The effects of dietary phytate and microbial phytase supplementation on amino acid availability in poultry diets are of considerable practical importance. Published data on the influence of exogenous phytase supplementation on the ileal digestibility of amino acids in poultry are reviewed in this paper, with emphasis on the factors causing variability in amino acid responses. Several modes of action have been proposed by researchers to explain the influence of phytate on protein digestion, but it is hypothesised that the de novo formation of binary protein-phytate complexes in the gut under acidic conditions in the proventriculus may be the main mechanism whereby phytate depresses the digestibility of dietary amino acids as bound protein is refractory to pepsin digestion. It is also likely that phytate promotes the flow of endogenous amino acids. The review demonstrates that the choice of inert marker used in the digestibility assays is a major factor responsible for the variable phytase responses reported in the literature. The important diet-related causes for the variability include differences among ingredients, dietary levels of Ca and nonphytate P and dietary electrolyte balance, and clearly amino acid responses with added phytase may be enhanced by considering these issues in poultry feed formulations. Phytase feed enzymes, however, do not degrade the majority of dietary phytate in poultry and consequently the negative influence of phytate on protein digestibility is not completely removed by phytase supplementation. It is proposed that the experimental use of ‘dephytinised’ feed ingredients may be useful to define the actual extent to which amino acid digestibility is compromised by dietary phytate. The efficacy of current phytase feed enzymes may be further enhanced by the simultaneous use of other exogenous enzymes, which complement their activity, increase substrate access and/or absorption of liberated nutrients.

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In the Chabo (Japanese Bantam) breed of native Japanese chickens, there are birds that have buff-like plumage. This plumage shows yellowish brown at the trunk and white for all the tail feathers and a part of the primaries. In other words, this plumage occurs when areas, normally black for “buff columbian” plumage are replaced by white ones. Genetic analyses revealed that the gene controlling the appearance of the white area is an incompletely dominant autosomal gene. The homozygous condition for the mutant gene completely inhibits the expression of black pigmentation, leading to the replacement of black areas with pure white ones. The inhibition effect in the heterozygote however, is incomplete, resulting in the white areas (feathers) that have a slight gray tinge and many minute gray or black speckles. The mutant gene also has a weak effect in inhibiting the expression of brown color. Furthermore, when birds have the mutant gene with a wild-type genetic background for other plumage color genes, they exhibited the “red-pyle” plumage pattern. Therefore, there is a high possibility that the mutant gene expressing white areas (feathers) in the Chabo is identical to the known dominant white (I) gene, because the effect and mode of inheritance of the mutant gene possessed by the Chabo are quite similar to those of the I gene. This could be the first finding of a dominant mutant gene controlling white plumage in Japanese fancy fowls.

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An experimental flock consisted of five broiler strains was used to evaluate the response to selection for breast and thighs weight with imposing restriction against low value portions of carcass over three generations. The linear models fitted for mean breast yield (BY), legs yield (LY), low value portions yield (LVPY), against generation showed an average improvement of 0.5%, 0.05%, and -0.2% per generation, respectively. The initial mean values for these traits were 21.6%, 22.8% and 29.1%, respectively. Genetic group showed significant influence on all the traits. Carcass weight (CW), breast weight (BW), legs weight (LW) and low value portions weight (LVPW) were significantly influenced by gender. Rate of feathering exhibited a significant impact on CW, BW, BY, and LW. Based on pooled data, the heritability estimate for CW, BW, LW and LVPW was 0.14, 0.16, 0.17 and 0.17, respectively. The estimate for corresponding yield traits was 0.11, 0.39, 0.10 and 0.31. Genetic correlations between absolute weight of carcass and cut-up parts were generally high (>0.85). However, the yield traits showed low correlations ranging from -0.05 to 0.22 with carcass weight. Imposing restriction for low value portions of carcass was found to be effective but merely through improvement in breast weight and yield. Negative influence of such a policy on thighs yield might be minimized using higher relative economic values for thighs weight in index construction process. Considering BY and LVPY instead of BW and LVPW in selection programs to create and improve particular lines could be more efficient based on their genetic characteristics and irrespective of constant lower variability in BY and LVPW.

