A study was conducted to provide genetic information on the matrilineal phylogeny and genetic diversity of Red junglefowl (RJF) and native chickens in Samar Island, Philippines and to identify the genetic distance between Philippine junglefowls and other RJF species in Southeast Asia using complete mitochondrial DNA D-loop sequences. A total of 5 RJFs and 43 native chickens from Samar Island were included in this study. The results showed that Samar RJFs had a nucleotide diversity of 0.0050±0.0016, which was lower than those of three subspecies of Gallus gallus: G. g. gallus, G. g. spadiceus, and G. g. jabouillei. Meanwhile, Samar native chickens showed lower nucleotide diversity (0.0056±0.0004) than domestic fowls in some neighboring Southeast Asian countries, but higher than those in African and European countries. Phylogenetic analysis showed that 3 haplotypes of Samar RJFs clustered to haplogroup D1, and that 2 haplotypes clustered to haplogroup D2. Chickens native to Samar Island showed 100% resemblance to those in the haplogroup shared by domestic chickens and RJFs. Haplogroups A and B and sub-haplogroups D1 and E1 were the more widely distributed matrilineal lineages in Samar Island. Phylogenetic analysis of Samar RJFs showed that they were closely related to Myanmar RJFs (99.6%), Indonesia RJFs (99.5%), and Thailand RJFs (99.1%). This study is an initial investigation estimating the matrilineal phylogeny and genetic diversity of chicken populations in Samar Island, Philippines for developing strategies aimed at the future conservation and improvement of valuable genetic resources.

Responses of an individual to food deprivation, such as a 16-h fast, are complex, and are influenced by environmental and genetic factors. Domestication is an ongoing process during which adaptations to changing environments occur over generations. Food deprivation by their caretakers is less for domestic chickens than for their junglefowl ancestors. Unlike domestic chicken, the junglefowl adapted over generations to periods of food deprivation, which may be reflected in differences in metabolic responses to brief periods without food. Here, we compared the blood glucose and plasma levels of non-esterified fatty acids (NEFA) among four populations when deprived of feed for 16 h. The four populations included a domestic White Rock experimental line (LWS) maintained for generations under ad libitum feeding, adult red junglefowl (RJF), and a reciprocal cross of the lines. Although there were significant differences in adult (31-week) body weight between the RJF (683 g) and LWS (1282 g), with the weight of F₁ crosses being intermediate, the amount of abdominal fat relative to body weight was similar for all populations. Patterns for blood glucose responses to a glucose bolus after a 16-h fast were similar for the initial and final points in the parental and cross populations. However, RJF reached their peak faster than LWS, with the reciprocal cross intermediate to the parental populations. Plasma NEFA concentrations were higher after the 16-h fast than in fed states, with no population differences for the fasting state. However, in the fed state, NEFA levels were lesser for LWS than for others, which was reflected further in percentage change from fed to fasted. This larger change in LWS suggests differences in mobilization of energy substrates and implies that during domestication or development of the LWS line, thresholds for responses to acute stressors may have increased.

We investigated means to improve the production of the indigenous Naked Neck chicken in Afghanistan. Specifically, we analyzed single nucleotide polymorphisms (SNPs) in the prolactin (PRL) (24 bp indel), growth hormone (GH) (T185G), and pituitary specific transcript factor 1 (PIT-1) (intron 5) genes. Blood samples were collected from 52 birds and genomic DNA was extracted. Polymorphisms in the mentioned loci were analyzed by PCR, allele-specific PCR, and PCR-restriction fragment length polymorphism (RFLP) using TaqI and MspI endonucleases. Cloning followed by DNA sequencing was performed to ascertain the accuracy of the PCR-RFLP analysis for PIT-1.Two alleles were found for the PRL 24 bp indel, GH (T185G), and PIT-1/TaqI, with the following respective allelic frequencies: PRL-In 0.64 and PRL-Del 0.36, GH-T 0.91 and GH-G 0.09, and PIT-1-A 0.64 and PIT-1-B 0.36. Regarding the PIT-1/MspI polymorphism, three novel MspI recognition sites, as well as two reported MspI recognition sites, were detected in intron 5. Moreover, during sequence screening, two novel SNPs were found that generated restriction sites for MseI. Therefore, our results suggest that the PRL indel, GH T185G, and PIT-1/TaqI polymorphisms may be used as selection markers for Afghanistan Naked Neck chickens. Intron 5 of PIT-1 in the Afghani Naked Neck chicken was highly polymorphic compared to the reported Gallus gallus PIT-1 gene (GenBank accession no. NC_006088.4).

