This study was conducted to determine the effect of reducing calcium (Ca) and available phosphorus (AvP) on performance, carcass yield, tibia traits and jejunum histomorphology in broilers. For this purpose, 480 one-day-old Ross 308 male chicks were distributed into four trial groups with eight subgroups. During the starter period, birds were fed with recommended or reduced Ca and AvP contents of 66.7 and 62.5 g/kg, respectively. Calcium and AvP contents of the groups were as follows: control: 8.70 g/kg Ca, 4.40 g/kg AvP for grower and 7.80 g/kg Ca, 3.90 g/kg AvP for finisher; LCP1: 8.30 g/kg Ca, 4.20 g/kg AvP for grower and 7.10 g/kg Ca, 3.50 g/kg AvP for finisher; LCP2: 7.90 g/kg Ca, 4.00 g/kg AvP for grower and 6.00 g/kg Ca, 3.00 g/kg AvP for finisher; LCP3: 7.00 g/kg Ca, 3.80 g/kg for grower and 5.00 g/kg Ca, 3.00 g/kg AvP for finisher. Performance variables have been calculated from the data of each period, and samples were obtained from the slaughtered birds on the final day of the trial (42nd day) for carcass and tibia traits and jejunum histomorphology. Reducing dietary Ca and AvP did not affect the broiler performance, carcass yield and mortality. Tibia ash decreased in LCP2 and LCP3 groups (P < 0.01). Villus width and villus surface area increased in LCP2 and LCP3. Overall, feeding with a diet 100 g/kg lower than the recommended Ca and AvP did not affect performance in broilers, but improved jejunal development.

The purpose of this experiment was to provide information relevant to the current debate concerning the optimisation of terminal stocking density for commercial broiler production. In a modern, controlled-environment house with 24 floor pens (each 11.4 m2), 4020 day-old broilers (Ross 308) were allocated to three terminal (42 days) stocking densities (28, 34 and 40 kg m-2) x two sexes x four replicates, according to a randomised block design. Group sizes varied from 130 to 208. Husbandry conditions were in accordance with normal commercial practice. Performance and behaviour were measured systematically during each of the six weeks of life, and additional measurements were made of leg health and litter condition. Data were analysed using ANOVA to determine the effects of stocking density, sex and age. The realised mean terminal stocking densities were 28.2, 33.5 and 38.5 kg m2. The main significant effects of stocking density treatment were a linear decline in food intake with increasing density during week six (the final week), and a reduced proportion of time spent panting deeply during weeks five and six at the lowest density. Increased (shallow and deep) panting shown by females in weeks two to five suggests that if thermal discomfort becomes a problem at higher stocking densities later in the growing period, it may do so earlier in females. There was no conclusive evidence from this study that broiler welfare is compromised any more at 40 than at 34 kg m−2. The fact that the proportion of time spent panting deeply in week six was considerably lower at 28 kg m2 than at 34 and 40 kg m−2 suggests that thermal comfort (and hence welfare) at this age may be improved at densities of less than 34 kg m−2. However, the significant effects of age, age x density, and age x sex on time spent panting deeply suggest that the age at slaughter and the sex of birds in single-sex flocks should be taken into account in future considerations of optimal maximum terminal stocking density.

Catching of broilers is the first stage in the transfer of birds to the slaughterhouse. The catching process entails a high risk not only of stress but also of injury and death to the birds. Associated injury and mortality rates have important implications not only for animal welfare but also for the economics of the procedure. Catching machines are advantageous with regard to labour costs and standards, and they may also reduce damage to the birds. In the present investigation the use of a sweeper-type catching machine was compared with manual catching under commercial conditions, data being collected during 43 mechanical and 40 manual catching events evenly distributed over one year. Dead-on-arrival rates were recorded, and 108 068 mechanically caught and 87 916 manually caught birds were examined for injuries on the shackles at the processing plant. Injury rates of all types were significantly reduced after mechanical catching. This improvement was highest with respect to leg injuries. There was no significant difference in the number of dead-on-arrivals except during the spring period, when there were higher losses of birds caught mechanically; this was thought to be attributable to climatic conditions. The loading of the transport containers with equal numbers of birds and the initial familiarisation period of the catching team with the machine are potentially problematic factors with potential for improvement. The catching machine investigated here, with its lower risk of injury to broilers than commercial manual catching, has the potential to limit impairment of bird welfare during catching.

