Feeding and somatic growth are closely related to each other, and are strictly governed by several endocrine and neuroendocrine systems in animals. Endocrine control of growth is an important subject in poultry industry. Ghrelin is a recently identified, growth hormone (GH)-releasing and feeding-promoting peptide in mammals, and the major source of its release is the stomach. From the comparative endocrinological aspects, ghrelin was considered to be present in avian species. In fact, ghrelin peptide and its cDNA encoding ghrelin precursor have been identified from the chicken proventriculus in 2002, and the presence of the ghrelin molecule has by now been shown in various avian species. In this review, we summarize the recent knowledge of ghrelin structure, distribution and function in birds.

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Characterization of genetic diversity by employing molecular tools is a prerequisite in developing strategies for conservation and utilization of poultry genetic resources. We assessed genetic variation within and between six Indian chicken populations (Naked Neck, White Silkies, Commercial Layer and Broiler, Giriraja and Desi) using nine microsatellite markers. Seven loci were polymorphic in all populations, with the number of alleles varying from 3 to 27per locus and 4.1 to 8.6per population. Average heterozygosity and gene diversity in the populations were 0.68 and 0.66, respectively. Some populations and loci deviated from Hardy-Weinberg equilibrium. Except Naked Neck, none of other populations was in genotypic disequilibrium for a single pairwise locus combination. F-statistics indicated that populations are genetically structured, ∼85% of the total genetic variation being due to genetic differentiation within the populations. Estimates of Latter’s F_ST and Nei’s D_S genetic distances revealed relatively close genetic similarity between Naked Neck and Giriraja, while White Silkies was the most distant. An estimated divergence time between Naked Neck and Giriraja was over100 years, with a comparatively longer (over 450 years) period of separation between Giriraja and White Silkies. We suggest that there is an essential room left for genetic improvement of Indian native breeds and commercial stocks.

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In the present study, the individual and combined effects of aflatoxin B₁ (AFB₁) and fumonisin B₁ (FB₁) on the quality of quail eggs were investigated. To this end, 288 8-week-old Japanese quail were randomly distributed into six experimental groups (48 birds per group) and fed the following diets for 140 days (five 28-day laying periods) : 1) 0 (control) ; 2) 10mg FB₁/kg ; 3) 50μg AFB₁/kg ; 4) 50μg AFB₁/kg+10mg FB₁/kg ; 5) 200μg AFB₁/kg ; and 6) 200μg AFB₁/kg+10mg FB₁/kg feed. Each treatment consisted of four replicates of twelve quail. Eggs laid in the last day of each 28-d laying period were collected and submitted for individual analysis for specific gravity, Haugh units and percentage shell. Results showed that by the end of the 4^th cycle, average egg weight was lower (P<0.05) in groups fed 50 or 200μg AFB₁/kg+10mg FB₁/kg combination diets. Specific gravity decreased (P<0.05) in the group fed 200μg AFB₁/kg+10mg FB₁/kg by the 5^th cycle. Feed intake and Haugh units were not affected (P> 0.05) by AFB₁ and/or FB₁. Only birds receiving the 200μg AFB₁/kg+10mg FB₁/kg diet had decreased (P<0.05) percent eggshell by the 4^th cycle. Data indicated that AFB₁ and FB₁ in combination have primarily additive effects on quail egg weight, specific gravity and percent eggshell at the concentrations used.

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Two separate randomised block design experiments were each carried out for 13 months to investigate the effects of replacing, in-part, soybean meal (SBM) and wheat by graded levels of faba beans (FB) and field pea (FP) in a basal diet of wheat-SBM, balanced for amino acids, similar in crude protein (CP) and metabolisable energy (ME) on Lohmann hens. Traits studied included ; egg production, feed consumption, body weight gain, feed, energy and protein utilisations, and egg quality. Increasing dietary FB up 400g/kg (no SBM) decreased hen-day egg production, from 85 to 75%. Average egg mass significantly reduced from 50.8-43.5g/(hen*d). Feed consumption was similar (110 to 113g/(hen*d)). Increasing FB increased ME and CP required for egg production. FB had no significant effect on the shell strength, shell fraction and yolk index of eggs ; meanwhile it decreased the yolk fraction, and increased yolk colour, albumen fraction and albumen index. Most traits studied, were statistically similar up to 160g FB/kg feed. Increasing levels of FP up to 500g/kg did not significantly affect hen-day egg production and egg mass per day, although feed consumption increased. Body weight gain linearly dropped with increasing FP. FP had no significant effect on any of the egg quality traits studied. 16% FB and 50% FP could be included in layers diet without any significant effects on egg production or quality.

