Research On Endocrine Mechanism Of Incubation And Its Nutrition Regulation

The studies were conducted to investigate the incubation and reproduction mechanism of American King Pigeon by analyzing the physical parameters and incubation related gene expression characters in different phases. Furthermore, investigated the nutrimental regulation of incubation behavior and laying performances in laying pigeon.The main contents and results are as follows:1. Change of biochemical parameterns and difference of viduct configration in different phases.The mechanism of incubation arising and ovary fouctional degradation was investigated by analyzing biochemistry parameters and observing the histological section of oviduct in different physiological stages of American king pigeon. (1) As compared to the laying period, the level of PRL increased whereas E2 decreased significantly in incubation (P<0.05). And the oviduct lumen became cabined, glandular organ became more obvious and the villi arranged more trimly and close in laying. (2) The level of prolctin(PRL) in serum had a tendence to increase first and then decriease, whereas the level of estradiol (E2) have a tendence to decriease first and then increase (P<0.05). (3) The results of different laying experience pigeon showed that, the level of PRL, E2 and FSH increased with laying experience. While albumin decreased with the laying experiences, which reach to the minimum at spent laying (P<0.05). Serum calcium decreased numerically from the primiparous to second laying, while increased from the second laying and reached to the maxmum at the fifth laying (P<0.05), and then decreased significantly at spent laying (P<0.05). There were higher level of progestogen observed in the primiparous and spent pigeon (P<0.05). According to the electronic microscope photograph of oviduct, the oviduct lumen became cabined, glandular organ became more obvious and the villi arranged more trimly and close in laying. Oviduct lumen from the primiparous, second and 5th laying was more combined, the villi was more trim and close, and better arranged than pullets. The lumen of oviduct from spent laying became loose and atrophied, and the villi was arranged ruleless. It's indicated that the physical condition of laying and incubation pigeon was stable, and the pigeon recovered well from nutrient loss during laying. And the relative high level of PLR in serum was crucial for incubation maintainance. Speculated that the ovary senescence have relation to the increasing of PRL, FSH and progestin, while decreasing of calcium in serum.2. Cloning and analyzing of incubation related genes.In order to understand the phylogenetic diversity of incubation related gene, the cDNA of PRL, vasoactive intestinal peptide (VIP) and folliclestimulating hormone (FSH) was isolated and cloned from female American silver king pigeon (Columbia livia) pituitary gland and ovary by a degenerate primer and nested reverse transcription polymerase chain reaction (RT-PCR) based strategy. The results showed that the cloned cDNA contains 658bp,322bp and 354bp nucleotides, respectively, and submitted to Genbank with accession number GU968532, FJ913875, and FJ913876,corresponding sequences of turkey (AAB60604.1), budgerigar (BAF81527.1), chicken (Genbank accession no. NP₉90797), comb duck (CAJ55836), duck(B AD 14942.1), domestic goose (AAY59658), helmeted guineafowl (BAG68294.1), Indian peafowl (BAG68293), Java sparrow (BAF96736.1), ostrich (BAF81528.1), quail (BAD10927), and Ring-necked pheasant (BAG68292.1) were 90.4%,93.2%,91.3%,95.0%,92.7%,92.2%,89.0%,91.3%,91.8%, and 88.6%, respectively. Phylogenetic analysis indicates that pigeon PRL is more closely related to the duck and goose orthologs compared to that of other species. The identities of VIP deduced amino acid sequence with the corresponding sequences of Beijing duck (DQ023227.1), chicken (CAA56867), goose (AAY59005), Java sparrow (BAF96737), turkey (P45644), white-throated sparrow (ADK26700), and zebra finch (XP002187804) were 95.9%,95.3%,95.5%,95.3%,97.2%, and 95.3%, respectively. And the identities of FSH deduced amino acid sequence with the corresponding sequnence of Japanese quail (BAC01164), duck (ABB60052.1), crested ibis (BAC07314), goose (ABX39193), chicken (NP₉89588), zebra finch (XP₀02194767), and ostrich (P80663) were 94.1%,97.5%,99.2%,94.3%,94.9%, 93.2%, and 92.5%, respectively.3. Tissue distribution and expression character in different physical phases of VIP, FSH, PRL and PRLR gene.This study was conducted to investigate incubation related gene tissue distribution and expression characters in different physical phases by detecting the mRNA expression in different tissues and phsaes through real-time quantitative PCR (FQ-PCR). (1) The results showed that, all the gene was widely expressed in tissues analyzed. Highest level of VIP mRNA expression was observed in the brain, and then oviduct, spleen, liver, and muscle (P< 0.05). PRL mRNA expressed highest in pituitary, and then spleen, oviduct, liver, heart, ovary, pancrease, and kidney (P< 0.05). The expression order of FSH was ovary, oviduct, spleen, brain, liver, and mucle (P< 0.05). And the PRLR expressed highest in oviduct, ovary, brain, liver, spleen, and mucle (P< 0.05). The high expression of aboved gene in brain and gonad indicated the modulation role in pigeon edocrine and reproductive behavior. (2) The ovary PRL mRNA expression increased significantly in incubation, compared to laying (P< 0.05), while the pituitary PRL and VIP mRNA increased numerically. The amount of VIP mRNA expression reached maxmum at spent laying (P< 0.05), whereas PRLR reached maxmum at pullets (P< 0.05). Interstingly, FSH and PRL expression increased with laying experience, and reached maxmum at spent laying (P < 0.05). Speculated that the increased plasma PRL in incubation pigeon have relation to the elevation of ovary mRNA expression. And the reproduction senescence might be related to the increasing of VIP and PRL mRNA expression and decreasing of PRLR.4. The effect of dietary y-aminobutyric acid (GABA) and glutamine (Glu) on laying performance of American King Pigeon.The study was conducted to evaluate the effect of nutrients on laying performance and incubation related gene expression on American King Pigeon by administration of GABA and Glu. Furthermore, investigated nutritional modulation on laying performance and approached to shorthen the laying interval. The results showed that, compared to the control group, dietary GABA significantly increased the level of plasma PRL and triglyceride, and the activity of plasma GTP in pigeon at laying interval period, and shorthened the laying interval (P<0.05). While dietary Glu significantly increased the level of plasma PRL in pigeon at laying interval period, and FSH in laying (P<0.05). And increased the PRL, VIP, and FSH mRNA expression whereas decreased the PRLR mRNA expression in pigeon at laying interval period (P<0.05). Suggested that dietary GABA shorten the laying interval by modulating the PRL level and nutrents content in laying and incubation. Glu stimulated the PRL, VIP, and FSH expression, while potentially accelerated the reproduction senescence in laying pigeon.