Effect of perch access on perching, health and production outcomes in commercial broiler breeder flocks.

There is a need for more knowledge about perch use in broiler breeders and the potential effects of perches on health and production outcomes. The aim of this study was to investigate the use of perches by commercial broiler breeders, effect of perch access on keel bone fractures (KBF), footpad dermatitis (FPD) and number of floor eggs. Two commercial breeder flocks (Ross 308) reared at the same facility were observed during the production period. Half of each flock was provided with 15 cm perch/bird and the other half had no perches. The perch group had two types of perches; a steel plate mounted on the hen feeder lines "feeder perch" (15 cm high) and elevated plastic perches (5 cm high). Perching by hens and roosters was recorded during the dark period by counting birds on each of the two perch types in 10 sections and in the corresponding patches on the control side at 25, 35, and 45 wk of age (WOA). FPD was scored in 100 random hens in each group at 30 WOA and end of lay, KBF was scored by postmortem in 100 random hens in each group at end of lay, and number of floor eggs (n) in each treatment was scored daily. More hens perched on the feeder perch with the steel plate mounted, compared to the feeder line without the steel plate, but this difference decreased with age (P < 0.0001). Within the perch treatment, more hens perched on the feeder lines compared to the plastic perches at all ages (P < 0.0001). When combining number of hens on the plastic and feeder perches, on average 6.7 birds perched per meter perch, which is full capacity given an average shoulder width of 15 cm/bird. Perch use among the roosters was low overall, but more roosters perched in the perch group compared to the control group at 35 WOA (P = 0.007). Between 47 and 53% of the hens had KBF at the end of the lay. At 30 WOA, birds housed with perches were more likely to have lower FPD. Perch treatment did not affect number of floor eggs. In conclusion, broiler breeder hens perch when the perches are sufficiently high and allow all birds to perch simultaneously, and access to perches may have positive effects on FPD.

Parallel Sequencing Reveals Campylobacter spp. in Commercial Meat Chickens Less than 8 Days Old.

Campylobacter from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent in outcome. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, where Campylobacter is generally not detectable until birds are at least 21 days old. Using parallel sequence-based bacterial 16S profiling analysis and targeted sequencing of the porA gene, Campylobacter was identified at very low levels in all commercial flocks at less than 8 days old that were tested from the United Kingdom, Switzerland, and France. These young chicks exhibited a much greater diversity of porA types than older birds testing positive for Campylobacter by culture or quantitative PCR (qPCR). This suggests that as the bacteria multiply sufficiently to be detected by culture methods, one or two variants, as indicated by porA type, dominate the infection. The findings that (i) most young chicks carry some Campylobacter and (ii) not all flocks become Campylobacter positive by culture suggest that efforts to control infection, and therefore avoid contamination of poultry meat, should concentrate on how to limit Campylobacter to low levels by the prevention of the overgrowth of single strains. IMPORTANCE Our results demonstrate the presence of Campylobacter DNA among fecal samples from a range of commercially reared meat chicks that are less than 8 days of age, consistent across 3 European countries. The recently developed, sensitive detection method indicates that infection occurs on commercial farms much earlier and more widely than previously thought, which opens up new opportunities to control Campylobacter contamination at the start of the food chain and reduce the unacceptably high levels of human disease.

The influence of human interaction on guinea pigs: Behavioral and thermographic changes during animal-assisted therapy.