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Two experiments were conducted to investigate the birds’ responses to diets of varying nutrient concentrations, one with 126 eight-week old F₁ crossbred (Rhode Island Red male×Fayoumi female) birds up to 20 weeks of age (growing stage) and another with ninety 20-week-old birds up to 22 weeks (pre-layer stage) under semi-scavenging condition in the poultry farm. Dietary treatments consisted of an arrangement of three diets that contained 14% crude protein (CP) and 2550kcal metabolizable energy (ME)/kg (low nutrient density ; LND), 15% CP and 2750kcal ME/kg (moderate nutrient density ; MND) and 16% CP and 2950kcal ME/kg (high nutrient density ; HND). The contents of CP, ME and calcium (Ca) in MND diet were fitted with the requirements calculated in this experiment based on five nutrient specifications in the world. All diets were formulated using locally available conventional feedstuffs and un-conventional feed ingredients employing a free software of computer program for least-cost feed formulation. The responses of grower birds to different diets showed that the highest body weight and live weight gain were achieved by the birds that received HND diet that differed significantly from those of LND diet (p<0.05). Uniformity, defined in this study, at 20 weeks of age was significantly highest in birds reared on HND than those of LND and MND groups (p<0.01). During the pre-layer period, the birds of LND diet group consumed the highest amount of feed that differed significantly from other dietary groups (p<0.01). Uniformity at 22 weeks of age in all groups improved but it was still higher in MND and HND diet groups. It may be concluded that it is possible to formulate least-cost poultry diets by incorporating locally available feed ingredients and the responses of birds to HND is most favorable and therefore its nutrient specifications may be followed for formulating diets of semi-scavenging F₁ crossbred (Rhode Island Red male×Fayoumi female) grower and pre-layer chickens.

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A 4×3 factorial experiment with four added dietary energy (fat) levels (0 (0.0), 24 (0.5), 48 (1.0), and 72 (1.5)kcal ME/kg (%fat)) and three protein levels (14.9, 15.5, and 16.1%) was conducted to determine the influence of dietary energy on performance, egg composition, egg solids, egg quality, and profits of Hy-line W-36 hens at different protein levels. The basal diets of the 16.1, 15.5, and 14.9% protein contained 2,784, 2,800, and 2,815kcal ME/kg, respectively. This experiment lasted 12 weeks. Hy-line W-36 hens (n=1440) in phase 3 (55 weeks of age) were randomly divided into 12 treatments (8 replicates of 15 birds per treatment). There was no interaction on performance, egg components, egg solids, and egg quality between protein and dietary energy. As protein level increased from 14.9 to 16.1%, percent yolk and yolk/albumen ratio linearly decreased and percent albumen linearly increased. Yolk color linearly increased as protein level decreased. Increasing dietary energy by the addition of poultry oil had no significant effect on performance, egg composition, egg solids, and egg quality. An ideal dietary energy level for optimal performance could not be determined for Hy-line W-36 hens during phase 3. Because feed ingredient prices and egg price vary, there can be no fixed ideal dietary energy level for optimal profits during phase 3.

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Freeze-drying is used as a method to stabilize proteins. The process itself may however cause protein unfolding and denaturation, but the risk is reduced if a stabilizing agent is added prior to freeze-drying. Here chicken antibody (IgY) preparations were freeze-dried in the presence or absence of lactose, sucrose and threalose as stabilizing agent at 0.3, 0.06 and 0.012M. The activity of freeze-dried IgY batches in the absence of stabilizing agent was similar before and after freeze-drying, but decreased slowly during eight weeks at 37°C. Addition of disaccharide resulted in a preserved activity after eight weeks in 37°C, compared to samples with no sugar added. The results were similar irrespective of sugar type and concentration (0.012-0.3M). This shows that IgY freeze-dried in the presence of disaccharide is very stable and a method to reduce the cost and simplify transport, storage and use of avian antibodies.

