ACKNOWLEDGMENTS 



The author wishes to express his sincere gratitude and 

 appreciation to all those who collaborated in the presentation 

 of this dissertation. 



Special appreciation is due to his advisor and chairman 

 of his supervisory committee, Dr. Lee R. McDowell, for his 

 guidance and friendship throughout all the stages of his 

 graduate work. Acknowledgements are also extended to Drs . D. 

 B. Bates, J. H. Conrad, R. J. Cousins and F. G. Martin, 

 members of his supervisory committee, for giving their 

 valuable time and knowledge toward the completion of this 

 research. Special recognition is due to Dr. Robert J. Cousins 

 for his assistance with the third part of the research and to 

 Dr. Frank G. Martin for his assistance in the statistical 

 analysis . 



The author is especially grateful to his parents Dr. and 

 Mrs. Aquiles and Teresita Rojas for their love, encouragement 

 and financial support during this academic endeavor. Also, 

 the author wishes to recognize the Organization of American 

 States for their financial support. 



He is deeply grateful to Mrs. Nancy Wilkinson at the 

 Animal Nutrition Laboratory for her guidance, assistance and 

 friendship in all phases of the research. Sincere 



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