Feather Cover Research Articles

Welfare indicators in laying hens in relation to nest exclusion

Consumer concerns about the welfare of laying hens are increasing, leading to increased interest in identifying reliable ways to assess welfare. The present study evaluated invasive and non-invasive welfare indicators in relation to a stressful challenge. The study included 126 Lohmann Selected Leghorn hens housed in furnished cages. Welfare indicators were measured between 61 and 70 wk of age in birds excluded from their nests for 5 consecutive d and control birds that had continuous access to nests. Baseline recordings were carried out in both groups prior to and post exclusion period. The assessed indicators were: corticosterone metabolites in droppings (FCM), corticosterone concentration in yolk, corticosterone concentration in plasma, irregularities of eggshells, heterophil to lymphocyte (H:L) ratio, tonic immobility duration, and feather cover. Behavioral observations showed that the birds had a clear preference for using the secluded nest sites, confirming that they were likely to perceive nest exclusion as an undesirable experience. Further, elevated levels of FCM in droppings, yolk corticosterone concentrations, H:L ratios and irregular eggshells were detected in both nest deprived and control birds during the exclusion. This suggests that these indicators were able to detect an increased stress response arising from nest deprivation, and it is hypothesized that the stress spread to birds in adjacent cages with access to nests. There was a positive and consistent correlation between FCM in droppings and eggshell irregularities, also supporting the use of eggshell irregularities as a potential non-invasive welfare indicator. However, the pattern of the stress response varied between indicators and correlations were generally few and inconsistent, highlighting the complexity of the relationship among welfare indicators.

The effect of northern fowl mite (Ornithonyssus sylviarum) infestation on hen physiology, physical condition, and egg quality

The northern fowl mite (NFM), Ornithonyssus sylviarum, is the most common ectoparasite of laying hens in North America. Infestation can cause a reduction in egg production, egg weights, and feed conversion efficiency. However, there is a lack of information on the effects of NFM on hen physiology, physical condition, and egg quality. Singly caged beak-trimmed White Leghorn hens (N = 32) were infested with mites at 25 wk of age. The condition of each hen was assessed at wk 0 (infestation) and wk 5 and 7 post-infestation to determine comb temperatures and feather, skin, and comb condition. Heterophil-lymphocyte (H/L) ratios and body weight (BW) were evaluated at wk 0 and wk 1, 3, 5, and 7 post-infestation. Egg weight, egg specific gravity, yolk color, Haugh unit (HU), and eggshell thickness were determined prior to infestation (wk −1) and at 1, 3, 5, and 7 wk post-infestation. The H/L ratio (P < 0.0001), HU (P < 0.0001), and egg specific gravity (P = 0.001) were lowest, and the egg yolk color was lightest (P = 0.087) at wk 5, the peak of infestation. At wk 5 and 7, more than 65% of the hens had red skin and more than 75% had scabs on the vent; in addition more than 84% had grey-black vent feathers. There were no effects of infestation on comb color, comb temperature, feather cover, BW, or eggshell thickness. It was concluded that infestation with NFM has negative effects on interior egg quality and hen integument. A decrease in H/L ratio was also observed at the peak of infestation. However, the effects of NFM on the immune system are unclear, and H/L ratio might not be a good stress measure in hens highly infested with NFM.

Animal welfare initiatives improve feather cover of cage-free laying hens in the UK

AbstractThis paper describes a case example where initiatives from private assurance schemes, scientists, charities, government and egg companies have improved the welfare of UK cage-free laying hens. The RSPCA and Soil Association farm assurance schemes introduced formal welfare outcome assessment into their annual audits of laying-hen farms in 2011. Feather loss was assessed on 50 birds from each flock on a three-point scale for two body regions: Head and Neck (HN) and Back and Vent (BV). In support of the observations, assessors were trained in feedback techniques designed to encourage change in farmer behaviour to improve welfare. In addition, during Year 2 farmers were asked about changes they had made, and intended to make on their farms. During 2011-2013 there were also wider industry initiatives to improve feather cover. Data were analysed from 830 and 743 farms in Year 1 and Year 2, respectively. From Year 1 to Year 2 there was a significant reduction in the prevalence of feather loss from 31.8% (9.6% severe) to 20.8% (6% severe) for the HN region, and from 33.1% (12.6% severe) to 22.7% (8.3% severe) for BV. Fifty-nine percent of 662 farmers reported they had made changes on their farms during Year 1 to improve bird welfare. For such a substantial industry change, attributing causation to specific initiatives is difficult; however, this is the first study to demonstrate the value to animal welfare of certification schemes monitoring the effectiveness of their own and other industry-led interventions to guide future policy.

