Browsing by Subject "Utilization"

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Beiträge zur Ermittlung der P-Verwertung bei der Japanischen Wachtel
(2008) Alfoteih, Yassen; Bessei, Werner
Although there are plenty of studies concerning the metabolism and requirement of phosphorous (P) in poultry, the availability of P from organic and inorganic sources has still to be elucidated. Lacking knowledge on the availability of P has not caused problems in the past since commercial diets have been supplemented with P levels far above the requirement. Only when the excretion of P has been recognized as a source of environmental pollution, and poultry producers were forced to reduce P supplementation in the diet according to the requirement, need more of accurate information on the availability of P has stimulated research in this field. A series of experiments on the utilization of P from different organic and inorganic sources has been carried out using Japanese quail as a model for other poultry species. In addition, the role of the Ca: P ratio on the availability of P was investigated. A total of 6 experiments have been carried out. All experiments were carried out using almost the same methodology. Chicks of a commercial fast growing line of Japanese quail of french origin were hatched at the research station of the University of Hoheheheim and reared up to 3 weeks under standard conditions using a starter diet. Starting from week four, the birds were fed the experimental diets and data for the P-balance were collected for 7 consecutive days (fifth week of age). The components to be tested were added to a basal diet containing all nutrients with the exception of Ca and P. The utilization of P was calculated as difference between P intake and P excretion. The basal diet without supplementation of test-components was included in experiments since P utilization of the basal diet was needed to calculate the partial utilization of P from the test-components. In experiment A1 the utilization of P from summer barley and oats was tested. In Experiment A2 experimental diets comprised three different sources of P, each of plant origin (winter wheat, winter barley and maize) and of inorganic sources mono-calcium phosphate (MCP), di-calcium phosphate (DCP) and mono-sodium phosphate (MNP) were used. Mixtures of P sources tested in experiment A3 (MCP+DCP, MCP+MNP, MCP+maize, Wheat+ barley and wheat+ maize) were examined in experiment A3. The P level in the experimental diets was adjusted to a range of 2 to 3 g/kg and the Ca-level to 3 to 5 g/kg. The Ca:P ratio was restricted to a maximum of 2:1. The supplementation of the different types of grain to the diets was 60.0 to 66.0 %. Calcium carbonate (CaCo3) and sodium bicarbonate (NaHCo3) were used to supplement Ca. The result showed that, there was no significant difference among the experimental diets on weight gain of the birds. P utilization was highest in the basal diet (66.6 %) followed by barley and oats (33.3 and 20.8 % respectively), while the standard diet showed the lowest utilization (7.87 %). In experiment A2 the utilization of P of the basal diet (94 %) was significantly higher than of all other P-sources wheat (60 %), maize (66 %), while diet supplemented with barley showed the lowest value (34 %) and the other sources an intermediate position between 47 and 53 %. The partial utilization was somewhat lower than the overall utilization in all diets. In experiment A3 the utilization of P of the basal diet was 69 % and did not significantly differ from the other diets. The combination MCP+MNP showed the highest utilization (76 %), followed by wheat+barley (53 %) and MCP+maize (50 %). The partial utilization showed the similar values as the overall utilization. The three following experiments (B1, B2 und B3) dealt with the effects of different Ca: P ratios on the utilization of P, feed intake, growth rate and selected bone criteria. Four different Ca levels (0.80; 1.20; 1.60 and 2.20 %) were combined with three P levels (0.30; 0.45 and 0.60 %) in experiment B1. During Experiment B2, experimental diets contained three Ca concentrations at levels higher than in experiment B1 (2.60; 3.00 and 3.30 %) and three P concentrations at levels lower than in B1 (0.10; 0.20 and 0.30 %). Experiment B3 was conducted with the same Ca and P concentrations as in experiment B2, but the duration of the balance period was extended from 1 to 3 weeks. In addition of the P utilization and growth rate Ca and P contents of the tibia bones was analyzed and some bone characteristics were measured by computer tomography. In experiments B1 and B2 neither the P nor the Ca concentration showed a consistent effect on feed intake, growth rate, feed conversion or mortality. The P utilization decreased with increasing P concentration and P intake. The effect of the Ca: P interaction on P utilization was only significant in experiment B1. In the extended balance period in experiment B3, the effects of Ca and P concentration as well as their interaction was significant for body weight in the first week of the experiment. From the second week onwards the effects of the sources of variance decreased and fell under the level of significance. The P utilization was only influenced by the P concentration. As in the previous experiments P utilization decreased with increasing P concentration. Bone characteristics showed tendencial response to Ca and P concentration, whereby with the lowest concentrations of Ca and P in the diet, the highest bone weight, ach content, Ca and P content was found. Elevating Ca supply meliorated the total area and cortical area of the tibia. However, the better tibia quality based on evaluating the Strain Strength Index (SSI) as a criterion for the stability of bone was found in groups fed diets with the highest level of P. The results of these experiments showed that there is an obvious variation in the availability of P from the organic and mineral resources. The utilized P value from mineral resources was underestimated, while the utilized P value from organic resources overestimated. The P utilization of the combinations of different P sources which diverged in their P utilization showed intermediate values. The P concentrations of the diets and the P intake were the main influencing factors on P utilization. This result pointed out that the birds were capable to cover their requirements from P through the diets, although the P contents in the diets were low. The P contents of tested diets have met already the requirement of P with quails or even exceeded. The recommendations of P supply in quail diets need to be reduced accordingly. Should quail be used as model for the study of P requirement in broilers, it is essential either to decrease the P content drastically in the diets, or to conduct the tests at earlier age. The lower requirement of P in quail from 3 weeks of age onwards explains the weak reaction of feed intake and growth rate in response to the low P concentration and to extremely high Ca: P ratios. Some bone characteristics responded to low P concentrations and high Ca: P ratios even at higher ages. This confirms previous findings that P requirement for bone building is evidently higher than the P required for growth. The question posed by this result, weather growth rate or bone characteristics should be used to determine the requirement of P in poultry.