The effect of different levels of hogweed powder (HP; Heracleum persicum), flavophospholipol (antibiotic), and probiotics in diet on the performance, carcass quality, blood biochemical parameters, immunity, and intestinal flora of broiler chickens was investigated. In total, 270-day-old male broilers were randomly assigned to six treatment groups as follows: control basal-diet and diet supplemented with flavophospholipol, probiotics, or 0.25, 0.5, and 0.75% HP. Birds in each group were divided into three subgroups with 15 chicks each. Results indicated that the treatment groups did not vary with respect to feed intake (FI), whereas those supplemented with the antibiotic or 0.5% HP showed significantly higher body weight gain (BWG) and improved feed conversion ratio (FCR). Carcass characteristics did not vary among treatments, with the exception of abdominal fat percentage, which was the lowest in broilers fed 0.5% and 0.75% HP. Supplementation of 0.5% and 0.75% HP decreased plasma cholesterol and triglyceride levels. Furthermore, dietary HP significantly reduced serum low density lipoprotein (LDL) levels compared to that in the other groups. Antibody titers against Newcastle disease vaccine were not markedly affected by the treatments, whereas titers against avian influenza vaccine were significantly higher in probiotic- and 0.75% HP-supplemented groups. Antibody production against sheep red blood cells (SRBC) and IgM and IgG levels were not significantly different among groups. The ileum Lactobacillus counts in broilers fed 0.5% or 0.75% HP were significantly higher than those in the other treatment groups, whereas Escherichia coli counts in all treatments were significantly lower than that in the control. Therefore, our observations indicated that HP positively affected the gut microbiota and enhanced feed digestion. In conclusion, supplementation of 0.50–0.75% HP in broiler diet during the entire rearing period improved BWG and decreased abdominal fat deposition.

Insulin-like growth factor-1 (IGF-1) is a key regulator of muscle development and metabolism in chickens. Recently, we have demonstrated that intracerebroventricular administration of IGF-1 significantly decreased food intake in broiler chicks. However, the molecular mechanisms underlying the IGF-1-induced anorexia and the anorexigenic effect of IGF-1 in different strains of commercial chicks have not been investigated. Neuropeptide Y (NPY, a hypothalamic orexigenic neuropeptide), agouti-related protein (AgRP, a hypothalamic orexigenic neuropeptide), and proopiomelanocortin (POMC, the precursor of hypothalamic anorexigenic neuropeptides) play important roles in the regulation of food intake in both mammals and chickens. Evidence shows that several cell signaling pathways in the hypothalamus are involved in regulating the feeding behavior of mammals. In the present study, we first investigated the effects of IGF-1 on the expression of appetite-regulating neuropeptides and phosphorylation of signaling molecules in the hypothalamus of broiler chicks. Intracerebroventricular administration of IGF-1 significantly increased the mRNA levels of POMC, whereas the mRNA levels of NPY and AgRP were not significantly altered. IGF-1 also significantly induced the phosphorylation of v-Akt murine thymoma viral oncogene homolog 1 (AKT) in the hypothalamus of chicks, but did not influence the phosphorylation of forkhead box O1, S6 protein, AMP-activated protein kinase, and extracellular signal-regulated kinase 1/2. We also compared the effect of IGF-1 on food intake in broiler chicks (a hyperphagic strain of chickens) and layer chicks. Results demonstrated that the threshold of IGF-1-induced anorexia in broiler chicks was higher than that in layer chicks. Our observations suggest that hypothalamic POMC and AKT may be involved in the IGF-1-induced anorexigenic pathway and that high threshold of IGF-1-induced anorexia in broiler chicks might be one of the causes of hyperphagia in broiler chicks. Overall, it appears that IGF-1 plays important roles in the central regulation of feeding behavior in chicks.

This study investigated bioaccumulation and toxicity derived from heavy metals in laying hens. The 160 52-week old laying hens were divided into 5 treatments with 8 replicates of 4 birds per pen. The treatments consisted of the control diet (without heavy metals), control diet with half the available dosage (AD, 5 ppm lead and 0.2 ppm mercury), AD (10 ppm lead and 0.4 ppm mercury), 2-fold AD (20 ppm lead and 0.8 ppm mercury), and 3-fold AD (30 ppm lead and 1.2 ppm mercury), and were provided to the laying hens for 8 weeks. Food and water were provided on an ad libitum basis at all times. Body weight and food intake were recorded once every two weeks, and eggs were collected and recorded daily. Two birds from each pen were euthanized to collect blood and organ samples on week 4 and 8. The 3-fold AD diet reduced food intake compared to that of the control and AD diets (P<0.05). Hens fed the half AD diet had darker yolk compared to those fed the control and AD diet on week 4 (P<0.05). Hens fed the 2- and 3-fold AD diets had increased relative liver weight, blood glutamic pyruvic transaminase and glutamic oxaloacetic transaminase levels (P<0.05), while F1 follicle weights decreased on week 4 and 8. No difference was found in egg production rate, egg quality, ovarian follicle, blood metabolites including protein, globulin, albumin, and urea nitrogen throughout the study (P>0.05). Heavy metal concentrations in the liver, eggs, and feathers were not detected at both week 4 and 8. Our results indicate that in-feed heavy metals for layer diets up to 30 ppm of lead and 1.2 ppm of mercury brought on hepatic dysfunction increasing blood metabolites that are associated with liver inflammation.

