Journal of Poultry Science最新文献

Imidazole dipeptides possess important bioregulatory properties in animals. This study aimed to evaluate the effect of high ambient temperature on muscle imidazole dipeptides (carnosine, anserine, and balenine) in broiler chickens. Sixteen 14-day-old male broiler chickens were divided into two groups, which were reared under thermoneutral (25 ± 1 °C) or cyclic high ambient temperature (35 ± 1 °C for 8 h/day) for 4 weeks. Chickens exposed to cyclic high ambient temperatures displayed lower skeletal muscle anserine and carnosine content than control chickens. Balenine could not be detected in the pectoral muscle of either group. The pectoral muscles of broiler chickens kept under cyclic high-temperature exhibited significantly lower mRNA expression of carnosine synthase 1, which synthesizes carnosine and anserine; but a significantly higher mRNA expression of carnosinase 2, which degrades carnosine and anserine. Our results suggest that heat exposure decreases pectoral imidazole dipeptide content in broiler chickens. This may be attributed to a lower expression of imidazole dipeptide-synthesizing genes, but higher levels of genes involved in their degradation.

Puerarin is an isoflavone extracted from Gegen (Pueraria lobata) and has been widely utilized to treat various human diseases; however, information regarding its benefits in animal production is limited. In this study, we aimed to investigate the influence of dietary puerarin supplementation on growth performance, immune organ index, immunoglobulin profile, antioxidant capacity, and intestinal morphology in pigeons. In total, 375 healthy 28-day-old White King pigeons were randomly divided into five groups, each consisting of five replicates and 15 pigeons per replicate. Each group was administered one of five dietary treatments: the basal diet, or the basal diet supplemented with 40, 80, 120, or 160 mg/kg puerarin. Treatment duration was 30 days following a 7-day acclimation period. Puerarin treatment did not significantly alter the growth performance of pigeons but afforded a significant linear enhancement in the thymus index (P < 0.05). Additionally, puerarin supplementation significantly increased serum immunoglobulin A and immunoglobulin M levels in pigeons in a linear manner (P < 0.05). Similarly, puerarin significantly and linearly increased the activities of total antioxidant capacity, superoxide dismutase, glutathione, and catalase in the serum and liver, and decreased the malondialdehyde content (P < 0.05). Moreover, the villus height (VH), crypt depth (CD), and VH/CD ratio of the small intestine (including the duodenum, jejunum, and ileum) increased linearly upon puerarin supplementation (P < 0.05). Collectively, these results indicate that puerarin supplementation could improve the immune response, antioxidant capacity, and intestinal morphology of pigeons.

Vaccination is important for reducing disease incidence in the poultry industry. To enhance immunity and vaccine efficacy, chicken cytokines associated with antibody production must be identified. In this study, we focused on interleukin-5 (IL-5), involved in antibody production in mice, measuring its expression and effects on antibody production. Concanavalin A-stimulated splenocytes were used for RT-PCR to clone IL5 cDNAs. Recombinant IL-5 was prepared from the clone and administered to chickens with antigen via the ocular-topical route twice every alternate week. IL-5 enhanced antigen-specific IgY and inhibited antigen-specific serum IgA production in serum. Our findings suggest that IL-5 plays an important role in chicken antibody production, with possible unique functions.

This study aimed to measure the effects of trehalose (Tre) supplementation on the growth, intestinal morphology, gut bacteria, and footpad dermatitis (FPD) of broiler chickens reared at different stocking densities (SD). Four hundred newly hatched Ross 308 male chicks were randomly allocated to four groups of eight, following a 2 × 2 factorial arrangement in a randomized complete block design using two SDs (normal, 11; high, 14 birds/m²) and two diets: basal with and without 0.5% Tre. Tre supplementation was provided during the starter/grower phase, but not the finisher phase. Data were analyzed using a two-way analysis of variance. We observed no significant effects of SD or Tre, individually or combined, on body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) during the starter/grower period. However, high SD decreased both BWG (P < 0.001) and FI (P < 0.05), and increased FCR (P < 0.001), during the finisher period. Whereas Tre reduced FCR (P < 0.05) as a main effect, no combined effect was observed on FCR. Over the total period, high SD negatively affected BWG and FCR (P < 0.001), and Tre significantly reduced FCR, with its effect unaffected by SD. No significant effects of SD or Tre were observed on jejunal morphology. The ileal abundance of Clostridium perfringens (P > 0.05) was not affected by high SD but was significantly reduced by Tre. Neither high SD nor Tre altered Lactobacillus spp. counts; however, high SD increased FPD lesion scores, whereas Tre had no effect. The study showed that Tre supplementation during the starter/grower period improved FCR during the finisher period, possibly by decreasing the abundance of C. perfringens in broiler chickens.