Physical Health Problems and Environmental Challenges Influence Balancing Behaviour in Laying Hens.

With rising public concern for animal welfare, many major food chains and restaurants are changing their policies, strictly buying their eggs from non-cage producers. However, with the additional space in these cage-free systems to perform natural behaviours and movements comes the risk of injury. We evaluated the ability to maintain balance in adult laying hens with health problems (footpad dermatitis, keel damage, poor wing feather cover; n = 15) using a series of environmental challenges and compared such abilities with those of healthy birds (n = 5). Environmental challenges consisted of visual and spatial constraints, created using a head mask, perch obstacles, and static and swaying perch states. We hypothesized that perch movement, environmental challenges, and diminished physical health would negatively impact perching performance demonstrated as balance (as measured by time spent on perch and by number of falls of the perch) and would require more exaggerated correctional movements. We measured perching stability whereby each bird underwent eight 30-second trials on a static and swaying perch: with and without disrupted vision (head mask), with and without space limitations (obstacles) and combinations thereof. Video recordings (600 Hz) and a three-axis accelerometer/gyroscope (100 Hz) were used to measure the number of jumps/falls, latencies to leave the perch, as well as magnitude and direction of both linear and rotational balance-correcting movements. Laying hens with and without physical health problems, in both challenged and unchallenged environments, managed to perch and remain off the ground. We attribute this capacity to our training of the birds. Environmental challenges and physical state had an effect on the use of accelerations and rotations to stabilize themselves on a perch. Birds with physical health problems performed a higher frequency of rotational corrections to keep the body centered over the perch, whereas, for both health categories, environmental challenges required more intense and variable movement corrections. Collectively, these results provide novel empirical support for the effectiveness of training, and highlight that overcrowding, visual constraints, and poor physical health all reduce perching performance.

Modelling moss-derived carbon in upland black spruce forests

Mosses play a key role in the carbon (C) cycle of upland black spruce (Picea mariana (Mill.) BSP) forests; however, national reporting models such as the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) do not include mosses. This study examined whether widely available plot-level merchantable tree volume could predict, for black spruce ecosystems in Canada’s boreal forest, the relative proportions of sphagnum and feather moss ground cover and moss net primary productivity (NPP). A field study found that merchantable tree volume was significantly related to tree canopy openness (R2 = 0.61, P &lt; 0.001), which could then be used to model the relative ground cover of feather moss (R2 = 0.5, P &lt; 0.001) and sphagnum (R2 = 0.45, P &lt; 0.001) and NPP of feather moss (R2 = 0.41, P &lt; 0.001) and sphagnum (R2 = 0.28, P &lt; 0.001). The resulting MOSS-C submodel increased the accuracy of the CBM-CFS3’s prediction of organic-horizon C five-fold and could explain large-scale variation in sites dominated by sphagnum with large organic-layer C pools but not fine-scale variation in dryer sites. To improve MOSS-C accuracy, future studies should focus on varying decomposition and fire regime parameters based on regional climate or plot-level vegetation parameters.

Incidence, Severity, and Welfare Implications of Lesions Observed Postmortem in Laying Hens from Commercial Noncage Farms in California and Iowa.

