Integrating animals into a farm supports a closed or semi-closed production system where nutrients are recycled and off-farm inputs are reduced. In comparison to other livestock, chickens can be a low-investment option for animal-crop integration of small-scale, diversified, vegetable farms. Although crop-animal integration poses many potential benefits to farms, soils, and the environment, there are significant food safety risks when considering the production of vegetables in close proximity to raw manure. The objectives of this study were to examine the effects of poultry integration with meat chickens (broilers) in two different seasons on soil health, food safety, vegetable yield, and poultry feed efficiency in organic vegetable cropping systems. We explored these effects in an open field study with three rotation treatments (two that integrated chickens and a no-chicken control): vegetables-cover crop (V-CC; control treatment), vegetables-cover crop-poultry (V-CC-P), and vegetables-poultry-cover crop (V-P-CC). In response to crop rotation, over three years, we monitored soil nutrient status, soil microbial biomass carbon (MBC), permanganate oxidizable carbon (POXC), and microbial catabolic potential and diversity using Biolog® microplates. The presence or absence of foodborne pathogens in soil and vegetables was also measured. Nitrate–nitrogen (NO3–N) was higher in V-P-CC in year 2 as compared to both V-CC and V-CC-P (P = 0.001 and <0.001, respectively). After poultry removal in the summer of year 2 and year 3 V-P-CC was on average two times higher in NO3–N as compared to V-CC and V-CC-P, respectively. After chicken removal in the autumn of year 3 V-CC-P was 2.1 and 1.8 times higher in NO3–N as compared to V-CC and V-P-CC, respectively. On average phosphorus (P) increased by 45% in year 2 and by 13.2% in year 3. Microbial biomass carbon (MBC) increased from after harvest (summer) in year 1 to the end of the season (autumn) of year 2 from 219.75 to 303.23 mg carbon (C) kg−1. Integrating poultry increased MBC by 25%, on average between both treatments across all sampling dates, compared to the V-CC (P = 0.042). The vegetable-cover crop control (V-CC) preferentially used carbohydrates, compared to V-P-CC which corresponded to greater amino acid usage. Escherichia coli O157:H7 was detected in all plots in the spring of year 3 and select replications of plots in the autumn of year 3. Salmonella spp. was found in one plot in year 2. No pathogens were detected on the spinach crop when leaf surfaces were tested. Integrating chickens into organic vegetable crop rotations increases NO3–N and has the potential for off-farm fertilizer reductions if time and stocking density are further examined. However, poultry feed is often an off-farm input and should be considered when determining the true N input of this system. Soil health may be improved, but MBC and other soil health indicators should be monitored with longer-term rotations. There are food safety risks that come with the integration of chickens into vegetable production and fields should be treated as if raw manure has been applied. Despite the potential benefits of integrating poultry into vegetable crop rotations, more research on these systems is required to determine optimum integration strategies that provide maximum benefit to the producer, the animals, and the environment.

Foodborne infections with antimicrobial-resistant Campylobacter spp. remain an important public health concern. Publicly available data collected by the National Antimicrobial Resistance Monitoring System for Enteric Bacteria related to antimicrobial resistance (AMR) in Campylobacter spp. isolated from broiler chickens and turkeys at the slaughterhouse level across the United States between 2013 and 2021 were analysed. A total of 1,899 chicken-origin (1,031 Campylobacter coli (C. coli) and 868 Campylobacter jejuni (C. jejuni)) and 798 turkey-origin (673 C. coli and 123 C. jejuni) isolates were assessed. Chicken isolates exhibited high resistance to tetracycline (43.65%), moderate resistance to ciprofloxacin (19.5%), and low resistance to clindamycin (4.32%) and azithromycin (3.84%). Turkey isolates exhibited very high resistance to tetracycline (69%) and high resistance to ciprofloxacin (39%). The probability of resistance to all tested antimicrobials, except for tetracycline, significantly decreased during the latter part of the study period. Turkey-origin Campylobacter isolates had higher odds of resistance to all antimicrobials than isolates from chickens. Compared to C. jejuni isolates, C. coli isolates had higher odds of resistance to all antimicrobials, except for ciprofloxacin. The study findings emphasize the need for poultry-type-specific strategies to address differences in AMR among Campylobacter isolates.