The incubation behavior of the Japanese Nagoya chicken breed is a commercial issue because it often causes a sudden and sharp drop in egg production. In this study, whether the incidence of incubation behavior in Nagoya laying hens was associated with calls and the presence of roosters in the same laying house was investigated. Four experiments were conducted using commercial layer-type Nagoya hens where the hatching time of the experimental birds and the treatment order in the presence of males were changed . In Experiment 1, the proportion of incubation behavior in the presence of roosters kept in another pen located between pen-rearing hens (51.3%) was higher than that in their absence (15.9%) or with only rooster calls (23.8%). In Experiments 2, 3, and 4, the proportion of incubation behavior in the presence of roosters (47.3%, 33.3%, and 37.9%, respectively) was higher than that in their absence (33.3%, 17.4%, and 25.6%, respectively). In all experiments, approximately 70% of the incubating hens observed in the absence of roosters exhibited incubation behavior, even in the presence of roosters. Therefore, the presence of roosters may enhance egg incubation behavior in Nagoya laying hens.

A germline chimera is a useful model for developing and differentiating germ cells in vivo. Gonadal germ cells (GGCs) collected from chicken embryonic gonads may be used to produce germline chimeras as donor cells. However, the migratory and proliferative abilities of GGCs after transfer into recipient embryos are unclear. Here, the migratory and proliferative abilities of GGCs collected from 7-day-old White Leghorn embryos and fluorescently labeled were analyzed following transfer into the dorsal aorta of 2.5-day-old Rhode Island Red (RIR) embryos. Five days after transfer, the numbers of male and female GGCs were significantly higher in the RIR gonads than those in non-gonadal RIR organs when 50 GGCs were transferred per embryo. To analyze the temporal migration of GGCs in intermediate mesoderm, 50 GGCs were again transferred. The numbers of male and female GGCs in RIR gonads increased significantly from days 3 to 6 after transfer. To analyze GGC migration and proliferation in the gonads, a single GGC was transferred into 100 male and 100 female embryos. Five days after transfer, the frequencies of settled and proliferated GGCs were 37% (37/100) and 24% (24/100) in males, and 23% (23/100) and 8% (8/100) in females, respectively. Thus, GGCs are a heterogeneous cell population that may or may not have migratory and proliferative abilities. The heterogeneity of GGCs may be greater in females than that in males. When 50 GGCs were transplanted, almost all those present in embryos had settled and proliferated in the gonads and mesonephros. The migratory and proliferative abilities of GGCs in recipient gonads were considerably diverse in individual GGCs or between donor sexes.

Slightly acidic electrolyzed water (SAEW) is used as a disinfectant for raw chicken meat. Because its volume for a single immersion exceeds 10 times the weight of meat, a large amount of wastewater is generated. Importantly, a higher frequency of immersion is believed to reduce microbial contamination. The objective of this study was to investigate the effect of SAEW immersion at different frequencies on the disinfection and quality of raw chicken legs, thereby possibly limiting the usage of SAEW. Immersion for 1, 3, and 5 times, with a 7:1 SAEW:meat ratio, and duration of 15 min was tested. Meat quality was evaluated based on total aerobic bacteria, Enterobactericeae, total volatile basic nitrogen, thiobarbituric acid reactive substances, and color. A higher immersion frequency lowered the numbers of total aerobic bacteria and Enterobacteriaceae. Moreover, two immersions with a SAEW:meat ratio of 4:1 and a total immersion time of 6 min reduced the bacterial load as effectively as a single 15-min immersion with a SAEW:meat ratio of 7:1. Higher frequencies of SAEW immersion also resulted in lower total volatile basic nitrogen and lipid oxidation after 0 or 3 days of storage. They did, however, magnify the change in color, resulting in brighter meat. Overall, SAEW treatments with two to five immersions can improve the quality of raw chicken legs and reduce wastewater generation.

