 2. A number of behaviour variables were moderately to highly correlated with production variables; for example, the proportion of birds that moved away from an approaching experimenter in an unfamiliar environment ('shute test') was negatively correlated with peak hen day production, (PKHDP). 3. Behavioural responses to humans accounted for between 23 and 63% of the variation in a number of production variables, including PKHDP and the duration of a high level of production. 4. Inclusion of farm factor variables increased the amount of variation accounted for by the behaviour variables. For example, adding the variable 'time/day spent in the shed by stockpeople' to the behaviour variables 'the proportion of birds that moved away from an approaching human' in the shute test and 'the number of times birds in cages adopted an erect posture' in response to an approaching human increased the variation accounted for in PKHDP from 53 to 61%. 5. The results suggest that fear of humans may be a factor that limits the productivity of commercial laying hens.     

Ultrastructural study of infectious bronchitis virus infection in infundibulum and magnum of commercial laying hens

The infundibulum and magnum of the oviduct were examined in hens in full lay which were infected with two Australian strains of infectious bronchitis virus (IBV). The ultramicroscopic changes in the infundibulum and magnum were compared with control hens which had eggs at different positions in the oviduct. The ciliated and granular cells of the surface epithelia and secretory epithelial cells of the tubular glands were the target cells of IBV. No pathological changes were recorded during 2-8 days post-infection (p.i.). Patchy loss of cilia occurred at 10-14 days p.i. Between 16 and 24 days p.i., there was no cilia loss and lymphoid nodules were observed in the muscularis layer of the infundibulum and magnum of some hens from both infected groups. Virus particles were detected mostly in the rough endoplasmic reticulum (RER) and Golgi complex between 10 and 12 days p.i. Cytopathology was noticed in various cell organelles between the 10th and 14th days p.i. There was an increase in RER deposits in infected cells, irrespective of egg position in the oviduct. The magnum was more affected than the infundibulum. Cellular changes were more severe in the infundibulum and magnum of T-infected hens as compared to N1/88-infected hens. Eggs with watery whites which were laid by infected hens could be attributed to cytopathological changes in the granular epithelial cells and tubular gland epithelial cells of the magnum resulting in reduced synthesis of albumen proteins. IBV can cause pathology in parts of the fully functional oviduct which may persist up to the 30th day p.i. However, both the challenge strains of IBV can cause a small number of hens to cease production. Loss of cilia in both the infundibulum and magnum pose a potential threat of secondary bacterial infection and also may affect fertility in breeder hens.     

"家禽肠道疾病及其预防措施"专栏(五) 产蛋母鸡的慢性肠炎

目前处理慢性肠炎的方法,是在不知病因的情况下通过增强母鸡的抵抗力和提高其康复率来控制疾病.这是荷兰两位家禽疾病研究人员的结论.