Impacts of Stocking Density on the Performance and Welfare of Broiler Chickens

The impact of management practices on the disease and mortality rates of broilers and layers kept by small-scale farmers in Dodoma urban district, Tanzania

The demand for chicken products in Tanzania has increased due to population growth and rising incomes. As a result, the production of broilers and layers has been promoted to fill the gap due to their high productivity. However, exotic breeds of chicken are susceptible to diseases, thus requiring good disease management practices. The current study aimed to increase production of exotic breeds of chicken in the Dodoma region, which is growing rapidly, by identifying management factors associated with disease and chicken mortality. One hundred and four households that keep broilers or layers were selected randomly from the Dodoma urban district. The households were interviewed to gather information about chicken diseases, mortality, and management practices. The proportion of sick and dead chickens per farm was determined and used in beta regression to test its association with management practices and chicken breed. The proportion of sick chickens in a flock was low when stocking density was low and in large households, but it was higher when the farmer lacked knowledge of disease management. Further, mortality rates were high when farmers lacked disease knowledge and cleaning frequency was low, and low when farmers had extensive experience in chicken production. Improvement of extension services and education programmes for poultry farmers on good disease management practices is necessary to increase the production of layers and broilers in the region.

Protective influence of supplementary betaine against heat stress by regulating intestinal oxidative status and microbiota composition in broiler chickens

To assess the impact of supplementing betaine (BT) under heat stress (HS) conditions on broiler performance and intestinal health from 21 to 42 days of age, a total of 150 male Ross 308 broilers were indiscriminately allotted to 3 treatments with 10 replications of 5 birds each. The control (CON) group was given a basal ration and accommodated at a thermoneutral condition (22 ± 1 °C), whereas the HS and HS + BT groups were raised under cyclic HS (33 ± 1 °C for 8 h and 22 ± 1 °C for 16 h per day) and received the basal ration without or with 1000 mg/kg BT, respectively. The HS reduced average daily gain (ADG); average daily feed intake; villus height (VH); VH to crypt depth (CD) ratio (VCR); activities of trypsin, lipase, glutathione peroxidase (GPX), and catalase; and enumeration of Lactobacillus and Bifidobacterium (P < 0.05) and augmented feed conversion ratio (FCR), CD, malondialdehyde (MDA) accumulation, and enumeration of Escherichia coli, Clostridium, and coliforms (P < 0.05). Conversely, BT supplementation heightened ADG, VH, VCR, trypsin activity, GPX activity, and populations of Lactobacillus and Bifidobacterium (P < 0.05) and lowered FCR, MDA accumulation, and Clostridium population (P < 0.05). Furthermore, the FCR value, trypsin and GPX activities, MDA content, and Bifidobacterium and Clostridium populations in the HS + BT group were nearly equivalent to those in the CON group. To conclude, feeding BT under HS conditions could improve broiler performance through improving intestinal health by specifically mitigating oxidative damage and enhancing the colonization of beneficial bacteria.

Microbiome of Ceca from Broiler Chicken Vaccinated or Not against Coccidiosis and Fed Berry Pomaces

American cranberry (Vaccinium macrocarpon) and lowbush/wild blueberry (V. angustifolium) pomace are polyphenol-rich products having potentially beneficial effects in broiler chickens. This study investigated the cecal microbiome of broiler-vaccinated or non-vaccinated birds against coccidiosis. Birds in each of the two groups (vaccinated or non-vaccinated) were fed a basal non-supplemented diet (NC), a basal diet supplemented with bacitracin (BAC), American cranberry (CP), and lowbush blueberry (BP) pomace alone or in combination (CP + BP). At 21 days of age, cecal DNA samples were extracted and analyzed using both whole-metagenome shotgun sequencing and targeted-resistome sequencing approaches. Ceca from vaccinated birds showed a lower abundance of Lactobacillus and a higher abundance of Escherichia coli than non-vaccinated birds (p < 0.05). The highest and lowest abundance of L. crispatus and E. coli, respectively, were observed in birds fed CP, BP, and CP + BP compared to those from NC or BAC treatments (p < 0.05). Coccidiosis vaccination affected the abundance of virulence genes (VGs) related to adherence, flagella, iron utilization, and secretion system. Toxin-related genes were observed in vaccinated birds (p < 0.05) in general, with less prevalence in birds fed CP, BP, and CP + BP than NC and BAC (p < 0.05). More than 75 antimicrobial resistance genes (ARGs) detected by the shotgun metagenomics sequencing were impacted by vaccination. Ceca from birds fed CP, BP, and CP + BP showed the lowest (p < 0.05) abundances of ARGs related to multi-drug efflux pumps, modifying/hydrolyzing enzyme and target-mediated mutation, when compared to ceca from birds fed BAC. Targeted metagenomics showed that resistome from BP treatment was distant to other groups for antimicrobials, such as aminoglycosides (p < 0.05). Significant differences in the richness were observed between the vaccinated and non-vaccinated groups for aminoglycosides, β-lactams, lincosamides, and trimethoprim resistance genes (p < 0.05). Overall, this study demonstrated that dietary berry pomaces and coccidiosis vaccination significantly impacted cecal microbiota, virulome, resistome, and metabolic pathways in broiler chickens.

Performance, blood biochemistry, carcass fatty acids, antioxidant status, and HSP70 gene expressions in Japanese quails reared under high stocking density: the effects of grape seed powder and meal

Japanese quails reared under high stocking density (SD) were evaluated for the effects of grape seed powder (GSP) and meal (GSM) supplementation on performance, blood biochemistry, thigh and breast muscle fatty acids, antioxidant status, and HSP70 gene expression. We randomly assigned 288 (15-day-old) quail chicks to six treatment groups in a factorial design (2 × 3) with four replicates, involving two density levels [160 cm²/bird (LD) and 80 cm²/bird (HD)] and three feed forms (FFs) [no supplementation, grape seed powder (3% GSP), grape seed meal (3% GSM)]. SD had a significant effect on live weight, but not on weekly feed intake, daily weight gain, and feed conversion ratio. Serum creatinine and aspartate aminotransferase levels were significantly affected by FF and SD × FF (p < 0.05). A high SD reduced the n-3/n-6 ratio of breast muscle and a significant interaction was found between FF (p < 0.001). The SD × FF interaction reduced the Σn-6 ratio in HDM's thigh muscle, whereas in LDM, the ratio increased (p < 0.01). At high SD, neither GSP nor GSM reduced biological markers of oxidative stress (p > 0.05). Compared to GSP, GSM had higher efficacy at reducing HSP70 levels related to high SD levels. Despite this, at high SD, a diet containing 3% of GSP and GSM was not effective in overcoming oxidative stress. Therefore, more studies using different doses of GSM and GSP in quail diets would be beneficial.