Collagen content and collagen fiber architecture in the skin of Shamo chickens were compared between sexes and body parts. Cervical, thoracic, dorsal, femoral, and crural skin samples were collected and their collagen content was analyzed. Collagen fiber specimens were prepared for scanning electron microscopy using the cell maceration method with a NaOH solution. Sex differences in collagen content were only observed in the femoral skin of mature chickens, but not in 10-week-old chicks. The difference in collagen content between body parts was obvious; femoral and crural skin had higher collagen content than those of other parts in both sexes. Scanning electron microscopy indicated that the collagen fiber architecture was quite different between the superficial and deep layers in the dermis, with the former consisting of loosely tangled band-like collagen fibers, and the latter composed of thick and dense layers of collagen bundles in a parallel arrangement. The width of collagen fibers in the superficial layer of the dermis differed between sexes in the dorsal, femoral, and crural skin. From these results, it is likely that the difference in collagen content in the femoral skin is not due to sex hormones but other factors, such as mechanical stimulation in daily activity. Additionally, collagen fiber width in the superficial layer is likely related to the difference in collagen content between sexes and between body parts.

The relaxin (RLN) gene is expressed in the reproductive tracts, such as the ovary and uterus, of mammalian species. Although RLN expression is detected in the chicken ovary, detailed clarification of the physiological role of RLN has not yet been reported. To address this issue, in the present study we aimed to examine the spatiotemporal expression and hormonal control of RLN in Japanese quail. By performing semi-quantitative and quantitative reverse transcription-polymerase chain reaction analysis, we found that RLN mRNA was mainly expressed in the granulosa and theca layers of the ovary. The expression level in the granulosa layer increased with the stage of follicular development. Results from granulosa layer culture experiments revealed that RLN mRNA expression increased with the addition of estradiol-17β, whereas the addition of progesterone suppressed RLN transcription. More detailed analysis indicated that RLN expression was highest in the stigma region of the follicle but significantly decreased as the time of the expected luteinizing hormone (LH) surge approached. Together, our findings demonstrated that the granulosa cells in the mature preovulatory follicles constitute the main source of RLN in the Japanese quail. Because RLN expression was highest in the stigma region and the expression dramatically decreased following the LH surge, the results further suggest that RLN may be related to tissue remodeling for the ovulation process in birds.

Immunization of egg-laying hens with viral antigens efficiently produces large amounts of virus-specific IgY antibodies from egg yolks. A supply of practical and economical antibodies against the rabies virus is being desired worldwide. We immunized hens with the antigen gene DNA of the rabies virus, purified specific IgY antibodies from the egg yolk, and characterized the immuno-protein chemistry for use as a diagnosis. To prepare specific IgY antibodies against rabies virus nucleoprotein (RV-N) by DNA immunization, laying hens were pre-injected with λ-carrageenan or Freund's complete adjuvant to increase local immune activity (pre-immune stimulation), and then immunized with RV-N recombinant plasmid DNA. RV-N-specific IgY antibodies were prepared from egg yolks of immunized hens. For comparison, conventional protein antigen immunization was also used to induce the production of RV-N-specific IgY antibodies. Laying hens were immunized with an RV-N protein antigen and RV-N-specific IgY was purified from egg yolks. The binding activity against RV-N antigens was examined using IgY samples prepared by DNA (with pre-immune stimulation) and protein immunization. Immunohistochemical staining showed that IgY antibodies prepared by protein immunization strongly detected viral antigens in the brain sections of dogs infected with the virus, whereas IgY antibodies prepared by DNA immunization did not. Enzyme-linked immunosorbent assay was performed using a commercially available rabies vaccine (inactivated virus) treated with 10% formalin and heating (60°C, 30 min and 90°C, 5 min). IgY prepared by DNA immunization had weaker reactivity with denatured antigens and lower antigen concentrations than IgY prepared by protein immunization. These results suggest that it is necessary to develop a DNA immunization method for inducing IgY antibodies against the rabies virus that strongly bind to native and denatured antigens to prepare specific IgYs that can be used for antigen detection in clinical tests.