Effects of different rearing systems on growth, small intestinal morphology and selected indices of fermentation status in broilers

Effect of rearing systems on immune status, stress parameters, intestinal morphology, and mortality in conventional and local chicken breeds

The majority of poultry meat used to be sourced from intensively housed birds. However, consumer preference has since demanded poultry producers develop more sustainable farming systems. Although free-range farming is considered beneficial for animal welfare, it is not as easy to standardize as an intensive system, which makes the choice of bird genotype appear crucial for alternative systems. In this study, we aimed to evaluate the effect of conventional and free-range rearing systems on the immune status, stress parameters, intestinal morphology and mortality in commercial hybrids (Ross 308) and local poultry strains, Bionda Piemontese (BP), Robusta Maculata (RM), BP x Sasso (BPxS), and RM x Sasso (RMxS). RNA was extracted from the jejunum and spleen to assess the mRNA expression of IL-2, IL-6, IL-10, IL-18, IL-1β, inducible nitric oxide synthase (iNOS), toll-like receptor (TLR)-4, and interferon gamma (IFN-γ). The heterophil:lymphocyte (H/L) ratio and intestinal histomorphometric evaluation were also calculated. We found that compared to the conventional system, the rearing system significantly affected the jejunum expression of IL-10, iNOS, IL-2, and IL-6, where these genes were upregulated in free-range system. A significant interaction between the rearing system and the genotype was also shown. More specifically, local breeds showed a significantly higher expression (P < 0.001) of IL-6 in the free-range system compared to the same genotypes in the conventional system. Moreover, IL-6 is constantly upregulated in local breeds within the free-range system compared to Ross hybrids. We also found significantly increased H/L and mortality rates in the latter, compared to the local breeds in the free-range reared system. The jejunum morphology also demonstrated a significantly higher villus height in BP and BPxS compared to the Ross hybrids. Overall, the results of our study confirm that the intense selection for growth in broiler chickens may have reduced their ability to react to the environmental stimuli related to free-range systems, resulting in a lower adaptability to a free-range environment, thus making them inappropriate for any farming system other than the conventional one. On the contrary, local chicken breeds are able to adapt and survive in the free-range system of rearing, and represent a genetic resource especially when adaptability to free-range conditions is required.

Global waterfowl production: stocking rate is a key factor for improving productivity and well-being-a review

Waterfowl is an important animal-protein source, which has the potential to get a bigger share in the animal production sector. However, waterfowl farming practices and welfare standards are not well established yet. Stocking rate is one of the farming standards that can enhance the productivity, behavior, and well-being of birds; however, rare studies are available in this area. Thus, this article (1) gives an overview of the recent global waterfowls' meat and egg production and their population distribution, (2) reviews the effects of stocking rate on social, feeding, and sexual behaviors, (3) shows the effects of stocking rate on growth performance, carcass weight, and meat quality of ducks and geese, and (4) declares the relationship between the stocking rate and egg production. Conclusively, an optimal stocking rate standard can improve behaviors, productivity (meat-egg), and meat quality. Moreover, using weight (kg)/m2 will help in affording the required space allowance for different ducks and geese under various housing systems. The fish-waterfowl production system could be a promising and sustainable solution for increasing waterfowl production, maintaining the welfare of birds, saving energy, and reducing the water footprint of waterfowl meat. Based on prior research findings, we recommended adopting the stocking rate (SR) standard for specific duck and goose breeds to achieve an optimal production-welfare balance.

Effects and Mechanisms of Cage versus Floor Rearing System on Goose Growth Performance and Immune Status

Currently, FRS and CRS are the two predominant dryland rearing systems in the goose industry. However, the effects of these two systems on goose growth performance and health, as well as the underlying mechanisms, have not been fully clarified. Thus, this study aimed to compare growth performance and immune status, as well as investigate the genome-wide transcriptomic profiles of spleen in geese, between CRS and FRS at 270 d of age. Phenotypically, the body weight and body size traits were higher in geese under FRS, while the weight and organ index of spleen were higher in geese under CRS (p < 0.05). Noticeably, the bursa of Fabricius of geese under FRS was degenerated, while that under CRS was retained. At the serum level, the immune globulin-G (IgG) and interleukin-6 (IL-6) levels were higher in geese under CRS (p < 0.05). At the transcriptomic level, we identified 251 differentially expressed genes (DEGs) in the spleen between CRS and FRS, which were mainly enriched in scavenger receptor activity, inflammatory response, immune response, neuroactive ligand-receptor interaction, phenylalanine metabolism, ECM receptor interaction, calcium signaling pathway, phenylalanine, tyrosine, and tryptophan biosynthesis, regulation of actin cytoskeleton, and MAPK signaling pathways. Furthermore, through protein-protein interaction (PPI) network analysis, ten candidate genes were identified, namely, VEGFA, FGF2, NGF, GPC1, NKX2-5, FGFR1, FGF1, MEIS1, CD36, and PAH. Further analysis demonstrated that geese in CRS could improve their immune ability through the "phenylalanine metabolism" pathway. Our results revealed that the FRS improved growth performance, whereas the CRS improved goose immune function by increasing levels of IL-6 and IgG in serum. Moreover, the phenylalanine metabolism pathway could exert positive effects on immune function of geese under CRS. These results can provide reliable references for understanding how floor and cage rearing systems affect goose growth performance and immune capacity.

