Animal Nutrition and Phosphorus Excretion in Beef and Swine

1. Animal Nutrition and Phosphorus Excretion in Beef and Swine Wendy Powers Department of Animal Science Iowa State University

2. Opportunities • Monogastrics • Phytase • Low phytate grains • Phytase enhancers and alternatives • Ruminants • Wider array of feed ingredients • Moving towards better feel for requirements • Total P = Available P

3. Phytase effects on P excretion • When used properly, as much as a 25% reduction in P excretion • Includes impact of reducing diet P to requirements • Smaller effect if not reducing diet P sufficiently • Smaller effect if already feeding a P needs • No negative effects on soluble P excretion

4. Low-phytate grains • HAP corn • Similar effect as with phytase • Additive effect when combined with phytase • Low phytate soybeans • New research findings

5. Swine excretion and performance effects of low-phytate soybeans • Quantify total and water-soluble excretion from swine fed low-phytate soybean meal alone and with supplementary phytase. • Determine if feeding low-phytate soybean meal has any adverse effects on swine performance.

6. Materials and MethodsDiets • Four dietary treatments • Control soybeans, no phytase (NP – np) • Control soybeans, phytase (NP – p) • Low-phytate soybeans, no phytase (LP – np) • Low-phytate soybeans, phytase (LP – p) • Each contained 1% indigestible marker

7. Materials and MethodsPigs • 96 pigs, allocated to 24 pens • Initial average BW = 18 kg • 10-wk trial • Final average BW = 83 kg

8. Materials and Methods • Individual pigs were weighed weekly • Feed was offered daily and refusals were weighed weekly • Individual fecal and urine samples collected weekly • Pooled by pen

9. ResultsAnimal Performance • No diet, phytase, or soybean effects on • ADG (0.98 kg) • ADFI (1.94 kg) • F:G (2.03)

10. ResultsNutrient Retention • No diet, phytase, or soybean effects on DM or OM retention (83.7%, 86.5%, respectively) • P retention • Greater in low-phytate soybean diets • 49.1% vs. 42.3% • Greater in diets with phytase • 47.3% vs. 44.1%

11. ResultsPhosphorus Excretion

12. ResultsPhosphorus Excretion

13. Conclusions • Low-phytate soybeans resulted in reduced mass of TP and WSP excreted • Including phytase in the diets, yielded an even further reduction in TP and WSP

14. Implications • Assuming fecal masses do not differ by diet…. • Assuming no diet effects in fecal P when pigs > 180 lb…. • Assuming fecal production is uniform over the grow-finish phase…. • Low-phytate soybeans resulted in a 12% reduction in TP excretion over the grow-finish phase

15. P Intake, Retention and Excretion Agristats, 1999 (control) Industry+Phy 17.1g P 12.2 g 17.0g P 12.2g 13.8 g 17.1g P 19.3 % 13.8 g P 26 g 6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results 36.2g P 30.8g P

16. P Intake, Retention and Excretion Agristats, 1999 (control) UMD Rcmd 17.1g P 12.2 g 16.9g P 12.2g 13.8 g 17.1g P 22.5 % 14.8 g P 26 g 6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results 36.2g P 31.7g P

17. P Intake, Retention and Excretion Agristats, 1999 (control) UMD Rcmd+Phy 17.1g P 12.2 g 16.9g P 12.2g 13.8 g 17.1g P 30.5 % 11.9 g P 26 g 6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results 36.2g P 28.8g P

18. P Intake, Retention and Excretion Agristats, 1999 (control) UMD Rcmd+Phy+25OHD3 17.1g P 12.2 g 16.8g P 12.2g 13.8 g 17.1g P 41.5 % 10.0 g P 26 g 6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results 36.2g P 26.8g P

19. Citric acid improving phytate-P utilization • CA alone – phytate degradation from 42% to 69% in whole wheat flour during bread baking • CA + exogenous phytase - phytate degradation up to 85% • CA alone, CA + phytase, CA + phytase + ascorbic acid  iron dialyzability 12-, 15-, and 24-fold, respectively Porres et al., 2001. J. Food Sci. 66(4):614-619

20. Combined nPP Sparing Effect of Phytase, Citric Acid and 25-Hydroxycholecalciferol 0.147% 0.144% 0.114% Angel et al., 2001 SEM 0.016 0.012 0.013

21. Opportunities • Monogastrics • Phytase • Low phytate grains • Phytase enhancers and alternatives • Ruminants • Wider array of feed ingredients • Moving towards better feel for requirements • Total P = Available P

22. P content of various feeds

23. P Mass Balance (continued) Summer-Yearlings Feedlot pen .35 % P diet 10.9 lb excreted 1.9 lb animal 12.8 lb intake REDUCED 52% REDUCED 44 % 5.3 lb excreted 1.9 lb animal 7.2 lb intake .24 % P diet Source: Erickson et al., 2000

24. P Mass Balance (continued) Feedlot pen Winter/spring-Calves .40 % P diet 12.5 lb excreted 2.5 lb animal 15.0 lb intake REDUCED 40% REDUCED 33 % 7.5 lb excreted 2.4 lb animal 9.9 lb intake .26 % P diet Source: Erickson et al., 2000

25. Challenges • Monogastrics • In vivo phytase efficacy is not 100% • Commercial availability of LP grains • Grain P > P needs • Pressure to feed DDGs • Ruminants • Grain P > P needs • Pressure to feed DDGs

26. Challenges Soybean meal Corn

27. Dietary P in Feedlot Diets .59 .52 .35 .27 Req.

28. Phosphorus content of common byproduct feeds

29. Acreage Needs

30. Acreage Needs

31. Digestibility of byproduct feeds • Creates a greater volume of manure Bierman et al., 1999. JAS

32. Critical to sample manure • Diet impacts on P concentration • Diet impacts on manure mass, independent of P content, but affects P concentration

33. Summary • Slowly making nutritional headway towards reducing P excretion • Opportunities continue to arise • Still searching for the low P grains • Endogenous losses prevent 0 P excretion • Feeding through the animal is an inefficient means of getting P to the land!