Dietary 25-hydroxy-cholecalciferol and additional vitamin E improve bone development and antioxidant capacity in high-density stocking broilers

This study aimed to investigate the effects of diets supplemented with 25-hydroxycholecalciferol [25-(OH)D3] and additional vitamin E on growth performance, antioxidant capacity, bone development, and carcass characteristics at different stocking densities on commercial broiler farms. A total of 118,800 one-day-old Arbor Acres broilers were assigned to a 2 × 2 factorial treatment consisting of two dietary vitamin levels (5,500 IU vitamin D3 and 60 IU vitamin E: normal diet, using half 25-(OH)D3 as a source of vitamin D3 and an additional 60 IU of vitamin E: 25-(OH)D3+VE diet) and two stocking densities (high density of 20 chickens/m2: HD and 16 chickens/m2: LD). The experiment lasted for 42 d. The results showed that high-density stocking negatively affected the growth performance of broilers during the first four weeks, whereas the vitamin diet treatment significantly improved the feed conversion ratios (FCR) during the last 2 wk. Vitamin diets increased catalase at 14 and 42 d, and the glutathione peroxidase (GSH-px) levels at 42 d in high-density-stocked broilers. The interaction showed that serum vitamin E levels were significantly improved at 28 d of age in high-density-stocked broilers as a result of the vitamin diets. Stocking density and dietary treatments were found to significantly affect bone development, with the vitamin diet significantly increasing metatarsal length and femoral bone strength in broilers from high-density stocking density at 28 d of age. High stocking density increased the proportion of leg muscles and meat yield per square meter. In general, 25-(OH)D3 and additional vitamin E suppressed oxidative stress and ameliorated the negative effects of high-density stocking on bone development in a commercial chicken farm setting. Vitamin diets improved the FCR of broilers, while high-density stocking resulted in better economic outcomes.

Genetic Comparisons of Body Weight, Average Daily Gain, and Breast Circumference between Slow-Growing Thai Native Chickens (Pradu Hang dum) Raised On-Site Farm and On-Station

To ensure that any new technology developed within an experimental station is appropriate to the community’s needs and compatible with the existing systems, on-site farm research is an important component in examining the effectiveness of agricultural research. The present study examined the growth performance and genetics of Thai native chickens under conditions typically experienced by farmers on smallholder farms (on-site farms) compared with at an experimental unit (on-station). There were 1694 Thai native chickens (Pradu Hang dum) used in this experiment, and they were divided into 613 chickens for the on-station and 1081 chickens for the on-site farm experiments. The individual chicken data included the birth weight (BW0) and body weight at 4, 8, 12, and 16 weeks of age (BW4, BW8, BW12, and BW16, respectively), ADG from 0−4, 4−8, 8−12, 12−16 weeks of age (ADG0−4, ADG4−8, ADG8−12, ADG12−16, respectively), and breast circumference at 8, 12, and 16 weeks of age (BrC8, BrC12, BrC16, respectively). A multiple traits animal model and a selection index were used to estimate the variance components, genetic parameters, and breeding values of growth traits. The results showed that the body weight, average daily gain, and breast circumference at 8, 12, and 16 weeks of age of Thai native chickens raised on-station were higher than those raised on-site at the farm among mixed-sex and sex-segregated chickens, while the birth weight and body weight at four weeks of age (BW0 and BW4) and ADG from 0−4 weeks of age (ADG0−4) were not significantly different (p > 0.05). The heritability estimates of body weight, average daily gain, and breast circumference in the chickens raised at the on-site farm and on-station were moderate to high, with on-station values slightly higher than on-site farm values. The heritability estimates of body weight were 0.236 to 0.499 for the on-site farm, and 0.291 to 0.499 for on-station. For average daily gain, the heritability estimates were 0.274 to 0.283 for the on-site farm and 0.298 to 0.313 for on-station; meanwhile, and for breast circumference, the heritability estimates were 0.204 to 0.268 for the on-site farm and 0.278 to 0.296 for on-station. Both phenotypic and genetic correlations among and between growth traits were positive and ranged from low to high values. The top 20% of the estimated breeding values and selection indices in the on-site farm and on-station experiments showed that the body weight at eight weeks of age (BW8), ADG from 4−8 weeks of age (ADG4−8), and breast circumference at eight weeks of age (BrC8) should be used as selection criteria for Thai native chicken breeding programs. In conclusion, the genetic parameters and breeding values in on-station experiments showed that the breeding program by selection index for improving growth performance is valid. Therefore, to implement such a breeding program in an on-site farm, an intensive or semi-intensive farm system should be considered to minimize the effect of genotype-environment interaction.

Characterization of CRH-Binding Protein (CRHBP) in Chickens: Molecular Cloning, Tissue Distribution and Investigation of Its Role as a Negative Feedback Regulator within the Hypothalamus–Pituitary–Adrenal Axis

Corticotropin (ACTH) is a pituitary hormone playing important roles in stress response within the hypothalamus–pituitary–adrenal (HPA) axis. The biosynthesis and secretion of ACTH are controlled by multiple factors, including corticotropin-releasing hormone (CRH). As a key hypothalamus-derived regulator, CRH binds to corticotropin-releasing hormone receptor 1 (CRHR1) in the anterior pituitary gland to regulate ACTH synthesis and release. Thus, CRH-binding protein (CRHBP), which binds CRH with high affinity to inhibit CRH-induced ACTH secretion from pituitary cells, draws wide attention. In contrast to the extensive investigation of CRHBP in mammals and other lower vertebrates, the gene structure, tissue expression and physiological functions of CRHBP in birds remain largely unknown. In the present study, using chicken (c-) as our animal model, we examined the gene structure, tissue expression and functionality of CRHBP. Our results showed that: (1) cCRHBP cDNA encodes a 345 amino acid precursor, which shares high sequence identity with that of mammals, reptiles, frogs and fish; (2) cCRHBP is abundantly expressed in the brain (cerebrum and hypothalamus), pituitary and ovary; (3) cCRHBP inhibits the signaling of cCRHRs induced by cCRH, thus reducing the cCRH-induced ACTH secretion from cultured chick pituitary cells; (4) stress mediators (e.g., glucocorticoids) and stress significantly upregulate CRHBP mRNA expression in chickens, supporting its role as a negative feedback regulator in the HPA axis. The present study enriches our understanding of the conserved roles of CRHBP across vertebrates. In addition, chicken is an important poultry animal with multiple economic traits which are tightly controlled by the HPA axis. The characterization of the chicken CRHBP gene helps to reveal the molecular basis of the chicken HPA axis and is thus beneficial to the poultry industry.

