Resumo
Objetivou-se avaliar a influência do tipo de casca (normal e vítrea) sobre os parâmetros de fertilidade, qualidade interna e externa de ovos, além da proteômica das estruturas da casca de reprodutoras pesadas. Para avaliação dos parâmetros de qualidade dos ovos, o experimento foi dividido em duas fases. No experimento 1 foram avaliados 240 ovos (120 de casca normal e 120 de casca vítrea), no prazo máximo de 24 horas após a postura, coletados igualmente entre quatro lotes de avós de frangos de corte da linhagem Ross, de duas linhas (macho e fêmea) e duas idades (38 e 46 semanas). No experimento 2 foram utilizadas 5 bandejas de 162 ovos de casca normal e a mesma quantidade para casca vítrea, de um lote de avós da linha macho da genética Cobb, com 40 semanas de idade. Para a análise proteômica foram utilizados ovos de quatro lotes de avós de frangos de corte (mesmos lotes do experimento 1 de qualidade), sendo selecionados 80 ovos, 20 de cada lote (pool de 10 ovos de casca normal e 10 ovos de casca vítrea) pela característica externa da casca. De cada lote foram coletados fragmentos da estrutura da casca (cascas e membranas das cascas), triturados manualmente, homogeneizados e depois selecionado 1 grama de cada pool para formar a análise final. Ovos de casca normal apresentaram maiores médias que ovos de casca vítrea para as variáveis Porcentagem de Albúmen, Índice de Gema, Índice de Albúmen e unidades Haugh, e menor média para Porcentagem de Magnésio na casca. A perda de umidade na incubação foi maior para os ovos de casca vítrea, em comparação com ovos de casca normal. Por proteômica, foram identificadas 309 proteínas (2989 peptídeos) diferentes nas 8 amostras avaliadas das estruturas da casca. Após análise estatística comparando todos os lotes e proteínas, foi identificada diferença somente para duas proteínas (ATPase- A0A1Y4CB63 e OVA fragmentos idêntica à OvoalbuminaA0A2H4Y8Q2), sendo que as diferenças entre as proporções foram significativamente maiores para casca vítrea. Dentre as proteínas encontradas destacam-se: Ovotransferrina, Ovalbumina, proteína OVA fragmentos, Proteína Y relacinado à Ovoalbumina, Serotransferrina, Ovomucóide, 2-c-methyl glycerol 4-phosphate cytidylytransferase, SERPIN, Proteína Não Caracterizada (Gene Ovostatina), Aplha-1-acid glycoprotein, ATPase e Proteína Não Caracterizada (Gene B5G11_16010). Ovos de casca vítrea têm qualidade interna inferior em relação aos de casca normal, além de perderem mais umidade na incubação (provavelmente por alterações na matéria orgânica/proteica na casca). A partir dos achados proteômicos é possível especular alguma alteração de expressão gênica no útero, que pode levar a superexpressões proteicas (por exemplo proteína OVA/ Ovoalbumina), com aumento do conteúdo orgânico da matriz e desarranjos nas camadas biomineralizadas de ovos de casca vítrea. Portanto, sugere-se novas pesquisas de perfil molecular entre as diferentes estruturas dos dois tipos de casca, além de estudos de manejos diferenciados a nível de campo e incubatório para ovos de casca vítrea.
