Low-phytic acid corn improves nutrient utilization for growing pigs.
Thirty-five crossbred barrows averaging 14.5 kg initial BW were used in a 5-wk experiment to compare the P availability and nutritional value of a low-phytate hybrid corn (LPC, 0.26% total P, 0.08% phytic acid P) homozygous for the lpa 1-1 allele with a nearly isogenic normal hybrid corn (NC, 0.25% total P, 0.20% phytic acid P). The pigs were fed individually twice daily in metabolism pens. Three semipurified diets were created in which corn was the only source of phytate. Diet 1 contained 72% NC, 0.15% estimated available P (aP) and 0.55% Ca. Diet 2 contained 72% LPC, 0.24% aP, and 0.55% Ca. The only differences between Diets 1 and 2 were the source of corn and the levels of aP. No inorganic P (iP) was added to these diets in order to measure the animal response to the different levels of aP in the corn hybrids. Diet 3 was NC Diet 1 supplemented with iP to equal the level of aP in LPC Diet 2. Diets 4 and 5 were practical corn-soybean meal diets formulated with each corn to meet all minimum nutrient requirements and contained 0.30% aP and 0.65% Ca. For the semipurified diets, pigs fed LPC Diet 2 had higher (P < 0.01) growth performance, bone breaking strength, P absorption and retention, Ca absorption and retention, and N retention than pigs fed NC Diet 1. However, when the NC diet was supplemented with iP to equal the aP in the LPC diet, most criteria were similar (P > or = 0.2), indicating an equal nutritional value for both corn hybrids after adjusting for phytate level. The only treatment difference, other than P excretion, between the practical corn diets supplemented with soybean meal was a higher (P < 0.05) bone breaking strength for pigs fed LPC Diet 5 compared with NC Diet 4. The use of LPC in pig diets reduced P excretion in swine waste by 50 and 18.4% in the semipurified and practical diets, respectively, compared with NC. Using our in vitro procedure designed to simulate the digestive system of the pig, the availability of P for pigs was estimated at 56% for LPC and 11% for NC.
Veum
T L
TL
Department of Animal Sciences, University of Missouri, Columbia, MO 65211-5300, USA. veumt@missouri.edu
Ledoux
D R
DR
Raboy
V
V
Ertl
D S
DS
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001682:Biological Availability; D001842:Bone and Bones / Q000502:physiology; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics; D004032:Diet / Q000662:veterinary; D004734:Energy Metabolism; D008297:Male; D009584:Nitrogen / Q000008:administration & dosage / Q000493:pharmacokinetics; D009753:Nutritive Value; D010758:Phosphorus / Q000378:metabolism*; D010833:Phytic Acid / Q000008:administration & dosage*; D011897:Random Allocation; D013552:Swine / Q000254:growth & development* / Q000378:metabolism; D003313:Zea mays / Q000235:genetics
D002136:Calcium, Dietary; D010758:Phosphorus; D010833:Phytic Acid; D009584:Nitrogen