Increasing susceptibility of broiler chickens to ascites syndrome has coincided with a continuing genetic and nutritional improvement in their feed efficiency and growth rate. Imbalance between oxygen supply and the oxygen required to sustain rapid growth rates and high food efficiencies is believed to be the primary cause of ascites. This imbalance is caused by exogenous and/or endogenous factors. Selection in fast growth broilers, have also resulted in the development of birds with changed anatomical, physiological, metabolic and hematological parameters including thyroid hormone activity, partial pressure of O2 and carbon dioxide in venous blood, cardiac β-adrenergic receptors and hematocrit levels that coincide with susceptibility to ascites in broiler chickens. Observations to date have indicated that the structural or endocrine changes are often linked with ascites susceptibility and may be influenced during the early stages of development, embryogenesis and incubation. In this review, particular attention is paid to the interactions between endogenous and exogenous factors as predisposing factors for development of ascites syndrome. Additionally, preventive management procedures like different lighting schedules, feed restriction protocols and supplementation of feed with antioxidants which reduce the incidence of ascites in broiler chickens are highlighted.
Neutral genetic variation is believed to provide useful information for conservation of farm-animal genetic resources. The aim of the present study was to assess genetic diversity in a small native chicken population composed of 4 groups, using neutral microsatellite markers. High within-group molecular coancestry coefficients ranging from 0.670 to 0.740 indicated that mating of closely-related individuals occurred within each group. The contribution of each group to genetic diversity was quantified to determine conservation priorities for the groups. The result suggested that 2 of the 4 groups represent greater reservoirs of genetic diversity and carry relatively large number of unique alleles that are missing in the other groups. Thus, these 2 groups were expected to play an important role in future conservation efforts. Genetic clustering analyses based on genotypes of individuals revealed that individuals belonging to 1 of the 4 groups were genetically distant from the others. To avoid inbreeding, future mating plans were designed by estimating molecular coancestry coefficients between candidate males and females. Appropriate mating patterns to maintain genetic diversity were established. Genetic characterization based on neutral molecular variations has the potential to provide valuable information for conservation of rare or endangered chicken breeds.
Domestic chickens have long been important to human societies for food, religion, entertainment, and decorative uses, yet the origins and phylogeography of chickens through Asia remain uncertain. In this study, the complete mitochondrial (mtDNA) D-loop sequences were analyzed for a total of 27 individuals of Cambodia (n=13), Myanmar (n=6), Bangladesh (n=3) Red junglefowls (RJFs) and Laos native chickens (n=5). Sequences of mtDNA D-loop of these chickens were compared with 67 D-loop chicken sequences annotated in the GenBank; White Leghorn, RJFs and other Asiatic chickens to identify the phylogenetic relationship within and among Cambodia, Myanmar, Bangladesh RJFs and Laos native chickens for the conservation and improvement of chicken genetic resources. The nucleotide variation of sequence among 23 haplotypes for within and among populations of Cambodia RJFs, Myanmar RJFs, Bangladesh RJFs and Laos native chickens supported the phenotypic variation of individuals of the populations. The 38, 28, 24 and 23 sites of single nucleotide polymorphism (SNP) in Cambodia, Myanmar, Bangladesh RJFs and Laos native chickens, respectively were observed. All RJFs and Laos native chickens have nucleotide insertion in mtDNA D-loop region comparing with White Leghorn. A phylogenetic tree was constructed using the nucleotide sequences of the complete mtDNA D-loop region of the 28 RJFs, 25 other chicken breeds and the 41 chicken haplotypes. Phylogenetic analysis showed total of 94 individuals those were separated into 8 clades. The phylogenetic analysis showed the close genetic relationship within and between the populations of each country. The genetic information from this study is the initial investigation using these populations in Myanmar, Cambodia, Bangladesh and Laos which may be useful in developing future strategies for conservation and improvement of valuable genetic resource.
