| Popis: |
1. 1. Experiments were conducted on 596 young chickens to determine the importance of the phosphorus, calcium, and manganese content of the feed as factors in the resistance of chickens to the nematode Ascaridia galli. 2. 2. Comparisons were made between the numbers and lengths of A. galli from different groups of chickens given about 200 A. galli eggs per fowl. 3. 3. In four experiments there were fewer and shorter A. galli from the fowls kept on a ration deficient in phosphorus than from the control groups maintained on adequate diets. These differences were statistically significant. 4. 4. Similarly, chickens given a diet which was deficient in calcium had significantly fewer and smaller worms than did the control fowls. 5. 5. The fewer and smaller A. galli from groups of fowls fed on low phosphorus and low calcium diets are attributed to the worms' requirements for these minerals, since phosphates and calcium have been found to be among the more important mineral constituents of the ascarid body. 6. 6. The results of these experiments appear to constitute the first experimental evidence of the requirement of phosphorus and calcium for the normal growth of a nematode. 7. 7. Chickens on the phosphorus deficient diet manifested typical deficiency symptoms of general debility; similarly the fowls on the calcium deficient rations showed typically retarded growth, pliable beaks, and usually rickets. 8. 8. Results on A. galli from tests on manganese were too variable to show a constant trend. 9. 9. The resistance of growing chickens to the fowl nematode, A. galli, appears not to be affected by a deficiency of phosphorus or of calcium in the diet of the host. |