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N-balance studies were carried out to assess the lysine requirement of fast growing chickens (Cobb 500) at different sex and age depending on crude protein deposition and efficiency of dietary lysine utilisation. The experiments were conducted within three age periods (I : 10-25d ; II : 30-45d ; III : 50-65d) and 72 chickens (36 males, 36 females) per age period. Experimental diets with six levels of graded CP content were based on high protein (HP)-soybean meal, wheat gluten and crystalline amino acids (L-Thr, DL-Met, L-Arg) in order to create lysine (4.30g Lys/100gCP) as the first limiting dietary amino acid (constant ratio Lys : Met+Cys : Thr : Arg=1 : 1.01 : 0.91 : 1.14). For application of a nonlinear N-utilization model, nitrogen maintenance requirement (NMR) and theoretical maximum for daily nitrogen retention (NR_maxT) were established as model parameters for further assessment of the lysine requirement depending on age, sex and daily CP-deposition. As an example, the calculated lysine requirement concentration for 60% of the theoretical potential for daily CP-deposition (10-25d : 1.10% lysine, 60g daily feed intake ; 30-45d : 1.03% lysine, 140g daily feed intake ; 50-65d : 0.96% lysine, 170g daily feed intake) was in close agreement with published data. However, the predicted feed intake is one of the most important factors of influence when amino acid requirement concentrations are established. The level of daily CP-deposition and the dietary amino acid efficiency as important factors influencing the amino acid requirement data need more attention in future requirement studies.

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Cryopreservation of poultry semen has been reported, but preservation of female genetic material has not been possible because of the large size of their yolk structure. Cryopreservation of primordial germ cells (PGCs) is an alternative way to preserve both female and male genetic material in chicken. In the present study, fertilized eggs were incubated for about 53 hours to obtain embryos at stage 14-16. The blood of the whole embryo was collected from the terminal vein or dorsal aorta using a fine glass micro pipette under a microscope. The PGCs were then purified using Nycodenz density gradient centrifugation. Four commercially available cryoprotectants (A, B, C and D) were used to preserve the PGCs, and DMSO was used as a control. The average recovery rate of PGCs after thawing was 58.2%, 52.9%, 46.5% and 39.4% with the A, B, C and D treatments, respectively. There was no significant difference between the A, B and C treatments and control (DMSO), which showed an average recovery rate of 49.9%. However, the recovery rate obtained using D cryoprotectant was significantly lower than using treatment A. The average viability of the PGCs after thawing were 86.0%, 82.3%, 81.1% and 84.8% for cryoprotectants A, B, C and D, respectively, and the control (DMSO) was 85.3%. There was no statistically significant difference between the four treatments and control. It was concluded that all of the available cryoprotectants examined in this study could be used for preservation of PGCs from embryos ; however, the use of cryoprotectant D should be avoided since the recovery rate was significantly lower, although the viability was not affected.

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A simple cock’s semen dilutor (two-stage) with minimum ingredients was developed in the present study. The stage-1dilutor was aimed to reduce the motility and metabolism during storage and the stage-2 dilutor was to be added just prior to insemination to revive the motility to facilitate the entry of spermatozoa into sperm host gland. Initially, the semen was diluted 1 : 1 with the stage-1 dilutor having lower pH that reduced the motility and metabolism. Subsequently, after 24h, the diluted semen was mixed slowly with another dilutor stage-2 at 1 : 2 ratios to revive the motility of the spermatozoa to normal level. Phosphate buffer was the base for both storage (stage-1) and recovery (stage-2) dilutors with a pH of 6.5 and 7.5, respectively. In stage-1 dilutor sodium glutamate to minimize metabolism of spermatozoa and antibiotics to check bacterial growth were used whereas these were absent in stage-2 dilutor. Glucose was added as energy source in the dilutor of both stages. The osmolarity of stage-1 and stage-2 dilutors was 346 and 327Osm/kg H₂0, respectively. This dilutor can be used to store the cock’s semen at room temperature (17-21°C) for 24h with sustained motility. This new approach for two-stage dilutor of cock’s semen storage at room temperature for extended period could be a useful A.I. tool under farm condition.

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The cells in the center of the area pellucida of the blastoderm have been used as donors for production of chimeric chickens, but the developmental fate of the cells has not been analyzed in detail. Also, little is known regarding the molecular mechanism of germline development and differentiation in early chick embryos. To clarify the developmental fate precisely, donor cells fluorescently labeled by PKH26 were analyzed in chimeric embryos. The cells were obtained from the center of the area pellucida of the donor and injected into the center of the area pellucida of the recipient. The dynamic states of the donor cells were tracked during development of the chimeric embryos, thereby allowing analysis of the developmental fate of the cells of the center of the area pellucida. The manipulated embryos that were injected with marked donor cells from the center of the area pellucida were cultured. The presence of the marked donor cells was confirmed in many embryos, through observation of embryos at each development stage under a fluorescence microscope. The results suggest that the migration system and developmental fate of cells from the center of the area pellucida are identical to those of primordial germ cells (PGCs). It was concluded that many PGCs or their precursor cells are localized in the center of the area pellucida of the blastoderm region.

