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Browsing by Person "Schmid, Britta Ariane"

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    Bestimmung des Verknöcherungsverlaufs des Brustbeins von schnell und langsam wachsenden Masthühnern
    (2007) Schmid, Britta Ariane; Grashorn, Michael
    According to EU marketing regulations for poultry chicken carcasses have to be marketed either as ?young chicken with a flexible breastbone processus? or as ?chickens with a rigid breastbone processus? due to their age at slaughter. Market prices of meat form young chickens are manifold higher than for old ones. Meanwhile, extensive (especially organic) broiler meat production has increased. As in these production systems age at slaughter has to be at least 81 days the question arises whether the breastbone processus is yet not ossified. Up to now the knowledge on the development of the breast bone in chicken is limited. More extended information is only available for bones of extremities. The objective of the present study was, therefore, to investigate the ossification process of breastbones in fast and slow growing broiler strains between first weeks of life and sexual maturity. Visual assessment and assistant characteristics (metric measurements, computerized tomography, chemical composition) of the breastbone and the Os coracoideum, should be applied to analyze the course of ossification. In total, 1000 fast growing broilers of the breed Ross 308 and 1000 slow growing broilers of the breed Isa S 457 were reared for this experiment under standard conditions in a temperature controlled poultry house. Finally, 480 chickens of each breed were used for determination of the breastbone characteristics. Starting with week 4, 12 cocks and 12 hens of each breed were slaughtered weekly until week 23 of life. Life weight and weight of breast meat were recorded besides breastbone characteristics. The breastbone was completely removed and its weight, as well as numerous measures of the breastbone were recorded: Breastbone weight (BBG), Breastbone length (L), Width between the Proc. craniolaterali (BPC), Width between the Trab. intermediae (BTI), Width between the Trab. lateralis (BTL), Length of the Trab. intermedia (LTI), Length of the Trab. lateralis (LTL), Length and width of the Inc. medialis (LIM and BIM), Length and width of the Inc. lateralis (LIL and BIL), Height at Rostrum (HR), Heigth of breastbone keel at 50% of total length (HK), Cartilage length of the Trab. mediana (LC), Relationship between LC and L, Weight of cartilage of the Trab. mediana (GK) and Relationship between GK and BBG. Furthermore, the Os coracoides were removed as bones of reference. Computerized tomography (pQCT) scans were taken at special reference points from 10 randomly sampled breastbones and their Os coracoids of each genotype and gender. The reference points of the breastbone were located at 33% and 66% of total length, whereas, the reference points of the Os coracoides were located at 50% of total length. Total area, Total density, Cortical area, Cortical density as well as SSI were measured by pQCT. Furthermore, photos were taken of characteristic breastbones from each gender and breed and 6 breastbones of each breed and gender were analyzed for contents of dry matter, ash, calcium and phosphorus. Fast growing broilers reached higher life weights and breast muscle weights than slow growing broilers. While weight differences between cocks and hens of the fast growing strain diminished at the end of the experiment, slow growing broilers still showed distinct weight differences between genders in week 23. The breastbone dimensions reached their final values at different times. Determination of breastbone characteristics by metric measurements of dimensions, by computerized tomography and by chemical analyses showed clearly that the ossification process of breastbones of hens is faster than for cocks. This was also reflected by the relations Cartilage length of the Trab. mediana (LC) / breastbone length (L) and Weight of cartilage of the Trab. mediana (GK)/ breastbone weight (BBG). Both indices were higher in males than in females. Breastbones of Ross 308 hens are ossified faster than of Isa S 457 hens. In general, most breastbone parameters differed between breeds. The development of the dry matter content of the breastbone was not finished till the end of week 23. The storage of inorganic material (ash, calcium and phosphorus) showed breed specific differences at the beginning of the experiment, but during the experiment the increase of inorganic material in breastbones was higher for hens than for cocks. The breastbone of a newly hatched chicken consists completely of cartilage and ossification started immediately after hatch from a central ossification centre to caudal and to cranial. Further ossification centres existed at the lateral Trabeculae. The ossification of the lateral Trabeculae progressed independently of the ossification of the breastbone processus. In the present investigation the direction of ossification to the caudal end of the breastbone processus was of special interest. The central ossification centre showed up in the front keel range of the breastbone. With the sprouting of blood vessels and increased metabolic activity the colour of the centre turned to deep red and spread to cranial and caudal. During the proceeding ossification process due to pneumatisation the deeply red coloured areas turned to bright and finally transparent, especially in the front of the breastbone. The results from computerized tomography of breastbones confirmed the visual observations of the ossification of the breastbone processus. Obviously, the ossification process of the breastbone needs a large time frame and ossification seems to be a multilayered process. The increase in breastbone dimensions is paralleled by an increased storage of inorganic material. The weight of the breastbones was decreasing with increasing age due to the reduction of the water content during the process of pneumatisation. The breastbone processus was not completely ossified in fast and slow growing broilers up to the end of the experiment (week 23 of life). The results on the ossification process in fast and slow growing broiler breeds clearly revealed that a prolongation of the fattening process does not affect marketing of broiler meat from extensive production. The breastbone processus is not fully ossified at the normal slaughter age of 81 to 84 days. But, the results also indicated that a more clear definition of the term ?ossified breastbone processus? is necessary as the breastbone is still not fully ossified on start of laying in hens.