The Effects of Providing Outdoor Access to Broilers in the Tropics on Their Behaviour and Stress Responses

Simple Summary

The effects of outdoor access for broilers have been tested under temperate conditions, where free-range systems have begun to be widely used. However, under tropical conditions, where the birds may be heat-stressed outside, the benefits of providing a free-range area may be less evident. We compared whether access to an outdoor area improved behavior and several physiological welfare indicators of broilers at two stocking densities in a tropical environment. There were no major effects of outdoor access on broiler behavior, except that resting was reduced by providing outdoor access to older birds and those at low stocking densities inside. However, outdoor access increased heterophil numbers in summer, but not in winter, which may indicate heat stress. We concluded that the effects of outdoor access on the welfare of broilers in the tropics are dependent on season and stocking density.

Abstract

The effects of outdoor access, stocking density, and age on broiler behavior, stress, and health indicators in a tropical climate were assessed over two seasons, winter and summer. Two hundred and forty Cobb500 male chickens were allocated to one of four treatments, with six replicates of ten birds in each: low stocking density indoors with outdoor access (LO); high stocking density indoors with outdoor access (HO); low stocking density indoors without outdoor access (LI); and high stocking density indoors without outdoor access (HI). Scan sampling was used to record their behavior both indoors and outdoors. At 28 and 42 days old, blood samples were obtained to determine the heterophil to lymphocyte (H/L) ratio. At 42 days old, chickens were culled and inspected for footpad dermatitis (FPD), and bone quality was examined. Their spleens and bursas of Fabricius were collected and weighed, relative to carcass weight (RW). A factorial analysis was used to test the effects of season (winter or summer), outdoor access (with or without), stocking density (low: 5 animals/m² or high: 10 animals/m²), and age (28 or 42 days) on the behavior and stress and health indicators. There were no major effects of providing outdoor access on behavior, except that resting was reduced by providing outdoor access to older birds and those at low stocking densities inside. Resting was also greater in indoor and high-density treatments during winter. The bursa of Fabricius was heavier in summer in outdoor birds. The tibia bones were shorter in the outdoor birds. Heterophil numbers were greater in the outdoor treatments in summer but not in winter. These results indicate that outdoor access can increase activity in some situations, and potentially increase bone strength, but it may also increase the risk of stress, particularly heat stress in summer.

Bird Welfare in Zoos and Aquariums: General Insights across Industries

Animal welfare is a priority across accredited zoological institutions; however, historically, research has been prioritized for mammals. Bird-focused studies accounted for less than 10% of welfare research in zoos and aquariums over the last ten years. Due to the lack of scientific publications on bird welfare, zoo scientists and animal practitioners can look to other industries such as agriculture, laboratories, and companion animal research for insight. This qualitative review highlights findings across industries to inform animal care staff and scientists on the welfare needs of birds within zoos and aquariums. Specifically, the review includes an overview of research on different topics and a summary of key findings across nine resources that affect bird welfare. We also highlight areas where additional research is necessary. Future welfare research in zoos and aquariums should prioritize studies that consider a diversity of bird species across topics and work to identify animal-based measures with empirical evidence. Moving forward, research from other industries can help develop innovative research on bird welfare within zoos and aquariums.

Effects of Stocking Density on Growth Performance, Antioxidant Status, and Meat Quality of Finisher Broiler Chickens under High Temperature

Environmental factors such as stocking density and high temperature can cause oxidative stress and negatively affect the physiological status and meat quality of broiler chickens. Here, we evaluated the effects of heat stress on the growth performance, antioxidant levels, and meat quality of broilers under different stocking densities. A total of 885 28-day-old male broilers (Ross 308) were subjected to five treatments (16, 18, 21, 23, and 26 birds/m2) and exposed to high temperatures (33 °C for 24 h) for 7 days. High stocking density (23 and 26 birds/m2) resulted in significantly decreased body weight (p < 0.01) and superoxide dismutase activity in the blood (p < 0.05) and increased (p < 0.05) rectal temperature and corticosterone. Additionally, the concentrations of heat shock protein 70 and malondialdehyde in the liver were higher in the 26 birds/m2 group (p < 0.05). Similarly, the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of breast meat increased linearly as the stocking density increased (p < 0.05). There was increased shear force in breast meat at low stocking density (p < 0.01). Thus, lower stocking density can relieve oxidative stress induced by high temperatures in broilers and improve the antioxidant capacity and quality of breast meat during hot seasons.

The Impact of Curcumin on Growth Performance, Growth-Related Gene Expression, Oxidative Stress, and Immunological Biomarkers in Broiler Chickens at Different Stocking Densities

Simple Summary

The primary goal of global poultry production is to optimize the amount of chicken produced per square meter of floor area. Consequently, stocking density (SD) and curcumin supplementation on broiler performance were investigated. Our results revealed that supplemental curcumin improved birds’ growth, behaviours, and immunity by lowering oxidative stress, enhancing humoral immune response, and modulating the suppression of growth-related gene expressions in broilers raised in high stocking density circumstances.

Abstract

Curcumin’s antioxidant properties reduce free radicals and may improve broiler growth. Therefore, the influence of stocking density (SD) and administration of curcumin in the diet on broiler performance was explored to clarify the impact of HSD and curcumin on the performance of growth, behavioural patterns, haematological, oxidant/antioxidant parameters, immunity markers, and the growth-related genes expression in broiler chickens. A total of 200 broiler chickens (Cobb 500, 2-weeks old) were allotted into 4 groups; SD (moderate and high) and curcumin (100 and 200 mg/kg diet)-supplemented HSD, respectively. Behavioural observations were performed. After a 28-day experimental period, tissue and blood samples were collected for analysis. Expressions of mRNA for insulin-like growth factor-1 (IGF-1), growth hormone receptor (GHR), myostatin (MSTN), and leptin in liver tissues were examined. HSD birds exhibited lower growth performance measurements, haematological parameters, circulating 3,5,3-triiodothyronine and thyroxine levels, antioxidant activities (GSH-Px, catalase, superoxide dismutase), immunoglobulins (A, G, M), and hepatic GHR and IGF-1 expression values. However, HSD birds even had an increment of serum corticosterone, malondialdehyde, pro-inflammatory cytokine (TNF-a, IL-2, IL-6) levels, hepatic leptin and MSTN expression. Moreover, HSD decreased drinking, feeding, crouching, body care, and increased standing and walking behaviour. The addition of curcumin, particularly at a 200 mg/kg diet, alleviated the effect of HSD through amending growth-related gene expression in the chickens. In conclusion, curcumin can enhance birds’ growth performance, behavioural patterns, and immunity by reducing oxidative stress and up-regulating the growth-related gene expressions of broilers under stressful conditions due to a high stocking density.

