The aim of the present review is to assess the potential usefulness of crossbred chickens in tropical environment. Poultry is a promising and emerging sector for poverty alleviation as well as an animal protein source in Bangladesh. Poultry production is yet lies in rural scavenging poultry in tropical country. Crossbreds are reared in scavenging, semi-intensive or intensive systems resulting in birds with good adaptability to tropical climate, highly resistant to disease and performing even better than pure exotic or indigenous chickens. Better growth performances are determined in indigenous naked neck (D. Nana) with Rhode Island Red (RIR), White Leghorn (WLH) or Fayoumi crossbreds in comparison with pure exotic, indigenous or other crossbreds. With respect to egg production, WLH×Fayoumi, RIR×Fayoumi, RIR×WLH and Fayoumi×WLH appear to be suitable combinations. However, crossbreds of D. Nana with RIR or Fayoumi produce more eggs than that of RIR or Fayoumi under scavenging conditions in a tropical climate. The best quality egg is found in WLH chickens but the highest egg shell thickness is found in D. Nana which affects hatchability of eggs. Of the above crosses, RIR×Fayoumi and their reciprocal crosses are found to be the best for fertility and hatchability. Accordingly D. Nana crossed with RIR or WLH or D. nana (indigenous full feathered chicken) results in improved fertility and hatchability of eggs. Although D. Nana crossed with an exotic broiler strain performs the best for meat yield traits, crossbred of D. Nana with RIR, WLH or Fayoumi improve meat yield traits. Therefore, the present review reveals that crossbreds of RIR×Fayoumi or D. Nana cockerels with RIR, WLH and Fayoumi hens may be considered for poultry production in tropical climate. This review emphasizes the use of D. Nana and its crosses with RIR, WLH or Fayoumi for their suitability in tropical regions.

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The Pearl Grey (PG) guinea fowl and the Single Comb White Leghorn (SCWL) chickens are considered egg layers among their species. The SCWL chicken has been developed extensively for commercial egg production whereas the PG guinea fowl is a seasonal and a poor egg producer. The objective of this study was to establish genetic relatedness of the two avian species to aid future programs of improving egg production in guinea fowl using the available resources such as genetic markers developed for the SCWL chicken. The genetic similarity between the PG guinea fowl and the SCWL chickens was evaluated using the random amplification of polymorphic DNA (RAPD). A total of 220 and 185 RAPD alleles were amplified in SCWL chickens and PG guinea fowl, respectively. The alleles ranged in size from 150-2650 and 200-2600bp in chickens and guinea fowl, respectively. The RAPD analysis yielded polymorphic bands in SCWL chickens and PG guinea fowl that constituted 13% and 9%, respectively, of the total number of alleles amplified in each species. Genetic similarity within SCWL chickens and PG guinea fowl was 95.6 and 92.2%, respectively. However, genetic similarity between SCWL chickens and PG guinea fowl was 31.3%. While the RAPD analyses seem useful in estimating genetic similarity between SCWL chickens and PG guinea fowl, the level of polymorphisms and the genetic diversity between the two avian species suggest the need to generate genetic resource information specific to guinea fowl for genetic improvement of the PG guinea fowl.

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The WW domain containing E3 ubiquitin protein ligase 1 (WWP1), which plays an important role in ubiquitin-proteasome pathway to degrade unneeded or damaged proteins, was recently identified as the responsible for chicken muscular dystrophy. Despite intensive studies on oncogenic characters, the role of WWP1 to muscular diseases has not yet been fully understood. Previously, we transfected either of wild and mutated types of WWP1 gene into C₂C₁₂ mouse myoblasts to monitor the expression pattern of muscle-differentiation markers, so that excessive WWP1 expression enhanced the expression of the myosin heavy chain (MyHC) Ia gene but lowered the expression of the MyHC IIb gene, while mutated WWP1 gene transfected into myoblasts was distinct from these cases in that the MyHC gene or genes expression inhibited the normal myoblast differentiation. However, the mechanism for the mutation to inhibit muscle differentiation remains elucidated. The current study attempted to suppress the WWP1 expression by RNAi technique and to observe its effect on C₂C₁₂ cells. The effect of WWP1 suppression was clearly different from that of the R441Q missense mutation in the WWP1 gene. The WWP1 suppression reduced the proliferation rate of C₂C₁₂ myoblasts, while clear difference was not observed in the proliferation rate by the transfection of the mutated WWP1 gene into the cells. Our RT-PCR analysis indicated that the reduction of the WWP1 expression is the specific effect mediated by RNAi and that the reduction of proliferation rate observed in this study is largely attributed to the suppression of the WWP1 expression. These data indicated that the mutation responsible for chicken muscular dystrophy does not eliminate the enzymatic activity and provides some new function for the gene.

