Probing undiscovered neuropeptides that play important roles in the regulation of pituitary function is essential for the progress of avian endocrinology and neuroendocrinology. Neuropeptide control of gonadotropin secretion at the level of the anterior pituitary gland is primarily through the stimulatory action of the hypothalamic decapeptide, gonadotropin-releasing hormone (GnRH). Until recently, any neuropeptide that directly inhibits gonadotropin secretion has not been identified. In 2000, we discovered a novel hypothalamic dodecapeptide that directly inhibits gonadotropin release in quail and termed it gonadotropin-inhibitory hormone (GnIH). A gonadotropin inhibitory system is an intriguing concept and provides us with an unprecedented opportunity to study the regulation of avian reproduction from an entirely novel standpoint. To elucidate the mode of action of GnIH, we have identified a novel G protein-coupled receptor for GnIH in quail. The GnIH receptor possessed seven transmembrane domains and specifically bound to GnIH. The GnIH receptor was found to be expressed in the pituitary and several brain regions including the hypothalamus. These results indicate that GnIH acts directly on the pituitary via GnIH receptor to inhibit gonadotropin release. GnIH may also act on the hypothalamus to inhibit GnRH release. To demonstrate the functional significance of GnIH and its potential role as a key neuropeptide involved in avian reproduction, we investigated GnIH actions on gonadal development and maintenance in quail. Chronic treatment with GnIH inhibited gonadal development and maintenance by the decreasing gonadotropin synthesis and release. Melatonin is a key factor for involved in GnIH neural function, because quail GnIH neurons contain melatonin receptor and melatonin treatment stimulates expression of GnIH mRNA and mature GnIH peptide. Thus GnIH is capable of transducing photoperiodic information via changes in the melatonin signal and to influence the reproductive axis of birds. It is concluded that GnIH, a newly discovered hypothalamic neuropeptide, acts as an important factor on avian reproduction.

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In all vertebrates, gonadotropin releasing hormone (GnRH) is a key component of the hypothalamo-pituitary-gonadal axis. In birds, two distinct forms of GnRH (cGnRH-I and cGnRH-II) have been characterized, and a third immunoreactive form similar to lamprey GnRH-III has been reported. Each GnRH is produced by a different population of neurons. cGnRH-I is predominantly synthesized in cells located in the preoptic and septal areas, whereas cGnRH-II and -III are produced in neurons located mainly in the mesencephalon and around the third ventricle, respectively. Although GnRH neurons have been shown to project fibers to the median eminence, it is still unclear whether all three peptides are released in the hypothalamo-pituitary portal vascular system. Nonetheless, in vitro as well as in vivo experiments confirmed that they all have the ability to induce the release of gonadotropins. In the anterior pituitary gland, GnRHs mediate their effects by binding to specific G-coupled protein receptors, and in chickens, two different receptors have been characterized (cGnRHR-I and cGnRHR-II). In addition to the full-length receptors, several splice variants have also been detected. Although the physiological relevance of these variants is not known, they may participate in the regulation of intracellular signaling. While the expression of the full-length cGnRHR-I appears to fluctuate during an ovulatory cycle, levels remain constant between reproductive stages in chickens. In contrast, pituitary levels of cGnRHR-II mRNA are directly correlated with the reproductive status of the bird. Whether these two GnRHRs are expressed by the same cells in the anterior pituitary gland is not known. However, since luteinizing hormone (LH) and follicle stimulating hormone (FSH) are produced by two different cell populations in chickens, it is possible that different combinations of GnRHs and GnRHRs differentially mediate the synthesis and release of these gonadotropins.