In the UK, broiler chickens are normally slaughtered at about six weeks of age when they weigh approximately 2.2 kg; this contrasts with the growth of an ‘unimproved’ traditional strain of bird such as a White Sussex, which would weigh about 800 g at the same age. Lameness, characterised by abnormal gait, posture and impaired walking ability, can be prevalent in these rapidly growing birds and has been highlighted as a major welfare concern. It is during the later stages of rearing, when the bird is becoming heavy and may be achieving weight gains of over 50 g per day, that lameness begins to have an economic and welfare impact on the flock and to compromise the behaviour of large numbers of birds. A study was carried out to identify potential differences in the expression of genes between groups of lame and normal broiler chickens using subtraction hybridisation. The first group comprised lame birds with measurable gait abnormalities, and the second group comprised sound (not lame) birds. Both populations came from within the same flock. After extraction of mRNA and creation of cDNA, subtractive hybridisation was performed to eliminate genetic sequences common to both populations. The resultant DNA was separated and presented for sequence data analysis and comparison with a large sequence database. Some examples of the subtracted sequences detected are given, and the potential significance of these sequence differences at the individual and group level is discussed.

An experiment was conducted to compare the effect of two levels of house stocking density (34kg m 2 and 40kg m’2) on broiler welfare and behaviour. The trial monitored 121 900 birds housed in eight flocks under commercial conditions and used a range of behavioural and productivity measures to assess welfare.

At the higher stocking density: i) the daily mortality was greater for part of the rearing period; ii) the incidence of leg problems, contact dermatitis and carcase bruising increased; Hi) the birds’ resting behaviour was increasingly disturbed; iv) locomotion and ground pecking decreased; and v) lying and preening patterns were affected, probably due to increased disruption by other birds.

Aspects of welfare were adversely affected at the higher stocking density. Further research is required to determine how stocking density affects welfare under different commercial conditions.

Six commercial hatcheries were visited in the United Kingdom, three of which processed laying hen chicks and three of which processed broiler chicks. The accelerations experienced by the chicks passing through the handling systems were evaluated using miniature data logging accelerometers, which were sent through the systems. The lengths, speeds, and heights of drops of the pathways within each system were also measured. The response of the chicks to the handling was measured in terms of mortality, orientation, righting time (as a measure of disorientation) and tonic immobility. The study showed there to be a range in the physical severity of handling across the hatcheries that could also be seen in terms of differences in the measurements made on the chicks. Nonetheless, the welfare of the chicks passing through the automated systems appeared to be generally acceptable. However, given the velocities and accelerations within these handling systems, there is scope for considerable damage to the chicks, and for poor welfare, if systems are not properly set up or maintained.

Walking ability is related to motor co-ordination which, in rodents, can be assessed by an established test in pharmacological studies — the rotarod test. The purpose of this study was to evaluate a modified rotarod test for chickens and its relation to the often-used gait score system. At the end of their rearing period, we tested 138 male chickens (Gallus gallus domesticus) from three differing growth performance strains: Ross 308 (fast-growing; n = 46), Lohmann Dual (medium-growing; n = 46) and Lohmann Brown Plus (slow-growing; n = 46). First, the chickens’ gait scores were assessed and, immediately following this, they were placed gently onto a steady rod. The velocity of the rotating rod gradually increased, and the latency to leave the rod was recorded. By using a linear mixed model, we were able to show that the latency to leave the rotating rod was significantly predicted by the gait score. Fast-growing chickens had shorter durations on the rotating rod, and these durations were associated with gait score. We conclude that the rotarod test provides an objective alternative method for assessing walking ability in chickens without the need for intense observer training or the risk of observer biases and propose that this novel methodology has the potential to function as a precise, objective indicator of animal welfare.