To conserve the Tosa-no-Onagadori (briefly Onagadori), one of the native Japanese chicken breeds designated as a Special National Natural Treasure of Japan, time-dependent changes in genetic diversity and structure were analyzed based on 20 microsatellites. From three varieties (black-breasted white, black-breasted red, and white) of the Onagadori reared in Nankoku City, Kochi Prefecture, Japan, blood samples were collected in 1999, 2005, and 2009-2010. Significant genetic differentiation was recognized among breeders and among varieties in the whole Onagadori population, but it was not observed between years. Focusing on breeders, some populations showed decrease in allelic richness (AR) and expected heterozygosity (HE) with advancing years. Focusing on varieties, AR of the black-breasted red variety showed significant loss from 1999 to 2010, resulting in the significant loss of AR in the whole Onagadori population. In contrast, the AR and HE of the black-breasted white and white varieties were constant across sampling years. The DA genetic distance among populations decreased with sampling years, and genetic homogeneity increased in the whole Onagadori population. Structure analysis supported K＝2, dividing the genetic constitution into Onagadori-specific one and the rest. In the black-breasted white variety, the birds that have Onagadori-specific genetic composition increased with time. On the contrary, in the black-breasted red and white varieties surveyed in 2009-2010, there was no bird that showed Onagadori-specific genetic background of more than 75%. To maintain the Onagadori in Nankoku City for a long term, regular monitoring of genetic diversity and systematic reproduction using excellent black-breasted white birds that have the Onagadori-specific genetic composition should be continued.
In contrast to other domestic and wild animals, the genetic variation of MC1R gene and association with plumage color has not been investigated in domestic goose. In the present study, we sequenced 714 bp fragment of the MC1R for 176 individuals from two goose breeds with three plumage color pattern (Landes goose, gray plumage, n＝58; Landes goose, spotted plumage, near black, n＝36; Zhedong White Goose, white plumage, n＝82). A total of five single nucleotide polymorphisms (SNPs) were detected, including c.210C>T, c.321C>T, c.411C>T, c.525C>T, and c.756G>A, which subsequently determined seven haplotypes (H1-H7). Among them, H2 and H4 were the predominant haplotypes. Association analysis revealed that haplotypes H2 and H5 were significantly associated with white plumage of Zhedong white goose, whereas H3 was significantly associated with gray plumage in Landes goose (p<0.01). Diplotypes H2H2 and H3H4 were associated with white plumage in Zhedong white goose and gray plumage in Landes goose (p<0.01), respectively. The results suggested that the genetic variation of MC1R is also significantly associated with the plumage color in domestic goose.
Since the growth promoter effect of antibiotics was found, many kinds of antibiotics have been used as feed additives for the improvement of growth performance. Since January 1, 2006, however, European Parliament prohibited the use of antibiotics as feed additives for promoting animal growth because of biosecurity threats arising from the increasing resistance of pathogens to antibiotics. Thereafter, various natural substrates having the growth promoter effect have been attempted to use as feed additives instead of antibiotics. Honeybees collect propolis from the cracks in the bark of trees, and it has the versatile pharmacological activities including antibacterial effect. Therefore, the present study aimed to examine the influence of propolis residue, which was the residue after ethanol extraction, on the cecal bacterial flora in the meat-type chicken, Nanbu Kashiwa. Twenty-eight-d-old female Nanbu Kashiwa were given an ordinary diet for 90 days. During last 10 days, an experimental diet including 2% of propolis residue was provided. At the end of experimental period, ceca were removed and DNA was isolated from cecal content. The V3 region of the bacterial 16S rRNA gene was amplified by PCR using the 357F-GC and 518R primers. To indentify the bacterial diversity, denaturing gradient gel electrophoresis (DGGE) was applied, and the optical intensity of DGGE bands was determined. The major bands were excised, and DNA was reamplified by PCR. The sequencing data were analyzed by the Basic Local Alignment Search Tool (BLAST) of DNA Data Bank of Japan. The bacteria identified by PCR-DGGE and BLAST were Lactobacillus aviaries, Lactobacillus, Olsenella, Coriobacterium, Paraprevotella, Prevotellaceae, Clostridiaceae and Bacteroidaceae. The DGGE band of which the optical intensity of the propolis residue group was lower than the control group was the family Prevotellaceae. The successful use of propolis residue to reduce the family Prevotellaceae showed the possibility to use propolis residue as alternative feed additives.