Effects of Different-Sized Cages on the Production Performance, Serum Parameters, and Caecal Microbiota Composition of Laying Hens

The effects of four different-sized cages—huge (HC), large (LC), medium (MC), and small (SC) cages—on the productive performance, serum biochemical indices, and caecal microbiota composition of Roman laying hens were investigated. At 44 weeks of age, a total of 450 hens were selected and allocated to the four groups, with six replicates each. Equal stocking density (0.054 m2 per bird) was maintained among the four groups throughout the experiment, and number of birds/cage changed for each treatment. After 2 weeks of preliminary trial, the formal experiment was performed from 46 to 60 weeks of age. The laying rate and feed conversion ratio (FCR) were determined daily, antibody titres were measured every 3 weeks, and serum biochemical parameters and caecal microbiota composition were analysed at 60 weeks of age. Compared to HC and SC, the higher laying rate and lower FCR in MC and LC indicated positive effects on egg production and feed efficiency, while SC showed the highest body weight gain (p < 0.05). With increasing cage size, the serum triglycerides (TG) and total cholesterol (T-CH) levels were reduced, and serum glutathione peroxidase (GSH-Px) activity improved, where birds raised in HCs had the lowest serum TG and T-CH and the highest GSH-Px activity. Twenty-nine different phyla and 301 different genera were detected in the caecal microbiota of birds in the four groups. Methanobrevibacter was significantly higher in the SC than in the other groups (p < 0.05). Faecalibacterium was most abundant in the MC compared with the other groups (p < 0.05) and was significantly positively correlated with serum GSH-Px concentration (R = 0.214, p = 0.0017). Lactobacillus was significantly less abundant in the LC and MC than in the HC and SC groups (p < 0.05) and was significantly positively correlated with body weight (R = 0.350, p = 0.0009) but negatively correlated with laying rate and FCR. In conclusion, MC were superior to HC and LC in improving feed conversion efficiency and caecal microflora composition compared to the SC. An appropriate increase in cage size is beneficial to laying hen production and health.

Untargeted metabolomics reveals the effect of rearing systems on bone quality parameters in chickens

The objective of this study was to investigate the effects of rearing systems on the bone quality parameters in chickens using a metabolomics strategy. A total of 419 male one-day-old chicks were randomly allocated to two groups, a floor rearing group (FRG, n = 173) and a cage rearing group (CRG, n = 246). At 6, 8, 10, and 12 weeks of age, all chickens were radiographed by a digital X-ray machine, and body weight was recorded. At 12 weeks of age, 12 birds were selected from each group to obtain tibia and femur, and bone quality parameters of bone mineral density (BMD), mineral content (BMC), breaking strength (BBS), stiffness, Young's modulus (YM), ash content, calcium content, and phosphorus content were determined. An untargeted metabolomics assay was performed to identify changes in the serum metabolic profile (n = 8 birds/group). The results showed that cage-reared chickens had wider tibiae and greater body weight compared with floor-reared chickens. There were no significant differences in BMC or BBS between the two groups (p > 0.05), but BMD, ash content, calcium content, and phosphorus content of the tibia and femur of FRG were significantly higher than those of CRG (p < 0.05). Greater stiffness and YM of the femur were also observed in birds raised in the FRG compared with those raised in the CRG (p < 0.05). Taken together, the results suggest that rearing systems affected bone quality parameters. Furthermore, 148 and 149 differential metabolites were identified in positive and negative ion modes by LC-MS/MS analysis, among which 257 metabolites were significantly correlated with 16 bone quality parameters, including leucine, myristoleic acid, glycocholic acid, and N-phenylacetamide. KEGG analysis indicated that 15 metabolic pathways, including six pathways of amino acid metabolism, two pathways of lipid metabolism, and two pathways of carbohydrate metabolism, were responsible for bone quality. Overall, the present study demonstrated the effect of rearing systems on bone quality parameters, and identified several metabolites and metabolic pathways associated with bone quality parameters.