The egg industry is moving away from the use of conventional cages to enriched cage and noncage laying hen housing systems because of animal welfare concerns. In this study, the prevalence and severity of lesions in noncage laying hens from commercial farms in two of the largest egg-producing states, California and Iowa, were evaluated by postmortem examination. Hens that died or were culled were collected during early, mid, and late stages of the laying cycle from 16 houses on three farms. Of the 25 gross lesions identified for study, 22 were observed, with an average of four lesions per hen. Vent cannibalism, reduced feather cover, keel bone deformation, and beak abnormalities were the most frequent lesions, observed in ≥40% of hens. Other common lesions were cloacal prolapse (30.5%), footpad dermatitis (24.3%), and septicemia (23.1%). Beak abnormality and enteric disease had the highest proportion of severe lesions. Pearson chi-square analysis revealed a number of stage-of-lay effects (P ≤ 0.05), some of which differed by state. For both states combined, the lesions observed more frequently during early lay were beak abnormalities, northern fowl mite infestation, and cage layer fatigue, whereas during mid lay, they were poor feather cover, vent cannibalism, footpad dermatitis, keel bone deformation, respiratory disease and roundworms. Feather pecking and cloacal prolapse were most common during late lay. Although differences in hen genetics, farm management practices, and environmental factors could all have affected the results of this study, the information provides a better understanding of hen health in noncage housing systems and could help to identify potential interventions to reduce hen welfare problems.

Can Non-Beak Treated Hens be Kept in Commercial Furnished Cages? Exploring the Effects of Strain and Extra Environmental Enrichment on Behaviour, Feather Cover, and Mortality

Commercial laying hens are prone to injurious pecking (IP), a common multifactorial problem. A 2 × 2 × 2 factorial design assessed the effects of breed (Lohmann Brown Classic (L) or Hyline Brown (H)), beak treatment (infra-red treated (T) or not (NT)), and environment (extra enrichment (EE) or no extra enrichment (NE)) on mortality, behaviour, feather cover, and beak shape. Hens were allocated to treatments at 16 weeks of age and data were collected every four weeks from age 19 to 71 weeks. Data were analysed in Genstat using mixed models. L hens had higher all and IP-related mortality than H hens (p < 0.003), whilst NT hens had higher mortality than T hens but only due to culling of whole cages (p < 0.001). Feather cover for L hens deteriorated more quickly with age at most body sites than H hens (age × breed × body site p < 0.001). For NT hens, feather cover was worse at most body sites (beak treatment × body site p < 0.001), and worsened more quickly with age (age × beak treatment p = 0.014) than T hens. L and NE hens performed more bird-to-bird pecking than H and EE hens, respectively (breed p = 0.015, enrichment p = 0.032). More damage to mats and ropes was caused by L and NT hens than by H and T hens, respectively (age × breed p < 0.005, beak treatment p < 0.001). Though H hens had fewer mortalities and better feather cover, breed effects may have been influenced by farm management practices, as they may have been better suited to H than L hens. Though EE hens performed less bird-to-bird pecking, the enrichments were less effective at reducing feather cover damage and mortality than expected.

The utilization of the Welfare Quality® assessment for determining laying hen condition across three housing systems

The Welfare Quality® Assessment protocol for poultry (WQA) provides animal-based measures allowing welfare comparisons across farms and housing systems. It was used to compare Lohmann LSL Classic White hens housed in an enriched colony (EC), aviary (AV), and conventional cage system (CC) on a commercial farm over 2 flock cycles. Hens (n = 100/system) were scored on a variety of measures. A baseline measurement was made at placement at 19 wk of age for 1 flock, since AV hens had been reared in an aviary pullet facility (AVP) while EC and CC hens were reared in a conventional pullet facility (CCP). Hens in all systems were then assessed at 52 and 72 wk of age. Necropsies were performed on all mortalities 1 wk before and after the WQA sampling. WQAs were analyzed using Mann–Whitney U and Kruskal–Wallis tests for prevalence and Fisher's exact tests for severity. There was an effect of rearing, with AVP having shorter claws (P = 0.01), dirtier feathers (P = 0.03), and more keel abnormalities (P < 0.0001) than CCP at placement. For the hens, there were several significant housing system effects across flocks and age periods (all P ≤ 0.05). AV and EC hens had more keel abnormalities than CC hens. They also had fewer foot abnormalities than CC hens, although those in AV hens were more severe. AV hens had consistently dirtier feathers than EC and CC hens. While AV hens had the best overall feather cover, feather loss patterns suggested that loss was due to head pecking for AV, whereas in EC and CC it was due to cage abrasion. The necropsy findings and the WQA results were similar, except that the WQA failed to find enteritis at 19 wk, although it was detected in the necropsies during this sampling period. These results show that the WQA is a useful tool for detecting hen condition differences across housing systems.

