Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Animal and Nutritional Sciences

Committee Chair

Joseph Moritz

Committee Member

Janet Tou

Committee Member

K. Marie Krause


Enzymes are commonly added to poultry diets to improve performance parameters that may in turn decrease costs to the producer. Pellet mill production rate aids are also utilized to reduce feed manufacture costs and may have additional benefits when fed to poultry that are associated with the increase in production rate. Past research has shown that Azomite (AZM) can increase pellet mill production rate in diets that include inorganic phosphate sources (IPS) of dicalcium phosphate (DCP) or tricalcium phosphate (TCP). In the first experiment the authors hypothesized that if production rate were held constant then pellet mill energy consumption would decrease for diets that contained AZM due in part to a lubricating and/or pellet die scouring effect. This could decrease dietary amino acid exposure to frictional heat and pressure within the pellet die, maintaining amino acid conformation, and amino acid digestibility. The objective was to determine the effect of AZM (0.25%) in diets with DCP and TCP on pellet mill energy consumption, subsequent live bird performance, and apparent ileal amino acid digestibility (AIAAD) when fed to broiler chicks for 21 days. Feed was manufactured in a 2 (IPS) x 2 (AZM inclusion) factorial across 4 days in a Latin square design. Post manufacture, three hundred twenty-day-old Hubbard × Ross 708 males (0.038kg ± 0.0014 SD) were allocated by weight to 8 replicates per treatment, 10 chicks per raised wire cage, in a randomized complete block design. Dietary treatments were arranged in a 2 x 2 factorial: DCP with or without AZM and TCP with or without AZM. On d21 ileal contents were collected for amino acid and titanium dioxide analysis. Statistical analysis (Glimmix, SAS 9.4) was performed on the factorial arrangement of treatments and multiple comparisons were made of all treatments with post-hoc test by Tukey’s. Pellet mill motor load decreased by 5% in diets containing TCP compared to DCP (P

Mixer added phytases must retain efficacy post conditioning and pelleting. Heat from saturated steam and friction upon pellet die extrusion may deactivate phytases. In addition, increasing phytase concentrations in diets may increase nutrient release from phytate. In this second experiment the objective was to assess two commercially available phytases that were concentrated at 500, 1,000, or 2,000 FTU/kg in mixed mash post steam conditioning at 82°C for 30 sec and extrusion through a 4.8 x 38mm pellet die on 0 to 44d Ross 708 male broiler performance, mineral digestibility, and tibia ash responses. The phytase sources were both derived from E. coli and expressed in Trichoderma Reesei, (QB) and expressed in Pichia pastoris, (OP). A 3 (Phytase level) × 2 (Phytase source) factorial arrangement of treatments within a randomized complete block design was utilized. A positive control and negative control diet based on available phosphorus (P) and total calcium (Ca) were also manufactured and analyzed within a multiple comparison. Crumbled and pelleted diets were fed to 8 replicate pens of 30 chicks in three phases. Live performance, d20 and d44 tibia ash, d44 hot boneless, skinless breast weight and mineral digestibility were measured. Day 44 live weight gain (LWG) and both d20 and d44 tibia measures increased for all phytase concentrations relative to the negative control (P<0.05).