Synthetic DL-methionine (DLM) supplements poultry diets to enhance production. The bioefficacy of liquid methionine is generally lower than that of powder methionine; however, if the level of total sulfur amino acids (TSAA) is set to the commercial recommendation, the bioefficacy of liquid methionine seems to be equal to that of powder methionine (equimolar basis). Absorption and transportation in the segment of the jejunum differ between liquid and powder methionine because multiple systems are involved. Methionine supplementation in a low-protein diet alleviates the negative effects of heat stress. The supplementation improves the amino acid balance and consequently promotes growth performance by enhancing feed efficiency, increases protein synthesis and decreases fat synthesis. Methionine supplementation also improves the immune response through direct effects (protein synthesis and breakdown) and indirect effects (derivatives of methionine). As various factors influence the methionine requirement, the requirements of commercial strains are higher than those recommended by NRC (1994). Moreover, the methionine requirement expressed as a percentage of diet declines during the starter and grower phases, while the requirement related to lysine is little changed (tends to increase).

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Body composition, fat deposition and meat quality are important traits in chickens. Melanocortin receptor (MCR) plays an important role in central melanocortin system (CMS) and muscle cells. The purpose of the present study was to analyze association of the MC3R and the MC4R genes with chicken carcass and meat quality traits. Using eight meat-type chicken populations constructed with 5 pure lines (developed from Chinese local breeds) and 3 crossbreeds (S01×D99, S01×S05, S01×S10), the association of 3 single nucleotide polymorphisms (SNP: MC3R-A1424G, MC4R-G923T and MC4R-C944T) of MC3R and MC4R gene with carcass and meat quality traits was studied. The results showed as follows: (1) the MC3R-A1424G genotypes were significantly associated with most carcass traits except for semi-eviscerated percentage and leg muscle percentage (LMP), the MC4R-G923T genotypes were significantly associated with live weight, carcass weight, leg muscle weight (LMW) and LMP, and the MC4R-C944T genotypes were not significantly associated with most carcass traits except for LMW and LMP; (2) to meat quality, the MC3R-A1424G genotypes significantly affected muscle crude protein (GP) value, and the allele A had positive additive effects on slaughter traits. The MC4R-G923T and the MC4R-C944T sites significantly affected muscle GP value and glutamic acid (Glu) value; (3) the haplotypes based on the 2 SNP of MC4R gene were also significantly associated with meat quality traits, but had no significant associations with carcass traits. The research built the base for further analysis on relation between genetic variation of MC3R and MC4R genes and the carcass and meat quality traits, and molecular marker's application in breeding.

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A broiler chick bioassay was carried out with forty eight 21-day-old Arian-broiler chickens to study the effect of site sampling on metabolizable energy (ME) and amino acid digestibility. The test diet contained corn and soybean meal as the major ingredients. Three next treatments were formulated to contain barley, wheat and wheat screening as the test ingredients at a level of 40% in the test diet. Chromic oxide was included in all diets as an indigestible marker. Apparent metabolizable energy (AME) and nitrogen-corrected apparent metabolizable energy (AMEn) based on excreta were significantly higher (P < 0.05) than ileal AME and AMEn in barley. With the exception of histidine, digestibilities of amino acids based on excreta were numerically higher than the ileal value. Significant differences between ileal and excreta-based digestibility of aspartic acid, arginine, threonine, lysine, valine and methionine indicating on a net catabolism of these amino acids in the large intestine. The current study suggests that determination of amino acid digestibility and metabolizable energy based on excreta collection will overestimate amino acid and energy availabilities in all test ingredients.

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The present study was conducted to investigate the effects of dietary protein levels (0, 10, 15, 20 and 30%) on the digestibilities of crude protein, crude fat, nitrogen-free extract and ash at different sites of fistulized chicken intestines. Chickens were fistulized to either the middle part of jejunum (MJ), distal end of jejunum (DJ), middle part of ileum, distal end of ileum or distal end of rectum. Intestinal digesta were collected from each site of intestine, and contents of crude protein, crude fat, nitrogen-free extract and ash were measured. The true digestibility of crude protein in intestinal digesta at MJ and DJ in the 10% group and at MJ in the 15% group was significantly lower than those in the 30% group. The digestibility of crude fat in intestinal digesta at MJ and DJ in both the 0 and 10% groups were significantly lower than those in other groups. The digestibility of nitrogen-free extract at MJ and DJ in the 0% group and at MJ in the 10% group were significantly lower than those in other groups. The digestibility of ash at all sites of intestines in the 0% group showed the lowest value among groups. These results clearly demonstrate that dietary protein level influences the digestibilities of protein, fat, carbohydrate and ash in chicken intestines.