Effect of different litter materials on foot pad dermatitis, hock burn and feather coverage in broiler chickens

An experiment was conducted to evaluate the feather coverage on breast and thighs in meat type chickens, reared on three different types of litter materials, including wood shavings, shredded paper and chopped wheat straw. The experiment lasted for 72 days. A total of 447 one-day-old meat type chickens were randomly allotted to the three litter materials, giving 149 birds per litter. On days 24, 47 and 72 of the experimental period, feathering on the breast and thighs was scored according to a 1–4 scale. In addition, the severity of foot pad dermatitis (FPD) and hock burn (HB) was evaluated at the same days by attributing scores from 1−3. Litter characteristics (moisture content, water absorbing capacity, bulk density, pH) were determined at the end of the experiment. Severity of FPD varied significantly (P &lt; 0.016) among the litter materials with chopped straw showing the highest severity scores and wood shavings showing the lowest. Litter material had no effect (P &gt; 0.016) on the severity of HB and on thigh feathering. Birds reared on chopped wheat straw presented the lowest breast feather coverage. Straw litter had the highest moisture content and pH value. In conclusion, wood shavings proved to be best litter material for meat type chickens rearing among the three tested litter materials.

Hydrogeological controls on post-fire moss recovery in peatlands

Summary Wildfire is the largest disturbance affecting boreal peatlands, however, little is known about the controls on post-fire peatland vegetation recovery. While small-scale variation in burn severity can reduce post-fire moss water availability, high water table (WT) positions following wildfire are also critical to enable the re-establishment of keystone peatland mosses ( i.e. Sphagnum ). Thus, post-fire moss water availability is also likely a function of landscape-scale controls on peatland WT dynamics, specifically, connectivity to groundwater flow systems ( i.e. hydrogeological setting). For this reason, we assessed the interacting controls of hydrogeological setting and burn severity on post-fire moss water availability in three burned, Sphagnum -dominated peatlands in Alberta’s Boreal Plains. At all sites, variation in burn severity resulted in a dichotomy between post-fire surface covers that: (1) exhibited low water availability, regardless of WT position, and had minimal ( i.e. lightly burned feather mosses and severely burned Sphagnum fuscum ) or (2) exhibited high water availability, depending on WT position, and had substantial (>50%) moss re-establishment ( i.e. lightly burned S. fuscum and where depth of burn was >0.05 m). Notably, hydrogeological setting influenced the spatial coverage of these post-fire surface covers by influencing pre-fire WTs and stand characteristics ( e.g. , shading). Because feather moss cover is controlled by tree shading, lightly burned feather mosses were ubiquitous (>25%) in drier peatlands (deeper pre-fire WTs) that were densely treed and had little connection to large groundwater flow systems. Moreover, hydrogeological setting also controlled post-fire WT positions, thereby affecting moss re-establishment in post-fire surface covers that were dependent on WT position ( e.g. , lightly burned S. fuscum ). Accordingly, higher recolonization rates were observed in a peatland located in a groundwater flow through system that had a shallow post-fire WT. Therefore, we argue that hydrogeological setting influences post-fire recovery in two ways: (1) by influencing vegetation structure prior to wildfire, thereby controlling the coverage of post-fire surface covers and (2) by influencing post-fire WT positions. These results suggest that post-fire moss recovery in peatlands isolated from groundwater flow systems may be particularly susceptible to droughts and future climate change.