Egg-laying capacity of parent flock geese at different stocking densities

This article presents the results of studies aimed at establishing the optimal stocking density of purebred and hybrid geese of the parent flock, taking into account the indicators of their live weight and egg production. When conducting research, the stocking density of geese was established depending on the breed and shape. Different stocking densities of geese in groups were achieved due to their different numbers in groups: Kuban 1.2; 1.5; 1.8 birds/m² , large gray 0.9; 1.2; 1.5 birds/m² , hybrid bird 1.0; 1.3; 1.5 birds/m² . It was revealed on the basis of the analysis of the productive qualities of adult geese that the optimal planting density of the Kuban geese is 1.8 heads/m² , large sulfur = 0.9, hybrid = 1.3. The safety of geese at a given stocking density ensured an increase in the safety of geese of the Kuban breed by 95.3%, large gray = 94.0%, hybrid = 97.0%. The live weight of Kuban geese increased by 0.9%, large gray geese = 0.10, hybrids = 1.2, egg production by 0.6%, 2.2% and 0.5%, respectively.

Effects of rearing system and antibiotic treatment on immune function, gut microbiota and metabolites of broiler chickens

BACKGROUND

In China, cage systems with a high space utilization have gradually replaced ground litter systems, but the disease incidence of chickens in cages is higher. Broilers in the ground litter pens may be stimulated by more environmental microbes during the growth process and show strong immune function and status, but knowledge of which microbes and their metabolites play an immunomodulatory role is still limited. This study aimed to explore the differences and correlations in the immune function, gut microbiota and metabolites and the importance of gut microbiota of broilers raised in cages and ground litter pens.

METHODS

The experiment involved a 2 × 2 factorial arrangement, with rearing systems (cages or ground litter pens) and antibiotic treatment (with or without broad-spectrum antibiotics in drinking water) as factors.

RESULTS

The results showed that, compared with the cage group, the ground litter broilers had stronger nonspecific immune function (Macrophages% and NO in blood), humoral immune function (IgG in blood, LPS stimulation index in ileum) and cellular immune function (T%, Tc%, ConA stimulation index and cytokines in blood). Antibiotic (ABX) treatment significantly reduced nonspecific immune function (Macrophages% and NO in blood, iNOS and Mucin2 mRNA expression in ileum), humoral immune function (IgG in blood and sIgA in ileum) and cellular immune function (T% and cytokines in blood, Th and Tc ratio, TLRs and cytokines mRNA expression in ileum). Furthermore, the ground litter broilers had higher α diversity of microbiota in ileum. The relative abundance of Staphylococcus, Jeotgalicoccus, Jeotgalibaca and Pediococcus in the ileum of ground litter broilers were higher. ABX treatment significantly reduced the α diversity of ileal microbiota, with less Chloroplast and Mitochondria. In addition, the levels of acetic acid, isobutyric acid, kynurenic acid and allolithocholic acid in the ileum of ground litter broilers were higher. Spearman correlation analysis showed that Jeotgalibaca, Pediococcus, acetic acid, kynurenic acid and allolithocholic acid were related to the immune function.

CONCLUSIONS

There were more potential pathogens, litter breeding bacteria, short-chain fatty acids, kynurenine, allolithocholic acid and tryptophan metabolites in the ileum of broilers in ground litter pens, which may be the reason for its stronger immune function and status.

Chicken jejunal microbiota improves growth performance by mitigating intestinal inflammation

Background

Intestinal inflammation is prevalent in chicken, which results in decreased growth performance and considerable economic losses. Accumulated findings established the close relationship between gut microbiota and chicken growth performance. However, whether gut microbiota impacts chicken growth performance by lessening intestinal inflammation remains elusive.

Results

Seven-weeks-old male and female chickens with the highest or lowest body weights were significantly different in breast and leg muscle indices and average cross-sectional area of muscle cells. 16S rRNA gene sequencing indicated Gram-positive bacteria, such as Lactobacilli, were the predominant species in high body weight chickens. Conversely, Gram-negative bacteria, such as Comamonas, Acinetobacter, Brucella, Escherichia-Shigella, Thermus, Undibacterium, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium were significantly abundant in low body weight chickens. Serum lipopolysaccharide (LPS) level was significantly higher in low body weight chickens (101.58 ± 5.78 ng/mL) compared with high body weight chickens (85.12 ± 4.79 ng/mL). The expression of TLR4, NF-κB, MyD88, and related inflammatory cytokines in the jejunum was significantly upregulated in low body weight chickens, which led to the damage of gut barrier integrity. Furthermore, transferring fecal microbiota from adult chickens with high body weight into 1-day-old chicks reshaped the jejunal microbiota, mitigated inflammatory response, and improved chicken growth performance.

