Proposed weaning formula for developing countries.
Explore the source record for details and available documents.
Animals, Laboratory↗
Biomedical subjects
Y S Hafez
Publications and source records attributed to Y S Hafez.
Methionine toxicity in chicks and poults.
In feeding experiments with poults, 2% DL-methionine caused a marked growth depression which could be alleviated by the addition of glycine. Homocystine at an equimolar level depressed growth to a lesser degree than methionine, and this growth depression could be alleviated by glycine. Betaine could alleviate the growth depression of homocystine but not that of methionine. Methionine-fed poults developed a cervical paralysis similar to that of a folic acid deficiency, but the addition of this vitamin at several times the requirement was ineffective in counteracting the toxicity of methionine in either chicks or poults.
Animals↗
The effect of diet on the toxicity of vanadium.
Five experiments were conducted with growing chicks to determine the effectiveness of various materials in modifying the toxicity of vanadium. The toxicity of vanadium (as it is measured by growth depression and mortality) was much greater when vanadium was added to a semipurified diet than when it was added to a practical diet containing natural ingredients. When EDTA was added to diets containing 50 to 200 p.p.m. vanadium, the growth depression was reduced from 22.1% and 75.9% to 8.4% and 36.7% respectively, and the mortality was reduced from 80% to 20% among chicks fed 200 p.p.m. vanadium. The addition of 10% lactose to a diet containing 100 p.p.m. vanadium increased the growth depression from 41% to 76.2% and caused 80% mortality. Chromium added to diets containing 100 and 200 p.p.m. vanadium improved the growth and reduced the mortality.
Animal Feed↗
The effect of pharmacological levels of dietary vanadium on the egg production, shell thickness and egg yolk cholesterol in laying hens and coturnix.
The addition of 100 p.p.m. of vanadium to a ration for White Leghorn laying hens caused a significant increase (p less than 0.01) in the egg shell thickness, but did not cause any significant change in the production, egg weight or egg ypok cholesterol content. The addition of 300 p.p.m. of vanadium caused a severe depression in the egg production which was the only symptom of vanadium toxicity to be observed. The addition of 50, 100, 200 or 300 p.p.m. vanadium to the ration of laying coturnix did not cause any significant change in egg production, egg weight, or egg yolk cholesterol content. The addition of the same levels of vanadium to one-day old male coturnix chicks did not cause any significant growth depression or mortality. We suggest that coturnix may be more resistant to vanadium toxicity than chickens.
Animals↗
Demonstration of the genetic stability of a Mycoplasma gallisepticum strain following in vivo passage.
A Mycoplasma gallisepticum strain designated 6/85 (MGI) exhibiting reduced virulence for both chickens and turkeys was sequentially passaged 10 times in each species. DNA extracted from organisms before passage and those isolated after the third, sixth, and 10th passages was studied by restriction endonuclease DNA analysis using BamHI, BglII, EcoRI, HindIII, and PstI endonucleases. The virulent-type strain designated S6 was used as a comparison. Comparison of DNA fragment patterns of MGI and S6 strains showed distinct differences, although some similarities were evident. Passage of the strain in vivo did not affect DNA fragment patterns of the MGI strain. Electrophoretic protein patterns produced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed very similar band patterns in both the MGI and S6 strains. The most notable differences were seen in bands located in the molecular-mass regions of approximately 46.5, 50-54, 58-64, and 105-140 kilodaltons. Alteration of band pattern profiles following in vivo passage of the MGI strain was apparent in a single band at approximately 86 kilodaltons that appeared to stain more intensely following passage.
Animals↗
Evaluation of a Mycoplasma gallisepticum strain exhibiting reduced virulence for prevention and control of poultry mycoplasmosis.
Two experiments were conducted to evaluate the virulence and vaccination efficacy of a Mycoplasma gallisepticum (MG) isolate designated MG Intervet 6/85. Virulence of the strain was determined by evaluation of airsacculitis scores following aerosol exposure to the isolate before and after 10 sequential passes in either commercial broiler chickens or commercial turkeys. Two-week-old specific-pathogen-free chickens were vaccinated by aerosol exposure. The birds were challenged with the R' strain of MG at either 4 or 8 weeks post-vaccination. Efficacy was evaluated by airsacculitis scores determined 21 days after challenge. Ten repetitive back-passes of the isolate in chickens and turkeys did not substantially increase the virulence. Virulence for both chickens and turkeys was minimal, while protection elicited by aerosol vaccination in young chickens against virulent R' strain was significant (P less than or equal to 0.05) compared with unvaccinated controls.
Aerosols↗
Mycoplasma gallisepticum vaccination-challenge: an egg-production model.
Specific-pathogen-free layer hens in maximum lay were exposed by aerosol to a broth culture of Mycoplasma gallisepticum R' strain. Egg-production loss of greater than 50% was evident 7-14 days following challenge of unvaccinated chickens, with a gradual recovery during the next several days. Various vaccine preparations were tested to determine the effect in the model. All vaccinated chickens exhibited significantly (P < or = 0.05) lower egg-production loss than the unvaccinated controls. The model provides a method for testing treatment effects on egg-production losses resulting from controlled exposure to M. gallisepticum and may be useful in simulating field exposure.
Animals↗