الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
 |  | from | 144 |  |  |
| | | from | 144 | | |
Abstract
This experiment was carried out at Poultry Experimental Farm, Animal and Poultry Production Department, Faculty of Agriculture, Assiut University, Assiut, Egypt.
The aim of the experiment was to study the effect of different dietary levels of calcium: phosphorus ratio, vitamin A, and vitamin D3 and the interrelationships between them on broilers performance, carcass quality, and some bone and blood parameters.
A total number of 432 of one-day old broiler chicks (Cobb 500) were randomly assigned in a factorial arrangement (2*3*3) to 18 equal treatment groups of two replicates each. The chicks were housed in pens as groups of 12 birds per replicate (Total 36 replicates). After one week of age, the weak chicks (not due to experimental circumstances) were discarded from all replicates and 8 chicks were remained in each replicate. Therefore, a total of 288 chicks were stayed understudy till the end of seven-week experiment. The light was provided for 23h/d over the 7-wk experiment. The temperature was kept at 32 0C during the first week, then gradually reduced 2 0C weekly till constant at 24 0C. The chicks were fed starter diet (21.8% protein) during the first three weeks of age then grower diet (18.8% protein) during the last four weeks of the experiment.
The two basal diets (starter and grower) were formulated to contain 0.89 Ca and 0.45 Pavail (2:1) or 1.33 Ca and 0.44 Pavail (3:1) .
The basal diets were fortified in the experimental diets with vit. A and vit. D3 to contain three levels of vit. A (1500, 15000 or 30000 IU/kg) and three levels of vit. D3 (200, 2000 or 4000 ICU/kg).
General Summary and Conclusions
Two control groups (general control; T1 and control 2; T10) received the two basal diets containing 0.89 or 1.33% Ca, 1500 IU vitamin A and 200 ICU vitamin D3, and the other groups from T2 till T18 were fed the experimental diets. Retinol was used as vit. A while cholecalciferol was used as vit. D3. Limestone was used to raise calcium percent from 0.89 to 1.33%.
Body weights were recorded at one day of age, then weekly till seven weeks of age. Feed consumption per replicate was recorded weekly. Body weight gain and feed conversion ratio from 0-3, 3-7 and 0-7 weeks of age were calculated.
At the end of the 7th week, 3 birds were chosen from each replicate then weighed, slaughtered, bleeded, and plucked. The carcass, and carcass parts (breast, legs and giblets) were, weighed and calculated as percentages relative to live body weight. Blood samples were collected at slaughter and serum was separated for determination of calcium, and phosphorus. Also, liver from each bird was taken at slaughter and frozen for vitamin A determinations. Right tibia from each slaughtered bird was taken for ash percentage determination. Diluted soluble ash was prepared for calcium and phosphorus determinations.
Data obtained from this experiment were statistically analyzed by ANOVA, and Duncan’s multiple range test was used to determine the significant differences between means when treatments effects were significant. The results could be summarized as follows:
2. Live Body Weight (L.B.W):
At three weeks of age body weight was significantly affected by Ca:Pa ratio and vit. A level. The lowest BW was proved for the group fed
General Summary and Conclusions
2:1 Ca:Pa ratio,15000 IU vit. A, and 200 ICU vit. D3, whereas the highest BW was recorded for the group fed 3:1 Ca:Pa ratio , 30000 IU vit. A, and 4000 ICU vit. D3.
At seven weeks of age, body weight was significantly affected by Ca:Pa ratio and the interaction between Ca:Pa ratio and vit. A level. The lowest BW was proved for the group fed 2:1 Ca:Pa ratio,1500 IU vit. A, and 4000 ICU vit. D3, whereas the highest BW was recorded for the group fed 3:1 Ca:Pa ratio , 15000 IU vit. A, and 2000 ICU vit. D3.
It is also worthy to mention that BW was significantly higher at 3 weeks of age when broilers fed 1.35% Ca, 30000 IU vit. A and 4000 ICU vit. D3, whereas BW was significantly higher at 7 weeks of age when broilers fed 1.35% Ca, 15000 IU vit. A and 2000 ICU vit. D3. That may refer to higher requirements of these nutrients at 3 weeks of age rather than at 7 weeks of age.
2. Body Weight gain (BWG) :
from one day old to 3 weeks of age, body weight gain was significantly affected by Ca:Pa ratio and vit. A level. The lowest BWG was proved for the group fed 2:1 Ca:Pa ratio,15000 IU vit. A, and 200 ICU vit. D3, whereas the highest BWG was recorded for the group fed 3:1 Ca:Pa ratio , 30000 IU vit. A, and 4000 ICU vit. D3.
from 3 to 7 weeks of age, BWG was significantly affected by Ca:Pa ratio, vit. A level, and the interaction between Ca:Pa ratio and vit. A level. The lowest BWG was proved for the group fed 2:1 Ca:Pa ratio,1500 IU vit. A, and 4000 ICU vit. D3, whereas the highest BWG was recorded for the group fed 3:1 Ca:Pa ratio , 15000 IU vit. A, and 4000 ICU vit. D3.
from one day old to 7 weeks of age body weight gain was significantly affected by Ca:Pa ratio, vit A level and the interaction
General Summary and Conclusions
between Ca:Pa ratio and vit. A level,. The lowest BWG was proved for the group fed 2:1 Ca:Pa ratio,1500 IU vit. A, and 4000 ICU vit. D3, whereas the highest BWG was recorded for the group fed 3:1 Ca:Pa ratio , 15000 IU vit. A, and 2000 ICU vit. D3.
It is also worthy to mention that BWG was significantly higher at (0- 3) weeks of age when broilers fed 1.35% Ca, 30000 IU vit. A and 4000 ICU vit. D3, whereas BWG was significantly higher at (0-7) weeks of age when broilers fed 1.35% Ca, 15000 IU vit. A and 2000 ICU vit. D3. That may refer to higher requirements of these nutrients at (0-3) weeks of age rather than at (0-7) weeks of age.
3. Feed Consumption (FC) :
from one day old to 3 weeks of age, feed consumption was significantly affected by Ca:Pa ratio, vit. A level, the interaction between Ca:Pa ratio and vit. D3 level, and between Ca:Pa ratio and vit. A level and vit. D3 level. The lowest feed consumption was proved for the group fed 2:1 Ca:Pa ratio,30000 IU vit. A, and 2000 ICU vit. D3, whereas the highest feed consumption was recorded for the group fed 3:1 Ca:Pa ratio , 15000 IU vit. A, and 200 ICU vit. D3.
from 3 to 7 weeks of age, feed consumption was significantly affected by Ca:Pa ratio, vit. A level, vit. D3 level, the interaction between Ca:Pa ratio and vit. A level, and between Ca:Pa ratio and vit. D3 level and between vit. A level, vit. D3 level and between Ca:Pa ratio , vit. A level and vit. D3 level . The lowest feed consumption was proved for the group fed 2:1 Ca:Pa ratio,1500 IU vit. A, and 4000 ICU vit. D3, whereas the highest feed consumption was recorded for the group fed 3:1 Ca:Pa ratio , 15000 IU vit. A, and 200 ICU vit. D3.