This study was conducted to evaluate the effects of dietary supplementation with Aspergillus awamori on the growth performance and antioxidative status in male broiler chickens exposed to high ambient temperatures. Twenty-four 15-d-old male broiler chickens were randomly divided into 2 dietary groups fed a corn-soybean meal-based diet supplemented without or with 0.05% of Asp. awamori. Six birds of each dietary group were kept under a thermoneutral condition (22°C), and 6 birds were exposed to heat stress (35°C, 9 h/d) for 15 d. Dietary Asp. awamori decreased feed intake and improved the feed conversion ratio in chickens kept at 22°C. Body weight gain and feed intake were decreased in chickens exposed to heat stress. There was no beneficial effect of dietary Asp. awamori on growth performance under the heat stress condition. However, the malondialdehyde content in skeletal muscle, as an index of lipid peroxidation, was decreased by dietary Asp. awamori in chickens kept at 22°C. Although the malondialdehyde content increased under the heat stress condition, dietary Asp. awamori alleviated the increased malondialdehyde. In addition, the α-tocopherol content in skeletal muscle was negatively affected by the exposure to heat stress, and dietary Asp. awamori recovered the reduction in the α-tocopherol content. Moreover, mRNA expression of glutathione peroxidase in liver was increased by dietary Asp. awamori under both of the thermal conditions. In conclusion, this study shows that dietary Asp. awamori improves the diminished antioxidative status under the heat stress condition partially because of its effect on the expression of hepatic antioxidant enzymes in broilers.
The effect of feed restriction and refeeding on enzymatic activity and gastrointestinal organ weight was evaluated in chickens at two ages, 7 and 35 d of age. At each age, the birds were 70% feed-restricted for 7 d (30% of ad libitum intake) followed by ad libitum refeeding for 3 d. The control groups were fed ad libitum during equivalent periods (10 d). Pancreatic activity of chymotrypsin, trypsin, amylase and lipase, and intestinal activity of sucrase and maltase were analyzed, and the weights of the proventriculus, gizzard, pancreas, small and large intestine were obtained. Trypsin and amylase activity were lower in the feed-restricted group than in the control groups at d14, whereas sucrase activity was lower in the feed-restricted group than in the control group at d42, showing that the effect of feed restriction on enzyme activity was age-dependent. Feed restriction decreased the weight of all organs in the starter and finisher periods. Upon refeeding, the organ weight increased and reached that of the control group only in chickens that were feed-restricted from d35 to d42. In the starter period, proventriculus and gizzard were less affected by feed restriction. In the finisher period, the gizzard was also the least affected organ, while the small intestine was the most affected. All effects of feed restriction were reversed after 3 days of ad libitum refeeding, indicating that the alterations were fast and reversible. Moreover, response to feed restriction and refeeding is age dependent.
The production method of germline chimeras by transfer of primordial germ cells (PGCs) can be used in gene banking of chickens. However, little is known about the reproductive capability of offspring obtained by mating of male and female germline chimeras. To cryopreserve chicken genetic resources at the cellular level in future, it is necessary to demonstrate whether offspring originating from donor-derived PGCs have normal reproductive capability. In this study, we attempted to obtain the pure Hinai-droi offspring by mating of male and female germline chimeras produced by the transplantation of Hinai-dori PGCs into the Akita White Leghorn line (WL) embryos. Hinai-dori offspring from germline chimeras were screened using the Hinai-dori-specific autosomal microsatellite marker, namely, ADL0315, which allows distinction between the Hinai-dori breed and Akita WL. After sexual maturity of the Hinai-dori offspring originating from donor-derived Hinai-dori PGCs, the reproductive capability (egg production rate, fertilization rate and hatchability) was examined. Percentage hen-day egg production was investigated between 21 and 60 wk of age, and fertilization rate and hatchability were investigated between 43 and 60 wk of age, respectively. Among the 105 progeny obtained by mating of male and female germline chimeras, a single brown-colored female hatchling was obtained. The results from molecular genotyping using the Hinai-dori-specific microsatellite marker ADL0315 were consistent with results from morphological identification, and the brown-colored female hatchling was identified as the pure Hinai-dori breed. The mean percentage hen-day egg production, fertilization rate and hatchability of the Hinai-dori hen were 36.4%, 58.1% and 53.2%, which were similar to those of normal Hinai-dori hens. These results indicated that the pure Hinai-dori offspring originating from donor-derived Hinai-dori PGCs has normal reproductive capability.