Conclusions

Our findings suggested that jejunal microbiota could affect chicken growth performance by mitigating intestinal inflammation.

Role of Physiology, Immunity, Microbiota, and Infectious Diseases in the Gut Health of Poultry

“Gut health” refers to the physical state and physiological function of the gastrointestinal tract and in the livestock system; this topic is often focused on the complex interacting components of the intestinal system that influence animal growth performance and host-microbial homeostasis. Regardless, there is an increasing need to better understand the complexity of the intestinal system and the various factors that influence gut health, since the intestine is the largest immune and neuroendocrine organ that interacts with the most complex microbiome population. As we face the post-antibiotic growth promoters (AGP) era in many countries of the world, livestock need more options to deal with food security, food safety, and antibiotic resilience to maintain agricultural sustainability to feed the increasing human population. Furthermore, developing novel antibiotic alternative strategies needs a comprehensive understanding of how this complex system maintains homeostasis as we face unpredictable changes in external factors like antibiotic-resistant microbes, farming practices, climate changes, and consumers’ preferences for food. In this review, we attempt to assemble and summarize all the relevant information on chicken gut health to provide deeper insights into various aspects of gut health. Due to the broad and complex nature of the concept of “gut health”, we have highlighted the most pertinent factors related to the field performance of broiler chickens.

Effect of stocking density and age on physiological performance and dynamic gut bacterial and fungal communities in Langya hens

Background

The characterization of colonization and dynamic changes related to gut microorganisms might be vital, as it presents an opportunity to quantify the co-variation between stocking densities and gut microbiome of dynamic distribution. The objective of this study was to determine the stocking density on physiological performance and dynamic distribution of gut microbiome (including bacterial and fungal communities) of Langya laying hens in the two development stages.

Methods

A randomized design with 2 × 3 factorial controls consisting of two development stages (24, 43 weeks-old) with three different stocking densities was performed. Three different stocking densities were allocated to a total of 300 11-week-old Langya laying hens (450 cm²/bird, 675 cm²/bird, 900 cm²/bird). Three housing densities were accomplished by raising different chickens per cage with the same floor size. The dependent variables of stocking densities at each sampling point were; growth performance, organs index, egg quality and the changes of dynamic gut bacterial and fungal communities in the cecum.

Results

Results showed that the stocking density didn’t affect liver index, eggshell thickness, breaking shell strength and egg shape index. Hens from the highest stocking density had the lowest body weight, fallopian tube index, egg weight and yolk colour score. Except for the yolk colour score, the measurement changes caused by age followed the opposite pattern as stocking density. We observed a substantial rise in taxa linked with health threats when stocking density was increased, including Talaromyces, Oscillospiraceae_UCG-002, Oscillospira, and Dielma. The opposite was observed with Bacteroides, Bifidobacterium, Lachnoclostridium, Eisenbergiella, and Kurtzmaniella. Also, most taxa were linked to polymicrobial infection in clinical cases, especially species whose percentage declined as the hens aged, such as Terrisporobacter, Faecalicoccus, Dialister, Cylindrocarpon etc. Whereas Sellimonas, Mitsuokella, Eurotium, Wardomyces and Cephalotheca had the opposite trend.

Conclusion

We speculated that excessive high density drove the abundance of bacteria and fungi connected with health problems. Where the gut microecology gradually reach a mature and balance status with age. Overall, this study demonstrates gut microbiome ecological processes in Langya layers at various stocking densities and finds possible connections between stocking density, microbiome and production performance. Our study will contribute to new insights associating suitable density patterns and production performance in laying hens by harnessing such a relative microbiome.

The importance of nutrition in alleviating high stocking density stress in poultry

In recent decades, the number of birds reared per unit area has dramatically spiked to increase profitability in egg and meat production. However, nowadays, the increase in sensitivity to animal welfare and consumer demands brings along with it a raised interest in stocking density. Stocking density is defined either as the number of animals or body weight per unit area or as the area per animal. High stocking density, which is a stress factor, can be defined as an increase in the number of animals per unit area or a decrease in the area per animal. Stress caused by high stocking density negatively affects the bird’s physiology and performance as well as the quality of the product obtained. The ideal stocking density should be 9 laying hens, 35 kilogrammes for broilers, and 45 quails per square metre. Otherwise, one will observe stress indicators in birds reared in more than the recommended stocking density per unit area and, consequently, a decrease in bird growth, egg production, feed efficiency, and egg or meat quality. Apart from increasing the concentrations of amino acids such as lysine, methionine, tryptophan and arginine, minerals such as selenium and chromium, and vitamins such as C and E in the diet, the addition of additives such as probiotics, humates, phytophenol compounds, and propolis is also effective in reducing or eliminating these negative effects caused by high stocking density. As a result, regulations in the nutrition of animals are effective in reducing/preventing such negative effects, thus improving animal welfare and ensuring the maintenance of optimum yield.