Dietary strategies to alleviate high-stocking-density-induced stress in broiler chickens – a comprehensive review

Stocking broilers at a high density has been a strategy to optimize the area of the cage and hence increase the efficiency of broiler production. If the environmental (microclimate) conditions and rearing management are not properly managed, stocking broilers at a high density may, however, result in stressful conditions that are harmful for the production, health and welfare of broilers. To ameliorate these unfavorable effects of overcrowding stress, dietary interventions have been conducted. Probiotics, prebiotics, synbiotics, plant-derived products, vitamins, propolis, amino acids, fatty acids, etc. have been supplemented in diets to deal with the harmful impact of stress induced by a high stocking density of broilers. This review covers the detrimental effects of overcrowding-induced stress on broiler development and attempts to ameliorate those negative effects by dietary interventions.

Progress on Infrared Imaging Technology in Animal Production: A Review

Infrared thermography (IRT) imaging technology, as a convenient, efficient, and contactless temperature measurement technology, has been widely applied to animal production. In this review, we systematically summarized the principles and influencing parameters of IRT imaging technology. In addition, we also summed up recent advances of IRT imaging technology in monitoring the temperature of animal surfaces and core anatomical areas, diagnosing early disease and inflammation, monitoring animal stress levels, identifying estrus and ovulation, and diagnosing pregnancy and animal welfare. Finally, we made prospective forecast for future research directions, offering more theoretical references for related research in this field.

Dietary Germinated Paddy Rice and Stocking Density Affect Egg Performance, Serum Biochemical Properties, and Proteomic and Transcriptomic Response of Laying Hens Exposed to Chronic Heat Stress

Germinated paddy rice (GPR) could be a good alternative feed source for poultry with stocking density and heat stress problems. A total of 72 Hy-line Brown laying hens raised under low (LSD, 0.12 m2/bird) and high stocking densities (HSD, 0.06 m2/bird) were investigated. Three dietary GPR levels (0, 74 and 148 g/kg) were used. It was found that average daily feed intake, hen-day egg production, and egg mass significantly decreased in the HSD group. The levels of serum glucose (GLU), phosphorous (P), corticosterone (CORT), total Ig, lysozyme (LZY), and superoxide dismutase activities (SOD) in the HSD group were higher than those in the LSD group. Dietary GPR significantly affected GLU, P, alternative complement haemolytic 50 (ACH50), total Ig, and LZY. Moreover, CORT level significantly decreased in 74 and 148 g/kg dietary GPR groups, whereas SOD significantly increased only in the 148 g/kg dietary GPR group. Serum samples were analyzed using liquid chromatography-tandem mass spectrometry, and 8607 proteins were identified. Proteome analysis revealed 19 proteins which were enriched in different stocking densities and dietary GPR levels. Quantitative real-time reverse transcription-PCR technique was successfully used to verify the differentiated abundant protein profile changes. The proteins identified in this study could serve as appropriate biomarkers.

Environmental Stress in Chickens and the Potential Effectiveness of Dietary Vitamin Supplementation

Environmental stressors can promote the vulnerability of animals to infections; it is therefore, essential to understand how stressors affect the immune system, the adaptive capacity of animals to respond, and effective techniques in managing stress. This review highlights scientific evidence regarding environmental stress challenge models and the potential effectiveness of vitamin supplementation. The major environmental stressors discussed are heat and cold stress, feed restriction, stocking density, and pollutants. Much work has been done to identify the effects of environmental stress in broilers and layers, while few involved other types of poultry. Studies indicated that chickens' performance, health, and welfare are compromised when challenged with environmental stress. These stressors result in physiological alterations, behavioral changes, decreased egg and meat quality, tissue and intestinal damage, and high mortalities. The application of vitamins with other nutritional approaches can help in combating these environmental stressors in chickens. Poultry birds do not synthesize sufficient vitamins during stressful periods. It is therefore suggested that chicken diets are supplemented with vitamins when subjected to environmental stress. Combination of vitamins are considered more efficient than the use of individual vitamins in alleviating environmental stress in chickens.

Potential impact of stocking density on growth, carcass traits, indicators of biochemical and oxidative stress and meat quality of different broiler breeds

The aim of the current study to investigate the potential impact of different stocking densities on growth performance, carcass traits, indicators of biochemical and oxidative stress and meat quality of Arbor Acres and Ross-308 broiler breeds to recommend the better stocking density with low production cost simultaneously with high quality. A total of 312 one-day old of each Arbor Acres broiler and Ross-308 were randomly classified into 3 experimental groups with different stocking density, each of 6 replicates. The first group (SD1) was 14 birds/m2 (28 kg/m2), while the second group (SD2) was 18 birds/m2 (36 kg/m2) and the third group (SD3) was 20 birds/m2 (40 kg/m2). The growth performance, carcass traits, meat quality hematological and biochemical parameters were measured. SD3 group possessed the lowest body weight. Alanine transaminase in Arbor Acres was 15 and 14% higher in SD3 when compared with SD1 and SD2, respectively. While, was 21 and 20% of Ross-308, respectively. SD3 revealed the highest values of cholesterol, TG, MDA, and LDL of both breeds when compared with SD1 and SD2, with the lowest levels of HDL, GPX, and IGG. Birds of SD3 was the nastiest carcass weight 873 (P = 0.000) and 1,411.60 g (P = 0.000); dressing percentage 63.07 (P = 0.000) and 75.83% (P = 0.000); breast weight 513.10 g (P = 0.000) and 885.50g (P = 0.000); thigh weight 359.90 g (P = 0.000) and 526.08 g (P = 0.000) when compared with SD1 and SD2 of Arbor Acres and Ross-308, respectively. The dressing % of SD1 and SD2 was approximately 19% better than that of SD3 of Arbor Acres, while it was 4% of Ross-308. The cooking loss and drip loss of breast and thigh muscles were higher in SD3 of both breeds. Moreover, SD3 possessed the highest bacterial count. In conclusion birds reared in medium stocking density revealed better performance and welfare than high density but similar to low density. Therefore, from the economic point, medium density was the best.

Effects of stocking density on the performance, tibia mineralization, and the expression of hypothalamic appetite genes in broiler chickens