Growth Processes in the Postembryonic Development in Altricial Birds on the Example of Song Thrush, Turdus Philomelos (Passeriformers, Turdidae): A Multivariate Approach

The paper explores the possibility of implementing the methods of multivariate statistics into studying the growth processes on the example of song thrushes, Turdus philomelos, Brehm, 1831, during their postnatal development as nestlings. The developmental trends in 12 morphometric traits in T. philomelos in the course of postembryogenesis is shown to be explained for 99.3 % by the first two principal components (PC). The major developmental trend (PC1 - 95.1 %) is defined by a highly correlative though irregular growth of linear forms of nestlings’ body parts, the two other trends relate to the body proportion formation (PC2 - 4.2 %). Th ere have been discovered the two growth stages: (1) of fast growth: from birth up to the 8th day with relative increment in growth of traits equal in average to 91.9 %, and (2) of slow growth: from the 8th to the 14th day, characterized by a reduction of an average growth increment being five times lower, and by intense feather cover development. There have been demonstrated that all the variables can be structured into the four groups or growth correlation pleiads (groups comprising similarly growing traits). The growth is shown to be most specific for the song thrush’s body, head and bill, being a part of a single pleiad. While still forming the three different growth pleiads the properties of the bird’s wing, leg, the 3rd and the 4th toes differ significantly less in respect to their growth characteristics.

Effect of dietary methionine content on growth performance, carcass traits, and feather growth of Pekin duck from 15 to 35 days of age

A study was conducted to establish the response of Pekin ducks to dietary Met from 15 to 35 d age. Experimental diets were formulated to contain 0.35, 0.45, 0.55, 0.65, and 0.75% Met (0.30, 0.39, 0.45, 0.56, and 0.68% on an analyzed basis, respectively) and 0.3% cysteine (0.25, 0.27, 0.26, 0.26, and 0.28% on an analyzed basis, respectively). Each diet was fed to 10 pens of 55 ducks/pen. Carcass yields and feather growth were determined at 28 and 35 d. Results showed that feeding 0.30% Met (0.55% Met+Cys) significantly impaired ADG, feed-to-gain (F:G) ratio, breast meat yield, and feather growth in comparison to the other dietary treatments (P < 0.05). BW, ADG, F:G, carcass and breast meat weight and yield, breast skin and subcutaneous fat weight and yield, the fourth primary wing feather length, and feather coverage showed significant quadratic broken-line or quadratic polynomial response to increasing dietary Met (P < 0.05). From 15 to 28 d age, the optimal Met requirement for the BW, breast meat yield, and the fourth primary wing feather length were 0.510, 0.445, and 0.404%, respectively, based on quadratic broken-line model, and correspondingly were 0.606, 0.576, and 0.559% by quadratic regression. For ducks from 15 to 35 d age, the optimal Met requirement for BW, breast meat yield, and feather coverage were 0.468, 0.408, and 0.484%, respectively, by quadratic broken-line model, and 0.605, 0.564, and 0.612%, by quadratic regression, respectively.

Sample Preparation Method for the Determination of Organochlorine Pesticides in Aquatic Organisms by Gas Chromatography

Sample preparation can be used in biology and ecology for gas chromatographic determination of organochlorine pesticides (OCP), namely, α-, β- and γ-isomers of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) in various aquatic organisms (molluscs, fish, birds and mammals) containing lipids (because organochlorine pesticides are lipophilic) in the internal organs and tissues, fat, skin and feather cover. The method is easy to implement and economically profitable; it can be used in laboratories without special extraction equipment, as well as in the field, with a minimum set of glassware and reagents. The result of this process is an increase of efficiency and precision of research through a more complete extraction of pesticides chemically bonded with lipids using n-hexane and a reduction of the number of steps needed for the extraction and purification of co-extrusive substances with concentrated sulphuric acid.