There is a need for a low-cost strategy that accelerates the genetic change in local chicken breeds. Therefore, the objective of this study is to develop a strategy for marker-assisted selection for growth in local chickens in the developing countries. The studied lines were a homozygous normally feathered selected line (CE1), homozygous naked-neck selected line (CE3) and their corresponding control lines (CE2 and CE4). Lines CE1 and CE3 have been selected for high 6-week body weight (BW) for five generations. Three generations were obtained for this study. In the current study, we consider the 6th generation as the base generation for marker-assisted selection study. Two subsequent selected generations were obtained from the base generation. The selected lines were significantly heavier at 6 weeks of age than their corresponding control lines by 24.15 and 27.07% in the base generation and by 51.4 and 34.5% in the second selected generation. A total of 34 polymorphic alleles in 19 loci were flown over generations and the flow trends were different in different lines and families within lines. Principal component analysis was applied to the data of both lines and two main components were found and three canonical correlations were obtained. Four and five alleles were persistently concomitant with the highly performed families in lines CE1 and CE3, respectively. These alleles would have brought 6-week BW into higher levels of performance by 25.1 and 16.6% in the second generation if they would have been considered in the selection for 6-week BW.

From two weeks of age female broiler breeder chickens were fed either on a commercial daily ration (R), twice that amount (2R), or ad libitum (AL). Motivation to eat in R and 2R birds was compared every third week with that of AL birds subjected to 3-72h food deprivation. AL and 2R birds grew three and two times faster than R birds to 20 weeks, and AL birds ate two to four times as much per day as R birds, depending on age and on whether birds of the same age or weight were compared. When feeding motivation was measured in 16min tests with an operant procedure, numbers of responses by R and 2R birds were not related in a consistent way to the time since their daily meal ended Responses by AL birds were correlated consistently with the preceding period of food deprivation, but it was not possible to express hunger in R and 2R birds in terms of equivalent deprivation in AL birds, as intended, because feeding motivation in the two situations differed in magnitude. Instead, it was calculated that motivation to eat in R and 2R birds, from 8 to 20 weeks, was 3.6 and 1.9 times greater than that of maximally (72h) deprived AL birds. Another measure of feeding motivation with different birds, rate of eating in 10min tests, produced a similar index of hunger with 2R but not R birds. It is concluded that broiler breeders fed on the commercial ration eat only a quarter to a half as much as they would with free access to food, and that they are highly motivated to eat at all times. The modern broiler breeder industry is caught in a welfare dilemma, since on the one hand stock appear to be chronically hungry, while on the other hand less severe food restriction leads to reduced fertility and health problems.

Possible welfare benefits of qualitative rather than quantitative food restriction were investigated with growing female broiler breeder chickens (Ross 1). In Experiment 1, body-weight gains from 2 to 6 weeks of age were compared among different diet dilution, appetite suppression and low protein treatments, with free access to food at all times, to identify qualitative treatments causing weight gains similar to that recommended in the Ross 1 Parent Stock Management Manual. Based on these results, four diet dilution (400g kg−1 unmolassed sugar-beet pulp, 300 and 600g kg−1 oat hulls, 500g kg−1 softwood sawdust) and one appetite suppression (50g kg−1 calcium propionate) treatments were compared with two quantitative restriction (the recommended daily ration and twice that amount) and one ad libitum control treatments, from 2 to 10 weeks of age, in Experiment 2. As well as growth, food intake, excreta production and digestibility, measurements were also made of behaviour and blood indices of stress. Several conclusions were drawn. Different methods of qualitative food restriction can be used to control growth rate within desired limits. Problems with these methods include reduced uniformity in weight gain, increased excreta production and/or increased cost. Although they appear to suppress abnormal oral behaviours, they do not alter the increased general activity which is correlated with suppression of growth rate, and which may more accurately reflect associated hunger. Suppression of abnormal oral behaviours may only rarely correspond with reduction in blood indices of stress, and so cannot be taken to indicate improved welfare. Some of these methods can add to physiological stress. Finally, there was insufficient evidence of improved welfare, based on both behavioural and physiological criteria, to justify advocating the suitability of any of these methods for commercial use.