The current study investigated the effects of stocking density (SD) on the performance, tibia mineralization, and the hypothalamic appetite genes expression in broilers. A total of 2,800 1-d-old male broilers (Cobb 500) were distributed in a completely randomized design to 1 of 5 SD treatments with 8 replicate cages for each treatment. The SD treatments were 12.5, 15.0, 17.5, 20.0, and 22.5 birds/m2, corresponding to 50, 60, 70, 80, and 90 birds per cage (4 m2/cage), respectively. The concentration of tibia phosphorus was determined by the ammonium metavanadate colorimetric method and the mRNA abundance in different tissues was measured by the real-time quantitative PCR method. The data were analyzed by the one-way and/or two-way analysis of variance and polynomial contrasts were used to determine the effect of increasing SD. Feed intake linearly decreased (P < 0.05) with increasing SD during d 1-42 production period. On d 42, body weight and tibia breaking strength were significantly lower in the groups of 17.5, 20.0 and 22.5 birds/m2 than in the groups of 12.5 and 15 birds/m2 (P < 0.01). Concentrations of ash and phosphorus in the tibia of broilers linearly decreased (P < 0.03) with increasing SD on d 42. The SD of 22.5 birds/m2 decreased the mRNA abundance of neuropeptide Y (NPY), NPY-receptor (NPYR) 1, and NPYR2 (P < 0.05), while it increased melanocortin receptor 4 mRNA abundance (P = 0.012) in the hypothalamus of broilers as compared with the SD of 12.5 birds/m2 on d 21 and 42. The mRNA abundance of hypothalamic cocaine and amphetamine-regulated transcript (CART), corticotrophin-releasing factor (CRF), and CRF-receptor 1 (CRFR1) were higher (P < 0.05) in the group of 22.5 birds/m2 than in the group of 12.5 birds/m2 on d 21. We concluded that increasing stocking density beyond 15 birds/m2 (corresponding to the 45 kg/m2 at 42 days of age) suppressed final BW and bone mineralization of broilers raised in multitier cage system. Hypothalamic NPY and CRF signaling might be involved in the anorexigenic effect of HSD.

Serum clinical biochemical markers of Hy-Line W-36 laying hens under the influence of increased stocking densities in cages of multilevel batteries

Today, the organism of hens is constantly exposed to numerous technological stressors in the conditions of industrial poultry farming, the least studied of which are long-term, which can cause the development of chronic stress. One of such stressors is the increased stocking density of hens, which is also a way of saving resources in egg poultry and is often used by producers to obtain more eggs per 1 m2 of poultry area. The aim of this study was to examine the effect of overcrowding, as a factor of chronic stress development, on the body of hens of a modern high-performance cross, which is necessary to select the best ways to keep them. Four groups of hens were formed for this purpose, which were kept at different stocking densities, according to European standards, Ukrainian standards and with increasing overcrowding. In this way, the gradually increasing intensity of the technological stressor was modeled. Long-term keeping of laying hens at high stocking density did not affect the content in the serum of total protein, albumin, urea and cholesterol, which were within the physiological norm. It was found that the increase in the stocking density of hens to Ukrainian standards, compared to the European, was accompanied by an increase in the activity of lactate dehydrogenase in the serum of their blood. With an increase in stocking density above European and Ukrainian standards, namely to 25.3 birds/m2, there was an increase in the activity of three enzymes – lactate dehydrogenase, aspartate aminotransferase and gamma-glutamyltransferase. It is proved that further overcompaction of hens to 26.7 birds/m2 is accompanied by an increase in serum glucose, creatinine, as well as a decrease in the ratio of calcium and phosphorus, which was confirmed by an increase in alkaline phosphatase activity. Also, increased activity of aspartate aminotransferase, lactate dehydrogenase and gamma-glutamyltransferase was observed. Thus, the main effects of chronic stress caused by prolonged keeping of hens at high stocking densities are reflected in the biochemical parameters of their serum, namely in the increase of glucose, creatinine, enzyme activity, as well as the violation of the ratio of calcium and phosphorus.

Effect of encapsulated Cosmos caudatus leaf extract on the physiological conditions, immune competency, and antioxidative status of broilers at high stocking density

The present study aimed to investigate the effect of encapsulated Cosmos caudatus leaf extract on the physiological conditions, immune competency, and antioxidative status of broiler chickens raised at a high stocking density. After 15 days of rearing, 370 Lohmann broiler chicks were assigned to five treatment groups, including T0 (chicks were raised at a density of 10 birds/m2 and received no additive), T1 (chicks were raised at a density of 16 birds/m2 and received no additive), T2 (chicks were raised at a density of 16 birds/m2 and received 0.5 g/kg encapsulated C. caudatus leaf extract), T3 (chicks were raised at a density of 16 birds/m2 and received 1.0 g/kg additive), and T4 (chicks were raised at a density of 16 birds/m2 and received 1.5 g/kg additive). On days 28 and 42, blood samples from two chicks per pen were collected. On day 42, the chicks that had been blood-sampled were sacrificed, and blood samples and lymphoid organs (i.e., bursa of Fabricius, spleen, and thymus) were collected. The daily weight gain and feed efficiency of broilers (P < 0.01) in groups T2 and T3 were higher than those of broilers in groups T0, T1, and T4. Daily feed intake was greater (P < 0.01) in groups T0 and T1 than in groups T2 and T3. The erythrocyte content and hematocrit value of groups T1, T2, T3, and T4 were greater (P < 0.05) than those of group T0. The mean corpuscular hemoglobin concentration in group T4 was lower (P < 0.05) than that in groups T0, T1, and T2. Leukocyte and lymphocyte levels were higher in group T1 (P < 0.05) than in other groups. Serum albumin was higher in chicks reared at a high density (P < 0.05) than in chicks reared at a normal density. Lesion scores were higher in group T1 (P < 0.05) than in other groups. Chicks in groups T1 and T2 showed more severe pathological changes in their bursa of Fabricius compared with those in groups T0, T3, and T4. Serum superoxide dismutase was higher in groups T2, T3, and T4 (P < 0.05) than in groups T0 and T1. Chicks in group T4 had higher (P < 0.05) malondialdehyde levels than chicks in other groups. In conclusion, a high stocking density influences the metabolic rate and physiological conditions of broiler chicks, as reflected by alterations in the blood profiles of the animals. Stress due to a high stocking density could damage the bursa of Fabricius, but feeding with encapsulated C. caudatus leaf extract, especially at a rate of 1.5 g/kg, could alleviate the cortical and lymphocyte cell depletion of broilers. Regardless of the stocking density effect, dietary supplementation with encapsulated C. caudatus leaf extract at doses of 0.5 and 1.0 g/kg could improve the daily weight gain of broilers.

Performance and Meat Quality of Broiler Chickens Reared on two Different Litter Materials and at two Stocking Densities

1. This study evaluated the performance and meat quality of broiler chickens reared on two litter materials and at two stocking densities.2. The chicks were allotted in a completely randomised design in a 2 × 2 factorial arrangement with two litter materials (wood shavings or rice straw) and two stocking densities (24 or 30 kg/m²), with six replicates per treatment. Broiler performance, carcase yield, prime cuts, blood plasma proteins, the enzymes alanine aminotransferase and aspartate aminotransferase, edible viscera, immune organs, intestine weight and length, abdominal fat, breast meat colour, pH, weight loss by defrosting, weight loss by cooking and shear force were evaluated.3. The density of 24 kg/m² positively influenced feed consumption and weight gain. The type of litter had a positive influence on feed conversion, with a lower value for birds raised on wood shavings.4. Breast production was improved in birds reared at a density of 24 kg/m² when compared to birds reared at a density of 30 kg/m². The rice straw bedding negatively affected abdominal fat (resulting in higher percentages) when compared to birds reared on wood shavings.5. The types of litter affected the enzyme aspartate aminotransferase in birds raised on wood shavings, although these values were not increased to the point of influence on the physiological functions of broilers.6. The colour of the breast meat, pH, temperature, weight loss after thawing or cooking, shear force, cholesterol, triglycerides, albumin, total proteins, glucose or alanine aminotransferase content were not influenced by the stocking densities or bedding.7. The use of wood shavings as poultry bedding at a stocking density of 24 kg/m²resulted in the best performance for broiler chickens at 42 days of age.

