Corn expressing an Escherichia coli-derived phytase gene: A proof-of-concept nutritional study in pigs

¹ Department of Animal Science, Purdue University, West Lafayette, IN 47907-2054
² Syngenta Biotechnology, Inc., 3054 Corn Wallis Road, Research Triangle Park, NC 27709
³ Syngenta Animal Nutrition, Chestnut House, Beckhampton, Marlborough, Wiltshire SN8 1QJ, United Kingdom

^* To whom correspondence should be addressed. E-mail: ladeola{at}purdue.edu.

	Abstract

Two experiments were conducted to investigate the concept that the addition of a corn expressing an Escherichia coli-derived gene (corn-based phytase; CBP) to a P-deficient diet would improve growth performance and P utilization in pigs. An Escherichia coli-derived microbial phytase (expressed in Pichia pastoris) sprayed onto a wheat carrier (Quantum) was included for comparison. In Exp. 1, 48, 10-kg pigs were blocked by weight into 6 blocks and allotted to 8 dietary treatments such that the weight among dietary treatments was similar and given free access to feed for 28 d. The dietary treatments were a negative control (NC) with no inorganic P supplementation; NC + 2, 4, or 6 g monosodium phosphate (MSP)/kg; NC + 16,500, 33,000, or 49,500 phytase units (FTU) CBP/kg; and NC + 16,500 FTU Quantum/kg. In Exp. 2, 24, 13-kg barrows were assigned to the NC, NC + 16,500 or 33,000 FTU CBP/kg, or NC + 16,500 FTU Quantum/kg in a nutrient and energy balance study consisting of 5-d adjustment and 5-d collection periods. Total collection method was used to determine nutrient and energy balance. Addition of CBP to the low-P NC diet linearly increased (P < 0.01) ADG, G:F, and plasma P concentration of pigs during the 28-d study. There was no difference in ADG, G:F, or plasma P concentration between pigs fed either CBP or Quantum phytase at 16,500 FTU/kg. Weight gain, G:F, and plasma P concentration of pigs increased (P < 0.01) with MSP supplementation, confirming P deficiency of the NC diet. Linear improvements (P < 0.05) in DM digestibility and energy retention were observed with CBP supplementation of NC diets. Although there were linear (P < 0.01) and quadratic (P < 0.05) increases in N digestibility, N retention was unaffected by CBP supplementation of NC diets in growing pigs. Phosphorus and Ca digestibilities and retentions improved linearly and quadratically (P < 0.01) with the addition of CBP to NC diets. There was no difference in digestive utilization of P or Ca between pigs fed CBP and Quantum phytase at 16,500 FTU/kg. The data showed that the addition of a corn expressing an Escherichia coli-derived gene to a P-deficient diet improved growth performance and indices of P utilization in pigs, and corn expressing phytase was as efficacious as Quantum phytase when supplemented to P-deficient diets for weanling pigs.

Key Words: corn-based phytase, growth performance, nutrient utilization, plasma phosphorus, weanling pigs