O nline J ournal of A nimal and F eed R esearch

Volume 10, Issue 4: 150-157; July 27, 2020

THE USE OF PREDICTED APPARENT METABOLIZABLE ENERGY

VALUES TO UNDERSTAND THE OIL AND FAT VARIABILITY IN

BROILERS

Agnes THNG^, Jun Xiang TING, Hui Ru TAY, Chin Yi SOH, Hwee Ching ONG, David TEY

Kemin Industries (Asia) Pte Limited, Animal Health and Nutrition, 12 Senoko Drive, Singapore 758200, Singapore

*Email: agnes.thng@kemin.com

ABSTRACT: The objective of this study was to analyze the predicted apparent metabolizable energy (AME) of

different oil samples across Asia Pacific region and investigate the AME values in broilers of different ages (< 21

or > 21 days old). A total of 635 oil and fat samples consisting of 93 fish oils, 36 coconut oils, 70 crude palm

oils, 42 refined palm oils, 43 soybean oils, 147 rice bran oils, 163 tallows and 41 lards were collected and

analyzed over a span of eight years (2011 to 2018). The free fatty acid (FFA) content of oil and fat samples were

analyzed through acid-base titration and the degree of saturation (ratio of unsaturation to saturated fatty acids;

U:S) were determined with Gas Chromatography with Flame Ionization Detector (GC-FID). The FFA and U:S of the

samples were then incorporated into the Wiseman equation to correlate the oil and fat qualities with the AME.

Our survey revealed AME variations were prevalent in most of the oil types studied, with fish oils and tallows

showing the largest energy gap within oil samples. The results showed that the predicted AME values for oil and

fat samples differ across countries, even within batches from the same supplier. Taken together, our

investigation suggests that there is a considerable variation in the AME values of oils and fats, which may affect

the feed formulation precision.

Keywords: Dietary energy, Fatty acid composition, Lipids, Oil quality, Poultry

INTRODUCTION

Vegetable oils and animal fats are usually added to animal diets to increase dietary energy concentration (Ravindran et

al., 2016 ). Since oils and fats confer at least twice as much energy as other food nutrients such as carbohydrates and

proteins (Ahiwe et al., 2018; Blair, 2018 ), there is a greater demand in optimizing the use of these products to meet the

energy requirements of poultries (Ravindran et al., 2016 ). Furthermore, high fat feeding in poultry has been proven to

improve the digestibility and absorption of non-lipid constituents (Blair, 2018 ). However, the quality of oils and fats are

highly variable, and their digestibility are dependent on their chemical structures (Codony et al., 2017 ). Poor processing

and storage conditions can also cause structural changes in oils and fats, leading to high fluctuations in the nutritional

values (FAO/WHO, 2001; Gibson and Newsham, 2018 ).

Fat digestion consists of the emulsification of dietary fat with bile salt, followed by the enzymatic hydrolysis of

triglycerides. The 2-monoglycerides, formed from partial hydrolysis of triglycerides, improve the solubility and absorption

of free fatty acids through the formation of micelles (Pond et al., 2004; Scanes et al., 2019 ). As such, low levels of 2-

monoglycerides will result in incomplete micellar solubilization of free fatty acids. It was previously reported that the total

micellar fatty acids were lowest in the duodenum of free fatty acid (FFA) – fed chicks where monoglycerides were present

at trace level (Hofmann and Borgstrom, 1962; Sklan, 1979 ). In addition, fat digestion is also highly dependent on the

degree of fatty acid saturation where Tancharoenrat et al. (2014) reported a higher digestibility with unsaturated fatty

acids such as oleic acid and linoleic acid in comparison to saturated fatty acids such as palmitic and stearic acids.

Additionally, the natural emulsifying properties of unsaturated fatty acids could also aid in mixed micelle formation and

absorption, resulting in better utilization of saturated fatty acids (Rodriguez-Sanchez et al., 2019 ). Given the importance of

FFA and the degree of saturation of oil (ratio of unsaturated to saturated fatty acids; U:S) in oil digestion and absorption,

the Wiseman equation incorporates both of these parameters into one general equation to predict the energy values of

different sources of oils and fats (Wiseman and Blanch, 1994 ).