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E2F1 (Adenoviral E2 promoter binding transcription factor 1), mediating cell proliferation and p53-dependent/independent apoptosis, has been shown to be involved in spermatogenesis in mouse testis. In this study, to obtain clues to the role of E2F1 in chicken testis development, we examined the expression of E2F1 in chicken testis at embryonic days 14 and 17, newly hatched, one week old and adult by comparing its expression in mouse testis at corresponding stages. Quantitative PCR analysis demonstrated marked differences between chicken and mouse in the expression profile in the course of chicken/mouse testis development; chicken testis showed the highest E2F1 expression in adult, whereas mouse testis showed the expression decreased with development. This observation indicated that the maturation process of testis in chicken is different from that in mouse.

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A method of freezing semen using N-methylacetamide (MA) as a cryoprotective agent was applied to Yakido, a chicken breed designated as a “Natural Monument” under the “Law for the Protection of Cultural Property” (Law No. 214, May 30, 1950) in Japan. Semen was collected from Yakido roosters, and pooled semen was diluted 1: 1 using semen diluent containing no cryoprotective agent. After equilibration at 5°C for 30min, diluted semen was further diluted 1: 1 using semen diluent containing MA at a final concentration of 9%. Diluted semen was packaged into 0.5-mL plastic straws and frozen by placing the straws in liquid nitrogen vapor followed by plunging into liquid nitrogen at -196°C. After storage in liquid nitrogen for about one month, frozen semen was thawed in ice water. Intravaginal artificial insemination (AI) was performed immediately after thawing semen without removing the cryoprotective agent. In Fertility Trial 1, AI was performed once a week for four consecutive weeks. Weekly fertility rates using frozen semen were 83.8±3.8%, 77.1±8.8%, 88.6±5.1%, and 77.3±5.7% for weeks 1, 2, 3, and 4, respectively. Hatchability was over 90% throughout the experimental period. In Fertility Trial 2, the duration of fertility was examined after intravaginal insemination for 2 consecutive days. Daily fertility rates using frozen-thawed semen were 90.0%, 90.0%, 91.7%, 88.9%, 100.0%, 100.0%, 100.0%, 55.6%, 60.0%, 25.0%, 30.0%, 30.0%, and 9.1% for days 1 through 13 after AI, respectively. Overall hatchability was 89.5%. These results indicated that freezing chicken spermatozoa using MA as a cryoprotective agent is a practical method of preserving chicken semen collected from genetically valuable chicken breeds.

