This Is AuburnElectronic Theses and Dissertations

The Effects of Phytase and Non-starch Polysaccharide Enzymes in Poultry Production




Gulizia, Joseph

Type of Degree

Master's Thesis


Poultry Science

Restriction Status


Restriction Type

Auburn University Users

Date Available



Feed is the largest expense in broiler production; therefore, feed additives have become commonplace in broiler diets to reduce feed cost and improve live performance. Exogenous enzymes have been used for over 50 years to improve nutrient digestibility and reduce inclusion of costly feed ingredients. Furthermore, nutritionists utilizing exogenous enzymes can be flexible with least cost formulations. Supplementing exogenous phytases and/or non-starch polysaccharide (NSP) degrading enzymes can reduce inclusion of inorganic phosphorus and costly energy contributing feed ingredients such as fat and oils. Reducing inclusion of fat and oils can also have a positive effect on pellet quality. Two trials were conducted to determine effects of feeding broilers varying inclusion rates of phytase and NSP degrading enzymes either separately or in combination in a nutrient reduced diet during starter, grower, and finisher periods. The objective of trial 1 was to evaluate supplementation of a heat stable phytase on broiler performance, tibia ash, and mineral excretion from 1 to 49 d of age. A total of 1,200 d-old Ross 708 x YPM male broilers were randomly distributed in 40 floor pens assigned to 5 treatments with 8 replicates per treatment. A positive control (PC) was formulated to contain recommended levels of available phosphorus and calcium, whereas the negative control (NC) contained 0.20% less available phosphorus and calcium compared to the PC at each feeding phase and 3 treatments with 500, 1,000, or 2,000 FTU/kg of phytase were manufactured using the NC. Inclusion of phytase maintained body weight (BW) on d 21, 35, and 49 compared to broilers fed the PC. Phytase supplementation allowed broilers to properly maintain skeletal integrity by d 21 and 49 as indicated by increased tibia ash. Additionally, birds fed the NC with and without phytase regardless of inclusion rate had reduced mineral excretion on d 28 and 49 compared to broilers fed the PC. These data indicated that phytase supplementation can help maintain broiler performance in calcium and available phosphorus reduced diets while decreasing total mineral excretion. The objective of trial 2 was to evaluate interactive effects of phytase (500 or 1,500 FTU/kg) and a multicarbohydrase containing α-galactosidase activity (CAG; 0, 0.1, or 0.2 g/kg) in a calcium, available phosphorus, and metabolizable energy (ME) reduced diet on broiler performance, processing yield, and nutrient digestibility from 1 to 42 d of age. A total of 2,250 d-old Ross 708 x YPM male broilers were randomly distributed in 90 floor pens assigned to 9 treatments with 10 replicates per treatment. A PC sufficient in phosphorus (PC-P) with the addition of inorganic phosphorus sources and a PC for energy (PC-E) with 100 kcal/kg more ME than the other treatments were formulated, whereas a NC was manufactured to contain 0.20% less available phosphorus and calcium and 100 kcal/kg less ME than the PC-P and PC-E, respectively, at each feeding phase. Six additional treatments contained 500 or 1,500 FTU/kg of phytase in combination with 0, 0.1, or 0.2 g/kg of CAG in the NC diet. During the entire grow out, broilers fed exogenous enzymes separately or combined in a NC diet had a BW comparable to broilers fed diets sufficient in calcium, available phosphorus, and ME. Between d 1 to 49, broilers fed a diet containing phytase and the highest inclusion of CAG (0.2 g/kg) had a numerically lower feed conversion ratio compared to other enzyme supplemented diets and was comparable to broilers fed a diet with 100 kcal/kg more ME. Broilers that consumed a diet combined with 0.2 g/kg of CAG and phytase had higher fillet yields. Lastly, broilers fed a diet with single or multiple exogenous enzymes had improved nutrient digestibility compared to broilers fed a NC and were comparable to broilers that consumed nutrient sufficient diets. These data illustrate how various broiler measurements can be improved or sustained with multiple exogenous enzyme supplementation. Overall, continued use of exogenous enzymes in broiler production is essential for improving performance and nutrient utilization while effectively mitigating feed cost.