Effects of different stocking densities on tracheal barrier function and its metabolic changes in finishing broilers

In the present study, we evaluated the effects of various stocking densities on the tracheal barrier and plasma metabolic profiles of finishing broilers. We randomly assigned 1,440 Lingnan Yellow feathered broilers (age 22 d) to 5 different stocking density groups (8 m-2, 10 m-2, 12 m-2, 14 m-2, and 16 m-2). Each of these consisted of 3 replicates. The interleukin (IL)-1β and IL-10 concentrations were substantially higher in the 16 m-2 treatment group than they were in the 8 m-2 and 10 m-2 treatment groups (P < 0.05). Nevertheless, IL-4 did not significantly differ among the 5 treatments (P > 0.05). The tracheal mucosae of the birds in the 16 m-2 group (high stocking density, HSD) were considerably thicker than those for the birds in the 10 m-2 group (control, CSD). Relative to CSD, the claudin1 expression level was lower, and the muc2 and caspase3 expression levels were higher for HSD. Compared with CSD, 10 metabolites were significantly upregulated (P < 0.05), and 7 were significantly downregulated (P < 0.05) in HSD. Most of these putative diagnostic biomarkers were implicated in matter biosynthesis and energy metabolism. A metabolic pathway analysis revealed that the most relevant and critical biomarkers were pentose and glucuronate interconversions and the pentose phosphate pathway. Activation of the aforementioned pathways may partially counteract the adverse effects of the stress induced by high stocking density. This work helped improve our understanding of the harmful effects of high stocking density on the tracheal barrier and identified 2 metabolic pathways that might be associated with high stocking density-induced metabolic disorders in broilers.

Role of dietary gamma-aminobutyric acid in broiler chickens raised under high stocking density

The present study was conducted to evaluate the effects of dietary gamma-aminobutyric acid (GABA) in broiler chickens raised in high stocking density (HSD) on performance and physiological responses. A total of 900 male broiler chicks (Ross 308) at 1 d old were assigned in a 2 × 2 factorial arrangement to 4 treatments (10 replicates per treatment) with stocking density, 7.5 birds/m² (low stocking density; LSD) or 15 birds/m² (HSD), and dietary GABA, 0 or 100 mg/kg. Chickens raised in HSD exhibited a decrease in body weight gain in all phases (P < 0.05) and feed intake in starter and whole phases (P < 0.01), and an increase in feed conversion ratio in the finisher phase (P < 0.01) compared with LSD-raised chickens. However, dietary GABA did not affect growth performance nor interacted with stocking density on production variables. The HSD vs. LSD increased relative liver weight on d 35 whereas dietary GABA increased relative liver weight and decreased relative bursa weight on d 21. Both stocking density and dietary GABA affected yield and quality of breast and leg muscles. Dietary GABA increased (P < 0.05) width of tibia on d 35 and interacted (P = 0.054) with stocking density on breaking stocking density on d 35. The HSD vs. LSD group lowered (P < 0.05) feather coverage scores. Significant interaction between stocking density and GABA on surface temperature of shank on d 21 was noted (P = 0.024). Dietary GABA exhibited an opposite effect on the concentrations of cecal short-chain fatty acids depending on stocking density leading to a moderate to significant interaction. Stocking density decreased alpha-1-acid glycoprotein whereas dietary GABA decreased heterophil-to-lymphocyte ratio and corticosterone in blood or serum samples. Serum biochemical parameters were altered by stocking density or dietary GABA. It is concluded that dietary GABA alleviated stress indices including corticosterone and heterophil-to-lymphocyte ratio, but failed to reverse stocking density-induced growth depression.

Antimicrobial Use in Broilers Reared at Different Stocking Densities: A Retrospective Study

Simple Summary

Broiler farms are authorized to house animals at different stocking densities (kg live weight/m²) provided that ammonia, carbon dioxide, temperature, and humidity levels are kept under specific limits set by European Union legislation. The role of stocking density on poultry health and welfare, and consequently on antimicrobial use, is still under debate. Herewith, we analyze veterinary prescription data for 2017 pertaining to a representative sample of Italian broiler farms that were authorized to house animals at 33 or 39 kg/m². The prescribed amounts of antimicrobials in each farm were converted into a total of Defined Daily Doses per year, a non-dimensional unit proposed by the European Medicines Agency (EMA). No differences in terms of antimicrobial use, mortality, and feed conversion rates were noted between the two considered groups, suggesting a minor role of stocking density on animal health and welfare.

Abstract

According to the Directive 2007/43/EC, broiler farms can house animals up to 39 kg/m², provided that specific environmental requirements are met. However, limited information is available about the effects of stocking density (SD) on broiler health and welfare, including the need for antimicrobial use. In this study, annual data on mortality, feed conversion rate, and antimicrobial use (AMU) are compared between broiler farms with stocking densities of 39 kg/m² (N = 257) and 33 kg/m² (N = 87). These farms were distributed throughout Italy and belonged to the same integrated poultry company. Antimicrobial use data were obtained from each farm and production cycle; AMU was expressed using the defined daily doses (DDD) method proposed by EMA. The annual AMU per farm was calculated as the median AMU over all cycles. Stratified analysis by sex and geographical area (Italy vs Northern Italy) showed no significant effect of stocking density on broiler mortality, feed conversion rate, and AMU. However, a higher AMU variability among farms with 39 kg/m² stocking density vs. those with 33 kg/m² was found. This study indicates that AMU does not apparently vary between animals reared at different stocking densities in intensive farms.

Transforming the Adaptation Physiology of Farm Animals through Sensors

Simple Summary

Strategy for the protection and welfare of farm animals, and the sustainable animal production is dependent on the thorough understanding of the adaptation physiology. Real-time, continuous, and precise measurement of the multi-dimensions and complex intricacies of adaptive capacity of farm animals namely the mental, behavioral, and physiological states are possible only through the sensor-based approaches. This paper critically reviews the latest sensor technologies as assessment tools for the adaptation physiology of farm animals and explores their advantages over traditional measurement methods. Digital innovation, diagnostics, genetic testing, biosensors, and wearable animal devices are important tools that enable the development of decision support farming platforms and provides the path for predicting diseases in livestock. Sensor fusion data from a multitude of biochemical, emotional, and physiological functions of the farm animals not only helps to identify the most productive animal but also allows farmers to predict which individual animal may have greater resilience to common diseases. Insights into the cost of adoption of sensor technologies on farms including computing capacity, human resources in training, and the sensor hardware are being discussed.

