Browsing by Subject "Computertomographie"

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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.
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    Evaluation of the availability of different mineral phosphorus sources in broilers
    (2012) Shastak, Yauheni; Rodehutscord, Markus
    Inorganic feed phosphates are an indispensable supplement for compounding poultry feed. The requirement of available P in broiler chicks cannot be covered only with plant ingredients as P in plant feedstuff is largely presented in form of phytate which is only partially available in avian species. Due to the increase in prices for feed phosphates and environmental concerns associated with excessive excretion of P by livestock, the knowledge about the availability of P from mineral sources has gained in importance during the last decade. However, there is still no standardized method available for assessing the P availability of inorganic feed phosphates. Without knowledge of the exact quantitative values of the P availability for different P sources, it is not possible to formulate adequate diets without the risk of deficiency or excess supplementation. There are various approaches which are used by different laboratories for the determination of P availability. The main problem is, however, that it is not clear how the differences between approaches affect the results. The development of a standardized method of P evaluation, which allows obtaining quantitative values for P availability, is the basis for optimizing the dietary P concentration in broiler diets. The major objective of this thesis was to compare various methodological approaches that are used internationally to determine P availability in terms of their suitability. Therefore, firstly the P availability of two mineral phosphates was determined in 3- and 5-wk-old broilers based on data for P retention and prececal digestibility. The P availability of both mineral sources was calculated for both ages of birds by regression analyses for comparison of both response criteria. Secondly, the tibia bone ash and other bone criteria were determined. A comparison of these bone response criteria was then carried out by relating these data to measurements made on P retention. Thirdly, the suitability of tibia P retention for the estimation of the whole body P retention was investigated at both ages of birds. Variation in P retention of birds in these studies was additionally caused by the level and the source of P in the diet. In a fourth study, the effect of the basal diet composition on the availability of a feed phosphate was investigated based on quantitative P retention. A phytin-containing corn-SBM-based as well as a purified basal diet was used. Moreover, the impact of the inorganic phosphate level on the IP6 hydrolysis of the corn-SBM-based diet was assessed on the basis of excreta collection. In the first study, a corn-SBM-based basal diet was used (0.35% P on dry matter basis). MSPa or DCPa was supplemented to increment the P concentration by 0.08%, 0.16%, and 0.24%. Two balance trials (n=8 birds per diet) and two digestibility trials (n=8 pens with 10 birds per diet) were conducted (8 treatments per diet). In 3-wk-old broilers, P retention for MSPa was 70% and significantly higher (P < 0.001) than for DCPa (29%), as calculated by linear regression analysis. Values determined for P pc digestibility at the same age were very similar (67% for MSPa and 30% for DCPa; P < 0.001). In 5-wk-old broilers, P retention was 63% (MSPa) and 29% (DCPa) (P < 0.001), and pc digestibility was 54% (MSPa) and 25% (DCPa) (P = 0.002). In conclusion, in 3-wk-old broilers results obtained with both approaches were the same. In 5-wk-old broilers, the ranking of the two P sources was the same for both approaches. Values differed not greatly between the two age periods. The second study was linked to the first one, and the experimental design was the same. The study comprised two periods with birds of different ages, but from the same hatch. The response criteria evaluated were tibia, tarsometatarsus, toe ash, and P, as well as the Quantitative Computed Tomography measurements of tibiae, blood Pi concentration, and body weight gain. Responses were evaluated and compared based on linear regression analysis. In general, MSPa had a greater slope than DCPa for all criteria studied. For the different bones, the ratio of slopes was very similar based on the amount of ash in both periods. Foot ash was proved to be as sensitive as tibia ash in both periods. Blood serum Pi and body weight gain were not sufficiently sensitive criteria for P evaluation. We concluded that the ranking of both mineral P sources based on bone criteria differed from the ranking that was based on P retention or pc digestibility. The third study was also linked to the first one. Thus, the experimental design was the same. On days 21 and 35, two chicks per treatment were randomly chosen. Contents of P and Ca were determined in tibiae-free bodies and tibiae. The whole body P to tibia P ratio was 21.3±1.3 at d 21 and 19.8±1.1 at d 35 of age. The slope of linear regressions between the tibia P and the whole body P for both ages was identical (17.7). Results indicated that changes in tibia P may be suitable to predict changes in whole body P retention. In the last experiment, a phytin-containing as well as a purified basal diet, both containing 1.8 g available P per kg feed dry matter, was supplemented with MSPa to increment the P concentration by 0.05%, 0.1%, and 0.15%. A retention trial with excreta collection from d 20-24 was conducted (n=7 birds per diet). The level of P did not significantly affect the total P retention either of the corn-SBM-based or of the purified basal diet (P > 0.05). However, increasing the P level significantly reduced (P = 0.015) the IP6 hydrolysis for the corn-SBM-based diets. Percentage P retention for MSPa was calculated by linear regression analysis. P retention for MSPa was 50% for the corn-SBM-based diet and 51% for the purified diet. We concluded that there was no difference in P retention from MSPa between corn-SBM-based and purified diets. It can be concluded from the results of the present thesis that both retention and pc digestibility can be used for evaluating mineral P sources in broilers based on a regression approach. The ranking of mineral P sources based on bone criteria differed from the ranking that was based on P retention or pc digestibility. There was no difference in P retention from MSPa between corn-SBM-based and purified based diets, but a significant effect of the P-level on the IP6 hydrolysis in corn-SBM-based basal diets was found.