Guinea pigs are often involved in animal-assisted therapy (AAT) but there is little knowledge about the effects of human contact on guinea pigs involved in AAT. The aim of this study was to investigate effects of availability of a retreat, presence of conspecifics, prior experience with AAT, and human interaction on indicators of welfare in guinea pigs involved in AAT. Guinea pigs of both sexes and different ages (n=20) were assigned to a randomized, controlled within-subject trial with repeated measurements. Each guinea pig was tested in four settings: (I) therapy with retreat possibility with conspecifics, (II) therapy with retreat possibility without conspecifics, (III) therapy without retreat possibility, and (IV) setting without human interaction. We measured changes in eye temperature, as a proxy to infer stress levels, at 5-s intervals with a thermographic camera. All sessions were video recorded and the guinea pigs' behavior was coded using continuous recording and focal animal sampling. For the statistical analysis we used generalized linear mixed models, with therapy setting as a fixed effect and individual guinea pig as a random effect. We observed a temperature increase relative to baseline in settings (I) therapy with retreat with conspecifics present and (III) therapy without retreat. The percentage of time a guinea pig was petted was positively correlated with a rise in the eye temperature independent of the setting. Time spent eating was reduced in all therapy settings (I-III) compared to the setting without HAI (human animal interaction) (IV). In the setting with retreat (I), guinea pigs showed more active behaviors such as locomotive behavior or startling compared to the setting without retreat (III) and the setting without HAI (IV). When no retreat was available (III), they showed more passive behaviors, such as standing still or freezing compared to therapy with retreat (I). Based on our results we identified the behaviors "reduced eating", "increased startle" and "increased freezing" as indicators of an increased stress level. Petting the guinea pigs was correlated with a rise in the eye temperature and might be a factor which can cause stress. Our results support the suggestion that guinea pigs involved in AAT should have a retreat possibility, should have access to conspecifics, and should be given time to adapt to a new setting. In this way, stress might be reduced.

Frequent range visits further from the shed relate positively to free-range broiler chicken welfare.

Little is known about the implications of accessing an outdoor range for broiler chicken welfare, particularly in relation to the distance ranged from the shed. Therefore, we monitored individual ranging behaviour of commercial free-range broiler chickens and identified relationships with welfare indicators. The individual ranging behaviour of 305 mixed-sex Ross 308 broiler chickens was tracked on a commercial farm from the second day of range access to slaughter age (from 16 to 42 days of age) by radio frequency identification (RFID) technology. The radio frequency identification antennas were placed at pop-holes and on the range at 2.7 and 11.2 m from the home shed to determine the total number of range visits and the distance ranged from the shed. Chickens were categorised into close-ranging (CR) or distant-ranging (DR) categories based on the frequency of visits less than or greater than 2.7 m from the home shed, respectively. Half of the tracked chickens (n=153) were weighed at 7 days of age, and from 14 days of age their body weight, foot pad dermatitis (FPD), hock burn (HB) and gait scores were assessed weekly. The remaining tracked chickens (n=152) were assessed for fear and stress responses before (12 days of age) and after range access was provided (45 days of age) by quantifying their plasma corticosterone response to capture and 12 min confinement in a transport crate followed by behavioural fear responses to a tonic immobility (TI) test. Distant-ranging chickens could be predicted based on lighter BW at 7 and 14 days of age (P=0.05), that is before range access was first provided. After range access was provided, DR chickens weighed less every week (P=0.001), had better gait scores (P=0.01) and reduced corticosterone response to handling and confinement (P<0.05) compared to CR chickens. Longer and more frequent range visits were correlated with the number of visits further from the shed (P<0.01); hence distant ranging was correlated with the amount of range access, and consequently the relationships between ranging frequency, duration and distance were strong. These relationships indicate that longer, more frequent and greater ranging from the home shed was associated with improved welfare. Further research is required to identify whether these relationships between ranging behaviour and welfare are causal.

Relationship between welfare and individual ranging behaviour in commercial free-range laying hens.

Laying hens housed in free-range systems have access to an outdoor range, and individual hens within a flock differ in their ranging behaviour. Whether there is a link between ranging and laying hen welfare remains unclear. We analysed the relationships between ranging by individual hens on a commercial free-range layer farm and behavioural, physiological and health measures of animal welfare. We hypothesised that hens that access the range more will be (1) less fearful in general and in response to novelty and humans, (2) have better health in terms of physical body condition and (3) have a reduced physiological stress response to behavioural tests of fear and health assessments than hens that use the range less. Using radio frequency identification tracking across two flocks, we recorded individual hens' frequency, duration and consistency of ranging. We also assessed how far hens ventured into the range based on three zones: 0 to 2.4, 2.4 to 11.4 or >11.4 m from the shed. We assessed hen welfare using a variety of measures including: tonic immobility, open field, novel object, human approach, and human avoidance (HAV) behavioural tests; stress-induced plasma corticosterone response and faecal glucocorticoid metabolites; live weight, comb colour, and beak, plumage, footpad, and keel bone condition. Range use was positively correlated with plasma corticosterone response, faecal glucocorticoid metabolites, and greater flight distance during HAV. Hens that used the range more, moved towards rather than away from the novel object more often than hens that ranged less. Distance ranged from the shed was significantly associated with comb colour and beak condition, in that hens with darker combs and more intact beaks ranged further. Overall the findings suggest that there is no strong link between outdoor range usage and laying hen welfare. Alternatively, it may be that hens that differed in their ranging behaviour showed few differences in measures of welfare because free-range systems provide hens with adequate choice to cope with their environment. Further research into the relationship between individual range access and welfare is needed to test this possibility.