As these macromolecules are important energy sources for animals, it is imperative for us to understand the

variation of oil quality based on apparent metabolizable energy (AME) across countries and oil types, and its impacts on

broilers. Previous reports showed that the fat utilization in broilers was age dependent where fat utilization improved with

age (Rodriguez-Sanchez et al., 2019 ). Animal nutritionists often struggle to formulate feed with adequate energy intake

due to the variation of the nutritional values in oil and fat samples that can lead to reduction in the performances of the

150

To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat

variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.

animals and substantial economic losses (Niu et al., 2009; Ahiwe et al., 2018 ). A better understanding of the AME of

different oil and fat samples can be gained by incorporating the FFA and U:S data into the Wiseman equation to generate

information on the quality of the oil and fat samples; this will allow nutritionists to make informed decisions on their use

for feed formulation to achieve consistent animal performance. In this study, the AME for oil and fat samples were

determined based on the Wiseman equation to highlight the importance of accurate information on dietary energy value

of feed.

MATERIALS AND METHODS

Instrumentation

DL 50 GRAPHIX auto-titrator (Mettler-Toledo, Ohio, United States) and DG113-SC glass electrode (Mettler-Toledo)

were used to determine free fatty acid content. 7890B GC-FID (Agilent Technologies, California, United States) with

Supelco SPTM-2560 (L × I.D. 100 m × 0.25 mm, df 0.20 μm thickness) (Sigma-Aldrich, Missouri, United States) was used

for chromatographic separation of fatty acid methyl esters (FAME).

Sample collection and preparation

A total of 635 oil and fat samples with plant and animal origins were collected across the Asia Pacific region and

analyzed over a span of eight years from year 2011 to 2018. These samples included tallow, rice bran oil, fish oil, palm oil

(crude and refined palm oil), soybean oil, lard and coconut oil. All samples were stored in plastic containers upon receipt

and kept in the chiller at 2 °C to 6 °C. Before analysis, the samples were either thawed at room temperature or melted in

the oven at 60 °C. All samples were analyzed within one week from the collection date.

Free Fatty Acid (FFA) content

The FFA content of oil and fat samples were determined with an in-house method, modified from the Association of

Official Analytical Chemists (AOAC) method (AOAC, 2012). Fifty (50) mL of 95% ethanol (Aik Moh Paints and Chemical Pte

Ltd, Singapore) was added to 1.0 g of oil or fat sample in a titration cup. The sample was stirred for 60 s under stirring

speed of 50% with an auto-titrator. After stirring, titration was done with 0.1 N sodium hydroxide (Merck KGaA,

Darmstadt, Germany) as the titrant using a pH sensor with measurement mode set as equilibrium controlled. The result

was calculated from the volume consumption of the sodium hydroxide titrant and its concentration. Based on the oil type,

the FFA content is expressed either as % oleic acid, % palmitic acid or % lauric acid.

Fatty Acid Methyl Esters (FAME) composition analyses

FAME composition of oil and fat samples were determined using an in-house method, with modification from

Association of Official Analytical Chemists (AOAC) method (AOAC, 2012). Four mL of 2% (w/v) methanolic sodium

hydroxide (Merck) was added to 40 mg of fat or oil sample and refluxed until there were no visible fat globules. 5 mL of

14% boron trifluoride in methanol (Sigma-Aldrich) was added and refluxed for another 2 mins. Finally, 10 mL of heptane

(Sigma-Aldrich) was added and refluxed for another 1 min. Subsequently, the content was cooled to room temperature.

Next, 15 mL of 26% (w/v) sodium chloride (Merck) was added and swirled vigorously. The top organic layer (heptane) was

filtered through sodium sulphate (Merck) and injected into the GC-FID for chromatographic separation. Extracted samples

were analyzed with helium at a flow rate of 0.85 mL/min as carrier gas and a split ratio of 40:1. Injection volume was set

at 0.4 µL with injection port temperature set at 260 °C. The GC oven temperature was programmed at 140 °C for the first

5 mins and raised to 235 °C at 5 °C/min for 15 mins, followed by 15 °C/min to 250 °C for 5 mins. The total run time

was 45 mins. Percentage composition of each FAMEs in oil and fat samples were calculated with Supelco 37 component

Fatty Acid Methyl Esters (FAME) Mix certified reference material (CRM) (Sigma-Aldrich) as reference standard.

Data analysis

Prediction of Apparent Metabolizable Energy (AME) using Wiseman equation

AME of samples were predicted using a general equation (Equation 1) with A, B, C and D based on the values shown

in Table 1 (Wiseman and Blanch, 1994; Wiseman et al., 1998 ).