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An experiment was conducted to determine the efficacy of dietary iron-soy proteinate (Fe-SP) and iron-methionine chelate (Fe-Met) on the performance of laying hens and iron content in egg yolk. Eight hundred Hy-Line Brown laying hens of 68wk old were housed in 400 cages of 2 birds each. Two hundred birds (10 cages×10 replicates) were assigned to one of the following four treatments: Control; non supplementation with Fe-SP or Fe-Met, Fe-Met 100; 100ppm iron supplementation with Fe-Met, Fe-SP 100; 100ppm iron supplementation with Fe-SP, Fe-SP 200; 200ppm iron supplementation with Fe-SP. Results of 35d feeding trial showed that there were significant differences in egg production, egg weight, feed conversion ratio and Haugh unit among the treatments. Egg weight and Haugh unit of Fe-SP 200 were significantly higher than the control. Hen-day egg production and feed conversion ratio of Fe-SP 100 and Fe-SP 200 were not significantly different from those of the control. Eggshell color was significantly improved in the Fe supplementation treatments compared to the control. The iron content of egg-yolk was maximized 5wk after feeding supplemental Fe and that of Fe-SP 100 was highest being 16.6% higher than the control. There were no significant differences in iron content of egg-yolk between source and level of iron supplementation. Copper content in the egg-yolk was not significantly affected by treatments but zinc content was significantly increased in iron supplemented treatments at 5^th week after feeding. In conclusion, Fe content of egg-yolk could be effectively increased by supplementing 100ppm iron as iron-soy proteinate for 5wks. No significant difference was found in Fe content of egg yolk between Fe-SP and Fe-Met.

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This experiment was conducted to determine the effects of molt-induction period on molting and post-molt performance of laying hens. White Leghorn hens at 64 weeks of age were used. After a 4-week preliminary period, they were divided into 5 groups (1 control and 4 treatment groups). The control-group hens were continuously fed a corn- and soybean-based layer ration ad libitum. In 1 of the 4 treatment groups, molting was induced by starvation for 2 weeks (MS group), and in the 3 others by ad libitum feeding of a molt diet (ME: 1.6Mcal/kg) based on rice hull, corn, wheat bran, and corn gluten feed for 2 (MF-2 group), 3 (MF-3 group), and 4 weeks (MF-4 group). During the post-molt production period, the hens were again fed the layer ration. During the molt-induction period, the heterophil: lymphocyte (H: L) ratio, the ovary and oviduct weight, and the energy intake were measured. Egg production, egg quality, body weight, and feed intake were measured throughout the experiment. During the treatment period, compared to the control group, the feed intake and body weight in the molted groups were significantly lower; the ovaries and oviducts of the hens in the molted groups were distinctly lighter (P < 0.01). On day 10 of molting, the H: L ratio in the MF groups was lower than that in the MS group. Additionally, egg production completely ceased within 6 d in the MS group and decreased to 3% at week 2 in the MF groups. No significant differences with regard to days required to regain 50% egg production were found between the MS and MF-3 groups. During the post-molt period, egg production and quality improved in the molted groups, the production in the MF-3 group was highest. We assume that ad libitum feeding of the molt diet for 3 weeks effectively induces molting and enhances post-molt production.

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Effects of exogenous thyroxine (T4) and triiodothyronine (T3) were compared on heat production and skeletal muscle protein breakdown in broiler chickens aged from 15 to 27d. T4 and T3 were mixed in the basal diet at concentrations of 1.2, 3.6 and 10.8mg/kg and 0.3, 0.9 and 2.7mg/kg, respectively. Plasma T4 and T3 concentrations were increased dose-dependently by dietary T4 and T3, respectively, while plasma T3 concentration was not increased by dietary T4. Both T4 and T3 retarded growth and increased feed conversion at the higher dose levels while food intakes were not changed significantly. Relative skeletal muscle weights tended to be increased by T4 and T3 probably because body fat contents were decreased intensely by the treatments as indicated by the decrement of abdominal fat. Both heat production and muscle protein breakdown were increased in a dose-dependent manner by either T4 or T3, and the potency of T4 was about one fourth of that of T3. In conclusion, thyroxine is active and has roles in heat production and skeletal muscle protein breakdown.