The development of shell-less culture methods for bird embryos with high hatchability would be useful for the efficient generation of transgenic chickens, embryo manipulations, tissue engineering, and basic studies in regenerative medicine. To date, studies of culture methods for bird embryos include the whole embryo culture using narrow windowed eggshells, surrogate eggshells, and an artificial vessel using a gas-permeable membrane. However, there are no reports achieving high hatchability of >50% using completely artificial vessels. To establish a simple method for culturing chick embryos with high hatchability, we examined various culture conditions, including methods for calcium supplementation and oxygen aeration. In the embryo cultures where the embryos were transferred to the culture vessel after 55-56 h incubation, more than 90% of embryos survived until day 17 when a polymethylpentene film was used as a culture vessel with calcium lactate and distilled water supplementations. The aeration of pure oxygen to the surviving embryos from day 17 yielded a hatchability of 57.1% (8 out of 14). Thus, we successfully achieved a high hatchability with this method in chicken embryo culture using an artificial vessel.
Ocimum gratissimum (OG) was investigated in this study to determine its effect on the immune capability of black-feathered Taiwan country chickens. A total of 90 four-week-old male chickens were randomly assigned to a control group, which was fed with basal diet (BD), and two experimental groups, which were fed with a 0.2 and 0.4 g/kg OG-supplemented BD. During the experimental period, feed intake and body weight were recorded every two weeks to determine growth performance and feed efficiency. Blood was collected from the brachial vein of the chicken wing to obtain blood characteristics at 12 weeks of age. OG supplementation yielded no significant difference in growth performance and blood characteristics. The hemagglutination test showed that, compared with the control, the 0.4 g/kg BD group was able to maintain a significantly higher antibody titer level over two weeks after goat red blood cells injection (p<0.05), suggesting that 0.4 g/kg improves humoral immune response. The phytohemagglutinin test showed that wattle swelling in the 0.2-0.4 g/kg BD groups was reduced more significantly than that in the control group (p<0.05), suggesting that OG supplementation reduces cell-mediated immune response. Taken together, these findings suggest that although OG does not enhance growth or blood characteristics, the inverse changes in humoral and cell-mediated immune response may improve the overall health of the chickens.
The present study evaluated the effect of monochromatic and combinations of light emitting diode light color on the performance and behavior of laying hens. At 12 weeks of age, 600 Hy-line Brown pullets were randomly divided into eight lighting treatments with three replicates of 25 birds in each room. The lightning was set-up as follows; white (W, control; 16 h/d), red (R; 618-635 nm; 16 h/d), green (G; 515-535 nm; 16 h/d), blue (B; 455-470 nm; 16 h/d), red→ green (R→G; 14 h→2 h/d), red→ blue (R→B; 14 h→2 h/d), red→ green→ blue (R→G→B; 12 h→2 h→2 h/d) and red→ blue→ green (R→B→G; 12 h→2 h→2 h/d) light treatments. The light colors significantly influenced egg production, which was higher for the combination R→G (89.56%) and monochromatic R (87.34%) and lower in the G (85.26%) and B (83.75%) light treatments. Conversely, egg weight was remarkably heavier in the B and G light treatments than those of monochromatic R and combination treatments. Concurrently, better feed conversion ratio was found for the combination R→G→B and R→G and the monochromatic R light treatment. Egg shells were significantly pigmented by the combinations of R→B→G and R→G→B. Furthermore, egg shell breaking strength increased following the G treatment. Higher frequencies of ground pecking, ground scratching, and tail wagging were observed in the R group and these behaviors were less frequent in the B groups. Birds under G and B lights spent a longer time perching. These results suggest that a combination of R→G and monochromatic R light enhanced egg production. In contrast, R light activated the bird’s movement, whereas B light decreased movement, and birds spent a longer time perching.