Different Non-cage Housing Systems Alter Duodenal and Cecal Microbiota Composition in Shendan Chickens

Housing systems are among the most important non-genetic factors affecting hen production performance and intestinal microbes. With increased interest in animal welfare, cage-free laying hen housing systems have become common, providing behavioral freedom and health benefits. The present study aimed to compare the effects of plastic net housing system (NRS) and floor litter housing system (LRS) on the composition and function of the duodenal and cecal microbiota in Shendan chicken, one of the most popular laying hen strains in China. The associations between the differential microbiota abundance and production traits and intestinal morphological parameters were determined. Compared with the LRS, the NRS improved the laying rate (p < 0.05) and increased the villus height (VH) of the duodenum (p < 0.05) and the VH-to-crypt depth ratio (VCR) of the cecum (p < 0.05). Alpha diversity analysis showed that LRS chickens had a significantly higher diversity and richness than NRS chickens. Beta diversity analysis demonstrated differences in the microbiota composition based on housing systems. Within the cecum, Proteobacteria and Kiritimatiellaeota were significantly more abundant in the LRS than in the NRS (p < 0.05), while Bacteroidetes were significantly less abundant in the LRS (p < 0.05). Phascolarctobacterium and Ruminococcaceae_UCG-005 were significantly less abundant in the LRS (p < 0.05) compare to the NRS. Within the duodenum, Lactobacillus was significantly less abundant in the LRS (p < 0.05) than in the NRS, while Pseudomonas was significantly more abundant in the LRS (p < 0.05). Cecal Phascolarctobacterium and Ruminococcaceae_UCG-005 were significantly positively correlated with eggshell strength (R = 0.608, p < 0.01) and egg weight (R = 0.526, p < 0.05), respectively. Duodenal Lactobacillus was significantly positively correlated with VH and VCR (R = 0.548 and 0.565, p < 0.05), while Pseudomonas was significantly negatively correlated with the Haugh unit (R = -0.550, p < 0.05). In conclusion, there are differences in the cecal and duodenal microbiota compositions of Shendan laying hens reared in different non-cage housing systems, and the NRS was superior to the LRS in improving the laying performance and intestinal morphology and microecological environment.

Effect of stocking density on growth performance, feather quality, serum hormone, and intestinal development of geese from 1 to 14 days of age

This study was conducted to investigate the effect of stocking density on growth performance, feather quality, serum hormone, and intestinal development of geese from 1 to 14 d of age. A total of 450 one-day-old geese were randomly allotted to 45 battery cage (0.65 m × 0.62 m) pens according to 5 stocking densities (15, 20, 25, 30, and 35 birds/m²). The results showed that ADG and ADFI were reduced (P < 0.05) as stocking density increased from 15 to 35 birds/m², but increasing stocking density did not influence (P > 0.05) feed conversion ratio (FCR) and body measurement traits. High stocking density significantly decreased (P < 0.05) the feather quality of back, thoracoabdominal, wing, and tail. No significant difference (P > 0.05) was found in serum concentration of adrenocorticotrophic hormone, cortisol, corticosterone, triiodothyronine, and thyroxine. The weight of cecum and intestine decreased (P < 0.05) as the stocking density increased. Increasing stocking density decreased (P < 0.05) jejunal villus height and villus height-to-crypt depth ratio, and increased (P < 0.05) jejunal crypt depth and ileal crypt depth in geese. Consequently, the high stocking density could depress the growth and impaired feather quality and intestinal development of geese. Under our experimental conditions, we recommend that the stocking density of geese from 1 to 14 d of age should not more than 20 birds/m².

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.

Effects of Different Non-Cage Housing Systems on the Production Performance, Serum Parameters and Intestinal Morphology of Laying Hens