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The effects of a single dosage of cadmium (Cd) administration on the survival rate, body weight (BW), egg production, egg quality characteristics and hatching outputs in 0, 0.1, 0.3, 1, 3 and 10mg CdCl₂/kg BW injected laying quail were studied. It was found that a 10mg Cd injection induced 41.7% mortality. A retainable significant BW loss in the 3mg dosed birds and a decreased egg production in the 1mg and 3mg dosed birds were observed during the first 3 days after injection, and the recovering of the egg production rate was delayed as the doses of Cd injection increased. Cd administration significantly increased the shell membrane weight in 0.1mg and 0.3mg injection, decreased the eggshell thickness in 0.3mg injection, and lowered the fertility rate in 0.3mg injection during the first 3 days of injection. The present study suggests that exposure to Cd, even by a single dosage, can hamper quail reproduction for a very short time, mainly by decreasing egg production and thinning the eggshell.

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Chicken cholecystokinin-1 receptor (chCCK1R) cDNA was isolated from a chicken brain and tissue distribution of the chCCK1R mRNA was determined by RT-PCR. The chCCK1R is composed of 429 amino acid residues and showed approximately 73% and 50% identity with those of mammalian CCK1R and CCK-2 receptor (CCK2R) at the amino acid level, respectively. In phylogenetical analysis, the chCCK1R belonged to a cluster of CCK1R and CCK-CHR, another CCK receptor cloned from chicken, was placed into a cluster of CCK2R. By RT-PCR analysis, whilst both chCCK1R and CCK-CHR mRNAs were widely expressed in the chicken tissues, the expression pattern for each receptor was slightly different. Abundant chCCK1R mRNA was observed in multiple tissues, while CCK-CHR mRNA expression was dominantly observed in the brain and proventriculus in the chicken. Taken together, chCCK1R is a potent peripheral CCKR and CCK-CHR cloned and characterized previously is classified as CCK2R in the chicken. Furthermore, mRNA expression for chicken CCKRs is possible to be regulated by tissue specific manner and that may be associated with the diverse roles of CCK and gastrin in the chicken.

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The aim of the study was to compare the slaughter quality of layer-type cockerels and broilers reared under identical conditions. The experimental materials comprised broiler (Ross 308 ; 100 males and 100 females) and layer-type (Messa 445 ; 100 males) chickens. The birds were reared in accordance with universally accepted technological standards. Broilers were reared to six weeks of age, and layer-type cockerels - to six, eight and ten weeks of age. Twelve Ross males, 12 Ross females (aged six weeks) and 12 Messa males (aged six, eight and ten weeks) were selected randomly for slaughter quality assessment. The birds were sacrificed, the carcasses were eviscerated and warm carcass weight, giblets weight (gizzard, heart, liver) and abdominal fat weight were determined. The carcasses were chilled for about 18 hours at 4°C and weighed again, and then divided into the following parts : neck, wings, legs, breast and back. These elements were dissected into lean, bones, skin with subcutaneous and intermuscular fat. Breast muscle weight was determined during breast dissection. At six weeks of age the mean body weights and carcass weights of layer-type cockerels were 3.9-fold and 4.6-fold lower, compared with broilers (666g vs. 2577g and 412g vs. 1897g respectively). The values of most slaughter quality indices were less desirable in layer cockerels - lower carcass dressing percentage, lower breast content of a carcass, lower meat percentage in a carcass. Only the percentage of fat with skin in a carcass was more desirable in layer-type chickens than in broilers.

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In order to produce a new dimension towards the development of comminuted meat product, chicken fat and skin (CFS) were used with chicken meat and incorporated at 15, 20 and 25 percent levels to chicken sausage. To substantiate the product qualities obtained after such incorporations, different quality parameters like physico-chemical properties, proximate composition, thiobarbiturate acid (TBA) value, microbial profile and organoleptic qualities from those sausage after cooking were evaluated. It was found that with the increase in amount of added CFS, emulsion stability (ES), emulsifying capacity (EC) of sausage emulsion decreased significantly (P<0.05) whereas the extract release volume (ERV), cooking losses increased significantly (P<0.05) with increase in CFS level. There were no significant differences in terms of microbial profile and there was a significant (P<0.05) difference in some organoleptic qualities like juiciness and overall acceptability. However, from the point of view of overall acceptability of sausage having 20% added skin and fat scored better and incorporation upto 20% is advocated to make maximum profit from such sausages in commercial practices.

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