Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Animal and Food Sciences

First Advisor

Dr. Sunday Tayo Adedokun


Two experiments were conducted to examine the effects of oil type, oil quality, phytase, and vitamin E (VE) supplementation in broiler chickens. Experiment 1 used 378-day-old male by-product Cobb breeder chicks with 9 treatments, 7 replicates, and 6 birds per replicate, structured as a 2x2x2+1 factorial arrangement of treatments for 14 days. The first 8 treatments were based on a marginally non-phytate phosphorus (NPP) deficient diet (0.31%), while treatment 9 was a positive control (PC) diet with adequate NPP levels (0.45%). There were 2 levels of phytase (0 vs 1000 FTU/kg), 2 levels of oil quality (fresh soy oil; peroxide value (PV) = 3 meqO2/kg and oxidized soy oil; PV =109 meqO2/kg), and 2 levels of additional supplemental VE (basal VE vs. basal VE+150 ppm) composed of mixed tocopherols containing 55-75% γ-tocopherol. In experiment 2, 384 day-old male by-product Cobb breeder chicks were randomly assigned to 8 treatments, with 8 replicates containing 6 birds per replicate for 20 days. The treatments consisted of 2 oil types (corn vs. soy oil), 2 oil quality levels (fresh corn oil, PV = 3 meqO2/kg, fresh soy oil; PV = 4 meqO2/kg, oxidized corn oil; PV =104 meqO2/kg and oxidized soy oil; PV = 109 meqO2/kg), and 2 levels of additional supplemental VE (basal VE vs. basal VE+150 ppm) composed of mixed tocopherols containing 55-75% γ tocopherol. In the first experiment, phytase supplementation improved (P < 0.05) feed efficiency, calcium utilization, bone-breaking strength, tibia ash, apparent metabolizable energy (AME), and AME corrected for nitrogen (AMEn). Oxidized oil with phytase produced a higher (P < 0.05) AME and AMEn compared to fresh or oxidized oil without phytase supplementation. Furthermore, oxidized oil with additional supplemental VE reduced (P < 0.05) crude fat utilization compared to oxidized oil without additional supplemental VE. In the second experiment, Oxidized oils reduced (P < 0.05) feed efficiency, energy utilization, and AMEn. Moreover, birds that received oxidized soy oil with VE had the lowest (P < 0.05) live weight and body weight gain compared to those that received diets containing fresh corn oil or soy oil with or without VE. Also, oxidized oils alone reduced (P < 0.05) nitrogen utilization and this effect was more pronounced in birds fed diets containing corn oil. Surprisingly, VE supplementation reduced (P < 0.05) crude fat, nitrogen, and energy utilization, as well as AME and AMEn. In conclusion, oil type, oil oxidation, and phytase supplementation influenced the growth performance, and energy and nutrient utilization, while additional VE supplementation at 150 ppm above the recommended VE levels in the basal diet provided little-to-no beneficial effects on these response measures.

Digital Object Identifier (DOI)