This study investigated the effects of plastic-net housing system (NRS) and floor-litter housing system (LRS) on the production performance, serum parameters and intestinal morphology of Shendan laying hens. A total of 1200 30-week-old hens were randomly allocated to the NRS and LRS groups, each of which included five replicates with 120 chickens in each replicate. The experiment was conducted from 32 to 40 weeks of age. Indoor airborne parameters were measured every 2 weeks, and indoor ground contamination was measured monthly. The laying rate and mortality of hens were recorded daily, and egg quality traits and serum parameters were measured every 2 weeks. At 40 weeks of age, four birds per replicate from each experimental group were selected for intestinal morphological observation. The results showed that the airborne bacteria number in the LRS was significantly higher than that in the NRS (p < 0.05) for most of the experimental period (except at 32 and 38 weeks of age), and the bacterial numbers on the surfaces of the floor and floor eggs in the LRS were approximately 10 times higher than those in the NRS (p < 0.05). Compared with the LRS, the NRS improved the laying rate (p < 0.05), reduced serum malondialdehyde (MDA) (p < 0.05) and corticosterone (CORT) concentrations and increased serum glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities, indicating favourable effects on antioxidative status. The NRS was significantly associated with an increased villus height (VH), villus height to crypt depth ratio (VCR) in the small intestine (p < 0.05) and increased VCR in the caecum (p < 0.05). Overall, the lower rate of bacterial contamination in the NRS than in the LRS indicated better environmental hygiene. The NRS enhanced the laying performance and antioxidant capacity of hens and was superior to the LRS in improving intestinal health. The current findings support the advantages of the NRS for the health and welfare of Shendan chickens during the peak laying period.

Productive and hematologic responses of country poultry subjected to different housing densities and water salinity levels

The aim of this research was to evaluate the production and hematologic responses of confined Rhode Island Red chickens consuming water with 3 different levels of salinity and housed at different densities. Seven hundred and twenty birds were distributed in 36 experimental boxes built inside a poultry house according to a completely randomized design with a 3 × 3 factorial scheme with 3 salinity levels (SL) of water (1, 4, and 8 dS/m) and 3 housing densities (8, 10, and 12 birds/m2). Four birds were evaluated from each experimental box, thus totaling 16 repetitions (birds) per treatment. The productive performance, carcass yield, and hematologic traits of the birds in different experimental conditions were evaluated. Increasing water SL resulted in a significant increase (P < 0.05) in water and feed consumption beginning in the sixth week of life, causing an increase in the percentage of carcass and heart weight, with no changes in serum responses. Increasing housing density led to a reduction in water and feed consumption, weight gain, and feed conversion, thus reducing the chickens' blood magnesium levels.

Effect of Fermented Products Produced by Bacillus licheniformis on the Growth Performance and Cecal Microbial Community of Broilers under Coccidial Challenge

This study investigated the effects of fermented products produced by Bacillus licheniformis (fermented products) on the growth performance and cecal microbial community in broilers exposed to coccidial challenge. A total of 108 one-day-old male broiler chicks (Ross 308) were randomly allotted to one of three treatments. Each treatment was distributed into six replicate cages with six birds each. The treatments consisted of a basal diet without treatment (NC), basal diet plus coccidial challenge (PC), and basal diet plus the coccidial challenge and 1 g/kg of fermented products (FP). The results indicated that FP increased the average daily gain of broilers at 21 to 35 days of age compared with the PC group (p < 0.05). The anti-coccidia index in the FP group was elevated compared with the PC group (p < 0.05). Principal coordinate analysis showed significant segregation in bacterial community composition in the cecal digesta among the groups. The genus Lactobacillus was more abundant in the cecal digesta of the FP group compared with the PC group (p < 0.05). There was a positive correlation between the abundance of the genus Lactobacillus in the cecal digesta and growth performance (body weight, average daily gain, and average feed intake). Furthermore, the abundance of the genus Lactobacillus in the cecal digesta was positively associated with the cecal short-chain fatty acid levels (formic acid, acetic acid, propionic acid, butyric acid, and isobutyric acid). These findings suggest that fermented products produced by B. licheniformis can ameliorate the average daily gain of broilers exposed to coccidial challenge. B. licheniformis-fermented product supplementation increases anti-coccidial activity and modulates gut microbiota composition by increasing beneficial microbes and decreasing harmful microbes in broilers under coccidial challenge.

Effects of housing systems and glucose oxidase on growth performance and intestinal health of Beijing You Chickens