Effects of different dietary protein levels during rearing and different dietary energy levels during lay on behaviour and feather cover in broiler breeder females

An experiment was conducted to determine the effects of different dietary protein levels during rearing and different dietary energy levels during lay on behaviour and feather cover in broiler breeder females. A 2×3×2 factorial arrangement of treatments was used. A total of 2880 Ross 308 14-day-old broiler breeder pullets were fed between weeks 2 and 22, a high (CPh) or low (CPl) crude protein (CP) diet. Between weeks 22 and 45, the breeders were fed either a high, standard, or low energy diet (3000, MEh1; 2800, MEs1; 2600, MEl1, kcal/kg AMEn (apparent metabolisable energy, corrected for nitrogen), respectively). Between weeks 45 and 60, the breeders were fed a standard or high energy diet (2800, MEs2; 3000, MEh2, kcal/kg AMEn, respectively). During rearing, CPl pullets received 12.1% more feed, resulting in a 137% increased eating time and 47% decreased eating rate. This increased feeding, sitting, and comfort behaviour while standing, walking, foraging, stereotypic object pecking, and bird pecking were reduced. Feather cover was poorer when pullets were fed a low protein diet during rearing, but this effect was not present during lay. A 7.6% lower feed intake for the MEh1 birds resulted in a 21% decreased eating time and 19% increased eating rate compared with the MEs1 birds. Birds on the MEh1 diet spent less time feeding and more time sitting, comfort, and stereotypic object pecking behaviour compared with the MEs1 birds. Birds fed the MEh1 diet showed a poorer feather cover during the entire lay compared with the MEs1 birds. A 7.7% higher feed intake for the MEl1 birds resulted in a 31% increased eating time and 18% decreased eating rate compared with the MEs1 birds. MEl1 birds spent more time feeding and less time foraging, comfort, and stereotypic object pecking compared with the MEs1 birds. No effect on feather cover was found for the MEl1 compared with the MEs1 birds. The MEh2 birds received 8.8% less feed resulted in a 16% decreased eating time and 9% increased eating rate. The lower feed intake resulted in less time spent feeding and standing, and more time spent foraging and comfort behaviours. Feather cover was not affected by dietary energy level during the second phase of lay. In conclusion, feeding broiler breeders a higher amount of feed due to a higher energy-to-protein ratio resulted in an increased eating time and less stereotypic object pecking behaviour what is an indication of reduced hunger and frustration. This was much more expressed during rearing than lay. However, a low daily protein intake during rearing and first phase of lay can lead to a poorer feather cover.

Welfare and performance in layers following temporary exclusion from the litter area on introduction to the layer facility

When introduced to the laying facility, pullets are sometimes temporarily excluded from the litter area in order to help them locate food and water, and to prevent floor-laid eggs. This procedure is not permitted in Sweden, because it involves denying access to both litter and space, which may have a negative effect on bird welfare. The present study investigated how the welfare and performance of layers were affected by this temporary exclusion on introduction of hens to the laying facility. The study included 600 floor-reared Dekalb White layers obtained at 16 wk age and housed in 6 groups of 100 in a conventional single-tier floor-laying system. Birds were either given full access to the litter area during the whole study or were excluded from the litter area during the first 2 wk after transfer to the laying facility. From 18 to 72 wk age, birds in both treatments had full access to the litter area. Excluding birds from the litter area for 2 wk resulted in better feather cover and reduced fearfulness, according to novel object and tonic immobility tests. Furthermore, birds initially excluded from the litter area produced eggs with a lower proportion of shell irregularities than birds with full access to the litter area throughout. No difference was found in corticosterone metabolites in droppings rate of lay, mortality, or proportion of floor-laid eggs. In conclusion, none of the parameters studied indicated that the welfare of laying hens was compromised by temporary exclusion from the litter area on introduction to the laying facility. In fact, some of the data suggested that bird welfare had improved.

Evaluating the Age-Dependent Potential for Protein Deposition in Naked Neck Meat Type Chicken