AME (MJ/kg fat) = A + B*FFA + C*e^D(U/S)

(1)

Apparent Metabolizable Energy (AME) variation

AME range was calculated as the difference between the highest and lowest predicted AME values whereas relative

variations were calculated as the ratio of calculated range against lowest predicted AME or literature AME.

Statistical analyses

Single measurement data were calculated for the AME of each oil type. Descriptive statistics were calculated using

Microsoft Excel 365 and presented in Table 3.

151

To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat

variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.

Table 1 – Empirical values of constants A – D used in Wiseman equation to predict the apparent metabolizable energy

(AME) values of poultry at different ages

Constant (unit)

Young broilers (< 21 days)^a

Old broilers (> 21 days)^a

A (MJ/kg)

B (MJ/kg)

38.112 ± 1.418

-0.009 ± 0.002

39.025 ± 0.557

-0.006 ± 0.001

C (MJ/kg)

-15.337 ± 2.636

-0.506 ± 1.186

-8.505 ± 0.746

-0.403 ± 0.088

^aEmpirical values of constants A – D were categorized into two groups, young broilers (aged < 21 days) and old broilers (aged > 21 days). All

young broilers (aged < 21 days) followed the same empirical values for constants A – D, likewise for old broilers (aged > 21 days).

RESULTS

Predicted Apparent Metabolizable Energy (AME) values for all samples

Using GC-FID and acid-base titration, all samples were analyzed for their lipid composition and FFA content

(Table 2). Descriptive analysis of eight different oil types were presented in Table 3. AME of young broilers

(aged < 21 days) and old broilers (aged > 21 days) were studied in this paper. Based on the GC-FID analyses, it was

determined that the U:S for crude palm oil was lowest amongst all samples analyzed while the U:S for soybean oil was the

highest, with relatively low FFA content of 1.01% oleic acid recorded (Table 3). When the data was further extrapolated

using Equation 1, it was found that the highest predicted mean AME values were from soybean oil, at 8362 kcal/kg

(young broilers) and 8672 kcal/kg (old broilers). On the other hand, the lowest predicted mean AME values were from

crude palm oil with the predicted AME values at 6617 kcal/kg (young broilers) and 7669 kcal/kg (old broilers) (Table 3).

It was apparent that the predicted AME values were inconsistent across all oil samples. In particular, a large spread

of AME for fish oil samples for different age groups of broilers was observed. The energy gaps for young (< 21 days old)

and old broilers (> 21 days old) were 2295 kcal/kg and 1417 kcal/kg, with a relative variation of 36% and 19%

respectively (Table 3). The AME gap for crude palm oil for young (< 21 days old) and old broilers (> 21 days old) were

found to be 1057 kcal/kg and 540 kcal/kg with relative variations of 17% and 7% (Table 3). Comparatively, refined palm

oil also showed a smaller AME spread relative to crude palm oil, with 506 kcal/kg for young broilers (8% variation) and

250 kcal/kg for old broilers (3% variation) (Table 3). As the three major oil groups (e.g. tallow, rice bran oil, and fish oil)

accounted for 63% of the total oil and fat samples collected and represented the majority of the oil and fat products

(Table 2), the data for these groups were further analyzed (Table 4).

Tallow

Large AME discrepancy of 2670 kcal/kg for young broilers with relative variation of 49% and 1565 kcal/kg for old

broilers with a relative variation of 23% were observed (Table 3). Out of 163 samples, 85% of the samples were received

from five different sources originating from South Korea (Table 4). Majority of the samples were from the same source,

supplier 1, where it accounted for approximately 78% of the tallow samples received from South Korea. Large spread of

AME was observed for supplier 1, at 1248 kcal/kg with a relative variation of 20% for young broilers and 626 kcal/kg

with a relative variation of 8% for old broilers (Figure 1). As such, supplier 1 from South Korea was singled out with

samples collected in eight batches over a span of five years, from year 2012 to 2016. The AME values observed were

inconsistent even within batches where the energy spread was in the range of 230 kcal/kg to 1063 kcal/kg with relative

variation of 3% to 17% (Table 5). Likewise, AME values for tallow samples from supplier 3 were inconsistent as well, with

energy spread at 1362 kcal/kg for young broilers (aged < 21 days) and 740 kcal/kg for old broilers (aged > 21 days)

(Figure 1). This translated to relative variations of 20% for young broilers (aged < 21 days) and 10% for old broilers (aged

> 21 days).