Perch use by broiler breeders and its implication on health and production.

Broiler breeders are commonly kept without perches, although perching has been shown to be a high-priority behavior in laying hens. We studied whether broiler breeders used elevated perches of different lengths during the night and how access to perches affected health and production. Using the Ross 308 hybrid, pens offering 4 different perch spaces per bird (5, 10, 14, and 20 cm) in a cross-over design were compared with pens without perches. The number of birds on perches at midnight were recorded 7 times during production. Prevalence of keel bone fractures, breast blisters, pododermatitis, and plumage quality of hens was assessed at 45 wk, and production was monitored daily. To determine subsequent effects on offspring, chicks from hens with and without perches were reared and their growth rate was assessed. Analysis found more broiler breeders perched at night when 14 cm perch length per bird was provided than with less available perch length (P = 0.0005), but there was no difference between 14 and 20 cm per bird. Perch use declined with age from about 50 to 20% (P < 0.0001). The number of eggs and hatchability were not affected by treatment. During a period of high temperatures, mortality was lower in pens with perches (P = 0.001). Keel bone fractures were present in 1/4 of hens and were not affected by the presence of perches. The growth of chicks was not affected by the parent treatment. In conclusion, our results suggest that perches were chosen for roosting by broiler breeders depending on their age and did not impair production.

Genetic selection to increase bone strength affects prevalence of keel bone damage and egg parameters in commercially housed laying hens.

The prevalence of keel bone damage as well as external egg parameters of 2 pure lines divergently selected for high (H) and low (L) bone strength were investigated in 2 aviary systems under commercial conditions. A standard LSL hybrid was used as a reference group. Birds were kept mixed per genetic line (77 hens of the H and L line and 201 or 206 hens of the LSL line, respectively, per pen) in 8 pens of 2 aviary systems differing in design. Keel bone status and body mass of 20 focal hens per line and pen were assessed at 17, 18, 23, 30, 36, 43, 52, and 63 wk of age. External egg parameters (i.e., egg mass, eggshell breaking strength, thickness, and mass) were measured using 10 eggs per line at both 38 and 57 wk of age. Body parameters (i.e. tarsus and third primary wing feather length to calculate index of wing loading) were recorded at 38 wk of age and mortality per genetic line throughout the laying cycle. Bone mineral density (BMD) of 15 keel bones per genetic line was measured after slaughter to confirm assignment of the experimental lines. We found a greater BMD in the H compared with the L and LSL lines. Fewer keel bone fractures and deviations, a poorer external egg quality, as well as a lower index of wing loading were found in the H compared with the L line. Mortality was lower and production parameters (e.g., laying performance) were higher in the LSL line compared with the 2 experimental lines. Aviary design affected prevalence of keel bone damage, body mass, and mortality. We conclude that selection of specific bone traits associated with bone strength as well as the related differences in body morphology (i.e., lower index of wing loading) have potential to reduce keel bone damage in commercial settings. Also, the housing environment (i.e., aviary design) may have additive effects.

H/L ratio as a measurement of stress in laying hens - methodology and reliability.

Measuring the ratio of heterophils and lymphocytes (H/L) in response to different stressors is a standard tool for assessing long-term stress in laying hens but detailed information on the reliability of measurements, measurement techniques and methods, and absolute cell counts is often lacking. Laying hens offered different sites of the nest boxes at different ages were compared in a two-treatment crossover experiment to provide detailed information on the procedure for measuring and the difficulties in the interpretation of H/L ratios in commercial conditions. H/L ratios were pen-specific and depended on the age and aviary system. There was no effect for the position of the nest. Heterophiles and lymphocytes were not correlated within individuals. Absolute cell counts differed in the number of heterophiles and lymphocytes and H/L ratios, whereas absolute leucocyte counts between individuals were similar. The reliability of the method using relative cell counts was good, yielding a correlation coefficient between double counts of r > 0.9. It was concluded that population-based reference values may not be sensitive enough to detect individual stress reactions and that the H/L ratio as an indicator of stress under commercial conditions may not be useful because of confounding factors and that other, non-invasive, measurements should be adopted.