The effect of an environmental enrichment — straw bales — on the behaviour of growing broiler chicks was investigated by comparing the behaviour of broilers kept in matched pairs of houses on commercial farms with and without bales. The birds provided with bales perched on them and clustered around them. The most striking result, however, was that, even away from the bales, birds in the enriched houses were more active (showing more walking and running and less sitting) than birds in unenriched houses. The study provides support for the ‘Freedom Food’ recommendation that activity in commercially kept indoor chickens can be increased by providing environmental enrichment in the form of straw bales.

For the detection and assessment of pain in animals both behavioural and physiological measurements are necessary. Cutaneous receptors which responded to noxious stimulation (nociceptors) have been identified in birds and have been characterized physiologically in the chicken. Following cutaneous nociceptive stimulation the chicken showed cardiovascular and characteristic behavioural changes consistent with those seen in mammals and indicative of pain perception. Following major burn trauma (partial beak amputation) there was behavioural and electrophysiological evidence fora pain-free period lasting several hours. This pain-free period was followed by pain-related behaviour with both anatomical and physiological evidence for long-term chronic pain.

While pain has been assessed following nociceptive stimulation and following trauma the painful consequences of chronic disease have not been investigated Spontaneous degenerative joint disease is widespread in certain strains of intensively reared poultry, and while we do not know what effect joint degeneration has on the joint capsule receptors, recent work has shown in the joint capsule of birds there are similar receptor types to those found in mammals and it seems likely that joint degeneration in birds may be accompanied by painful sensations.

Experimental work has clearly detected painful conditions in birds but the alleviation of pain with analgesic drugs is not possible at present because analgesic agents have not been systematically investigated in birds.

Comparing pain in birds with mammals it is clear that, with regard to the anatomical, physiological and behavioural parameters measured, there are no major differences and therefore the ethical considerations normally afforded to mammals should be extended to birds.

In the event of a notifiable disease outbreak, poultry may need to be culled in situ. This should be performed swiftly and humanely to prevent further spread of the pathogen while preserving the welfare of the animals prior to death. Here, we examined the aversion of broiler chicks (Gallus domesticus) to three lethal gas mixtures at various concentrations to determine the least aversive mix that could be used in whole-house gassing. For 1 h, individual chicks (n = 36) were allowed to place their heads inside three feeding and drinking stations (FDS) in order to access food and water. Each FDS was filled with a different gas mixture, and birds could access each FDS as much as they liked. Twelve chicks each were tested at low (50% carbon dioxide [CO2] in air, 70% argon [Ar] in CO2, 70% nitrogen [N2] in CO2), medium (55% CO2 in air, 80% Ar in CO2, 80% N2 in CO2) or high (60% CO2 in air, 90% Ar in CO2, 90% N2 in CO2) concentrations of gas mixtures. Aversion was assessed based on the time birds spent with head in each FDS (with more time indicating less aversive), and the frequency of head shakes relative to time spent with head in the FDS (with a lower proportion indicating less aversive). Data were analysed by ANOVA. On average, birds spent < 3 min with their head in any FDS. Mixtures containing 90% Ar or N2 in CO2 and 80% argon in CO2 were least aversive and mixtures containing 70% N2 in CO2 and 60% CO2 in air were most aversive, based on time spent with head in. Head shakes s−1 were more frequent with low concentration gas mixtures compared to high concentrations, and with all CO2 in air mixtures, which suggests that the intensity of head shaking is related to the concentrations of CO2. From these results, one concentration of each of the three gas mixtures (90% N2 in CO2, 80% Ar in CO2, and 50% CO2 in air) were chosen for assessment on a further 12 birds and the results showed that both inert gas mixtures were less aversive than 50% CO2 in air based on time spent with head in. Frequency of head shakes s−1 did not differ between the three mixtures. Birds found all gases aversive, however it is concluded that inert gas in CO2 mixtures were least aversive compared to CO2 in air and these gases also caused less signs of respiratory discomfort.