Rice bran oil

All rice bran oil samples received were from Thailand since 2012. From 2012 to 2014, the predicted ME values

were highly variable as shown in Figure 2. However, from 2015 onwards, the predicted AME values were calculated to be

more consistent where the energy values ranged from 7500 kcal/kg to 8000 kcal/kg (relative variation of 7%) with only

seven outlier samples. High FFA content of 12.50% oleic acid was observed (Table 3).

Fish oil

Majority of the fish-based oil samples were from Indonesia and Thailand (63% of fish oil samples). Figure 3 showed

that fish oils from Thailand consisted of large energy gaps of 2295 kcal/kg (young broilers) and 1417 kcal/kg

(old broilers). Similarly, when the AME for different batches of fish oils from the same supplier (supplier A) in Thailand

were determined, it was found that the AME ranged from 6442 kcal/kg to 8738 kcal/kg with relative variation of 36% in

young broilers (Table 4). Likewise, a difference of 1926 kcal/kg in terms of AME variation (30%) was observed between

fish oil samples from Indonesia (Table 4).

152

To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat

variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.

DISCUSSION

The quality and efficiency of feed formulations are highly dependent on two main factors, the extent and accuracy of

animal nutritionists’ knowledge on raw materials’ qualities and compositions, as well as the nutrient requirements of

targeted species (Lall and Dumas, 2015 ). Animal nutritionists struggle to formulate feed with adequate energy when lipid

energy values stated in traditional feed tables often deviate from the actual energy value due to various reasons such as

poor storage and processing conditions. It is also likely that these values did not account for the species and age

dependent metabolism. While Baião et al. (2005) reported that the AME for tallow was in the range of 7000 kcal/kg,

Figures 1(A) and 1(B) indicated that regardless of animal age groups, inconsistency in AME values of tallow were

apparent where energy variations occurred even within the same supplier with relative variation as high as 17% for the

same batch of tallow samples. Without proper lipid quality evaluations, this will eventually lead to poorer animals’

performances and economic losses.

The predicted mean AME of soybean oil is the highest as compared to other oil types. One of the main contributing

factors is the presence of high unsaturated fatty acids where the recorded U:S ratio was 4.71 (Table 3). Consistent to a

previous study conducted by Rodriguez-Sanchez et al. (2019) where it was reported that hydrolysis in unsaturated diets

were relatively more efficient than saturated diets which results in higher digestibility and absorption. The AME of

soybean oil ranged from 6665 kcal/kg to 8796 kcal/kg for young broilers (aged < 21 days) and 7716 kcal/kg to

8997 kcal/kg for old broilers (aged > 21 days). In comparison, a study showed that the AME of soybean oil is at 8790

kcal/kg (Baião et al., 2005 ), demonstrating 12% relative variation from the literature value. Low fatty acid content

(1.01% oleic acid) was also observed for soybean oil. The presence of high FFA decreases bile secretion which in turns

reduces micellar formation, leading to poor absorption of digested materials (Ravindran et al., 2016; Rodriguez-Sanchez

et al., 2019 ). A study conducted by Wiseman and Salvador (1991) showed that AME is inversely proportional to the FFA

content, with the effect being more pronounced in younger broilers. In agreement with the study conducted by Wiseman

and Salvador, our survey also showed that the AME values of young broilers were more divergent as compared to older

broilers, demonstrating their sensitivity to oil quality variations possibly due to less developed physiological capacity in fat

utilization (Rodriguez-Sanchez et al., 2019 ).

Our results showed that from year 2015 onwards, the AME values for rice bran oil samples collected from Thailand

were more consistent (Figure 2). One plausible reason could be due to technological improvements made to the

manufacturing or transporting processes in Thailand. While more consistent AME values were observed over the years,

the FFA content of rice bran oil remains the highest among the eight oil types analyzed (Table 3). As rice bran contains

endogenous lipase capable of digesting and hydrolyzing the triglycerides present to form FFA (Goffman and Bergman,

2003, Vallabha et al., 2015 ), it is possible that the samples collected were likely to be extracted from poor quality rice

bran where the triglycerides had been hydrolyzed (Rajan and Krishna, 2009 ). Interestingly, while high FFA content was

observed in rice bran oil (Table 3), its AME remains one of the highest among the other oil types. One of the reasons could

be due to the relatively higher U:S where the presence of unsaturated fats aid in the solubilization and absorption of FFA

(Hofmann and Borgstrom, 1962 ).