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Natural infections with influenza viruses have been reported in a variety of animal species including human, pigs, horses, sea mammals, mustelids and birds. Occasionally devastating pandemics occur in domestic chickens (broiler and layers) and human. During November 2003 to March 2004 in many countries in Asia, there are outbreaks of H5N1 avian influenza virus, causing of death of infected patients and devastated poultry industry. Some groups of Thai indigenous chickens are survivable recommended as resistance. These traits were related to immunogenetics, especially, the major histocompatibility complex (MHC) class I and class II molecules. The chicken MHC class II was investigated as candidate genes for avian influenza resistance. Seven hundred and thirty Thai indigenous chickens of small holder farms in the rural area of avian influenza outbreaks in the central part of Thailand were used in this study. They were separated into two groups, 340 survivable chickens and 390 dead chickens (resistance and susceptible). Genomic DNA were precipitated from blood samples and feathers. Diluted DNA was amplified to identify MHC haplotype. Data were statistically analyzed by χ2 analysis to test significant differences of influences of MHC class II haplotypes on avian influenza traits. The results represented ten MHC class II haplotypes, A9, B12, B13, B14, B19, B21, B2, B4, B5, and B6, and included eighteen of their crossbred. The homozygous B21 from these collected samples had 100 percent of survival rate and they were the major survival group. In addition, the heterozygous B21 also showed high survival rate because of co-dominant expression of these genes. In the other way, the homozygous B13 had 100 percent of mortality rate and they were the major group of high mortality rate. These results confirmed that MHC class II haplotypes influenced on avian influenza resistant traits in Thai indigenous chicken. The MHC genes can be used as genetic markers to improve disease resistant traits in chicken.

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The Japanese Silkie (Ukokkei) is a breed of domestic fowl with several unique characteristics. Skeletal analysis revealed that an extra cartilaginous digit was apparent transiently in the wing bud of Japanese Silkie embryos between stages 32 and 36. In contrast, an extra digit of the leg resembled digit 2 in terms of its skeletal elements. Whole-mount in situ hybridization analysis revealed that Shh, Bmp-2, and Hoxd-13 genes are ex- pressed in the presumptive region of the extra digit in the leg buds at stage 26. Expression of Shh and Hoxd-13 was also apparent in the anterior region, including the presumptive area of the extra digit, in the developing wing bud of Japanese Silkie embryos. The Japanese Silkie fowl thus warrants further investigation as a potential model animal for the study of limb development.

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In this study, we examined production efficiency in broiler chickens fed diets based on three wheat cultivars (Equinox, Regency and Claire) that resulted in different particle spectra (P<0.05) on hammer milling to 4mm, yet did not differ significantly in nutrient composition or non-starch polysaccharide content. The parameters evaluated in this 21-day feeding trial included weight gain, feed intake, feed conversion ratio, apparent metabolisable energy, transit time and relative losses of particle sizes of various classes during transit through the digestive tract. Weight gain, feed intake and apparent metabolisable energy were not (P>0.05) influenced by the treatments. The mean transit time also did not differ significantly (P>0.05) between diets, but the diet with the higher (P<0.05) relative proportion of coarser particles and giving greatest (P<0.05) reduction in the number of larger particles following digestion, resulted in the best (P<0.05) feed conversion ratio in broiler chickens. The present data suggest that coarse feed particle size is advantageous in terms of feed efficiency in broilers fed wheat-based diets.

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The goal of this study was to determine the effect of feeding rosemary and α-tocopheryl acetate on hen performance and egg quality. Ninety-six Lohmann laying hens, 32-week-old, were allocated into four groups. One of the groups was given a control diet (CONT), two groups were given diets supplemented with ground rosemary at 5 and 10g/kg (ROS-5 and ROS-10, respectively), whereas the other group a diet supplemented with 200mg/kg α-tocopheryl acetate (VIT-E). Following 60 days feeding, hen performance and some egg quality characteristics were determined, whereas the oxidative stability of the refrigerated stored eggs and liquid yolks was also examined. Results showed that there were no significant (P>0.05) differences in egg production, feed consumption, feed conversion ratio, egg weight and shape, yolk diameter, height and color, Haugh units, and shell thickness, among the dietary treatments. The extent of lipid oxidation in eggs differed (P<0.05) between the dietary treatments, but did not change with the storage time. In liquid yolks, lipid oxidation was lower (P<0.05) in the ROS-5 group compared to the CONT group. The ROS-10 group, in turn, exhibited lower (P<0.05) oxidation rate than the ROS-5 group, a finding suggesting that rosemary exerted a dose dependent antioxidative activity. The VIT-E group presented lower (P<0.05) lipid oxidation rate compared to all other groups.