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The objective of this research was to evaluate the effects of dietary supplementation of blood meal (BM) on carnosine (L-Car) and anserine (L-Ans) content in the chicken breast muscle (CBM). In Experiment 1,384 Ross® broiler chicks of 1d old were assigned to 3 dietary treatments: 100% basal diet (BM-0), 95% basal diet+5% BM (BM-5), and 90% basal diet+10% BM (BM-10). In Experiment 2, 144 Ross® broiler chicks of 1 d old were fed BM-treated diets, including 0% BM (BMI-0), 5% BM (BMI-5), and 10% BM (BMI-10), with isocalorie and isonitrogen adjustment. Broilers were reared in stainless steel cages for 5wk in both experiments. In Experiment 1, the content of L-Car and L-Arg increased as the birds aged. The increase was quadratic in L-Car and linear in L-Ans. The content of L-Car linearly (P<0.01) increased as the level of BM increased at wk 4 and 5, but there was no significant difference between BM-5 and BM-10 treatment. Conversely, the content of L-Ans linearly (P<0.01) decreased as the level of BM increased at wk 1, 3, 4, and 5. In Experiment 2, the content of L-Car and L-Arg showed quadratic increase as the birds aged. The content of L-Car showed a significant (P<0.01) negative quadratic response as the level of BM increased at wk 1, 3, and 5. The content of L-Ans showed a significant (P<0.05) positive quadratic response as the level of BM increased at wk 3 and 5. The growth performances were not significantly affected by treatments in Experiment 1; in Experiment 2, however, a linear decrease (P<0.01) in feed intake and weight gain, and a linear increase (P<0.01) in feed conversion ratio were observed as the BM was increased. In conclusion, addition of 5% BM in broiler diet increases the L-Car but not L-Ans in CBM.

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Effect of phytase produced by thermo-protective coating technology (coated phytase) on performance and nutrient utilization of broiler chicks fed a corn-soybean meal-based pelleted diet was investigated. A total of 144-one-day-old male broiler (Ross) chicks were divided in 24 groups and fed 4 diets (6 groups per diet) for 21 days. The diets included a mash or pelleted basal diet without or with the coated phytase at 500FTU/kg in a 2×2 factorial arrangement. Calcium and non-phytate P values in the basal diet were 22 and 51% lower compared with NRC (1994) recommended values, respectively. All the diets contained titanium oxide as an indigestible marker. There was no interaction (P>0.05) between diet form and phytase on any of response criteria measured in this study except body weight gain and feed intake such that phytase supplementation improved (P<0.05) these 2 response criteria, but improvements were greater for pelleted diet than mash diet. Phytase supplementation increased (P<0.05) tibia ash and ileal P digestibility, by 10.5 and 38.1%, respectively. Phytase supplementation did not, however, affect (P>0.05) the ileal digestibilities of Ca, crude protein and amino acids. In conclusion, coated phytase supplementation to corn-soybean meal-based diet for broilers resulted in improved growth performance, bone mineralization and P digestibility regardless of diet type (mash versus pellet). These findings suggest that the efficacy of the coated phytase used in the current study was not influenced by the pelleting process.

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Effects of the oral administration of fucoxanthin (FX), a major carotenoid of algae, on plasma fucoxanthinol (FX-OH) concentration, plasma antioxidative status, and meat color and lipid stability during chilling storage in broiler chicks were investigated. One-week-old male broiler chicks were divided into control and FX treatment groups. For the FX treatement group, FX was given into the crop of each bird at a volume of 10mg per day per bird for 2 weeks. After 2 weeks of treatment, the plasma, liver, and superficial pectoral muscle were harvested. FX was not detected in either the plasma or liver of control and FX-treated birds, although FX-OH was detected in both the plasma and liver of the FX-treated group. Plasma antioxidative activity against a peroxyl radical derived from 2,2′-azobis-(2-amidinopropane) dihydrochloride was observed in FX-treated chicks but not in control chicks. FX treatment did not affect the L* and a* values nor the lipid peroxide content of superficial pectoral muscle during 6 days of chilling storage. However, FX treatment increased the b* value of superficial pectoral muscle compared to the control group (P<0.05). These results indicated that FX was incorporated and converted into FX-OH during absorption, and that FX-OH acted as an antioxidant in chick plasma. It was also revealed that the FX treatment for broiler chicks affected their meat color. Our results suggested that FX is a potent antioxidative feed ingredient for enhancing both the plasma antioxidative status and meat color in broiler chicks.