Nest use is influenced by the positions of nests and drinkers in aviaries.

The influence of the nest location and the placement of nipple drinkers on nest use by laying hens in a commercial aviary was assessed. Twenty pens in a laying hen house were equipped with the same commercial aviary system, but the pens differed in the nest location and the placement of nipple drinkers. Nests were placed along the walls in 10 pens, and nipple drinkers were installed in front of the nests in 5 of these pens. The other 10 pens were equipped with nests placed on a tier within the aviary (integrated nests). Nipple drinkers were installed in front of the nests in 5 of these pens. A total of 225 Lohmann Selected Leghorns were housed per pen. The hens were offered 4 nests per pen: 2 facing the service corridor of the laying hen house and 2 facing the outdoor area. The numbers of nest eggs and mislaid eggs were counted daily per pen. At 25, 36, and 43 wk of age, the nest platforms were videotaped and the behavior of laying hens in front of the nests was analyzed. The nest location affected the stationary and locomotive behaviors in front of the nests. Hens in front of the integrated nests and the nests with drinkers displayed more stationary behaviors than hens in front of wall-placed nests or nests without drinkers. No difference in the number of nest eggs could be detected, but the integration of the nests inside the aviary led to a more even distribution of hens while nest searching. In the pens with wall-placed nests, significantly more hens laid eggs in the nests at the wall near the service corridor than at the wall near the outdoor area. Due to this imbalance, crowding in front of the preferred nests occurred and pushing and agonistic interactions on the nest platforms were significantly more frequent. Placement of nipple drinkers in front of nests had no effect on the number of eggs laid in those nests.

Prevalence of keel bone deformities in Swiss laying hens.

The goal of this study was to evaluate the prevalence of keel bone deformities of laying hens in Switzerland. The keel bones of 100 end-of-lay hens from each of 39 flocks (3900 in total) were palpated. On average, 25·4% of the hens had moderately or severely deformed keel bones and the overall prevalence including slight deformities was 55%. 3. Variation between flocks was considerable. Thus, the prevalence of moderately or severely deformed keel bones ranged from 6 to 48%, and the overall prevalence including slight deformities ranged from 20 to 83%. Aviary housing was associated with a higher prevalence of total, and severe or moderate deformations, compared with floor pens. There were no significant differences in the number of deformities between the different plumage colours, hybrids or perch materials.

Effects of housing, perches, genetics, and 25-hydroxycholecalciferol on keel bone deformities in laying hens.

Several studies have shown a high prevalence of keel bone deformities in commercial laying hens. The aim of this project was to assess the effects of perch material, a vitamin D feed additive (25-hydroxyvitamin D(3); HyD, DSM Nutritional Products, Basel, Switzerland), and genetics on keel bone pathology. The study consisted of 2 experiments. In the first experiment, 4,000 Lohmann Selected Leghorn hens were raised in aviary systems until 18 wk of age. Two factors were investigated: perch material (plastic or rubber-coated metal) and feed (with and without HyD). Afterward, the hens were moved to a layer house with 8 pens with 2 aviary systems. Daily feed consumption, egg production, mortality, and feather condition were evaluated. Every 6 wk, the keel bones of 10 randomly selected birds per pen were palpated and scored. In the second experiment, 2,000 Lohmann Brown (LB) hens and 2,000 Lohmann Brown parent stock (LBPS) hens were raised in a manner identical to the first experiment. During the laying period, the hens were kept in 24 identical floor pens but equipped with different perch material (plastic or rubber-coated metal). The same variables were investigated as in the first experiment. No keel bone deformities were found during the rearing period in either experiment. During the laying period, deformities gradually appeared and reached a prevalence of 35% in the first experiment and 43.8% in the second experiment at the age of 65 and 62 wk, respectively. In the first experiment, neither HyD nor the aviary system had any significant effect on the prevalence of keel bone deformities. In the second experiment, LBPS had significantly fewer moderate and severe deformities than LB, and rubber-coated metal perches were associated with a higher prevalence of keel bone deformities compared with plastic perches. The LBPS laid more but smaller eggs than the LB. Again, HyD did not affect the prevalence of keel bone deformities. However, the significant effect of breed affiliation strongly indicates a sizeable genetic component that may provide a basis for targeted selection.

