Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

Joseph S. Moritz.


Phytogenic feed additives are purported to possess antimicrobial properties as well as nutrient sparing characteristics that may aid in alleviating high diet costs; however, in order for PFAs to assist nutritionists in decreasing diet cost, matrix values must be determined and implemented in feed formulation. Study 1 evaluated proposed matrix values for a commercially available PFA and assessed nutrient sparing when the product was combined with commercial phytase, carbohydrase and protease. The most remarkable proposed matrix values were 32.2 kcal/kg for metabolizable energy and 0.07% for both Ca and AP. The objective of Study 2 was to determine true amino acid digestibility (TAAD) and nitrogen corrected true metabolizable energy ( TMEn). Dietary treatments for both studies included a basal, basal with phytogenic product matrix value, basal with phytogenic product matrix value and phytogenic product, and similar treatments evaluating the phytogenic product matrix with exogenous enzyme products. Decreasing the basal diet by the proposed phytogenic matrix values decreased broiler live weight gain and increased feed conversion ratio (P≤0.05). However, when the same diet included the phytogenic feed additive, live weight gain and feed conversion ratio were restored to that of the basal diet (P>0.05). The proposed matrix values of the specific PFA tested were justified. However, the PFA was not additive or synergistic with exogenous enzymes. Nitrogen corrected true metabolizable energy and TAAD data did not differ when the diets varied based on the PFA per se (P>0.05). However, when the PFA was incorporated using proposed matrix values and used in conjunction with exogenous enzymes and their matrix values, TMEn and several tested TAAD values were decreased (P≤0.05). Mechanistic speculation for decreased nutrient digestibility may perhaps involve reductions in gut microflora due to the PFA as well as simultaneous reduction in substrate concentrations.