To determine whether lame broilers are in pain it is necessary to compare measures of lameness and mobility before and after analgesic treatment. Such measures should not be unduly affected by other bird characteristics. This study assessed the performance of lame (gait score, GS 3-4) and non-lame (GS 0-1) broilers using two mobility tests: (i) a novel test to assess broiler ability to access resources when housed in groups (Group Obstacle test); and (ii) a Latency-to-Lie (LTL) test. Outcome test measures included number of obstacle crossings, latency to cross an obstacle, and time taken to sit in shallow water. Associations between outcome test measures and other bird characteristics (established lameness risk-factors), including strain, sex, age, mass, contact dermatitis and pathology, were also investigated. The performance of high-GS and low-GS broilers differed in both mobility tests and no other bird characteristics were as consistent a predictor as lameness. This demonstrates that mobility impairments are closely related to lameness assessed using GS, and that there is a component of lameness that cannot be explained by other bird characteristics (eg being male and heavy). This component may represent pain or discomfort. Both mobility tests are suitable for further application with analgesic testing to classify lameness-associated pain in broilers.

In this study, an appropriate visual scoring system for foot-pad dermatitis was validated, considering the histologically measured depth of the inflammation zone and the histopathological grade (no lesion, mild lesion, ulcer). The aim being to evaluate whether the visual, macroscopic scoring of foot-pad dermatitis can represent the histological, microscopic findings. Two hundred Ross 308 broiler chicken feet (birds aged 39-42 fattening days) were collected at a slaughterhouse and scored macroscopically according to a modified version of the Welfare Quality® Assessment Protocol for Poultry. Afterwards, 200 histological slides (one per foot) were prepared, the extent of the inflammation measured and all slides scored by veterinarian pathologists using Michel et al's modified scheme. The statistical relationship between microscopic and macroscopic score and depth of inflammation were estimated via regression models. Increasing macroscopic score was found to be linked with an increase in microscopic score and the depth of inflammation. In particular, feet without lesions and feet with ulcers were identifiable using the macroscopic score. Macroscopic scoring of foot-pad dermatitis can mirror histological findings once certain limitations are taken into account (superficial lesions were not clearly identifiable). Foot-pad dermatitis is considered a useful indicator of animal welfare and our findings suggest that visual, macroscopic scoring could be a practicable assessment tool.

For monitoring purposes there is a need for a protocol to measure foot-pad dermatitis (FPD) on-farm. Therefore, we studied the effect of number of birds sampled, number of locations sampled and sampling location in a broiler house on the accuracy of measurement, in order to construct a protocol that can be applied in practice. Samples were taken from eight commercial flocks (Ross 308) at up to ten locations with up to 25 birds sampled per location. Foot-pad lesions were scored in all birds for both feet using the Swedish scoring method. No significant differences in FPD score were found between the first five birds and all birds sampled at a particular location. Although locations near the walls did not differ in FPD score from locations in the central area of a house, the severity of foot-pad lesions was unevenly distributed over the house. A model was constructed showing the inaccuracy related to the number of locations sampled in the house and the number of birds sampled per location. The model shows that in situations with at least five locations differences in inaccuracy are relatively small when a total of 100 birds or more is sampled. Inaccuracy is largest in a flock with variation in foot-pad scores, as compared to flocks with little variation. The results of this experiment can be used to determine the optimal sample size in a commercial broiler house.