Simple SummaryGrowth rates of fast-growing chickens are reduced by a higher ambient temperature (AT) because of difficulties in dissipating heat through the feather coverage. Naked neck meat type genotypes could be helpful in increasing the tolerance for high AT. However, basic model parameters of this genotype necessary to further assess amino acid requirements are as yet unavailable. The experiments were conducted to estimate both the daily nitrogen maintenance requirement (NMR) and the potential for daily nitrogen retention NRmaxT). These observed model parameters provide the basic information to characterize the growth potential of the genotype for further application in modeling of individual amino acid requirements of naked neck meat type chicken.The introduction of the naked neck gene (Na) into modern meat type chicken is known to be helpful in increasing the tolerance for a high ambient temperature (AT) by reducing the feather coverage which allows for a higher level of heat dissipation compared to normally feathered (na/na) birds. In addition, reduced feather coverage could affect requirements for sulfur containing amino acids. As a prerequisite for further modeling of individual amino acid requirements, the daily N maintenance requirement (NMR) and the threshold value of daily N retention (NRmaxT) were determined. This was carried out using graded dietary protein supply and exponential modeling between N intake (NI) and N excretion (NEX) or N deposition (ND), respectively. Studies with homozygous (Na/Na) and heterozygous (Na/na) naked neck meat type chicken utilized 144 birds of average weight (50% of each genotype and sex) within two N balance experiments during both the starter (days 10–20) and the grower period (days 25–35). Birds were randomly allotted to five diets with graded dietary protein supply but constant protein quality. The observed estimates depending on genotype, sex and age varied for NMR and NRmaxT from 224 to 395 and 2881 to 4049 mg N/BWkg0.67/day, respectively.

Featherless and feathered broilers under control versus hot conditions. 1. Breast meat yield and quality

The improved genetic potential of contemporary commercial broilers cannot be fully expressed under hot conditions that depress growth rate, decrease breast meat yield, and reduce meat quality. The negative heat effects are attributed to the insulating feather coverage, which, under high ambient temperatures (AT), hinders dissipation of the excessive internally produced heat. Accordingly, featherless broilers (sc/sc), their feathered sibs (+/sc), and contemporary broilers (+/+) were subjected to control AT (26°C) and hot AT (32°C) to test the hypothesis that lack of feathers contributes to higher breast muscle yield and better meat quality, especially under hot conditions, and that differences related to lack of feathers are related to cardiovascular capacity. In 2 similar trials, the superior genetic background of the contemporary broilers was manifested under control conditions; their mean BW was about 15% higher than the means of the featherless broilers and their feathered sibs. The hot conditions depressed BW of the 2 feathered groups by approximately 25%, with hardly any effect on featherless broiler BW. Breast meat yield (% of BW) in the featherless broilers was higher than in those with feathers, especially under the hot AT. Furthermore, the featherless broilers were characterized by superior meat quality as indicated by lower drip loss, lower lightness, and higher redness. The superior meat quality of the featherless broilers could be explained by their larger hearts and higher hematocrit values, suggesting superior cardiovascular capacity to supply oxygen and nutrients to the breast muscles. On the practical side, the results clearly indicate that modern featherless broilers can reach normal BW, as well as yield and quality of breast meat, under hot conditions as well. It appears that broiler meat production in hot regions and climates can be substantially improved by introducing the featherless gene into contemporary commercial broiler stocks. This has become more feasible since the recent development of a simple DNA test to identify carriers of the recessive sc mutation.

Effects of growth pattern and dietary protein level during rearing on feed intake, eating time, eating rate, behavior, plasma corticosterone concentration, and feather cover in broiler breeder females during the rearing and laying period