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Two experiments were conducted to determine whether the excess essential amino acids in low protein diets affects the performance, nitrogen excretion and abdominal fat deposition of broiler chicks. Essential amino acids were classified into seven groups, (1)branched-chain amino acid (BCAA ; leucine+isoleucine+valine) (2)hydroxy amino acid (Thr ; threonine) (3)sulfur-containing amino acid (Met ; methionine) (4)aromatic amino acid (AAA ; phenylalanine+Tyrosine) (5)basic amino acid (BAA ; lysine+arginine) (6)glycine (Gly) (7)tryptophan (Trp) and were supplemented to low crude protein (19% CP) diet at the level of 150% (Experiment 1) and 200% (Experiment 2) of the Japanese Feeding Standard requirement. Seven amino acids supplemented diets, low CP and control (21% CP) diets were fed to 7-day-old chicks for 14 days. Body weight gain of the chicks fed the low CP and amino acids supplemented diets were did not differ among the treatments. Significant reduction in feed intake compared to the control diet were not seen in excess amino acids supplemented diets. Low CP and amino acids supplemented diets significantly increased abdominal fat weight than the control diet in experiment 1, however in experiment 2, compared to the control diet, abdominal fat weight were significantly higher in chicks fed the Gly and Trp supplemented diet among the groups. Nitrogen excreted were not reduced in chicks fed the low CP diets. These results show that the supplementation of excess amino acids to the low CP diet had little effect on abdominal fat deposition of broiler chicks in 1 to 3 wks of age.

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Dietary chitosan, a polymer of glucosamine, decrease the absorption of dietary fat and then reduce the abdominal fat deposition in broiler chickens. Chitosan is also digested and absorbed in the form of glucosamine by hens and broilers. Thus, in broiler chickens, dietary chitosan may decrease lipogenesis and triglyceride (TG) synthesis in the liver in addition to decrease fat absorption, consequently resulting in a reduction of body fat deposition. However, little research has been done to determine whether dietary glucosamine decreases hepatic TG synthesis and body fat deposition in broiler chickens. The present experiment was conducted to determine the effects of dietary chitosan or glucosamine HCl on fat absorption, hepatic TG contents and body fat deposition in broiler chickens. Broiler chickens at 14d old were fed on a control diet based on corn and soybean meal or diets containing 5% chitosan or glucosamine HCl for 3 weeks. Dietary chitosan and glucosamine HCl did not affect feed intake, body weight gain, feed efficiency and breast muscle weight. Dietary chitosan significantly (P<0.05) decreased fat digestibility, the contents of total lipid and triglyceride in the liver and abdominal fat weight. The concentration of plasma very low density lipoproteins (VLDL) tended to decrease in broilers fed on the chitosan diet. Dietary glucosamine HCl significantly (P<0.05) reduced hepatic total lipid and triglyceride contents, plasma VLDL concentration and abdominal fat deposition with no influence on fat digestibility. These results suggest that dietary chitosan may decrease the body fat deposition by reducing intestinal fat absorption and hepatic TG synthesis and dietary glucosamine may decrease the body fat deposition by reducing hepatic TG synthesis in broiler chickens.

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Chitosan, a polymer of glucosamine, decrease the absorption of dietary fat and then reduce the abdominal fat deposition in broiler chickens. Chitosan is digested by hens and broilers. Thus, chitosan may decrease lipogenesis and triglyceride (TG) synthesis in the liver. However, little research has been done to determine whether dietary chitosan regulate hepatic lipid metabolism in chickens. Administration of antithyroid agent such as propylthiouracil (PTU) induces excessive lipid deposition in livers of chickens. The present experiment was conducted to determine the effect of dietary chitosan on liver lipid concentrations in broiler chickens fed on PTU containing diets. Male broiler chickens at 14d old were fed on the basal diet based on corn and soybean meal or a PTU containing (0.03%) diets supplemented with or without 5% chitosan for 2 weeks. Administration of PTU increased (P<0.05) thyroid weight, liver weight and the contents of total lipid and TG in the liver. Dietary chitosan did not affect feed intake, body weight gain, feed efficiency, thyroid weight, liver weight and plasma TG concentration, but decreased (P<0.05) the contents of total lipid and TG in the liver regardless of dietary PTU treatment. These results suggest that dietary chitosan may not affect excessive lipid deposition in the liver induced by PTU, although a part of dietary chitosan may be absorbed and reduce lipogenesis and TG synthesis in the liver in broiler chickens.