Fractures occurring in conscious broiler chickens are painful and severely compromise animal welfare. The aim of this study was to investigate the effects of pre-slaughter handling procedures on the frequency of wing fractures. Wings were examined for fractures in 11,609 broilers, from 12 different flocks, slaughtered in two abattoirs: one using bi-phasic CO2 stunning (CS); and one using electric water-bath stunning (ES). The same broilers were examined: i) in lairage, representing fractures attributed to catching and transportation; ii) after evacuation of transport containers and shackling (only ES); and iii) post-stunning. The mean frequencies of wing fractures were: in the lairage; 0.8% (CS 0.73%, ES 0.88%); after shackling prior to stunning; 2.90% (only ES); and after stunning; 2.35% (CS 1.80%, ES 2.90%). Regardless of stunning method, significantly more fractures occurred during pre-slaughter handling at the abattoirs than during catching/transportation. The difference in prevalence between CS and ES was not significant. All fractures observed in the ES occurred in conscious animals, whereas in the CS it was not possible to distinguish between fractures occurring in conscious or stunned broilers. From a welfare perspective, fractures occurring on-farm/transport result in prolonged suffering and are thus considered more serious in risk assessments of broiler welfare, even though more fractures occur at the abattoir. Monitoring of wing fractures at abattoirs should be included as an indicator of broiler welfare.

People's awareness of livestock welfare has increased in recent years and veterinarians have a critical role to play in maintaining and improving these standards. The aim of this study was to explore the attitude of veterinary students to livestock welfare and an online questionnaire was utilised to gauge the opinions of students from the Bursa Uludag University Faculty of Veterinary Medicine in Turkey. A five-point Likert scale covered judgments ranging from ‘Strongly disagree’ to ‘Strongly agree.’ Female students were found to have a higher score for questions related to the welfare of livestock than males. It was also found that students yet to undertake courses in clinical science and animal welfare, ie first and second years, gave higher scores than third, fourth and fifth years who had completed both of these. Moreover, students having owned or dealt previously with livestock provided lower animal welfare scores than their counterparts who had done neither. Seemingly, the sensitivity of veterinary students decreases during the latter stages of their education. To conclude, we suggest further investigation into the extent to which veterinary medicine education influences students’ attitudes to animal welfare as they progress through the course.

Carbon dioxide stunning of broilers is not permitted in Germany. However, the competent authority can license a system for testing, during which scientific evaluation with regard to animal welfare is required. Between 2004 and 2011 several aspects of three systems have been evaluated in Germany and Italy under practical conditions including: (i) supply to the stunning system; (ii) induction conditions; (iii) stunning effectiveness; and (iv) process control. The systems were: (i) LINCO progressive gas-stunning system in which broilers in their transport crates are lowered stepwise into a pit filled with CO2 and exposed to slowly increasing concentrations of CO2 in air up to between 50 and 65% with total dwell times between 275 and 440 s depending on birds’ weight; (ii) Stork PMT two-phase gas-stunning system (40% CO2/30% O2/30%N2 for 1 min/80% CO2 for 2 min) in which broilers are tipped onto a belt, on which they pass through the gas atmospheres; and (iii) Anglia Autoflow two-phase CO2-stunning system, in which the birds are exposed to the atmosphere in their crates. Results on the third system are pending as the investigation is still ongoing. In systems (i) and (ii) analysis of behaviour showed that birds were only exposed to high CO2 concentration (> 40%) after becoming unconscious. Stunning effectiveness was very high but, nevertheless, occasionally birds (0.027% LINCO system and 0.003% Stork PMT system) were able to regain consciousness. Examples of evaluation of behaviour during induction are presented in this paper and animal welfare aspects are compared. Controlled-atmosphere stunning systems for broilers using less than 40% CO2 until animals are unconscious, show obvious advantages compared to electrical water-bath stunning, for example, the avoidance of shackling and achieving high stunning effectiveness.

The objective of this paper is to analyse the effects of three different stocking densities on the production, stress and fear parameters of female broilers during a 46-day production period. Chickens were randomly distributed among nine floor pens in groups of 30 broilers with different space allowances for each treatment; namely eight, 20 and 30 chicks m−2. Chicken growth rate was monitored from day eleven to 46 and indicators of stress, including haematocrit, heterophil/lymphocyte ratio and concentrations of plasma corticosterone, as well as tonic immobility, were measured on days 22 and 46. On day 46, the incidence of foot and skin lesions was assessed, and stress was induced to analyse the response of broilers to each stocking density. High stocking densities cause acute stress in broilers; the effects of low and intermediate stocking densities, however, are not so evident, particularly in relation to tonic immobility and response to acute stress.