Large energy gaps were observed in fish oil with 36% variation in young broilers (< 21 days) and 19% variation in old

broilers (> 21 days). This is likely due to the presence of different fish oils with different oil quality grades such as salmon

fish oil and crude tuna fish oil. There are different standards for different fatty acid compositions of different fish origins.

For instance, while the standard for C22:6 (n-3) docosahexaenoic acid of tuna oil ranges from 21.0 – 42.5% of total fatty

acids, similar standard for wild salmon oil ranges from 6.0 – 14.0% (FAO/WHO, 2017 ). Fish oils are also susceptible to

lipid oxidation due to the high degree of unsaturation (European Food Safety Authority (EFSA, 2010 ) where unsaturated

fatty acids are prone to oxidation (Dominguez et al., 2019 ). Comparatively, refined palm oil has lower AME spread as

compared to crude palm oil. This is likely due to the refining processes that may have possibly removed the impurities,

and therefore confers a more consistent oil quality in refined palm oil.

Given these analyses, it is evident that having a proper lipid analysis in place is fundamental for accurate estimation

of dietary energy in feed formulations.

Table 2 – Number of oils and fats collected across Asia Pacific region, per oil type

Oils and fats

Tallow

Count

163

147

Rice bran oil

Fish oil

Crude palm oil

Soybean oil

Refined palm oil

Lard

Coconut oil

153

To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat

variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.

Table 3 – Descriptive analysis data of the eight different oil types for broilers

Apparent Metabolizable Energy (AME) of poultry (broiler)

Crude palm oil Soybean oil Refined palm oil

Tallow

Rice bran oil

Fish oil

<21

Lard

Coconut oil

Item

<21

>21

<21

>21

<21

>21

<21

>21

<21

>21

<21

>21

<21

>21

Statistics (kcal/kg)

Minimum

Maximum

Range

5448

8118

2670

6742

6949

7087

6886

6930

8495

1565

7744

7853

7913

7820

6709

8138

1429

7608

7710

7787

7635

7566

8503

937

6442

8738

2295

6912

7183

7916

7370

7530

8947

1417

7826

7965

8373

8076

6359

7416

1057

6509

6601

6674

6617

7524

8064

540

6665

8796

2131

8321

8579

8589

8362

7716

8997

1282

8624

8807

8814

8672

6533

7038

506

7652

7902

250

6002

7825

1822

6996

7115

7347

7084

7399

8320

922

6685

7914

1229

7159

7493

7664

7411

7705

8375

670

1^stquartile

8332

8488

8567

8194

7616

7666

7704

7669

6858

6908

6964

6886

7810

7835

7862

7824

7878

7934

8060

7925

7926

8121

8229

8075

Median

3^rdquartile

Mean

SE of mean

374

191

265

147

581

329

172

463

279

114

398

200

323

192

Standard deviation, 

Nutritional parameters

FFA (%)^a

2.66

1.28

12.50

2.70

4.62

2.14

7.07

1.10

1.01

4.71

0.34

1.20

1.35

1.48

8.45

2.10

U:S ratio

< 21 = Young broilers of age less than 21 days; > 21 = Old broilers of age more than 21 days; SE = Standard error; FFA = Free fatty acid content; U:S = unsaturated: saturated fatty acid. Free fatty acid

content is expressed as % palmitic acid for crude and refined palm oil, % lauric acid for coconut oil and % oleic acid for the rest of the oil types.

Table 4 – Details of samples collected from the different countries for the three major oil types (Tallow, rice bran oil and fish oil), with minimum, maximum, range and mean

apparent metabolizable energy (AME) of young broilers (< 21 days)

Oil types

Tallow

Rice bran oil

Fish oil

AME (< 21 days) (kcal /kg)

AME (< 21 days) (kcal/kg)

Country

Min

Max

Mean

n_s

Min

Max

8138

1429

Mean

7635

147

n_s

Min

Max

Mean

7367

n_s

Thailand

6709

6442

8738

2295

Indonesia

Vietnam

6499

6575

7919

7199

7440

7948

7861

8425

8321

8233

7199

7826

7948

8309

1926

1746

313

7416

7103

8028

7199

7633

7948

8031

6299

5448

5826

6002

6240

6073

6503

5448

6333

6561

6372

6640

8118

6520

6503

8118

6316

5989

6138

6345

Philippines

Singapore

Taiwan

1112

546

638

1878

448

386

South Korea

7003 138

New Zealand

India

6370

6503

448

Total

2670

6886 163

6709

8138

1429

7635

147

6442

8738

2295

7370

AME (< 21 days) = Apparent metabolizable energy for young broilers of age less than 21 days; Min = Minimum; Max = Maximum; R = Range; n = number of observations; n_S= number of suppliers.