An experiment was conducted to evaluate the effect of growth patterns (GP) and dietary crude protein levels (CP) during rearing (2–22 weeks of age) on feed intake, eating time, eating rate, behavior, plasma corticosterone concentration, and feather cover in broiler breeder females during the rearing and laying period. A total of 768 day-old Ross 308 broiler breeder chicks, of which 288 hens were followed during the laying period, were allotted to 6 different treatments during the rearing period according to a 2×3 factorial design, with 8 replicates (pens) per treatment. Two growth patterns were followed by a restricted feeding regime up to a target body weight (BW) at 20 weeks of age of 2200g (standard growth pattern=SGP) and 2400g (high growth pattern=HGP) and 3 dietary protein levels (high=CPh, medium=CPm, and low=CPl). During lay, all birds were fed a standard breeder diet and followed a standard growth pattern. During rearing, HGP birds were fed on average 6.5% more feed than SGP birds. In HGP birds, eating time (min/day) during the rearing period increased by 17%, whereas eating rate (gfeed/min) decreased by 8%, compared to SGP birds. This prolonged feeding behavior of HGP birds, but stereotypic object pecking and animal pecking was not reduced. Feather cover was not affected by growth pattern during the rearing and laying period. Only at 16 weeks of age a lower plasma corticosterone concentration was found for the HGP birds. HGP birds showed more feeding and sitting behavior, but less foraging behavior during the rearing period, while during the laying period only more walking behavior was observed. In order to maintain target weights, feed intake levels of CPm and CPl during rearing were set 4.6 and 10.0% higher than CPh, whereas eating time was increased by 22 and 63% and eating rate was decreased by 9 and 26%, respectively. A prolonged eating time during rearing for CPm and CPl birds resulted in more time spend feeding and resting and less stereotypic object pecking and animal pecking compared to CPh birds during rearing. In contrast to the rearing period, feed intake and eating time were not affected by CP level during rearing at 22 weeks of age, whereas eating rate was increased by 8 and 16% for CPm and CPl, respectively, compared to CPh. At 27 weeks of age the effect of CP level during rearing on eating rate had disappeared. Plasma corticosterone concentrations were not affected by dietary protein level during the rearing and laying period. Feather cover was inferior by lowering the dietary protein level, in particularly during the first 11 weeks of rearing. No effect of GP was found on feather cover. It is concluded that dietary protein levels positively affected some behavioral traits during the rearing period, whereas these traits were only slightly affected by growth patterns. However, the physiological parameter (plasma corticosterone concentration) was not affected.

Effects of fiber supply in furnished cages on performance, egg quality, and feather cover in 2 egg-laying hybrids

SUMMARY Poultry may obtain fiber from the feed or from the ingestion of, e.g., fibrous litter materials. In earlier studies, it was shown that insoluble fiber may stimulate digestion and exert a calming effect on laying hens. Fiber may also influence the metabolism of minerals and fat, which might affect egg quality. In this paper, we describe the effects of 2 means of fiber supply on production performance, feather cover, and egg quality in Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) hens housed in furnished cages between 20 and 60 wk of age. Insoluble fiber was supplied by either including 3% ground straw pellets in the feed or by substituting the saw dust in the litter bath with crumbled straw pellets. Overall, hens were frequently pecking the litter, but litter bath occupation, litter pecking, and litter intake was higher in LB than in LSL. In LB, more crumbled straw pellets were consumed from the litter bath compared with saw dust. Compared with the control, adding straw pellets to the feed reduced egg shell thickness in LB but not in LSL. Otherwise, treatments had no significant effects on production performance, egg quality, or feather cover. Therefore, litter may constitute a significant source of insoluble fiber to laying hens, but notable hybrid differences in the interaction with litter were observed.

Use of infrared thermography to assess laying-hen feather coverage

Infrared thermography (IRT) was compared with the traditional 4-scale feather scoring (FS, with 1 representing the worst feather coverage and 4 the best) method for assessing feather coverage of laying hens. The feather coverage of 6 body parts (head, dorsal neck, front neck and crop, back, breast, and belly), body surface temperature distribution, and relative change in sensible heat loss of 60 laying hens (Lohmann SL white breed) at 28, 56, or 73 wk of age (20 hens per age group) were compared by using IRT. For all the 6 body parts and the area-weighted overall, the area of excellent feather (EF) determined by IRT was positively correlated with the 4-scale scores determined by FS (P < 0.05), whereas the areas of fair feather (FF), no feather (NF), and body surface temperature were negatively correlated with FS scores (P < 0.05). Feather deterioration occurred for elder hens at all body parts. Feather coverage of the hens was classified as 98.7% EF, 1.3% FF, and 0% NF at 28 wk of age; 70.2% EF, 20.6% FF, and 9.2% NF at 56 wk of age; and 35.4% EF, 17.1% FF, and 49.5% NF at 73 wk of age. As a result of less feather coverage and higher surface temperature, sensible heat loss was speculated to be higher for 56- and 73-wk-old hens than for 28-wk-old hens, potentially leading to higher feed-to-egg conversion for the elder hens. It was concluded that IRT is a promising technique or tool that may provide a more objective and quantitative evaluation of laying-hen feather conditions and delineation of bird thermoregulation.