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The goal of this study was to evaluate the influence of diets containing soyabean meal (SBM) protein replaced with discarded cashew nut meal (DCNM) protein on the growth indices and, breast and hind limb muscles of broilers. Three hundred and sixty growing broilers aged 5 weeks were used for the investigation. The control diet had 25.0g 100g^-1 SBM and this was replaced on equi-protein basis at 10, 20, 30, 40 and 50% levels by DCNM. The experimental diets were fed for 21 days (5^th-8^th weeks of age). Thereafter, the chickens were slaughtered and the carcass, organs and the breast and hind limb muscles dissected out and measured. The final weight (FW), average weight gains (AWG) and the fat retention (FR) tends to be significantly influenced by the dietary treatment. The FW and AWG of birds on DCNM-based diets were higher than those fed the control diet with about 4.2-9.6% and 3.1-14.9%, respectively. Of the carcass characteristics measured only the drumsticks, wing, head and belly fat tend to be significantly (P<0.05) influenced by the dietary treatments. The relative weight of the heart of the birds increased from 4.6±0.6g kg^-1 body weight in those fed the control diet to 5.6±0.5g kg^-1 body weight in birds fed 50% SBM+50% DCNM-based diet while the relative weight of the spleen (1.6±0.2g kg^-1) of birds fed the control diet tend to be significantly (P<0.05) higher than those fed the DCNM-based diets (1.0±0.1-1.3±0.3g kg^-1 body weight). The weights, lengths and breadths of the Musculus supra coracoideus, Pectoralis thoracicus and Gastrocnemeus did not varied widely among the treatments as indicated by the low coefficient of variation values (1.9-7.0%). Giving the relative abundance of the DCNM in Nigeria, it was suggested that DCNM could be used to replace expensive SBM in broiler diets.

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The effect of T-2 toxin (2.35mg/kg of feed) on lipid peroxidation and on the antioxidant defence system was studied in blood plasma, red blood cells (RBC), liver and spleen of broiler chickens. The influences of antioxidant vitamin E (10.5mg/animal/day)+selenium (0.045mg/animal/day) and toxin binder (yeast cell wall extract, 2mg/kg of feed) supplementations on pathophysiological changes associated with the consumption of T-2 toxin contaminated feed was also investigated. T-2 toxin did not enhance the lipid peroxidation processes but had effect on the ascorbic acid and glutathione redox system. The antioxidant and toxin binder supplementation beside T-2 toxin load has beneficial effect on the antioxidant status, primarily the activity of the glutathione peroxidase (GSH-Px).

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Two experiments were conducted to determine the true metabolizable energy corrected to zero nitrogen balance (TME_n) and true amino acid availability (TAAA) of three local barley varieties, two-row Litani (L₂), two-row Pamir-35 (P₂), and six-row Rihan-03 (R₆) and to study the effect of enzyme supplementation on their apparent metabolizable energy corrected to zero nitrogen balance (AME_n). Forty grams of glucose, corn, or barley variety grains was precision intubated to eight individually caged Babcock B 380 roosters. The TME_n of L₂, P₂, and R₆ (3224, 3419, and 3253kcal/kg, on dry matter basis (DM), respectively) was lower than that of corn (P<0.05). All the TAAA values in P₂ and that of methionine, cystine, lysine, threonine, proline, and valine in L₂ and R₆ were comparable with that of corn. Again, compared to corn, all other TAAA values in L₂ and R₆ were significantly lower, except for serine, glutamic acid, and isoleucine in R₆. In the AME_n experiment, a reference diet containing 55% glucose and diets containing 50% corn or L₂, P₂, and R₆ at the expense of glucose, supplemented with either 0 or 0.1% enzyme, were each fed in 4 replicates (cages) to 4 birds/cage for 4 d, during which total excreta were collected at 48 and 96 h. Enzyme supplementation resulted in an AME_n improvement of 4.33, 11.5, and 17.2% for L₂, P₂, and R₆, respectively with an average AME_n of 3243kcal/kg DM. In conclusion, TAAA in P₂ was similar to corn whereas that of some amino acids such as arginine and leucine were lower in L₂ and R₆. Enzyme supplementation to barley diets resulted in an average AME_n improvement of 11%. The current findings can assist and encourage poultry producers in formulating least cost rations containing local barley varieties.

