PowerPoint-Nelson Ruiz - The Poultry Federation

New insights on the urease 

activity range for soybean meal: 

a worldwide opportunity for the 

poultry industry 

Nelson Ruiz, PhD 

Nelson Ruiz Nutrition, LLC 

Suwanee, GA 30024 

Arkansas Nutrition Conference 

September 5, 2012

Objective 

The subject of the discussion today is the 

urease activity range 

0.05 – 0.20 pH units

UREASE ACTIVITY RANGE 

Δ pH = 0.05-0.20 

(INDICATED ADEQUATE SBM PROCESSING) 

< 0.05 = CONCERNS ABOUT OVERHEATING 

> 0.20 = CONCERNS ABOUT UNDERHEATING 

OVERHEATED 

UNDERHEATED 

MAILLARD REACTIONS 

AFFECTS AMINO ACID 

DIGESTIBILITY 

“LYSINE” 

ANTI-NUTRITIONAL 

FACTORS 

TRYPSIN INHIBITORS 

LECTINS

Agenda 

• Literature review 

– Challenges to the range 

• Rapid feed passage in broilers and the upper 

limit of the urease activity range 

• Why the urease activity range should be 

changed to 0.000 – 0.050 pH units 

• Implications to the poultry industry worldwide

Literature review 

A careful review of the Poultry Science journal 

back to 1981 and the Applied Poultry Research 

Journal back to vol. 1, reveals that both the 

lower level and the upper level of the range 

have been challenged just a couple of times.


In 1987 Dale et al. at the Georgia Nutrition 

Conference presented evidence that the lower 

level of the range was basically baseless. 

Soybean meals (SBM) with urease activity (UA) 

values below 0.05 pH units not necessarily 

resulted in poor performance of broiler 

chickens


Actually, not only urease activity was unable to 

predict overheating of SBM, a very different 

in vitro technique was necessary to estimate 

overheating: solubility of the protein in a 

0.2% KOH solution

Effect of heating raw soy flakes 

on chick performance and in vitro parameters 

Heat 

Treatment 

(minutes) 

Body 

Weight gain 

(g) 

Feed/Gain 

Urease 

Activity 

(pH units) 

KOH 

Protein 

Solubility, (%) 

0 (raw) 342 2.44 2.40 99 

5 429 2.29 2.04 88 

10 481 2.00 0.23 79 

15 496 2.09 0.00 75 

20 450 2.03 0.00 72 

30 407 2.33 0.00 58 

60 296 276 0.00 38 

(Combined data of two experiments, Dale et al., 1987)


Waldroup and co-workers (1985) 

documented at Arkansas that the upper 

level of the UA range can be as high as 

0.50 pH units without detrimental effect 

on broiler performance.

Rapid Feed Passage

Rapid Feed Passage 

Rapid feed passage events in broiler flocks 

started to be reported in different 

geographies in the 1990s

Rapid Feed Passage 

• Kouwenhoven et al., 1992 

• López et al., 1998 

• Butcher et al., 1999 

• Miles and Butcher, 2002

Rapid feed passage is defined as the 

condition in which… 

• Droppings lose their normal shape 

• Do not display the characteristic uric acid 

cover 

• Contain undigested feed visible to the naked 

eye 

• Droppings have a yellowish-orange color

Feed passage syndrome in broiler chickens 


(“tránsito rápido in Spanish) 


• Droppings are watery, although not always 

• Litter becomes wet and slippery 

• Droppings contain more sloughed intestinal 

tissue than normal. 

• Birds lack uniformity 

• Birds display poor pigmentation 

• Upon necropsy proventriculitis is frequently 

observed, but not always





As a consequence of a feed passage outbreak: 

- Litter quality is poor 

- Feed conversion is negatively affected 

- Body weights are lower than the standard 

- Economic losses can be huge


Rapid feed passage outbreaks 


• Between 1998 and 2004 I was exposed to six 

major RFP outbreaks in 4 different South 

American Countries while working for the 

ContiLatin Division of the Continental Grain 

Company. 

• Although we didn’t have a clue about what 

was the cause, one thing was for sure: SBM 

was involved.




By the time the 6th outbreak hit (2004) we 

had already a pretty good idea that high 

trypsin inhibitors in SBM were correlated to 

these outbreaks, but only until this event we 

were able to collect sufficient evidence to 

conclude that indeed such a correlation 

existed.




• Based on the analyses of these six outbreaks 

Ruiz and Belalcázar presented their 

conclusions at the 2005 PSA meeting. 