The objective was to evaluate the influence of the eggshell type (normal and vitreous) on the parameters of fertility, internal and external quality of eggs, in addition to the proteomics of eggshell structures of broiler breeders. To evaluate the egg quality parameters, the experiment was divided into two phases. In experiment 1, 240 eggs (120 of normal shell and 120 of vitreous shell) were evaluated, within a maximum of 24 hours after laying, collected equally between four lots of Ross broilers, two lines (male and female) and two ages (38 and 46 weeks). In experiment 2, five trays of 162 eggs with normal eggshell and the same amount for vitreous eggshell were used, from a lot of grandparents of the male line of the Cobb genetics, at 40 weeks of age. For the proteomic analysis, eggs from four lots of broiler grandparents (same lots from experiment 1 of quality) were used, with 80 eggs selected, 20 from each lot (pool of 10 eggs with normal shell and 10 eggs with vitreous shell) by the external characteristic of the shell. Fragments of the shell structure (shells and shells membranes) were collected from each lot, manually crushed, homogenized and then selected 1 g from each pool to form the final analysis. Normal shell eggs showed higher averages than vitreous shell eggs for the variables Albumin Percent, Yolk Index, Albumin Index and Haugh units, and lower average for Magnesium Percent in the shell. The loss of humidity in the incubation was higher for eggs with vitreous shell, compared with eggs with normal shell. By proteomics, 309 different proteins (2989 peptides) were identified in the 8 samples evaluated from the shell structures. After statistical analysis comparing all lots and proteins, a difference was identified only for two proteins (ATPase- A0A1Y4CB63 and OVA fragments identical to OvoalbuminA0A2H4Y8Q2), and the differences between the proportions were significantly higher for vitreous shell. Among the proteins found, we highlight: Ovotransferrin, Ovalbumin, OVA protein fragments, Protein Y related to Ovoalbumin, Serotransferrin, Ovomucoid, 2-c-methyl glycerol 4-phosphate cytidylytransferase, SERPIN, Uncharacterized Protein (Ovostatin Gene), Aplha-1 -acid glycoprotein, ATPase and Uncharacterized Protein (Gene B5G11_16010). Vitreous shell eggs have a lower internal quality than normal shell eggs, in addition to losing more humidity during incubation (probably due to changes in the organic / protein matter in the shell). From the proteomic findings it is possible to speculate some alteration of gene expression in the uterus, which can lead to protein overexpression (for example OVA / Ovoalbumin protein), with an increase in the organic content of the matrix, and breakdowns in the biomineralized layers of vitreous shell eggs. Therefore, we suggest new researches of molecular profile between the different structures of the two types of shell, in addition to studies of different field and hatchery managements for vitreous shell eggs.
Resumo
The eggshell is an important structure for two reasons. Firstly it forms an embryonic chamber for the developing chick, providing mechanical protection and a controlled gas exchange medium. Secondly it is a container for the market egg, providing protection of the contents and a unique package for a valuable food. The superficial structure of the shell has been known for over 100 years. The shell consists of 97% calcium carbonate, and this is provided to the hen in the diet. However, the chemical must be broken down in the digestive system and then re-synthesized in the shell gland to form the shell. This results in a turnover of blood Ca of ~ 100 times each 24 hours. Provision of calcium to layers has been researched at length, but the key work, conducted at Cornell University in the 1960's, showed the necessity for sources with large particle size, for example, oyster shells. Subsequent research has defined guidelines that, if correctly followed, will yield reliable and optimum eggshell quality. Breakage or cracking of eggshells in market channels is a serious concern. Cracks result from a combination of shell strength and integrity, and the extent of the "insult" received by the egg during handling. Measurement of shell strength, and assessment of "insults" is important to the poultry industry. Most recent research has identified the ultra-structure of the shell, with resulting opportunities for industrial remedies, and possible new selection criteria, to ensure maximum shell quality throughout the egg industry.
Resumo
The eggshell is an important structure for two reasons. Firstly it forms an embryonic chamber for the developing chick, providing mechanical protection and a controlled gas exchange medium. Secondly it is a container for the market egg, providing protection of the contents and a unique package for a valuable food. The superficial structure of the shell has been known for over 100 years. The shell consists of 97% calcium carbonate, and this is provided to the hen in the diet. However, the chemical must be broken down in the digestive system and then re-synthesized in the shell gland to form the shell. This results in a turnover of blood Ca of ~ 100 times each 24 hours. Provision of calcium to layers has been researched at length, but the key work, conducted at Cornell University in the 1960's, showed the necessity for sources with large particle size, for example, oyster shells. Subsequent research has defined guidelines that, if correctly followed, will yield reliable and optimum eggshell quality. Breakage or cracking of eggshells in market channels is a serious concern. Cracks result from a combination of shell strength and integrity, and the extent of the "insult" received by the egg during handling. Measurement of shell strength, and assessment of "insults" is important to the poultry industry. Most recent research has identified the ultra-structure of the shell, with resulting opportunities for industrial remedies, and possible new selection criteria, to ensure maximum shell quality throughout the egg industry.