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A floor-pen trial was conducted to evaluate the effect on broiler performance of adding phytase and xylanase, alone or in combination, to diets based on corn and wheat. A cohort cage trial was also conducted to determine the influence of treatments on tibia ash and nutrient utilization. Five diets were formulated and included a positive control (PC) containing adequate levels of available P and calcium; a negative control (NC) with reduced levels of available P and calcium; and three NC diets supplemented with phytase, xylanase or phytase plus xylanase. Weight gain and feed efficiency were depressed (P < 0.05) in birds fed the NC diet, but performance was improved to the level of birds fed the PC diet when the NC diet was supplemented with 500FTU/kg phytase. The addition of xylanase alone to the NC diet had no effect (P > 0.05) on broiler performance. However, the combination of xylanase and phytase improved the feed efficiency compared with the NC diet. Adding phytase to the NC diet improved (P < 0.05) the tibia ash contents. The addition of phytase and xylanase individually had no effect (P > 0.05) on energy metabolizability. However, when combined together, the two enzymes were additive in their effects on energy utilization. Individual additions of phytase and xylanase had no effect (P > 0.05) on ileal digesta viscosity, but the xylanase-phytase combination lowered (P<0.05) digesta viscosity compared with the NC diet. Enzyme treatments had no effects (P > 0.05) on the intestinal morphology and intestinal digesta counts of lactobacillus and anaerobic bacteria. Overall, these results suggest that combining phytase and xylanase in diets based on corn and wheat will be beneficial in terms of the feed efficiency and energy utilization of broilers.

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In laying hens, dietary betaine supplementation is reported to reduce abdominal fat, however, the mechanism of which remains largely unknown. The present study investigated the effect of dietary betaine supplementation on mRNA expression and the promoter CpG dinucleotide methylation profiles of chicken lipoprotein lipase (LPL) gene. The experiments were carried out with 120 laying hens which were randomly allocated to four diets supplemented with 0, 0.04, 0.06 and 0.08% betaine. The mRNA levels of LPL gene was investigated by using real-time RT-PCR. The CpG methylation profiles at LPL promoter region were analyzed by using bisulfite sequencing method. The results indicated that betaine supplementation at levels of 0.06 and 0.08% tend to decrease LPL mRNA expression in both 165-day-old and 180-day-old hens. In 180-day-old hens, two distinct CpG methylation profiles at the promoter region of chicken LPL gene were revealed: in control and 0.04% betaine groups, in which LPL mRNA expressions in abdominal adipose tissue were higher, CpG methylation occurs mainly at 1^st to 8^th sites, the remaining sites were less methylated; whereas in 0.06 and 0.08% betaine groups, in which LPL mRNA expressions in abdominal adipose tissue were lower, methylation levels of 1^st-8^th CpG sites were decreased, while those of the remaining sites increased.

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Developmental changes in the levels of carnosine (β-alanyl-L-histidine), its derivative anserine (β-alanyl-1-methyl-L-histidine), and their constituents including β-alanine, L-histidine and 1-methylhistidine in the pectoralis muscle were investigated. Comparisons were made between broiler and layer type chickens at various embryonic stages (E14 and E18) and hatch (P0). Carnosine and anserine levels increased toward hatch and carnosine levels were higher in broilers than in layers. The β-alanine level was highest at E18 in both types of embryos. L-Histidine and 1-methylhistidine levels were comparable during embryogenesis, but 1-methylhistidine greatly increased at P0. No significant differences in dipeptide constituents were found between broilers and layers. In conclusion, concentration of carnosine was higher in broilers than in layers.

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Pituitary adenylate cyclase-activating polypeptide (PACAP), a member of secretin/glucagon/VIP family, has a potent action on the pancreatic secretion in mammals. The present study aimed to clarify the distribution of neural elements containing PACAP27 or 38 in the chicken pancreas. These two peptides were detected in the neural elements and showed the similar distributional pattern in the chicken pancreas. Intrapancreatic ganglia containing PACAPs-immunoreactive cells were found in the interlobular connective tissue. Nerve fibers showing immunoreactivity for PACAPs made the dense network around arterioles and were distributed in lamina propria of secretory ducts and the exocrine pancreas. Double labeling immunohistochemistry for PACAPs and islet hormones revealed that PACAPs-immunoreactive nerve fibers were in contact with B and D cells in B islets, but rarely distributed in A islets. These data suggest that PACAPs have relation to the regulation of the secretion from exocrine tissue and B and D cells in B islets of the chicken pancreas.