• A detailed description of these outbreaks was 

published in Feedstuffs in January of 2012




Rapid feed passage is known as “transito 

rapido” in Spanish, and as a form of 

“dysbacteriosis” in Europe and other countries

What this rapid feed passage 

issue has to do with the upper limit of 

the urease activity range

RAPID FEED PASSAGE OUTBREAKS IN LATIN AMERICA 

“RELATIONSHIP TO UREASE ACTIVITY AND TRYPSIN INHIBITOR” 

COUNTRY 

ECUADOR 

COLOMBIA 

ECUADOR 

COLOMBIA 

COLOMBIA 

VENEZUELA 

PERU 

COLOMBIA 

PERU 

COLOMBIA 

ECUADOR 

VENEZUELA 

COLOMBIA 

COLOMBIA 

COLOMBIA 

COLOMBIA 

TRYPSIN INHIBITOR 

mg/g SBM 

. 1.90 

2.20 

2.40 

2.40 

2.60 

2.80 

4.00 

4.04 

4.20 

4.82 

5.50 

5.60 

6.00 

6.80 

5.90 

7.29 

FEED PASSAGE 

OUTBREAK 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

DATA ADAPTED FROM TABLE 2 (Ruiz, 2012) DATA PRESENTED AT PSA ANNUAL MEETING (Ruiz and Belalcazar, 2005)

Rapid feed passage outbreaks vs. 


Trypsin inhibitors 

The best interpretation of the data that we 

had for these 6 events of RFP is that one cause 

(not necessarily the only one) of RFP in 

broilers fed SBM had to do with the trypsin 

inhibitor level in the meal and its level of 

inclusion in the formula.




Trypsin inhibitors 

Because of these data we concluded and 

presented at the PSA annual meeting in 2005 

that trypsin inhibitor levels in commercial SBM 

should not be higher than 3.0-3.5 mg/g, but 

also suggested that the lower the TI content 

the better provided solubility in KOH were at 

least 78%.




Trypsin inhibitors and UA range 

However, when the levels of trypsin inhibitors 

are related back to their corresponding values 

in terms of urease activity, it becomes evident 

that the UA values at which RFP occurs (at 

expected levels of inclusion of SBM by leastcost 

formulation) are within the current 

range of adequacy for SBM quality!

RAPID FEED PASSAGE OUTBREAKS IN LATIN AMERICA 

“RELATIONSHIP TO UREASE ACTIVITY AND TRYPSIN INHIBITOR” 

COUNTRY 

ECUADOR 

COLOMBIA 

ECUADOR 

COLOMBIA 

COLOMBIA 

VENEZUELA 

PERU 

COLOMBIA 

PERU 

COLOMBIA 

ECUADOR 

VENEZUELA 

COLOMBIA 

COLOMBIA 

COLOMBIA 

COLOMBIA 

UREASE ACTIVITY 

ΔpH units in SBM 

.01 

.02 

.03 

.03 

.05 

.06 

.09 

.08 

.09 

.14 

.17 

.19 

.25 

.28 

.29 

.33 

O.05-0.20 

TRYPSIN INHIBITOR 

mg/g SBM 

1.90 

2.20 

2.40 

2.40 

2.60 

2.80 

4.00 

4.04 

4.20 

4.82 

5.50 

5.60 

6.00 

6.80 

5.90 

7.29 

FEED PASSAGE 

OUTBREAK 

NO 

NO 

NO 

NO 

NO 

NO 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

YES 

DATA ADAPTED FROM TABLE 2 (Ruiz, 2012) DATA PRESENTED AT PSA ANNUAL MEETING (Ruiz and Belalcazar, 2005)

Y 

R 2 = 0.9308 

Y = 0.056(X) 

- 0.0814 

X = Y + 0.0814 

0.0564 

X

UREASE ACTIVITY (pH units) 

TRYPSIN INHIBITORS vs. UREASE ACTIVITY 

(Belalcázar and Otálora, 2012) 

0.70 

0.60 

Y = 0.0738X - 0.1224 

R 2 = 0.9748 

N= 104 

0.50 

0,40 

0.30 

0.20 

0.10 

0.00 

0.00 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 

TRYPSIN INHIBITORS (mg/g)

Why the UA range changed 

• Because the bird has changed 

• Modern broilers are much more efficient than 

broilers of decades ago, but their feed intake 

is also much greater.