Hereditary hydrocephalus internus in a laboratory strain of golden hamsters ( Mesocricetus auratus).

Golden hamsters of one common laboratory strain had a high incidence of hydrocephalus internus. When a severity score of hydrocephalus was used, a major autosomal recessive locus could be identified. However, when a binary score (hydrocephalus, no hydrocephalus) was used, no such major locus could be detected and results of test matings were not consistent with Mendelian inheritance. Golden hamsters with severe forms of hydrocephalus had a dorsally compressed and ventrally intact hippocampus. Implications for the behavior and well-being of affected hamsters are unknown but researchers using this strain should be aware of the likely presence of hydrocephalus.

Effects of feed restriction on growth and reproduction in randombred and selected lines of Japanese quail.

Feed restriction (70% of ad libitum consumption) was carried out from 1 d after hatching until 44 d in a randombred quail line and until 28 d in a quail line selected for high 4-wk BW. Body weights of restricted quail were significantly lower than ad libitum controls during restriction. Two weeks after restriction ended, however, BW were no longer different. Mortalities were twice as high under restriction. Hatchability of eggs was not affected by restriction, but restricted quail of the selected line laid fewer double-yolk eggs than ad libitum controls.

Heritabilities of growth curve parameters and age-specific expression of genetic variation under two different feeding regimes in Japanese quail (Coturnix coturnix japonica).

This study investigated genetic variation in growth and final size in relationship to differences in heritabilities under good and poor feeding conditions. Heritabilities of growth and final size were estimated for several traits under ad libitum and restricted feeding conditions. A 30% feed restriction from hatching to 44 days of age in Japanese quail chicks decreased body weight and tarsus length at 44 days of age and the length of the third primary convert feather at 24 days of age relative to controls fed ad libitum. Wing length at 44 days of age was not significantly different for ad libitum fed and restricted quail. Genetic variances for body weight and tarsus length were very large throughout growth which resulted in heritability estimates close to one for these traits. The genetic correlations among feeding treatments were low, indicating that different genes were affecting growth under the two treatments. Growth was described by the components: asymptote, growth period, and shape of the growth curve following the modified Richards growth curve model (Brisbin et al. 1986). Tarsus length, which had high heritability of the parameter 'growth period' of the model, tended to display a higher heritability under the restriction than under ad libitum feeding. Body weight and feather length, which had either no heritable or low heritable 'growth periods' estimates, tended to be more heritable under ad libitum feeding. The shape parameter of the growth curve was not heritable for any trait, except tarsus length under restricted feeding.

Heritability of growth curve parameters and heritability of final size: a simulation study.

Simulations of nestling growth in Great Tits (Parus major) were used to show the consequences genetic variation in the parameters of growth curves could have on the amount of genetic variation in final body weight. This was done for the case of good environmental conditions (i.e. adequate food supply), and for poor environmental conditions (food limitation). A three-parameter process-error growth model based on the Richards curve (Brisbin et al., 1986) was used. The three parameters were the asymptote, the shape, and the time to complete approximately 95% of growth. In simulations, where only the asymptotic value was heritable, genetic variation in final weight was larger under good conditions than under poor conditions. Food limitations decreased the amount of genetic variation and the heritability estimate of final size. Similarly, sib competition, (based on body size differences of nestlings within broods) combined with food limitations lowered heritabilities. Sib competition under good conditions had no effect on heritabilities. In contrast, when the time to complete approximately 95% of growth was heritable, heritabilities for final size were not lower under poor conditions either without or in the presence of sib competition. This model suggests that different amounts of genetic variation in final size under good and poor conditions could be linked to the amount of genetic variation present in the growth curve parameters. The results agreed with an empirical study on body weight in a passerine bird, the Great Tit, where only the asymptote displayed heritable variation and more genetic variance was expressed under good conditions.