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An experiment was conducted to study the effect of dietary supplementation of probiotic Lactobacillus sporogenes (L. sporogenes) on performance and serum biochemico-lipid profile of broiler chickens. One hundred and twenty, day-old commercial broiler chicks were distributed equally into 3 groups of 40 chicks each, which was further replicated to 8 groups of 5 each. The chicks were placed on one of three dietary treatments : basal, basal with probiotic (6×10⁸ spore of Lactobacillus sporogenes per g) at 100 or 200mg per kg feed. Body weight gain increased and feed conversion ratio improved significantly due to dietary supplementation of 100mg probiotic per kg diet. However, no further benefits on the above parameters could be observed by increasing the level of supplementation from 100 to 200mg per kg. Leg abnormality score is not influenced by probiotic supplementation in the diet. However, the bone breaking strength and bone ash content increased significantly by probiotic supplementation at 100mg per kg diet. The concentration of protein and calcium increased significantly due to dietary supplementation of L. sporogenes. Neither concentration of inorganic phosphorus nor activities of enzymes such as serum glutamate-oxaloacetate transminae (SGOT), serum glutamate-pyruvate transaminase (SGPT) and alkaline phosphatase (ALP) in serum were influenced due to L. sporogenes supplementation. Serum total cholesterol, low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein (VLDL) cholesterol and triglycerides were reduced significantly by dietary supplementation of L. sporogenes at 100mg per kg diet. However, high-density lipoprotein (HDL) cholesterol of birds was not influenced by L. sporogenes supplementation. It is concluded that dietary supplementation of Lactobacillus sporogenes (6×10⁸ spore per g) at 100mg per kg diet significantly enhanced body weight gain, improved feed conversion ratio, bone ash and bone breaking strength and lowered total cholesterol, VLDL cholesterol and triglycerides concentrations in the serum of broiler chickens.

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This study was conducted to investigate the response of broiler chickens to diets containing breadfruit meal (BFM). Two hundred and fifty-six (256) day-old unsexed Anak 2000 broiler chicks were randomly allotted to the eight dietary treatments consisting of four replicates of eight chicks each. The experimental layout was a 2×4 factorial arrangement with two types of breadfruit meal (raw and cooked breadfruit meal) and four levels (0, 10, 20, 30%) of each BFM (Table 2). The diets were balanced for energy and crude protein. Cooking of the BFM increased (P<0.05) daily weight gain of birds while it decreased (P<0.05) with increase in inclusion level of BFM. The interaction between processing and inclusion levels of BFM was significant (P<0.05) for daily weight gain, feed/gain and protein efficiency ratio. Crude fibre (CF), ash and nitrogen free extract (NFE) digestibility reduced (P<0.05) in cooked BFM diets while inclusion of BFM increased the NFE digestibility and reduced ash digestibility. Processing of BFM had no effect (P>0.05) on the measured serum metabolites except serum glutamate pyruvate transaminase (SGPT) which was reduced (P<0.05) with processing of BFM. Uric acid decreased (P<0.05) while globulin increased (P<0.05) with increased inclusion level of BFM. Relative weights of breast muscle, drumstick and thigh were higher in birds fed cooked BFM. Total cost of feed consumed per bird and cost of feed per kg weight gain decreased (P<0.05) in the BFM diets. Total cost of feed consumed per bird was higher (P<0.05) in cooked BFM but the cost of feed per kg weight gain decreased (P<0.05) in the cooked BFM.

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In order to use shrimp meal (SM) made from headless black tiger shrimp waste as a protein source for poultry diets, chemical composition of SM and growth performance, dry matter (DM) digestibility and nitrogen (N) retention in broilers given diets containing SM ranged from 0% to 16% were measured. Comparing with the data in the previous reports, SM used in the present study was rich in fiber and ash, hence poor in CP. Amino acid profiles revealed that SM had lower concentration of methionine+cysteine, lysine, isoleucine, leucine, tryptophane than soybean meal. The results of orthogonal polynomials revealed that body weight gain, feed intake, feed efficiency, DM digestibility and N retention decreased with increasing levels of SM and the results of ANOVA showed that, in most case, these parameters did not change significantly when SM level was at and below 8%. However, these parameters in birds given 8% SM diets did not differ from those in birds given 12% and 16% SM diets. Taking this into account, the safer level to add SM to a broiler diet seems to be 4%. Decreased body weight gain may be resulted from decreased feed intake, feed efficiency and DM digestibility. In conclusion, it is suggested that SM can be used as a protein source in a broiler diet as far as it is included at and below 4%.