1957 

RANDOMLY BRED MALES SINCE 1957 

DAY 43 DAY 57 DAY 71 DAY 85 

2001 

HAVENSTEIN et al., 2003 

MALE ROSS BROILERS IN 2001

Why the UA range changed 

Using the data from the simulation conducted 

by Havenstein et al. (2003) with “1957” 

broilers versus “2001” broilers it is possible to 

estimate the trypsin inhibitor intake of the 

“1957” birds fed 1957 diets and compare it 

with the estimate of TI intake by the “2001” 

birds fed 2001 diets.

TRYPSIN INHIBITOR INTAKE 

FROM 48% SOYBEAN MEAL 

PERFORMANCE DATA 

(42 DAYS OF AGE) 

AND 

DIET COMPOSITION 

TAKEN FROM 

HAVENSTEIN et al., 2003 

AVERAGE 

BODY WT 

AVERAGE 

FEED INTAKE 

(g) 

TI CONTENT 

IN SBM 

(mg/g) 

AVERAGE DIET 

TI CONTENT 

(mg/g) 

AVERAGE CUMULATIVE 

TI INTAKE 

(mg/BIRD) 

1957 

539 

1261 

2 

4 

6 

0.476 

0.952 

1.428 

600 

1200 

1800 

2001 

2672 

4355 

2 

4 

6 

2007 

4014 

6021


Trypsin inhibitors vs Urease activity 


Trypsin Inhibitor 

content in SBM 48 

mg/g 

Expected Urease Activity 

in SBM 48 

pH units 

2 0.000-0.055 

3 0.062-0.136 

4 0.136-0.210 

5 0.210-0.284 

6 0.284-0.357

Consequently… 

THE RECOMMENDED NEW RANGE 

SHOULD BE 0.000 – 0.050 

pH UNITS

Implications for the poultry 

industry worldwide 

First, it is time for the poultry industry to 

adjust quality standards to today's reality. 

Broiler producers are losing money every time 

they have to deal with a rapid feed passage 

outbreak in the field.



Poultry companies know how much it costs 

them and the industry each year if a rapid 

feed passage outbreak results in a loss of just 

one point of feed conversion. The losses don't 

stop with poor feed conversion because the 

more trypsin inhibitors present in the feed, 

the wetter the litter is going to be.



Poor quality litter relates to poorer air quality 

due to ammonia, poorer flock uniformity, 

downgraded carcasses due to blistered breasts 

and loss of the paws to their specific markets.



Second, it is an opportunity for both the oilseed 

and poultry industries to come together and 

discuss the reasons why such a change is 

needed with respect to the adequacy of the 

urease activity range which is presently being 

used. Trading on the basis of quality is a winwin 

situation for all concerned



Let’s just assume that the trading range is 0.000- 

0.050 pH units as proposed above. Then let’s 

propose a margin of variation of up to 0.070 

pH units, but after 0.075 pH units a discount 

table is established or negotiated in a manner 

similar to those used in discounts for crude 

protein and moisture.



Alternatively, a premium may be negotiated for 

the new range (again, provided solubility of 

the protein in KOH is at least 78%) with the 

premium being discounted beyond 0.075 pH 

units, for instance. 

.



Third, a considerable amount of work has being 

published in reference to the toxicity of 

trypsin inhibitors (and other antinutritional 

factors in raw soybeans) which clearly 

document that birds (broilers, layers, 

breeders) do not adapt to high trypsin 

inhibitors in the diet (Nesheim and Garlich, 

1966; Ruiz et al., 2008).



Therefore, it would be advantageous to 

continue to develop commercial soybean lines 

that have low concentrations of or no trypsin 

inhibitors and market them because of their 

added value.


South American corn contaminated with 


fractions of raw soybeans 

This is a fact: 

Imported Argentine and Brazilian corn have 

arrived in Colombia with 0.30-0.40 mg of 

trypsin inhibitors per gram

FIELD 

THANK 

DATA CONFIRMATION 

YOU 

BY 

VERY 

LABORATORY 

MUCH 

EXPERIMENTS 

SBM 

SBM 

McNAUGHTON et al. (1981) 

BROILERS (21 DAYS OF AGE) 


(pH 0.02) 


(1.77 MG/G) 

EXCELLENT 

PERFORMANCE 


(pH 0.19) 


(12.12 MG/G) 

VERY POOR 

PERFORMANCE 

CLARK AND WISEMAN (2007) 

BROILERS (25 DAYS OF AGE) 

SBM 


(1.90 MG/G) 

EXCELLENT 

PERFORMANCE 

HIGH ILEAL AMINO ACID 

DIGESTIBILITY 

Y = 0.056(X) 

- 0.0814 


(pH 0.025)

PowerPoint-Nelson Ruiz - The Poultry Federation

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