We investigated the effects of housing systems and dietary glucose oxidase (GOD) on the growth performance and intestinal health of Beijing You chickens (BYC). The experiment was designed as a factorial arrangement of 2 housing systems × 2 dietary treatments. Chickens were fed a basal diet or a diet with 200 U/kg GOD and were reared on the floor with deep litter or in the cages. Compared with the litter floor groups, the decreased average daily feed intake of 1 to 42 d, decreased feed conversion ratio (FCR), improved average daily gain of 42 to 77 d, and the whole period were identified in the cage rearing groups (P < 0.05). The FCR of 42 to 77 d and the whole period, the 42-d ileal pH, and 77-d jejunal and ileal pH decreased with the supplement of GOD (P < 0.05). Additionally, 16S rRNA gene of ileum contents was sequenced by high-throughput sequencing. Sequencing data indicated that the Firmicutes phylum of 42 d and the Bacteroidetes phylum were significantly higher in the litter group with GOD supplement (P < 0.05). The jejunal Occludin, Mucin-2 mRNA expression levels were higher in the litter floor groups than those in the cage rearing groups on 42 d (P < 0.05). The Mucin-2 and TNF-α mRNA expression levels increased with cage rearing on 77 d (P < 0.05). The Occludin and TLR-4 mRNA expression levels increased with the supplementation of GOD on 77 d (P < 0.05). Moreover, the upregulation effects of Occludin and ZO-1 mRNA expression levels were more obvious in the litter floor group fed with GOD diet on 77 d (P < 0.05). The serum endotoxin content of 42-day-old cage rearing groups were higher than that of the litter floor groups, and the serum endotoxin content significantly decreased with the supplement of GOD on 77 d. The results indicated that the litter floor systems were beneficial to the development of intestinal barrier junction in the early stage, but the cage systems were more conducive to the growth performance of BYC. The dietary GOD could inhibit the harmful bacteria and promote the beneficial bacteria, which might be related to the improvement of the growth performance and intestinal barrier function.

Rearing cage type and dietary limestone particle size: I, effects on growth, apparent retention of calcium, and long bones attributes in Lohmann selected Leghorn-Lite pullets

Effects of rearing cage type and dietary limestone particle size (LPS) on growth, apparent retention (AR) of nutrients, and bone quality were investigated. The treatments were arranged in a 2 × 3 factorial with cage (conventional, CON and furnished, FUR) and LPS (fine, < 0.595 mm, F; medium, 0.595 to < 1.68 mm, M; and 1:1 mixture of F and M wt/wt; FM). A total of 900-day-old Lohmann LSL-Lite chicks were placed in CON (20 chicks/cage) and FUR (30 chicks/cage) based on BW. The diets were formulated according to breeder's nutrient specifications for starter, grower, and developer phases. At the end of 4, 12, and 16 wk of age (woa), 2 pullets/cage were euthanized for samples. At 12 and 16 woa, 1 pullet/cage was transferred to metabolism cages for AR measurements. There was no interaction (P > 0.05) between cage type and LPS on response variables. At 4 woa, body (P = 0.002) and bone (P < 0.05) weight was higher for CON than FUR pullets, but this was reversed (P < 0.01) at 16 woa. Pullets fed M LPS had higher (P < 0.05) AR of Ca, whole body mineral density (BoMD), and whole body mineral content (BoMC) than pullets fed F LPS. However, pullets fed F LPS had higher (P < 0.05) femur bone mineral density (BMD) and tended (P = 0.059) to have higher tibia bone breaking strength (BBS) than pullets fed M LPS at 16 woa. Pullets reared in CON cages had higher (P < 0.05) AR of Ca than FUR pullets. At 4 woa, CON pullets had lower (P < 0.05) femur and tibia BMD but higher tibia (93 vs. 83 N P = 0.012) BBS than FUR pullets. However, at 16 woa, FUR pullets had higher (P < 0.05) BoMD, BoMC, and tibia BBS than CON pullets. In conclusions, cage type and dietary LPS had independent effects on Ca utilization and skeletal development. Despite poor Ca retention, FUR caged pullets showed improved bone quality at 16 woa. Finer LPS improved femur mineral density suggesting coarser LPS had limited effects on pullet bone quality.

Effects of rearing systems on growth performance, carcass yield, meat quality, lymphoid organ indices, and serum biochemistry of Wannan Yellow chickens

This study was conducted to investigate the effects of free-range system (FRS) and conventional cage-rearing system (CRS) on growth performance, carcass yield, meat quality, lymphoid organ indices, and serum biochemistry of Wannan Yellow chickens. At 56 days of age, a total of 640 male chickens were randomly allocated to FRS and CRS groups, each of which included 4 replicates with 80 chickens in each replicate. The experiment lasted from 56 to 112 days of age. The results showed that CRS chickens exhibited better final body weight, average daily feed intake, average daily gain, and feed conversion ratio, whereas FRS chickens showed better breast and leg yields, shear force, meat color, lower drip loss, and decreased abdominal fat deposition. Moreover, the absolute thymus weight and thymus to body weight ratio of FRS birds were significantly higher than those of CRS birds (p < 0.05). Additionally, FRS chickens had significantly reduced glucose, total protein, triglyceride, and cholesterol contents, but enhanced levels of high-density lipoprotein cholesterol (p < 0.05). In conclusion, the FRS has advantages in breast and leg yields, meat quality, and some serum biochemical parameters of Wannan Yellow chickens, whereas it has negative effects on growth performance.