Education of children about farm animal welfare could affect welfare standards, through influence on current and future purchasing of animal products, and improve general consideration for animals. Establishing success requires evaluation. Here, a farm animal educational event for 13 to 14 year-old schoolchildren, focusing on chicken biology, welfare and food labelling, was assessed. Alterations in knowledge, attitude and a proxy measure of behaviour towards animals and their welfare, key aspects expected to impact on animal welfare, were investigated using questionnaires. These key aspects were predicted to increase following event attendance and remain higher than in the non-attending control group three months later. Knowledge and positive behaviour towards specific poultry species increased significantly in attendees but, although remaining greater than pre-attendance, tended to diminish over time. Value afforded to animal life was unaffected by the event. Consideration of welfare needs was significantly greater overall in attendees than non-attendees, but appeared to be characteristic of children choosing to attend the event, rather than the event per se. Importance attributed to animal welfare followed a hierarchy from survival-relevant, eg freedom from hunger and thirst, to less critical needs, eg stimulation. The specific species under consideration had the most significant effect on attitudes; consistent with predictions based on perceptions of the animals’ ‘complexity’, cognitive ability, similarity to humans and use. Further investigation into the aetiology of attitude and potential barriers to attitude change is required to effect attitude change and determine whether attitude alteration could support maintenance of shifts in knowledge and behaviour.

Little is known about the early history of the chicken (Gallus gallus domesticus), including the timing and circumstances of its introduction into new cultural environments. To evaluate its spatio-temporal spread across Eurasia and north-west Africa, the authors radiocarbon dated 23 chicken bones from presumed early contexts. Three-quarters returned dates later than those suggested by stratigraphy, indicating the importance of direct dating. The results indicate that chickens did not arrive in Europe until the first millennium BC. Moreover, a consistent time-lag between the introduction of chickens and their consumption by humans suggests that these animals were initially regarded as exotica and only several centuries later recognised as a source of ‘food’.

Necrotic enteritis (NE), caused by Clostridium perfringens (CP), is one of the most common of poultry diseases, causing huge economic losses to the poultry industry. This review provides an overview of the pathogenesis of NE in chickens and of the interaction of CP with the host immune system. The roles of management, nutrition, probiotics, and vaccination in reducing the incidence and severity of NE in poultry flocks are also discussed.

Toxoplasma gondii infections are common in humans and animals worldwide. Domestic free-range chickens (Gallus domesticus) are excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Chickens can be easily infected with T. gondii; however, clinical toxoplasmosis is rare in these hosts. Chickens are comparatively inexpensive and thus are good sentinel animals for T. gondii infections on the farms. Here, the authors reviewed prevalence, the persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from chickens worldwide for the past decade. Data on phenotypic and molecular characteristics of 794 viable T. gondii strains from chickens are discussed, including new data on T. gondii isolates from chickens in Brazil. This paper will be of interest to biologists, epidemiologists, veterinarians and parasitologists.

Recently, we found that in ovo feeding of l-leucine (l-Leu) afforded thermotolerance, stimulated lipid metabolism and modified amino acid metabolism in male broiler chicks. However, the effects of in ovo feeding of l-Leu on thermoregulation and growth performance until marketing age of broilers are still unknown. In this study, we investigated the effects of in ovo feeding of l-Leu on body weight (BW) gain under control thermoneutral temperature or chronic heat stress. We measured changes of body temperature and food intake, organ weight, as well as amino acid metabolism and plasma metabolites under acute and chronic heat stress in broilers. A total of 168 fertilized Chunky broiler eggs were randomly divided into 2 treatment groups in experiments. The eggs were in ovo fed with l-Leu (34.5 µmol/500 µl per egg) or sterile water (500 µl/egg) during incubation. After hatching, male broilers were selected and assigned seven to nine replicates (one bird/replicate) in each group for heat challenge experiments. Broilers (29- or 30-day-old) were exposed to acute heat stress (30 ± 1°C) for 120 min or a chronic heat cyclic and continued heat stress (over 30 ± 1°C; ages, 15 to 44 days). In ovo feeding of l-Leu caused a significant suppression of enhanced body temperature without affecting food intake, plasma triacylglycerol, non-esterified fatty acids, ketone bodies, glucose, lactic acid or thyroid hormones under acute heat stress. Daily body temperature was significantly increased by l-Leu in ovo feeding under chronic heat stress. Interestingly, in ovo feeding of l-Leu caused a significantly higher daily BW gain compared with that of the control group under chronic heat stress. Moreover, some essential amino acids, including Leu and isoleucine, were significantly increased in the liver and decreased in the plasma by l-Leu in ovo feeding under acute heat stress. These results suggested that l-Leu in ovo feeding afforded thermotolerance to broilers under acute heat stress mainly through changing amino acid metabolism until marketing age.