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The objective of the present study was to determine if acetylsalicylic acid (ASA) would have further antioxidative effects beyond lowering rectal temperature of stressed laying Japanese quail and hence improve its physiological status. During summer season when daily high temperatures averaged between 33 and 36°C and relative humidity averaged between 60 to 70%, four treatment groups of adult Japanese quail each containing three replicates of fifteen females were fed either a control diet containing 0% ASA or the control diet supplemented with 0.025, 0.05 or 0.1% ASA from 8 to 16 wk of age. Rectal body temperature was significantly decreased by feeding 0.05 and 0.1% ASA. Hen-day egg production was significantly increased for quails fed the diet containing 0.05% and 0.1% ASA. Shell thickness seemed to be thicker at the higher levels of ASA. Serum T₃ concentration was decreased significantly (P≤0.05) in quails fed 0.1% ASA (0.38ng/ml) in comparison with controls (0.62ng/ml), but serum T₄ concentration was not significantly affected. Dietary ASA had a positive effect on humoral immunity and quails fed 0.05 and 0.1% ASA had a significantly higher total antibody titer compared to other treatments. ASA treatments caused a significant decrease in serum cholesterol, glucose and hepatic TBARS as an indicator for lipid peroxidation, as well as enhancement in the activity of antioxidative enzymes GSH-Px and SOD in a dose dependent manner. These antioxidative effects were accompanied with a significant reduction in corticosterone levels due to ASA treatments. Therefore, it could be concluded that feeding diets containing 0.05 or 0.1% ASA during the summer season could have potential benefits for poultry welfare and productivity because of reducing body temperature and oxidative stress, which consequently allowing more physiological resources to be used for responding to environmental stressors.

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It has been known that glutamine synthetase (GS, L-glutamate ammonia ligase) is an enzyme that catalyzes ATP-dependent condensation of glutamate and ammonia to form glutamine, and that GS and growth hormone (GH) are proteins that are induced by glucocorticoid-treatment during the development of animals. To understand the relationship between these glucocorticoid-inducible proteins, we studied pituitary GS and GH cells during the development of chick embryos, Gallus domesticus. GS cells were immunohistochemically identified in epithelia of Rathke’s pouch as early as embryonic day 4 (E4) following corticosterone-treatment. The population of GS cells and GS activity gradually increased by E14, and then rose sharply after E16. Pituitary GS activity was precociously induced by corticosterone-treatment starting around E7. GH cells were first demonstrable in the pituitary gland on E11, and then increased until hatching. Corticosterone-treatment also caused premature induction of GH in the pituitary cells after E8, but not before. Dual-fluorescence immunohistochemistry showed a large population of GS cells in the cephalic lobe that was identical to the ACTH cells, and in the caudal lobe of the gland they were the same as the GH cells. Ontogeny of pituitary Pit-1 protein, an important transcription factor of GH, was also studied by immunohistochemistry. Pit-1 positive cells appeared at E6 and increased in number by E12 of development. The population of Pit-1 cells was, however, not affected by corticosterone-treatment. These result demonstrate that glucocorticoid receptors are present in pituitary GS cells even before day 8 when GH cells start to differentiate, and that a large population of GS cells may have some physiological roles in the gland. This is the first report showing that pituitary GS is a glucocorticoid-inducible marker protein to regulate pituitary functions.

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Roosters immunized prepubertally with the avian infectious bronchitis virus (AIBV) have a high incidence of epididymal calcium stones, reduced daily sperm production and lower serum testosterone as adults. The aim of the present study was to determine when and how stones are formed following vaccination with AIBV. Specific pathogen free roosters were either immunized with the live attenuated AIBV (vaccinated group, n=38) or with the vehicle (nonvaccinated group, n=33) at 2, 6 and 10wk of age. Testes and epididymides were studied histologically at 12, 16, 20 and 26wk of age. Abnormalities were not observed in testes of either vaccinated or nonvaccinated group at any age observed. The epididymal region of the vaccinated group was normal until 16wk. However, aggregations of sperm, cell debris and macrophages and stones were present in the proximal efferent ductules in the vaccinated group at 20wk and 26wk of age. These efferent ductules showed expanded lumen, reduced mucosal folds and low columnar epithelium. Next to these affected ductules were normal efferent ductules. On the other hand, epididymal stones also occurred in the nonvaccinated group (2/8, 25%) at 26wk but the frequency was lower than that in the vaccinated group (8/14, 57%). These results indicate that epididymal stone formation begins with aggregations of sperm, cell debris and macrophages immediately after puberty, which is followed by calcium deposition. It is suggested that the prepubertal vaccination with AIBV accelerates epididymal stone formation.

