Effects of Dietary Calcium and Phosphorus Concentrations and Addition of Phytase on Growth Performance of Nursery Pigs

Authors

F. Wu, Kansas State University, ManhattanFollow
M. D. Tokach, Department of Animal Science and Industry, Kansas State UniversityFollow
J. M. DeRouchey, Kansas State University, ManhattanFollow
S. S. Dritz, Kansas State University, ManhattanFollow
J. C. Woodworth, Kansas State University, ManhattanFollow
R. D. Goodband, Department of Animal Science and Industry, Kansas State UniversityFollow

Keywords

calcium, nursery pigs, phosphorus, phytase

Abstract

A total of 720 nursery pigs (PIC 1050 × 280, initially 13.4 ± 0.47 lb) were used in a 42-d growth study to determine the effects of feeding 2 calcium (Ca) and 3 standardized total tract digestible (STTD) phosphorus (P) concentrations on growth performance and bone ash content. Pens of pigs (10 pigs/pen, 12 pens/treatment) were blocked by initial pen weight, and within blocks pens were allotted randomly to 1 of 6 dietary treatments. Dietary treatments were arranged in a 2 × 3 factorial, with 2 levels of Ca (0.58 vs. 1.03%) and 3 levels of STTD P (0.33 and 0.45% without phytase, and 0.45% with 0.12% of the P being released by phytase). Diets were provided in 3 phases, with pigs fed experimental diets during phase 1 (d 0 to 14) and phase 2 (d 14 to 28), followed by a common phase 3 diet from d 28 to 42. For the majority of the feeding periods, Ca × P interactions were observed for growth responses (P < 0.05). From d 0 to 28, when diets contained low Ca concentration, pigs fed 0.45% STTD P with phytase had greater (P < 0.01) ADG and ADFI compared with those fed 0.45% STTD P without phytase or 0.33% STTD P. When high Ca was fed, ADG and ADFI were similar among pigs fed 0.45% STTD P with or without phytase but were greater than those fed 0.33% STTD P. Feed efficiency was poorer (P < 0.01) when low STTD P and high Ca were added to diet compared with other dietary treatments. During phase 3, pigs previously fed 0.33% STTD P had similar ADG, but decreased (P < 0.05) ADFI and improved F/G compared with pigs previously fed 0.45% STTD P with or without phytase. However, pigs fed 0.33% STTD P, with high Ca were not able to fully compensate for the negative effects of P deficiency, resulting in decreased (P < 0.05) overall ADG and ADFI compared with pigs fed 0.45% STTD P diet with or without phytase. On d 21, 1 median-weight gilt from each pen was euthanized and fibulas were collected for analysis of bone ash content. Pigs fed 0.33% STTD P had decreased (P < 0.05) bone ash concentration compared with those fed 0.45% STTD P with or without phytase when high Ca was added to diets, but this P effect was not observed when diets contained low Ca concentration (Ca × P interaction, P = 0.007). In conclusion, excess Ca in diets decreased growth performance and bone ash concentration of nursery pigs when diets were deficient in STTD P. Adding phytase to achieve 0.45% STTD P in diets improved ADG and ADFI of pigs compared with diets containing 0.45% STTD P without phytase, indicating a potential underestimation of the P release from phytase or an increased availability of other nutrients liberated by phytase.

Recommended Citation

Wu, F.; Tokach, M. D.; DeRouchey, J. M.; Dritz, S. S.; Woodworth, J. C.; and Goodband, R. D. (2017) "Effects of Dietary Calcium and Phosphorus Concentrations and Addition of Phytase on Growth Performance of Nursery Pigs," Kansas Agricultural Experiment Station Research Reports: Vol. 3: Iss. 7. https://doi.org/10.4148/2378-5977.7472