Effect of stocking density and sex on growth performance, meat quality, and intestinal barrier function in broiler chickens

The objective of the current experiment was to investigate the effect of stocking density and sex on growth performance, meat quality, and intestinal barrier function in broiler chickens. The experiment was conducted in a completely randomized design with a 2 × 4 factorial arrangement consisting of sex and four different stocking densities in battery cages. A total of 540 1-d-old Ross 308 broiler chickens were allotted to one of eight treatments with five replicates. Within each sex, birds were raised at four different stocking densities of 15.2, 20.2, 25.3, or 30.4 birds/m2 from 1 to 28 d of age. Different stocking densities were achieved by raising a different number of birds per battery cage with identical floor size (0.76 m × 0.78 m). At the end of the experiment, two birds per replicate were euthanized by CO2 asphyxiation to collect tissue samples for further analyses. Results indicated that no interactions between sex and stocking density were observed for all measurements except for serum lipopolysaccharide (LPS) concentrations. Increasing stocking density decreased (linear, P < 0.01) body weight gain and feed intake, but had no negative effects on meat quality. Trans-epithelial electrical resistance values, a measure of intestinal permeability, were decreased (linear, P < 0.01) with increasing stocking density, regardless of sex. Accordingly, serum LPS concentrations were increased (linear, P < 0.01) with increasing stocking density. However, increasing stocking density increased serum LPS concentrations in male broiler chickens, but had no effects on female broiler chickens, showing an interaction (P < 0.01). The expression of zonula occludens-1 (ZO-1) and junctional adhesion molecule B (JAM-2) was decreased (linear, P < 0.05) with increasing stocking density. In conclusion, increasing stocking density decreases broiler performance regardless of sex and this negative effect is likely associated with decreased intestinal barrier function.

Proteome and microbiota analysis reveals alterations of liver-gut axis under different stocking density of Peking ducks

This study aimed to determine the impact of stocking density on the liver proteome and cecal microbiota of Peking ducks. A total of 1,200 21-day-old ducks were randomly assigned to 5 stocking density groups of 5, 6, 7, 8 and 9 ducks/m², with 6 replicates for each group. At 40 days of age, duck serum and pectorals were collected for biochemical tests; liver and cecal contents of ducks were gathered for proteome and microbiota analysis, respectively. Serum MDA increased while pectorals T-AOC reduced linearly with enhancing stocking density. Duck lipid metabolism was altered under different stocking density as well. Serum LDL-C increased linearly with increasing stocking density. Proteome analysis revealed fatty acid biosynthesis proteins such as acyl-CoA synthetase family member 2 and fatty acid oxidation related proteins including acyl-CoA dehydrogenase long chain and acyl-coenzyme A oxidase were enriched in high stocking density group. Additionally, high stocking density increased oxidative response associated proteins such as DDRGK domain containing 1. Furthermore, increasing stocking density diminished proteins of anti-oxidant capacity including regucalcin and catalase. 16S rDNA analysis revealed that higher stocking density was accompanied with decreased microbial diversity, as well as depletion of anti-inflammatory bacterial taxa, including Bacteroidales, Butyricimonas and Alistipe. Besides, reduced bile acid metabolism-associated bacteria such as Ruminococcaceae, Clostridiales and Desulfovibrionaceae were found in the high-density group. Both proteome and 16S rDNA results showed inflammation and chronic liver disease trend in the high-density group, which suggests the involvement of the liver-gut axis in oxidative stress.

Effects of different rearing systems on growth performance, carcass traits, meat quality and serum biochemical parameters of Chaohu ducks

This study was conducted using a total of 360 22-day-old Chaohu ducks to evaluate the effect of rearing system on growth performance, carcass traits, meat quality and serum parameters of male and female Chaohu ducks. The birds were divided and raised in separate pens according to sex and rearing system, with three replicate pens of 30 male or 30 female ducks per pen for each rearing system. The rearing systems consisted of a floor rearing system (FRS) and a net rearing system (NRS). Results showed that ducks raised in NRS had better growth performance, whereas, ducks raised in FRS exhibited better carcass traits and meat color, and lower intramuscular fat. For the serum parameters, NRS significantly decreased high-density lipoprotein cholesterol content, and enhanced total protein and triacylglycerol contents. Male ducks had lower abdominal fat percentage, and higher growth performance and shear force, but there were no other significant differences between sexes. No rearing system × sex interaction was observed in the present study, revealing that rearing system had the same effect on both sexes. In conclusion, NRS was beneficial to the growth performance of Chaohu ducks, whereas this system had some negative effects on carcass traits, meat quality and serum profiles.