Animal Nutrition and Phosphorus Excretion in Beef and Swine

Wendy Powers

Department of Animal Science

Iowa State University

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

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

Low-phytate grains

• HAP corn – Similar effect as with phytase– Additive effect when combined with phytase

• Low phytate soybeans– New research findings

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.

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

Materials and MethodsPigs

• 96 pigs, allocated to 24 pens– Initial average BW = 18 kg

• 10-wk trial– Final average BW = 83 kg

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

ResultsAnimal Performance

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

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%

ResultsPhosphorus Excretion

TP, g per kg WSP, g per kg

WSP, % of TP

NP - np 19.7 10.9 0.56

NP - p 18.1 10.2 0.57

LP - np 16.7 8.9 0. 54

LP - p 13.9 8.2 0.60

ResultsPhosphorus Excretion

TP, g per kg WSP, g per kg

WSP, % of TP

Control soybeans

19.0a 10.5a 0.56

Low-phytate soybeans

15.3b

(-19.5%)

8.7b

(-17%)

0.57

Phytase added

15.9a

(-14%)

9.3a

(-6%)

0.59a

No phytase 18.4b 9.9b 0.55b

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

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

P Intake, Retention and Excretion

12.2 g

26 g

13.8 g12.2g

6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results

36.2g P

17.1g P

17.1g P

Agristats, 1999 (control)

Industry+Phy

30.8g P

13.8 g P19.3 %

17.0g P

P Intake, Retention and Excretion

12.2 g

26 g

13.8 g12.2g

6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results

36.2g P

17.1g P

17.1g P

Agristats, 1999 (control)

UMD Rcmd

31.7g P

14.8 g P22.5 %

16.9g P

P Intake, Retention and Excretion

12.2 g

26 g

13.8 g12.2g

6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results

36.2g P

17.1g P

17.1g P

Agristats, 1999 (control)

UMD Rcmd+Phy

28.8g P

11.9 g P30.5 %

16.9g P

P Intake, Retention and Excretion

12.2 g

26 g

13.8 g12.2g

6.38 lb bird 1.93 feed to gain 49 days of age RA0109 exp results

36.2g P

17.1g P

17.1g P

Agristats, 1999 (control)

UMD Rcmd+Phy+25OHD3

26.8g P

10.0 g P41.5 %

16.8g P

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

Combined nPP Sparing Effect of Phytase, Citric Acid and 25-Hydroxycholecalciferol

0

0.05

0.1

0.15

Exp 1 Exp 2 Exp 3

70ug 25OHD3

3% Citric Acid

500 U/kg Phytase

Angel et al., 2001

0.114%

0.144%0.147%

SEM 0.016 0.012 0.013

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

P content of various feedsCorn grain 0.35 Citrus pulp 0.12

Barley 0.39 Brewer’s grains 0.67

Wheat 0.43 Bakery waste 0.36

Sorghum 0.35 Whole cottonseed 0.60

Alfalfa hay 0.30 Fishmeal 3.05

Corn silage 0.26 Urea 0

SMB 0.70 Canola meal 1.10

DDGs 0.80 Beet pulp 0.09

Feedlot pen

7.2 lbintake

1.9 lbanimal

5.3 lbexcreted

Summer-Yearlings

12.8 lbintake

1.9 lbanimal

10.9 lbexcreted

.35 % P diet

.24 % P diet

REDUCED44 %

P Mass Balance (continued)

Source: Erickson et al., 2000

REDUCED

52%

9.9 lbintake

2.4 lbanimal

7.5 lbexcreted

Winter/spring-Calves

15.0 lbintake

2.5 lbanimal

12.5 lbexcreted

P Mass Balance (continued)

Source: Erickson et al., 2000

REDUCED33 %

.40 % P diet

.26 % P diet

Feedlot pen

REDUCED

40%

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

Challenges

00.10.20.30.40.50.60.70.80.9

1

9 15 31 60 105 169 255

Pig weight, lb

Total P, %

Avail P, %

Soybean meal

Corn

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

85% corn 85% corn +supplement

byproduct byproduct +supplement

% d

iet

P (

DM

-ba

sis)

supplementbyproductcornroughage

.27.35

.52

.59

Dietary P in Feedlot Diets

Req.

Phosphorus content of common byproduct feeds

Feed %P(DM)

Feed %P(DM)

WDGS 0.65 Corn 0.35MWDGS 0.65 SBM 0.70DDGS 0.65DDGS(NRC) 0.83CCDS 1.00Corn glutenfeed

0.90

Acreage NeedsFeed, lb DM/d Corn-soy DDGS-CDS

Corn silage 12 12

Corn 7 -

SBM 2 -

DDGS - 6.25

CDS - 1

P land needs(acre/hd-yr)

0.61 0.90

** Both diets high in energy

***DDGS-CDS diet also high in CP and P

Acreage Needs

Feed, lb DM/d Corn WDGSCorn cobs 12.6 14.4SBM 3.4 2.7Corn 3.4 -DDGs - 2.2Dical .08 .08

P land needs(acres/hd-yr)

0.63 0.65

Digestibility of byproduct feeds

• Creates a greater volume of manure

Ingredient, lb/100 lb diet WCGF All corn Dry-rolled corn 43.5 88.8 WCGF 41.5 - Corn silage 5.0 - Alfalfa hay 5.0 - Molasses - 6.2 Ground corn 2.72 1.92 Minerals + urea 2.28 3.08 Feces recovered 7.2 kg 3.53 kg

Bierman et al., 1999. JAS

Critical to sample manure

• Diet impacts on P concentration

• Diet impacts on manure mass, independent of P content, but affects P concentration

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!