Grape skin is a source of polyphenols with antioxidant and antimicrobial properties. Little information is available regarding its application in animal feeding. The present study investigated the effect of inclusion of fermented (FS) and unfermented (UFS) grape skin at two different doses (30 g/kg, FS30 and UFS30, and 60 g/kg, FS60 and UFS60) and 200 mg/kg vitamin E (α-tocopheryl acetate) in a corn–soybean diet on growth performance, ileal protein digestibility, ileal and excreta total extractable polyphenols content and digestibility, intestinal microbiota and thigh meat oxidation in broiler chickens. Growth performance was depressed in chickens fed UFS and FS diets. A reduction in ileal protein digestibility was also observed in birds fed UFS, being this effect more pronounced in those fed 60 g/kg. The dietary inclusion of grape skin increased both ileal and excreta polyphenols contents, being higher in birds fed UFS than in those fed FS. Excreta moisture content increased in birds fed UFS and FS diets. No effect of dietary inclusion of grape skin was observed on ileal counts of lactic-acid bacteria and Clostridium, but UFS inclusion in the diet reduced ileal count of Escherichia coli as compared with FS dietary inclusion. After 7 days of refrigerated storage, values of thiobarbituric acid reactive substances (TBARS) were lower in chicken meat when grape skin was added in the diet at 60 g/kg instead of 30 g/kg, and meat from birds fed 60 g/kg of grape skin reached TBARS values similar to those of birds supplemented with vitamin E. In conclusion, high doses of grape skin polyphenols depressed growth performance and protein digestibility, and increased excreta moisture content. Unfermented grape skin contained more polyphenols than FS, and its inclusion in the diet led to higher ileal and excreta polyphenols contents and to a lower ileal count of E. coli. Furthermore, the antioxidant potential of the polyphenols present in grape skin was observed after 7 days of meat storage, with the dose of 60 g/kg of grape skin being as effective as vitamin E supplementation in maintaining oxidative stability of meat.

Sodium and chloride are the key factors maintaining normal osmotic pressure (OSM) and volume of the extracellular fluid, and influencing the acid–base balance of body fluids. The experiment was conducted to investigate the effects of dietary Na+ and Cl− level on growth performance, excreta moisture, blood biochemical parameters, intestinal Na+–glucose transporter 1 (SGLT1) messenger RNA (mRNA), and Na+–H+ exchanger 2 (NHE2) mRNA, and to estimate the optimal dietary sodium and chlorine level for yellow-feathered chickens from 22 to 42days. A total of 900 22-day-old Lingnan yellow-feathered male chickens were randomly allotted to five treatments, each of which included six replicates of 30 chickens per floor pen. The basal control diet was based on corn and soybean meal (without added NaCl and NaHCO3). Treatments 2 to 5 consisted of the basal diet supplemented with equal weights of Na+ and Cl−, constituting 0.1%, 0.2%, 0.3% and 0.4% of the diets. Supplemental dietary Na+ and Cl− improved the growth performance (P<0.05). Average daily gain (ADG) showed a quadratic broken-line regression to increasing dietary Na+ and Cl− (R2=0.979, P<0.001), and reached a plateau at 0.1%. Supplemental Na+ and Cl− increased (P<0.05) serum Na+ and OSM in serum and showed a quadratic broken-line regression (R2=0.997, P=0.004) at 0.11%. However, supplemental Na+ and Cl− decreased (P<0.05) serum levels of K+, glucose (GLU) and triglyceride. Higher levels of Na+and Cl− decreased duodenal NHE2 transcripts (P<0.05), but had no effect on ileal SGLT1 transcripts. The activity of Na+ /K+-ATPase in the duodenum decreased (P<0.05) with higher levels of dietary Na+ and Cl−. In conclusion, the optimal dietary Na+ and Cl− requirements for yellow-feathered chickens in the grower phase, from 22 to 42 days of age, to optimize ADG, serum Na+, OSM, K+ and GLU were 0.10%, 0.11%, 0.11%,0.17% and 0.16%, respectively, by regression analysis.