Within the past few decades, intensive rearing practices have been developed to keep pace with the increasing demand for the high quality, low cost protein source that poultry provides. For example, chickens are housed routinely in crowded environments under adverse conditions and chicken strains with rapid growth, high protein-to-fat content and superior egg laying characteristics have been genetically selected. A major negative consequence of these practices has been an increase in the incidence of diseases. Enteric diseases in particular have emerged as a major problem threatening the future viability of the poultry industry. A variety of methods have been used to combat avian diseases in the commercial setting including improved farm management practices, use of antibiotic drugs, selection of disease resistant chicken strains and manipulation of the chicken immune system. In the latter category, development of vaccines against the major avian diseases has become a priority in the poultry industry. For the development of practical vaccines and new control strategies against enteric pathogens, comprehensive understanding of host intestinal immune system and basic immunobiology of host-microbes interactions leading to the protection is necessary. Recent progress in poultry genetics and functional genomics technology would facilitate the development of logical control strategies against enteric diseases of poultry in the coming decade. This paper will highlight recent progress in host immunobiology and vaccine strategies to Eimeria and Salmonella infections.

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Single Comb White Leghorn laying hens (Hyline) were fed ad libitum in order to estimate energy expenditure of behavioral activities (BA) such as standing, eating or body movements et cetera under artificial day-night cyclic ambient temperatures (Ta) 33-25°C, 25-33°C and constant Ta 29-29°C. The light (12h)-dark (12h) periods synchronized with the Ta, commencing at 09 : 00. Body movement of the hens was detected by the Actigraph as activity count (ACT), while standing time (STN) et cetera were measured by the infra-red beam switches. Heat production (HP) was measured by the indirect calorimetry. HP, ACT and STN of each hen were measured continuously for 48h. The daily food intake (FI) of the hens were in a decreasing order at 29-29°C, 25-33°C and 33-25°C, respectively. On the other hand, the daily HP were in a reverse order of FI at 29-29°C, 25-33°C and 33-25°C, respectively. As the ACT and STN increased significantly during the dark periods under higher Ta, this may have induced higher HP. Energy expenditure of BA when expressed by the ACT were 19%, 22% and 30% of the daily HP at 33-25°C, 29-29°C and 25-33°C, respectively.

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Avian perivitelline membrane, an investment homologous to the zona pellucida of mammalian oocytes, is composed of two glycoproteins. Previous studies have indicated that one of the components, a glycoprotein homologous to mammalian ZPC, is produced and secreted by the granulosa cells of maturing follicles in quail ovary. In the present study, to investigate the hormonal regulation of ZPC production, [3H] leucine incorporation into ZPC was compared in granulosa cells cultured in a medium containing follicle-stimulating hormone (FSH), luteinizing hormone, or prolactin, and a stimulatory effect of FSH was observed. By measuring ZPC protein in the medium and mRNA in the cells with Western blotting and Northern blotting analyses, respectively, we found that addition of FSH stimulated not only ZPC protein production but also ZPC mRNA expression in the granulosa cells. These results suggested that FSH stimulates ZPC protein production at the gene transcription level.

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Apolipoprotein B (apoB) containing lipoproteins are major lipoproteins in blood and the elevated concentration in plasma may lead to increased transport of lipoproteins into adipose tissues resulting in the excessive fat deposition. Aims of the present study were to prepare monoclonal antibodies against chicken apoB and to development enzyme linked mmunosolvent assay (ELISA) methods with the antibody which would be provided for studies on lipoprotein metabolism in chickens. A monoclonal antibody, CAB4, was prepared using a purified chicken apoB and specific reactivity of the antibody was verified by Western blot analysis and immuno-precipitation of apoB in plasma and primary hepatocyte cultures in chickens. ELISA method with monoclonal anti-chicken apoB antibody developed in this study was applicable to measure apoB concentration in plasma and cell cultures within the range of 0 to 500ng/ml with the intra- and inter-assay variation of less than 10.6%. Using the present ELISA method, plasma apoB concentrations in broiler chickens starved for 8h were shown to be 0.44mg/ml against 1.02mg/ml in fed chicken counterparts. The monoclonal antibodies against chicken apoB and ELISA method developed in the present study could be potentially used for studies on the lipoprotein metabolism focusing on the optimization of lipid metabolism in chickens.

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Mustard meal (MM), which is a residue of essential oil extraction, had high moisture content (77%). It took 3 days to dry under the sun or 48 hours to dry in an electrical oven at 65°C or 8 hours in a gas heated pan of initial temperature 120-140°C. The chemical composition of MM from the 3 drying processes was similar. It contained on DM basis 30-32% CP with relatively high EE (19-22%) and CF (12-13%), while ash and NFE were 5-6% and 28-31%. Metabolizable energy (ME) of the samples from the 2 among the 3 drying processes was determined. The result revealed that although the CP content of MM was only 50% of soybean meal (SBM), it had higher EE. Therefore its ME value was higher than SBM. The apparent ME and true ME of sun-dry MM was 2.888 and 3.348kcalg DM (or 2.724 and 3.161kcal/g air dry), while those of gas dried meal was lower, i.e. 2.435 and 2.892kcalg DM (or 2.328 and 2.765kcal/g air dry), respectively.

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A simple method for sexing chicken embryos was devised using DNA prepared from blastodermal cells. A cluster of cells was collected from the area opaca of a stage X blastoderm, and DNA was prepared by the boiling method (10-minute boiling and 3-minute centrifugation). DNA was also prepared by the extraction method (DNA extraction kit) as a control. PCR analysis was carried out using the prepared DNA, and the sex of embryos was clearly identified by both the boiling and extraction method. This simple and rapid method of embryo sexing using blastodermal cells isolated from the area opaca enables us to identify the sex of a large number of chicken embryos in a limited time.

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Studies were conducted to induce multiple ovulation in Japanese quail. Laying quail were injected with 20I.U./quail of PMSG once a day for 5 successive days followed by a single treatment with 50μg/quail of oLH about 24hr after the last PMSG injection. The hens were decapitated 8 to 9hr later. Other quail received only oLH or vehicle 12hr before the predicted time of ovulation. All quail in the vehicle-injected control group ovulated at the expected time. The injection of oLH resulted in premature oviposition and ovulation. Within the PMSG-primed and oLH injected group, 10 out of 19 quail were induced to ovulate single or several follicles (ovulation rate, 53%), whereas 9 quail failed to ovulate. Daily egg laying during PMSG administration was without relationship with rate of multiple ovulation. Most of the PMSG-primed and oLH injected quail had heavier ovaries with many yellow follicles arranged in non-hierarchical way in contrast to ovaries of control and only oLH-treated birds. The results showed very variable responses of quail to oLH treatment in the PMSG-primed birds. Our method is not recommendable for common use because of inefficiency of egg collection after low rate of multiple ovulation which requires expense and labour.

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