Resistant starch (RS) has received increased attention due to its potential health benefits. This study was aimed to investigate the effects of dietary corn RS on immunological characteristics of broilers. A total of 320 broiler chicks were randomly allocated to five dietary treatments: normal corn–soyabean (NC) diet group, corn starch diet group, 4 %, 8 % and 12 % RS diet groups. This trial lasted for 42 d. The relative weights of spleen, thymus and bursa, the concentrations of nitric oxide (NO) and IL-4 in plasma at 21 d of age, as well as the activities of total nitric oxide synthase (TNOS) and inducible nitric oxide synthase (iNOS) in plasma at 21 and 42 d of age showed positive linear responses (P < 0·05) to the increasing dietary RS level. Meanwhile, compared with the birds from the NC group at 21 d of age, birds fed 4 % RS, 8 % RS and 12 % RS diets exhibited higher (P < 0·05) relative weight of bursa and concentrations of NO and interferon-γ in plasma. Birds fed 4 % RS and 8 % RS diets showed higher (P < 0·05) number of IgA-producing cells in the jejunum. While compared with birds from the NC group at 42 d of age, birds fed 12 % RS diet showed higher (P < 0·05) relative weight of spleen and activities of TNOS and iNOS in plasma. These findings suggested that dietary corn RS supplementation can improve immune function in broilers.

Nutritionists have been discussing whether the dietary supplementation of cyst(e)ine is required as a part of the dietary methionine (Met) in the total sulfur amino acid (TSAA) requirement to achieve optimum performance in broilers. Part of Met is converted to cysteine (Cys) to meet the Cys requirement, especially for feather growth. The TSAA requirement has been determined by using graded levels of free Met in the diet, without supplementation of free cyst(e)ine. It has also been argued that the Met to Cys ratio (Met : Cys) changes with age and even with different Met sources. The objective of this study was to evaluate the two sources of Met, while determining the proportion of Met and Cys in total dietary TSAA that optimize the performance of broilers. A performance assay was carried out in a factorial arrangement (5 × 2) using 1080 broilers from 42 to 56 days of age fed diets having different dietary proportions of Met and Cys (44 : 56, 46 : 54, 48 : 52, 50 : 50 or 52 : 48) while maintaining the same dietary TSAA in the diets. Two synthetic Met sources (dl-Met or l-Met) were used for each of the diets with different dietary Met : Cys ratios. Twenty-one broilers of the same age were fed the diets 44 : 56, 48 : 52 and 52 : 48 by supplementing the diet with L-(15N) Met or L-(15N2) Cystine to study the metabolism of TSAA. No differences were observed between Met sources for feed intake, BW gain and feed conversion ratio (FCR; P > 0.05); however, FCR was numerically improved at 50 : 50 Met : Cys. Regarding TSAA utilization, the conversion of Met to Cys increased with increase in Met : Cys ratios, but the concentration of Met intermediates decreased. Broiler chickens responded to different dietary proportions of sulfur amino acids by altering their sulfur amino acid metabolism, and diets containing 50 : 50 Met : Cys is recommended for broilers of age 42 to 56 days.