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Electron microscopic observations have revealed an electron density gradient in the chalaziferous layer of avian egg. The density is highest in the innermost sub-layer, which is bound with the vitelline membrane, and is thus traditionally referred to as the vitelline membrane outer layer (VMO). After high-concentration salt treatment, two proteins, VMO-I and VMO-II, are liberated from the egg envelopes of quail (Coturnix japonica), which results in the separation of the chalaziferous layer from the vitelline membrane. VMO-I and VMO-II were purified through gel-filtration and subjected to antisera produced in rabbits. The molecular sizes of these two proteins were estimated to be 9 to 15kDa for VMO-II and 18kDa for VMO-I. Their amino acid sequences were very similar to those of chickens. Immunofluorescent and immunoelectron micrographs showed that VMO-II was produced by the luminal epithelium and VMO-I by both the luminal and glandular epithelia of the infundibulum. Immunogold particles for the labeling of both proteins were distributed throughout the chalaziferous layer, as well as in the chalazae, with a density gradient similar to that mentioned above. In salt-treated envelopes, immunogold labeling was completely absent when stained with anti-VMO-II antiserum and weak with anti-VMO-I antiserum. Immunohistochemical studies revealed that purified VMO-II bound with vitelline membranes of salt-treated envelopes, and ligand blotting tests revealed that ZP1 and ZP3 were the molecules bound by VMO-II; the binding was inhibited by various kinds of sugars. VMO-II might play a role in the binding of the chalaziferous layer with the vitelline membrane, a process that leads to the anchoring of the chalaza cord.

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Sex-linked dwarf (SLD) of White Leghorn (WL; S23MA line, Okazaki station, Japan) and White Plymouth Rock (WPR; 15 line, Hyogo station, Japan) strains were established from the MA line (WL) and 16 line (WPR) of a normal growing line, respectively. However, the responsible genes in the two lines of SLD chicken have not been identified. In this study, we characterized the phenotypes and identified the responsible genes in the SLD chickens of these two strains. SLD chickens of both strains showed low body weight, short tarsometatarsus length, and high blood growth hormone (GH) level compared with the normal growing lines. From these particular results, it was indicated that the SLD chickens might possess a defect in the growth hormone receptor (GHR). We identified two types of mutations in the GHR gene in each SLD chicken by Northern blot and polymerase chain reaction analyses. The S23MA line had a single base mutation in the splice donor site of the exon 5/intron 5 on the GHR gene, whereas the 15 line lacked a large part of exon 10 of the GHR gene, which contained 27 highly conserved amino acids at the 3′ end of the coding region and 3′-UTR. Furthermore, it was revealed that growth retardation was caused by reduction in food intake of the SLD chickens. These two genetically distinguishable lines of dwarf chickens would serve as an effective tool for analyzing novel GH function and GHR signal transduction in chickens.

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The aim of this study was to determine whether ghrelin was present in the internal contents of eggs. Ghrelin in the internal contents of fertilized eggs incubated for 0 to 5 days was measured by a time-resolved fluoro-immunoassay. Ghrelin was identified in both yolk and albumen of the fresh fertilized eggs before incubation with a higher concentration in the yolk than albumen. The concentration in the whole fertilized egg internal contents (mixture of yolk, albumen and embryo) did not show significant changes during 5 days of incubation. These results suggest that ghrelin is contained in the internal contents of fertilized eggs, which may affect the functions of embryonic cells during early stage of development in chickens.

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The colibacillosis caused by avian pathogenic E. coli (APEC) is responsible for a significant loss of productivity and mortality in the poultry industry. The pathogenicity of these bacteria is based on the presence and expression of various virulence factors. In this study, the presence of the 19 virulence-associated genes in APEC was determined using PCR. Among the 118 E. coli isolates from the chickens with colibacillosis, all contained at least one of the 19 genes as approximately 95% of the isolates contained fimC. Interestingly, the clpG gene, which has not been detected in APEC previously, was detected in half of the isolates. The ColV plasmid-associated genes such as colV, tsh, iucC, iucD and iss genes were also detected in 57.6, 55.9, 50.0, 47.5, 47.5 and 41.5% of isolates, respectively. With regard to the fimbrial genes, the papA (14.4%), papC (14.4%) and papG genes (15.2%) were identified at relatively low rates, none of the isolates harbored afa8D, f17A or facA, and only 3 of the isolates (2.5%) contained eaeA. In this study, 94 isolates harbored two or more of the genes, and there were 43 different patterns of gene combination in the isolates. The most common pattern, which was found in 14.4% (17 isolates), was clpG-fimC-iutA-colV-tsh-iucC-iucD-irp2-fyuA-vat-iss. Overall, these results suggest that APEC strains in this area commonly contain multiple virulence factors and approximately half of the APEC strains contained the ColV plasmid-associated genes. Especially, colV and tsh were detected more than half of the isoaltes.

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