Abstract

Despite recent scientific advancements, there is a gap in the use of technology to measure signals, behaviors, and processes of adaptation physiology of farm animals. Sensors present exciting opportunities for sustained, real-time, non-intrusive measurement of farm animal behavioral, mental, and physiological parameters with the integration of nanotechnology and instrumentation. This paper critically reviews the sensing technology and sensor data-based models used to explore biological systems such as animal behavior, energy metabolism, epidemiology, immunity, health, and animal reproduction. The use of sensor technology to assess physiological parameters can provide tremendous benefits and tools to overcome and minimize production losses while making positive contributions to animal welfare. Of course, sensor technology is not free from challenges; these devices are at times highly sensitive and prone to damage from dirt, dust, sunlight, color, fur, feathers, and environmental forces. Rural farmers unfamiliar with the technologies must be convinced and taught to use sensor-based technologies in farming and livestock management. While there is no doubt that demand will grow for non-invasive sensor-based technologies that require minimum contact with animals and can provide remote access to data, their true success lies in the acceptance of these technologies by the livestock industry.

Assessment of Stocking Rate and Housing System on Performance, Carcass Traits, Blood Indices, and Meat Quality of French Pekin Ducks

Commercial practice in poultry production management has been susceptible to increased problems, driven by concerns about safety of food and animal welfare. Thus, the main proposal of the present study was to evaluate the influence of different stocking densities on performance, blood, and carcass traits of Pekin ducklings reared on two different floor types (wood shaving litter, WSL or plastic slatted floor, PLS). A total of 450 one-day-old ducklings were randomly allocated into six equal experimental groups stocking density (nine, 15 and 21 birds/m2 during the first 14 d and three, five and seven birds/m2 until 49 days) reared on two floor types (WSL and PLS), five replicate pens each. Increased stocking density reduced body weight (BW), weight gain (WG), and feed conversion ratio (FCR) values and increased feed intake (FI) in both floor types at 14 days old. At 49 days old, reared ducklings on PLS type verified higher BW and WG and reduced FCR values. Moreover, increasing stocking density in both floor types significantly reduced the breast, thigh, and left fillet percentages. Conversely, reared birds floored on PLS system decreased the triglycerides (TG) and increased the total cholesterol (TC) serum content. Furthermore, the meat contents of TG and TC were decreased in birds reared on higher stocking density but not affected by floor type. Further, serum antioxidant indices were reduced in PLS birds on low stocking densities. In conclusion, housing Pekin ducklings on PLS improved their growth performance, carcass traits, meat cholesterol, and antioxidant status, particularly at stocking density of three and five birds/m2.

Effects of Outdoor Access and Indoor Stocking Density on Behaviour and Stress in Broilers in the Subhumid Tropics

Studies investigating the welfare of commercial-line broiler chickens raised in houses with outdoor access in the tropics are scarce, and none have investigated whether responses vary according to indoor conditions. Hence, we assessed the effects of providing outdoor access at two indoor stocking densities on broiler chickens' growth, behaviour, stress responses and immunity in a tropical region of Mexico. One hundred and sixty chickens were assigned to one of four treatments in a factorial design: with or without outdoor access and low or high stocking density indoors. Ad libitum sampling was used to build a purpose-designed ethogram. Scan sampling was used to record the number of birds engaged in each activity of this ethogram, both indoors and outdoors. Heterophil/lymphocyte (H/L) ratio and serum corticosterone levels were tested in weeks four and six of age. When the birds were 42 days old, they were slaughtered, and the bursa and spleen harvested and weighed. In an interaction between stocking density and outdoor access, birds at the high stocking density with no outdoor pens spent the least time walking and preening and more time lying (p < 0.05). Birds given outdoor access foraged more, but only at indoor low stocking densities (p < 0.05). Outdoor access reduced heterophil/lymphocyte ratio, indicating reduced stressor response. Birds with low stocking density indoors and outdoor access appeared more responsive to stressors, with elevated corticosterone and reduced spleen and bursa weights (p < 0.05). There were welfare benefits of outdoor access, principally in terms of increased activity, which were reflected in slower growth in the birds with outdoor access.

On-farm broiler chicken welfare assessment using transect sampling reflects environmental inputs and production outcomes

To evaluate the utility of transect sampling for assessing animal welfare in large chicken flocks, we quantified relationships between environmental inputs, welfare problems detected using transect sampling, and production outcomes. We hypothesised that environmental inputs including environmental complexity (i.e. number of environmental enrichment types provided), space allowance, underfloor heating (presence or absence), and photoperiod regimen (18 h continuous vs 16 h intermittent) would correspond to variations in welfare assessment findings, which would predict production outcomes. We conducted on-farm welfare assessment of Norwegian broiler flocks at approximately 28 days of age. We sampled four transects (rows between feeder and drinker lines) per flock to determine litter quality and the proportions of chickens with compromised welfare as indicated by visual signs of walking difficulties, illness, skin wounds and small bird size. Production outcome measures included mortality, reasons for carcass rejection at slaughter, footpad dermatitis, growth rate, feed conversion and an integrated production index. Greater environmental complexity was associated with a reduction in skin wounds and total welfare problems on the farm, lower mortality, fewer rejections due to wounds and underweight birds, and fewer rejections overall. Higher space allowances within levels of environmental complexity were associated with fewer walking difficulties and welfare problems overall, a reduction in rejections due to wounds, and a higher growth rate and production index. Underfloor heating was associated with a reduction in rejections due to leg deformity, and intermittent light was associated with lower illness and skin wound rates on the farm, and lower mortality. Furthermore, fewer welfare problems and better litter quality on the farm were associated with fewer carcass rejections at slaughter. Thus, data from transect sampling varied with environmental inputs and production outcomes, supporting the validity of transect sampling for practical, animal-based on-farm welfare assessment.