Incidences of myopathies such as white striping (WS), woody breast (WB) and spaghetti meat (SP) in breast meat from young broilers have been observed globally over the past decade. Some industry reports suggest up to 20% WB occurrence in fast growing heavy broilers (~4.0 kg) with an estimated cost of more than US$500 million/year to the US industry alone, but may actually be far higher. The proportions and severity of the anomaly appear to be flock-dependent and are related to factors such as genetics, nutrition (e.g. protein level during the fast-growing phase), growth rate, activity of the birds at young age, sudden bursts of activity, number of embryonic stem cells and litter management. These three myopathies can appear together or individually, but it appears that they are all related. When meat is processed, these myopathies represent quality issues (firmer meat and/or lower water binding, aesthetics) but do not present a food safety issue. The poultry industry is now focusing on ways to reduce or eliminate the occurrence of these myopathies. Recently some improvements have been made as more is learned about the interactions between environmental and management (e.g., nutrition) factors, and some producers are already implementing new procedures. Breeding programmes are starting to show some promise and are expected to help reduce WB (estimated at 10% of birds per year) and deliver more solutions in the future.

Today's broiler is characterised by faster-, leaner-growth. A large part of this progress is attributed to the genetic selection that had, and continues to improve growth rate and composition of gain at steady pace. As an illustration of such increases in performance, 2.3 kg live gain (slaughter weight) has been reduced from requiring 52 days in 1995 to 36 days in 2017 - a reduction of 0.73 days per year. In addition, meat yield has increased as a proportion of the carcass, being 12% of body weight in the year 1957 and increasing to 20% in 2001 Recent work in 2017 using high density diets has shown to capacity of birds to attain an FCR of 1.19 at 2500 g live BW. Current research suggests that the optimum level of energy may be well below the recommendation by the primary breeders. For example, reducing energy from 100 to 92.5% (around -200 kcal/kg of diet) resulted in only 2 points loss in body weight corrected FCR. Indeed, very recent work showed that a similar reduction of -200 kcal/kg feed in finisher AME resulted in similar, or higher gains and breast yield while having no effect on FE. Published data regarding the balance between energy and protein in feed suggests an optimum AA density between 100 to 120% of breeder recommendations. It can be therefore suggested that today's broiler needs a higher ratio of essential amino acids to energy. In addition to a net increase in the absolute requirement of amino acids, there is an argument for higher dietary ratio of lysine: essential amino acids which will support increased meat production and may better fit modern broiler genetics.

Artificial intelligence (AI) already represents a factor for increasing efficiency and productivity in many sectors, and there is a need for expanding its implementation in animal science. There is a growing demand for the development and use of smart devices at the farm level, which would generate enough data, which increases the potential for AI using machine learning algorithms and real-time analysis. Machine learning (ML) is a category of algorithm that allows software to become accurate in predicting outcomes without being explicitly programmed. The essential principle of machine learning is to construct algorithms that can receive input data and use statistical analysis to predict an output. Exploitation of machine learning approaches, by using different training inputs, derived the prediction accuracy of growth and body weight in broiler chickens that ranged from 98 to 99%. Furthermore, a neural network with an accuracy of 100% identified the presence or absence of ascites in broiler chickens, while the support vector machine (SVM) model obtained an accuracy rate of 99.5% in combination with machine vision for the recognition of healthy and bird flu-challenged chickens. Consequently, machine learning algorithms, besides accurate growth prediction of broiler chickens, can successfully contribute to health disorders prediction. It is obvious that machine learning has a great potential for application in the future. This paper analyses machine learning applications in broiler growth and health prediction, and its ability to cope with high inputs of data and non-linearity can successfully replace common methodology.

Water makes up over 98% of all molecules in the body and it is necessary for several biological processes. Water quality has been shown to influence animal's performance. In recent years, interest in water treatment technology has increased, particularly in poultry. Magnetised water is one of water treatment that has attracted poultry researchers and breeders, due to its low cost compared to chemical and physical water treatments. Water magnetisation changes water properties, making it become more fluid, alkaline and energised. Unfortunately, the information detailed in the literature provides opposite views on the effect of magnetised water on poultry's performance. However, magnetised water, particularly with high gauss (more than 1000 gauss/month) could improve health (immunity), growth (approximately +4 % in weight) for broilers and enhance some egg production traits for hens, such as eggshell thickness (approximately +9 %). This review provides information detailed in the existing literature on the influence of magnetised water on poultry health and production.