Effects of wood vinegar (WV) on red mites, safety test for chicks, and egg production performance were examined. In the counting of red mite numbers at cage knots using RGB color range of red mites by the image analyzer, the red mite were decreased after spraying (P<0.01). In a WV safety test for 8-day-old chicks, one ml of water, original WV, or WV diluted 500 and 1,000 times were tube-fed twice daily for 6 days. The rate of body weight gain was decreased in original WV group than that in the control (P<0.05), but it was not different in both WV dilution groups compared with that in the water-only group. In spraying one ml WV to the hen’s face twice per day for 8 days, the egg production performances of WV group did not changed so much compared with those of the control and initial day. These results suggest that the WV did not reduced production performance. From these results, WV could exterminate red mites, and did not reduce egg production, suggesting that WV is a useful natural substance to exterminate red mites without harmful effect.
Glyphosate (N-(phosphonomethyl) glycine) is a most popular herbicide in agricultural practices throughout the world. It is possible that glyphosate spread in the ecosystems can reach plants, animals. The present work was directed to investigate the glyphosate residue in different organs of broiler chickens using ELISA and to study the possibility of its neutralisation using humic acid, Chlorella vulgaris and Saccharomyces boulardii. Results showed that glyphosate residues could be detected in the animal feed and different organs as liver, spleen, lung, intestine, heart, muscles and kidney. Humic acid, Chlorella vulgaris and Saccharomyces boulardii showed neutralization of the antimicrobial effect of glyphosate in vitro. Also, feed supplementation of commercial broiler with humic acid (0.2%) leads to a significant decrease in the glyphosate content, i.e. by 53%, 28%, 44%, 50%, 56%, 16%, 63% and 0% in serum, liver, spleen, lung, gastro-intestinal tract, heart, muscles and kidney, respectively. There were no significant effects of humic acid on the production parameters. This enlightenment will help to overcome the negative effect of glyphosate residues on gastrointestinal microbiota and protect consumers from glyphosate residues in chicken meat.
Numerous parameters have been proposed to evaluate eggshell quality in order to reduce losses from damaged eggshells. The uniformity of eggshell thickness (UET), as a newly proposed parameter, is defined as the reciprocal of the coefficient of variation of the eggshell thickness of multiple points on the eggshell surface. In this study, we further evaluated the relationship between UET and eggshell quality of eggs from Lohmann Brown layers. Three hundred and thirty fresh eggs from 40-week-old hens were collected. Egg weight, eggshell weight, eggshell thickness, shape index, and breaking strength were measured, and UET, static stiffness, fracture toughness, and elastic modulus were calculated. The relationship between UET and other eggshell quality parameters was analyzed. Results show that UET is positively correlated with eggshell thickness, breaking strength, static stiffness, and fracture toughness (r=0.297, 0.430, 0.409, and 0.171, respectively, P<0.01). In order to analyze the effect of UET on eggshell quality, eggs were divided into three groups according to their eggshell thickness (thin, medium, and thick), and eggs within each thickness group were subdivided into three subgroups based on their UET (low, medium, and high). Relationship between UET and eggshell quality was analyzed. Result showed that eggs with higher UET in the thin group had higher breaking strength, static stiffness, fracture toughness, and elastic modulus than those with lower UET in the medium group, indicating that eggs with thinner but more uniform eggshells were stronger than those with thicker but less uniform eggshells. Our study suggested that UET has a significant influence on breaking strength, static stiffness, fracture toughness, and elastic modulus and should be included in evaluating eggshell quality.