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This study was conducted to determine the effect of Echinacea purpura, levamisole and vitamin E on humoral and cell-mediated immunity of broilers. Total of 200 one-day-old male broiler chickens (Ross 308), were randomly distributed to experimental groups included control, vitamin E (150mg/kg diet), 0.1% aqueous Echinacea, levamisole (15mg/kg BW). Vaccination against Newcastle disease (ND) and avian influenza (AI; H9N2) were performed. The hemagglutination inhibition (HI) titers against both vaccines were determined on serum samples at days 21 and 42. Chicks were injected into breast muscle with sheep red blood cells (SRBC) at 14 and 35 days. Blood samples were drawn at 7 days after the first and the second injections. The antibody levels against SRBC were measured by hemagglutination test. The cell-mediated immunity was determined via phytohemagglutinin (PHA) and dinitrochlorobenzene (DNCB). Antibody titers against AI, ND, total anti-SRBC at 21 day and IgM at 21 and 42 days of age were not affected by the treatments (P>0.05). Although cell-mediated immune responses by DNCB (31 day) and PHA (42 day), total anti-SRBC antibody, IgG and IgG/IgM ratio (42 day) (P<0.01), IgG and IgG/IgM ratio (21 day) (P<0.05), were affected by some of the used treatments. In conclusion, taking into account the public urge in withdrawn of chemicals, interest in nutraceuticals in animal production and observed results, use of Echinacea extract and vitamin E as immunomodulator feed adjuncts needs further study.

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The aim of present study was to determine whether the expression of transforming growth factor-βs (TGFβs) in the utero-vaginal junction (UVJ) of hen oviduct was changed by the stimulation with sperm. Localization of immunoreactive TGFβ3 (irTGFβ3) in the UVJ that contained sperm storage tubules (SST) were examined by immunocytochemistry with or without insemination. Changes in the mRNA expression of three types TGFβ isoforms (TGFβ2, β3 and β4) in the vagina or UVJ cells co-cultured with fresh chicken sperm were observed by real-time PCR. The irTGFβ3 were localized in the surface epithelia of UVJ of all the inseminated and non-inseminated birds. The immunoreaction products were not present in the SST cells of non-inseminated hens but were appeared in the SST at 1d of insemination, and showed positive staining even after 10 or 20d of insemination. The expression of three types TGFβs were significantly increased in the cultured UVJ cells after stimulation by fresh sperm, however, the vaginal cells that were co-incubated with sperm did not show any alteration of their expression for all three types of TGFβs. These results suggest that the interaction between sperm and SST cells may up-regulate TGFβs expression in the SST which may play significance role in the sperm survival in SST.

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Heat stress (HS) causes poor growth, immunosupression and high mortality, through physiological dysfunction. We have reported that ‘acute’ HS increases mitochondrial reactive oxygen species (ROS) and oxidative damage in the skeletal muscle of broiler chickens (Cobb), but that this is not for the case for males of the laying-type white leghorn (WLH) strain of chickens (Mujahid et al., 2005b). We have now studied the effects of ‘chronic’ HS on performance and oxidative damage to skeletal muscle in different strains of chickens. Meat-type male chickens (Ross and Cobb) and male laying-type chickens (WLH) of 14d of age were arranged according to a factorial design (3 strains×4 conditions): control (24°C), cyclic (32-24-32°C: 32°C for 8h/d, 32-24-32HS), constant (32 and 34°C, 32HS and 34HS, respectively) for 14d. Feed consumption and body weight gain were measured. Thiobarbituric acid reactive substances (TBARS) content in skeletal muscle was measured colorimetrically with BHT (butylated hydroxytoluene) and expressed as malondialdehyde (MDA) equivalent. Body weight gain and feed consumption for the 3 strains (Ross, Cobb and WLH) were decreased by 32HS and 34HS, but not by 32-24-32HS. The decrease in weight gain of WLH chickens for the 32HS and 34HS conditions was smaller than for broiler chickens (Ross and Cobb). The 32HS and 34HS groups showed slightly enhanced MDA levels (P<0.05) in the skeletal muscle of all 3 strains, but not for the 32-24-32HS group. The results suggest that depression in growth performance due to chronic heat stress is more evident in meat-type chickens (Ross and Cobb) than male laying-type chickens (WLH), and that reduction in the performance are associated with enhancement of oxidative damage to skeletal muscle.

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