Recently, we showed that oral administration of crystallized L-citrulline (L-Cit) caused hypothermia under a control thermoneutral temperature (CT) and provided thermotolerance under high ambient temperature (HT) in chicks. The aim of this study was to clarify whether oral administration of a medium containing L-Cit-producing live bacteria can reduce body temperature in chicks under CT. In Experiment 1, 7-day-old chicks were orally administered either a medium (containing mainly L-Cit-producing live bacteria and 277 mM L-Cit) or an equimolar amount of L-Cit to determine their effects on body temperature (acute treatment). In Experiment 2, chicks were subjected to the same treatment from 7 to 13 days of age (chronic treatment). Rectal and surface body temperatures were recorded daily after 1 h of treatment. Both acute and chronic oral administration of the medium, but not of the equimolar amount of L-Cit, significantly reduced the rectal and surface body temperatures of the chicks. Chronic administration of the medium resulted in consistently low rectal and surface body temperatures during the entire experimental period. In conclusion, acute or chronic administration of the medium containing L-Cit-producing live bacteria, but not of the equimolar amount of L-Cit, reduced the rectal and surface body temperatures of the chicks. Our results suggest that medium containing L-Cit-producing live bacteria can be used as a new feed supplement for lowering the body temperature of chicks.

Testosterone (T) is known to induce aggressive behavior, mainly in male animals. Subcutaneous implantation of T-filled silastic tubes, rather than intramuscular injection of T, is generally recommended for long-term treatment using exogenous T. However, the effect of T implantation on chicken aggressive behavior has not been investigated. In addition, the concentration of T required to induce aggressive behavior or whether rearing conditions such as isolated- or grouped-raising affect T-induced aggressive behavior in chickens is not known. The present study aimed to examine the relationship between the lengths of T-filled tubes, blood T concentration, and aggressive behavior in group- and isolation-raised male layer chicks. The testes were bilaterally removed and silactic tubes of various lengths filled with crystalline T were subcutaneously implanted at 14 days of age. A social interaction test was performed to quantitatively assess chick aggressive behavior at 32 days of age. Comb weight and size were used to assess the activation of endogenous androgen receptors. Total aggression frequencies (TAF) and aggression establishment rate (AER) were used to evaluate aggressiveness. Significant positive correlations (P<0.001) were observed between the comb parameters and plasma T concentration. In the isolation-raised chicks, the TAF and AER were high irrespective of the lengths of the implanted T tubes or the corresponding plasma T concentrations. However, in the group-raised chicks, the AER tended to differ between the T-implanted aggressors (P=0.0902), and the AER significantly increased with implantation of 1.0-cm-long T-filled tubes (P<0.05), which corresponded to approximately 47 pg/mL plasma T concentration. These results suggest that both grouped raising and approximately 47 pg/mL plasma T concentration are required for the induction of T-dependent aggressive behavior, and that isolation-induced aggressive behavior is T-independent in male layer chicks.

The aim of this study was to examine whether Salmonella enteritidis (SE) vaccination affects innate immune function and histone modifications responsible for epigenetic reprogramming in the follicular theca of laying hens. White Leghorn laying hens were administered the SE vaccine or phosphate buffered saline (PBS; control) one week before sample collection. The largest follicles (F1) were collected for total RNA and histone protein extraction. Gene expression levels of immune molecules (Toll-like receptors [TLRs], cytokines, and avian β-defensins [AvBDs]), and histone modifications in the follicular thecal tissues, were examined using real-time PCR and western blot, respectively. The results showed that the expression levels of TLR1-1, 2-1, 4, and 15 were upregulated by SE vaccination. Although vaccination caused no significant change in cytokine expression, AvBDl, 2, 4, and 7 expression levels were significantly upregulated in the vaccinated group. In addition, the relative density of histone H3-lysine9 dimethylation (H3K9me2) was increased by the vaccination. These results suggest that SE vaccination enhances innate immune functions in the ovary of laying hens, including upregulating TLR and AvBD expression, and is also associated with an increase in histone H3K9me2 in thecal cells.

The aim of this study was to determine the changes in chicken breast meat quality (water-holding capacity, color, texture, myofibrillar fragmentation index (MFI), total protein solubility, thiobarbituric acid reactive substances (TBARS), total viable count (TVC), and lactic acid bacteria (LAB) count) due to storage under superchilling conditions (−1.3°C) and fluctuating temperatures (ranging from −20°C to −5°C) as compared to the quality of meat stored at chilled (2–4°C) and frozen (−20°C) temperatures, respectively. Results indicated that the TVC and LAB count of the chilled and superchilled breast meat increased with storage time. TVC of the chilled and superchilled breast meat reached the safety level of 7 log cfu/g at approximately day 8 and18, respectively. This suggested that the superchilling method extended the storage duration by 10 days. Weight loss and TBARS of the chilled and superchilled samples tended to increase with increasing storage time. The color, texture, protein solubility, and MFI were stable throughout the entire storage period of the chilled (9 days) and superchilled (28 days) samples. Results indicated that while three cycles of storage temperature fluctuation influenced the weight loss and dry matter of the meat, they did not affect the TVC, LAB count, texture, color, pH, MFI, and protein solubility. The superchilling technique (−1.3°C) could extend the shelf-life of meat and maintain the quality of chicken breast meat. Fluctuations in temperature during frozen storage decreased the water-holding capacity of chicken breast meat, indicating that temperature stability should be maintained during frozen storage.