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The influence of a non-feed removal molting program on certain parameters of cell mediated and humoral immune response of the laying birds during 2^nd and 3^rd production cycles were recorded. Birds at the end of their 1^st production cycle were induced to molt through the supplementation of high dietary zinc oxide (3000mg/Kg) for their 2^nd and 3^rd production cycles. Macrophage engulfment (%) and engulfment/cell were significantly increased after the use of opsonized sheep red blood cells (SRBC) for co-incubation during 2^nd production cycle. Lipopolysacchrides (LPS) greatly enhanced the production of nitric oxide, as compared to the SRBC stimulation during the 2^nd production cycle. Zinc feeding strengthened the antibody response against Newcastle disease virus (NDV) and egg drop syndrome virus (EDS) at the peak of the 2^nd and 3^rd production cycles, but decreased at 5% production stages. NDV also provoked a better antibody response when compared to EDS. Zn concentration in plasma showed a positive correlation with an increase in egg production. Our results validate the strengthened immune response during the 2^nd production cycle after zinc-induced molting.

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An experiment was conducted with three hundred broiler chicks to evaluate the influence of dietary supplementation of probiotic Bacillus subtilis on performance and immunocompetence in broiler chicks. Body weight gain of birds fed diet supplemented with 50 mg/kg of probiotic were significantly higher during 1-21 and 22-42 days than birds fed the control diets. Feed conversion of birds fed diet supplemented with 50mg/kg of probiotic were significantly better from 22 to 42 days than birds fed the control diets. In each of the 7, 14, 21 and 28 days of age, twenty birds per dietary group were injected intravenously (brachial vein) with 0.1ml of 0.5% sheep red blood cell (SRBC). The probiotic had positive effect on production and persistency of antibody in response to SRBC antigen. Antibody production against Newcastle disease virus in 50mg/kg probiotic supplemented group was significantly higher at 10 days of post immunization compared to control. The results suggest that the use of probiotic containing Bacillus subtilis had positive effect on performance and immune system of broiler chicks.

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A 28-d experiment was conducted to evaluate the effects of fumonisin B₁ (FB₁) on hematological and serum biochemical parameters of young laying Japanese quail fed fumonisin contaminated rations. To this end, 128 7-wk-old birds were randomly distributed into four experimental groups (32 birds per group) and fed rations containing 0 (control), 10, 50 or 250mg FB₁/kg feed. Each treatment consisted of four replicates of eight quail. At the end of the trial, blood samples from 12 birds per treatment were collected and submitted to analysis. Compared with controls, quail fed 250mg FB₁/kg for 28 days had reduced (P<0.05) red blood cell counts and hematocrit values. No differences (P>0.05) were found among leukocyte counts obtained in control birds and FB₁-treated groups, and a lower percentage of lymphocytes (P<0.05) was observed in birds fed 50 and 250mg FB₁/kg. Serum protein, albumin, γ glutamyl transferase and uric acid were similar (P>0.05) among the treatments studied. Aspartate aminotransferase concentrations were higher (P<0.05) for birds receiving 10, 50 and 250mg AFB₁/kg, when compared to the control group. Results indicated that FB₁ at levels≥10mg/kg is toxic in young laying quail, emphasizing the importance of controlling fumonisin contamination of quail rations.

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The present experiment was designed to ascertain whether gelatin-substrate slide technique devised for detection of the proteolytic activity of acrosomal contents can be used for quail sperm, and to determine whether treatment with the endocrine disrupting chemical, diethylstilbestrol (DES), has deleterious effect on the modulation of acrosomal proteolytic activity (APA) in quail sperm. It was observed on the slide under a phase-contrast microscope that a halo formed around a single spermatozoon resulting from localized proteolytic digestion of gelatin. The mean halo diameters of sperm showed a dose-dependent decrease with increasing levels of trypsin inhibitor, ovomucoid which drastically blocked the halo formation. These findings indicate that the gelatin-substrate slide technique may be a more effective and more simplified method for evaluation of APA in quail sperm. The mean halo diameters were significantly (P<0.05) low (52.2μm) in sperm collected from DES-injected quail compared with those of sperm without injection (86.3μm) implying that treatment with DES provides a decrease of APA in agreement with the acrosomal damage.

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