Journal of Animal Science, Vol 74, Issue 6 1288-1297, Copyright © 1996 by American Society of Animal Science

JOURNAL ARTICLE

Adverse effects of wide calcium:phosphorus ratios on supplemental phytase efficacy for weanling pigs fed two dietary phosphorus levels

H. Qian, E. T. Kornegay and D. E. Conner Jr
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.

Ninety-six weanling pigs (initial BW = 9.3 kg, initial age = 37 d) were used in a 4-wk experiment to evaluate the response to three Ca: total (t) P ratios (1.2:1, 1.6:1, or 2.0:1) fed in combination with two P levels (.07 or .16% available that correspond to .36 or .45% tP) and two phytase levels (PY; 700 or 1,050 units/kg of diet). A 3 x 2 x 2 factorial arrangement of treatments was employed using a corn-soybean meal diet. Performance, serum mineral concentrations and alkaline phosphatase (ALP) activity, Ca and P digestibility and excretion, and bone mechanical measurements were examined. Average daily gain (P < .001), average daily feed intake (P < .01), and gain:feed (P < .05) were decreased linearly as the Ca:tP ratio became wider. The digestibility of P and Ca were decreased (P < .001) linearly as the Ca:tP ratio became wider. The digestibility of P (P < .001) and fecal P excretion (P < .01) were increased at the higher level of P. Increasing PY from 700 to 1,050 units (U)/kg of diet increased (P < .05) P digestibility and decreased (P < .01) P excretion but did not improve bone measurements. Shear force, stress and energy, and percentage of ash of both metacarpal and 10th rib linearly decreased (P < .001 to .05) as the Ca:tP ratio became wider, and bone measurements were generally greater for pigs fed the higher P level. Serum Ca concentration increased (P < .01) and the P concentration decreased (P < .001) as the Ca:tP ratio increased, but Mg, Zn, and ALP activity were not influenced by the Ca:tP ratio. Serum Ca and P concentrations were affected by PY supplementation over the 4-wk trial, but serum Mg and Zn concentrations were not affected by dietary treatments. Adverse effects of a wide Ca:tP ratio were greater at the low P diet for all responses. In addition, the activity of supplemental PY in diets seemed to be decreased as the Ca:tP ratio became wider and this negative effect of Ca:tP ratio seemed greater at the low P level, and seemed to parallel the effects of Ca:tP ratio on performance, P digestibility, bone, and serum measurements. Narrowing the dietary Ca:total P ratio from 2.0:1 to 1.2:1 led to an approximate 16% increase in phytase efficacy for improving performance, digestibility, bone measurements, and serum Ca levels.

This article has been cited by other articles:

				T. L. Veum and M. R. Ellersieck Effect of low doses of Aspergillus niger phytase on growth performance, bone strength, and nutrient absorption and excretion by growing and finishing swine fed corn-soybean meal diets deficient in available phosphorus and calcium J Anim Sci, April 1, 2008; 86(4): 858 - 870. [Abstract] [Full Text] [PDF]

				T. N. Nortey, J. F. Patience, P. H. Simmins, N. L. Trottier, and R. T. Zijlstra Effects of individual or combined xylanase and phytase supplementation on energy, amino acid, and phosphorus digestibility and growth performance of grower pigs fed wheat-based diets containing wheat millrun J Anim Sci, June 1, 2007; 85(6): 1432 - 1443. [Abstract] [Full Text] [PDF]

				T. L. Veum, D. R. Ledoux, and V. Raboy Low-phytate barley cultivars improve the utilization of phosphorus, calcium, nitrogen, energy, and dry matter in diets fed to young swine J Anim Sci, April 1, 2007; 85(4): 961 - 971. [Abstract] [Full Text] [PDF]

				D. V. Brana, M. Ellis, E. O. Castaneda, J. S. Sands, and D. H. Baker Effect of a novel phytase on growth performance, bone ash, and mineral digestibility in nursery and grower-finisher pigs J Anim Sci, July 1, 2006; 84(7): 1839 - 1849. [Abstract] [Full Text] [PDF]

				T. L. Veum, D. W. Bollinger, C. E. Buff, and M. R. Bedford A genetically engineered Escherichia coli phytase improves nutrient utilization, growth performance, and bone strength of young swine fed diets deficient in available phosphorus J Anim Sci, May 1, 2006; 84(5): 1147 - 1158. [Abstract] [Full Text] [PDF]

				C. W. Hastad, S. S. Dritz, M. D. Tokach, R. D. Goodband, J. L. Nelssen, J. M. DeRouchey, R. D. Boyd, and M. E. Johnston Phosphorus requirements of growing-finishing pigs reared in a commercial environment J Anim Sci, October 1, 2004; 82(10): 2945 - 2952. [Abstract] [Full Text] [PDF]

				K. F. Knowlton, J. S. Radcliffe, C. L. Novak, and D. A. Emmerson Animal management to reduce phosphorus losses to the environment J Anim Sci, January 1, 2004; 82(13_suppl): E173 - 195. [Abstract] [Full Text] [PDF]

				F. O. Omogbenigun, C. M. Nyachoti, and B. A. Slominski The effect of supplementing microbial phytase and organic acids to a corn-soybean based diet fed to early-weaned pigs J Anim Sci, July 1, 2003; 81(7): 1806 - 1813. [Abstract] [Full Text] [PDF]