The utility of infrared thermography for evaluating lameness attributable to bacterial chondronecrosis with osteomyelitis

Bacterial chondronecrosis with osteomyelitis (BCO) is a leading cause of lameness in broilers. Infrared thermography (IRT) is a noninvasive technique for measuring infrared radiation from an object and can be used to evaluate clinical health. Two replicated studies compared the effect of light intensity on broilers grown on a wire flooring model that experimentally increased their susceptibility to and incidence of BCO lameness. Day-of-hatch male broiler chickens were placed into 6 pens on wood shavings litter, and at 1 wk one of 3 light intensity treatments (2, 5, or 10 lux) was allotted. At 4 wk half of the population from each pen was moved to a pen with wire flooring and the same light intensity. At 1, 4, 5, and 8 wk, an IRT image of the legs of 5 clinically healthy broilers from each pen was taken. The right and left proximal femora and tibiae of sound and lame broilers were scored for femoral head necrosis (FHN) and tibial head necrosis (THN) lesion severity. There were minimal effects of light intensity and flooring. In Study 1, but not Study 2, broilers on wire flooring weighed less on day 38 (P = 0.007) and days 57 to 58 (P = 0.003) compared to those on litter. The proportion of broilers that became lame on wire flooring was 52% in Study 1 and 14% in Study 2. The proportion of sound broilers from litter and wire flooring pens with subclinical signs of BCO in their right or left proximal growth plates was over 45% for FHN and 92% for THN, and lame broilers had more severe (P < 0.0001) FHN and THN compared to sound broilers. IRT surface temperatures of the hock joint, shank, and foot were consistently lower (P < 0.0001) in broilers that became lame when compared to sound. Therefore, IRT surface temperatures of broiler leg regions may be useful for detecting lesions attributed to BCO.

Effect of stocking density on behavioral traits, blood biochemical parameters and immune responses in meat ducks exposed to heat stress

High stocking density (HSD) and heat stress (HS) caused by climate change can lower blood homeostasis and negatively impact the behavioral traits of animals. The objective of this study was to explore the influence of stocking densities on behavioral traits, blood parameters, immune responses, and stress hormones in meat ducks (Cherry valley, Anas platyrhynchos) exposed to HS. A total of 320 meat ducks were assigned to four groups with different stocking densities using a randomized complete block design. The ducks were then reared for 42 days. The assigned density groups were as follows: (1) control group (CON, three birds m- 2 , normal environmental heat conditions); (2) low stocking density (LSD, three birds m- 2 , heat stress conditions); (3) medium stocking density (MSD, four birds m- 2 , heat stress conditions); and (4) high stocking density (HSD, six birds m- 2 , heat stress conditions). To induce HS, the environment of the poultry house was set to a temperature of 34 ± 2 ∘ C with a relative humidity of 70 % from 11:00 to 16:00 for the finisher period (from day 22 to day 42 of the rearing period). Concentrations of blood triacylglycerol, total cholesterol, low-density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were higher in the HS groups compared with the CON group, with HSD showing the highest levels ( P < 0.05 ). The concentrations of high-density lipoprotein cholesterol (HDL-C) and glucose were lower in the HSD groups than in the CON group ( P < 0.05 ). Red blood cell (RBC) and platelet (PLT) counts were lower in HS groups compared with the CON group, with the HSD group displaying the lowest counts ( P < 0.05 ). Blood pH values were also higher in the HS groups than in the CON group, with the highest values observed in the HSD group ( P < 0.05 ). Concentrations of blood p CO 2 ,HCO 3 , and T CO 2 were higher in the HS groups than in the CON group, with HSD showing the lowest levels ( P < 0.05 ). The concentration ofPO 2 was higher in CON than in any of the HS groups, with the lowest levels found in the HSD group ( P < 0.05 ). The concentrations of blood IgG and corticosterone were increased in the HS groups compared with the CON group ( P < 0.05 ). Animal behavioral trait scores were also higher in HS groups than in the CON group ( P < 0.05 ); these scores were the highest in the HSD group. Overall, animal behavioral traits, blood biochemical parameters, and immune responses in meat ducks exposed to heat stress were highest in the HSD group, but not significantly different between the LSD or MSD groups.

Effects of fumonisin B1 and mycotoxin binders on growth performance, tibia characteristics, gut physiology, and stress indicators in broiler chickens raised in different stocking densities

The present study was carried out to investigate the effects of stocking density, fumonisin B1 (FB), and mycotoxin binder (TB) on growth performance, bone quality, physiological stress indicators, and gut health in broiler chickens. Day-old Ross 308 male broiler chicks (n = 1,440/experiment) were randomly allocated to 72 floor pens in a 3 × 2 × 2 factorial arrangement, using 3 stocking densities (12.5 birds/m2 [HSD], 10 birds/m2 [MSD], or 7.5 birds/m2 [LSD]), 2 levels of purified FB (0 or 10 ppm), and 2 levels of TB (0 or 0.2%). Each treatment had 6 replicates (n = 6/treatment) and experiments lasted 34 days. All data were analyzed using 3-way ANOVA with stocking density level, FB, and TB as main factors. Body weight gain and feed intake were lower (P < 0.05) in broilers kept at HSD and MSD compared to LSD-housed counterparts. Birds fed an FB-contaminated diet exhibited a higher feed-to-gain ratio compared with those fed an FB-free diet (P < 0.05). None of the treatments affected intestinal morphology or ileal secretory immunoglobulin A levels. Stocking density affected tibia breaking strength (P < 0.05), which was lower in chickens housed at HSD compared with LSD-housed chickens. The heterophil/lymphocyte ratio (H/L ratio) was elevated (P < 0.05) in HSD and MSD groups compared with the LSD group. Serum nitric oxide (NO) levels were elevated (P < 0.05) in chickens fed the FB-contaminated diet compared with the control diet-fed counterparts. Significant interaction (P < 0.05) between FB and TB on serum NO levels was noted. In summary, increasing stocking density lowered growth performance and bone quality, but increased the H/L ratio. Dietary TB did not affect FB-induced increases in the feed-to-gain ratio. No interaction was observed between stocking density and FB for the measured variables.

Effects of genotype and stocking density on broiler performance under three feeding regimes

Ross 308 and Cobb Avian 48 broilers were used in a 49-day study. The effects of genotype, stocking density, and limited-time feeding on growth performance and carcass characteristics were investigated. Overall, Ross consumed more feed, gained more body weight, and was heavier at marketing age than Cobb. Ross also had a higher drumstick percentage, but the percentages of the other carcass parts were similar in the two genotypes. Birds reared at the stocking density of 30 kg BW/m(2) gained more body weight and were heavier at marketing than those raised at 40 kg BW/m(2), but both groups consumed similar quantities of feed and had similar carcass percentages. Neither genotype nor stocking density influenced feed conversion ratio and mortality rate, but genotype x stocking density interaction significantly affected feed consumption and mortality rate. The feed-restricted birds consumed less feed, gained less weight, were lighter at market age, and had lower percentages of breast, neck, and heart than the full-fed birds. Feed restriction also significantly lowered mortality rate but had insignificant effects on feed conversion ratio and percentages of carcass, breast, back, drumstick, neck, wing, gizzard, heart, liver, and abdominal fat. For profitable poultry production in the tropics and subtropics, it is recommended that Ross 308 raised at the stocking density of 30 kg BW/m(2) and subjected to 10-h daily feed removal from 7 to 35 days of age in a 49-day production period be considered.