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Avian uncoupling protein (avUCP), sharing 71-73% amino acid homology with both UCP2 and UCP3, is one of the mitochondrial anion carrier proteins. Its precise physiological roles in the cell remain elusive. A confusing aspect of these UCP variants (namely, UCP2, UCP3 and avUCP), is that their expression is enhanced in response to fasting ; that is, in response to basal metabolic state in which such energy expenditure would be expected to be depressed. In this study, we examined progressive alterations in the expression of genes encoding for mitochondrial uncoupling proteins, not only UCP but also avian adenine nucleotide translocator (avANT), in the skeletal muscle tissue of fasted chickens. The expression of avUCP gene was markedly enhanced after 12h of fasting and then diminished slightly but remained elevated after 96h of fasting compared to time 0 levels. In contrast, avANT was up-regulated only after 24h of fasting but continued to be further increased after 96h. Taken together, these results demonstrate that transcription of each of the mitochondrial anion carriers, avUCP and avANT, is independently up-regulated during fasting periods, implying different control mechanisms and consequences of each in metabolic adaptations involved in prolonged fasting.

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The biological activities of androgen are largely mediated via androgen receptor (AR). Although a partial sequence AR cDNA was revealed in canaries and zebra finch, AR cDNA has not been cloned in quail and chickens. To understand the physiological function of androgen and to apply it for other purposes, AR cDNA is necessary. Hence, this study was aimed to isolate the cDNA of AR and to reveal changes in mRNA expression using RT-PCR analysis in male reproductive organs of quail under different day-lengths and castration treatment. We found that a partial length of quail AR cDNA contains a 1385bp sequence encoding 343 amino acid residues and had high homology to other vertebrates. Quail were raised under continuous light regimen from 4 to 6 weeks old (6LL) and they were divided into 3 groups under the following conditions up to 9 weeks old : (1) continuous light regimen group (24h light ; 9LL), (2) short days regimen group (8h light and 16h darkness ; 9SD) and (3) castration group in which testis were surgically removed at 6 weeks old and raised under continuous light regimen (9CAS). Although weekly changes in the cloacal gland protrusion area showed significantly progressive increase at 7-9 weeks old in 9LL group and a progressive decrease in 9SD group, there were no changes in AR mRNA levels in the gland. In contrast, in 9CAS group, although the cloacal gland protrusion area decreased after castration treatment, AR mRNA levels increased in the gland. On the other hand, AR mRNA levels in epididymis and vas deferens increased in 9LL group, but there were no differences in 9SD and 9CAS groups from 6LL. The testicular AR mRNA levels did not change after long or short days treatment. These results indicate there is tissue-specific regulation in AR mRNA expression in quail.

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A study was being conducted to compare and assess the quality of chicken and duck patties prepared from broiler, spent hen and duck. The meat emulsions were analyzed for pH, moisture, protein, fat, total plate count (TPC), total psychrophilic count (TPSC) and emulsion stability and the cooked patties were analyzed for pH, moisture, protein, fat, cooking yield, total plate count (TPC), total psychrophilic count (TPSC), thiobarbituric acid (TBA) value and sensory qualities such as, appearance, flavour, tenderness, juiciness and overall acceptability. The patties prepared from broiler meat showed significantly highest moisture content, emulsion stability and cooking yield and on the other hand, the fat content was significantly highest in duck patties. The TPC, TPSC, TBA values and sensory qualities of all the patties were within the acceptable level up to 14^thday of refrigerated storage. There were no major drawbacks of the patties prepared from spent hen and duck in comparison to those of broilers. Therefore, as the values of the major parameters studied are within the range of standard values, the spent hen and duck meat can also be encouraged for preparing nutritionally sound and acceptable patties.

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