154

To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.

Table 5 – Details of tallow samples collected from South Korea, Supplier 1, with minimum, maximum, range

calculated for apparent metabolizable energy (AME) of young broilers (< 21 days)

AME (< 21 days) (kcal/kg)

Percentage

variation (%)

Count

Min

Max

Batch

Batch 1

Batch 2

Batch 3

Batch 4

Batch 5

Batch 6

Batch 7

Batch 8

6240

6546

6612

6710

6630

7258

7173

6908

7303

7124

7428

7488

7413

7258

7173

7137

1063

578

815

778

783

230

AME (< 21 days) = Apparent metabolizable energy for young broilers of age less than 21 days; Min = Minimum; Max = Maximum; R = Range;

NA = Not Applicable

Figure 1 - Variations in minimum, first quartile, median, third quartile and maximum in predicted apparent

metabolizable energy (AME) for both (A) young broilers (aged < 21 days) and (B) old broilers (aged > 21 days)

differentiated by the different tallow suppliers in South Korea.

Figure 2 - Predicted apparent metabolizable energy (AME) trend graph for young broilers (aged < 21 days) with

emphasis on year 2015 onwards, for rice bran oils.

155

To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat

variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.

Figure 3 - Variations in minimum, first quartile, median, third quartile and maximum in predicted apparent

metabolizable energy (AME) for both (A) young broilers (aged < 21 days) and (B) old broilers (aged > 21 days)

differentiated by the different fish oil suppliers in Thailand.

CONCLUSION

In conclusion, our data suggested that there is a considerable variation of the AME values in oils and fats. The AME

variation that existed across oil samples from different regions and even within batches from similar suppliers may affect

the feed formulation precision if the variation remains unaccounted for. Generic lipid energy values extracted from the

traditional feed table were typically inaccurate as the animal species and age dependent metabolism were likely not

considered in these tables. Furthermore, poor storage and processing conditions may deteriorate the oil quality as well.

Inevitably, inconsistent AME values will not only contribute to huge economic losses but may also impact the animal

performances adversely due to inaccurate feed formulations that fail to meet the caloric requirements of the animals. In

view of these concerns, it is important to have a proper lipid evaluation tests in place for a more accurate lipid profile (e.g.

AME value) estimation. Additionally, oil quality parameters such as peroxide and p-anisidine values should also be

considered for oxidative stability evaluation as oil and fat quality may deteriorate over time. To improve oil and fat

qualities, bio-emulsifiers and antioxidants can be used concurrently to improve oil and fat qualities in the context of

oxidative stability and feed fat variability control.

DECLARATIONS

Corresponding Authors

Agnes Thng, e-mail: agnes.thng@kemin.com . Jun Xiang Ting, email: junxiang.ting@kemin.com . Hui Ru Tay, email:

huiru.tay@kemin.com . Chin Yi Soh, email: chinyi.soh@kemin.com . Hwee Ching Ong, email: hweeching.ong@kemin.com .

David Tey, email: david.tey@kemin.com .

Authors’ Contribution

A. Thng proposed the design of study, prepared the manuscript and performed the laboratory analysis. J.X. Ting, H.R.

Tay, C.Y. Soh and H.C. Ong assisted with the laboratory analyses. D. Tey reviewed and edited the manuscript.

Conflict of interests

The authors declared that there is no conflict in this study.

Acknowledgements

The authors thank the suppliers from the Asia Pacific region for the collection of oil and fat samples. We also thank

Dr C. Sugumar for his scientific contributions in this study, and Ms R.Lye, Drs J. Tan, K.P. Chan and H. Chirakkal for their

constructive feedbacks on the manuscript draft. This study was supported by Kemin Industries (Asia) Pte Limited, Animal

Health and Nutrition.

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To cite this paper: Thng A, Ting JX, Tay HR, Soh CY, Ong HC and Tey D (2020). The use of predicted apparent metabolizable energy values to understand the oil and fat

variability in broilers. Online J. Anim. Feed Res., 10 (4): 150-157.