2020, Scienceline Publication  
JWPR  
Poultry Research  
J. World Poult. Res. 10(2S): 180-183, June 14, 2020  
Journal of World’s  
Research Paper, PII: S2322455X2000023-10  
License: CC BY 4.0  
DOI: https://dx.doi.org/10.36380/jwpr.2020.23  
The Effect of Methionine on Performance, Carcass Characteristics  
and Gut Morphology of Finisher Broilers under Tropical  
Environment Conditions  
Nazim Rasul Abdulla1, 6, Mohamed Idris Alshelmani2, 5*, Teck Chwen Loh1,2, Hooi Ling Foo3,4 and Mohamad Amirul Zainudin1  
1Department of Animal Science, Faculty of Agriculture;  
2Institute of Tropical Agriculture and Food Security;  
3Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences;  
4Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.  
5Department of Animal Production, Faculty of Agriculture, University of Benghazi, Benghazi, Libya.  
6Department of Animal Resource, Salahaddin University, Erbil, Kurdistan Region, Iraq.  
*Corresponding author’s Email: mohammed.alshelmani@uob.edu.ly; ORCID: 0000-0003-3891-4003  
Received: 18 Feb. 2020  
Accepted: 23 Mar. 2020  
ABSTRACT  
The present study was conducted to determine the effect of DL- and L-methionine on growth performance, carcass  
characteristics, and gut morphology during the finisher phase in the tropical environment. A total of 560 one-day-old  
broiler chicks (Cobb 500) were purchased and raised for 35 days. The chicks were divided into four dietary  
treatments with seven replicates (20 birds per replicate). The basal diet was offered to the chickens during the starter  
and finisher phases. The DL-methionine was supplemented to the finisher diet as at 0.260% (T1) and 0.179% (T2).  
Correspondingly, the L-methionine was supplemented to the finisher diet with the same ratios; 0.260% (T3) and  
0.179% (T4). The findings revealed no significant differences in growth performance between the two forms of  
methionine. The obtained results indicated no significant differences in carcass characteristics, the villi heights and  
crypt depth among the dietary treatments. In conclusion, DL-methionine can be used in broiler nutrition as substitute  
for L- methionine which is more expensive in poultry industry.  
Key words: Carcass characteristics, Growth performance, Gut morphology, Methionine, Tropical environment  
value compared with L-Met in broiler chicken production.  
Because the effectiveness of DAAO is very low in the  
young birds (D’Aniello et al., 1993), some reports argued  
that DL-Met might not efficiently meet the intestinal cell  
requirements for young chickens during the first pass  
metabolism compared with L-Met (Shen, et al., 2015).  
Thus, the objective of the current study was to evaluate the  
effect of dietary supplementation of DL-Met and L-Met on  
broiler growth performance.  
INTRODUCTION  
The protein content is one of the major factors that affect  
the productivity of farm animals. Supplementation of  
animal diets with amino acids to enhance the quality of  
dietary protein or to replenish the amino acid pool is a  
common practice in monogastrics.  
Methionine (Met) is an essential amino acid in farm  
animals. It is known as a first limiting amino acid in  
poultry (Thakur, et al., 2016, Wen, et al., 2017). Adequate  
levels of dietary Met is required to support the optimum  
growth (Vinod Kumar and Mandal, 2005) and carcass  
yield of fast-growing commercial broilers (Ojano-Dirain  
and Waldroup, 2002). The Met is also capable to enhance  
growth, maximize meat yield, reduce carcass fat and  
balance nutrient intake. Routinely, supplemented Met is  
mostly provided as DL-Met (99% purity powder), which  
contains 50% L-Met and 50% D-Met. D-Met can be  
completely absorbed by the intestine (D'Aniello, et al.,  
1993). Primarily in the liver or kidney, D-Amino Acid  
Oxidase (DAAO) converts D-Met to L-Met. Literature has  
clearly demonstrated that DL-Met has 100% nutritional  
MATERIALS AND METHODS  
Ethical approval  
The feeding trial was conducted under the guidelines  
of the Research Policy on Animal Ethics of the Universiti  
Putra Malaysia.  
Birds and experimental diets  
A total of 560 male broilers (Cobb 500) one-day-old  
chicks were obtained from a local commercial hatchery  
and raised for 35 days in 28 deep litter pens. The chicks  
To cite this paper: Abdulla NR, Alshelmani MI, Loh TCh, Foo HL and Zainudin MA (2020). The Effect of Methionine on Performance, Carcass Characteristics and Gut  
Morphology of Finisher Broilers under Tropical Environment Conditions. J. World Poult. Res., 10 (2S): 180-183. DOI: https://dx.doi.org/10.36380/jwpr.2020.23  
180  
J. World Poult. Res., 10(2S): 180-183, 2020  
were weighed and randomly distributed into four treatment  
Table 1. The composition of experimental finisher diets  
groups. Each treatment group was divided into seven  
replicates with 20 chicks for each replicate. The DL-Met  
was supplemented in the finisher diet as follows: T1=  
0.260%, T2=0.179%. Correspondingly, the L-Met was  
supplemented in the finisher diet with the same ratios to  
obtain T3=0.260%, and T4= 0.179%. (Table 1). The feed  
was provided as a mash form, and the drinking water and  
feed were offered ad libitum for 35 days. The diets were  
formulated based on the content of amino acids analyzed  
by Evonik Company (Singapore). The lighting was  
continued 24 hours per day. The chicks were vaccinated  
against Newcastle disease, infectious bronchitis infectious  
and bursal disease vaccine as described by Alshelmani, et  
al. (2017). The birds were fed with starter diets from 0-14  
days, and finisher diet from 15-35 days.  
(15-35 days)  
Dietary treatments  
Ingredient (%)  
T1  
T2  
T3  
T4  
Yellow corn  
57.90  
28.17  
4.98  
5.00  
1.66  
0.94  
0.250  
57.96  
28.16  
5.01  
5.00  
1.66  
0.94  
0.252  
57.90  
28.17  
4.98  
5.00  
1.66  
0.94  
0.250  
57.96  
28.16  
5.01  
5.00  
1.66  
0.94  
0.252  
Soybean meal 48%  
Palm oil  
Wheat bran  
DCP1 18%  
Calcium carbonate  
Sodium bicarbonate  
Salt  
0.248  
0.260  
0.247  
0.179  
0.248  
0
0.247  
0
DL-Methionine  
L-Methionine  
L-Lysine  
0
0
0.260  
0.186  
0.080  
0.026  
0.100  
0.150  
0.050  
0.179  
0.186  
0.080  
0.026  
0.100  
0.150  
0.050  
0.186  
0.080  
0.026  
0.100  
0.150  
0.050  
0.186  
0.080  
0.026  
0.100  
0.150  
0.050  
L-Threonine  
Valine  
Vitamin premixa  
Mineral premixb  
Choline chloride  
Total  
Samples and data collection  
Body weight was measured individually, and feed  
intake was recorded for each replicate every week. Body  
Weight Gain (BWG) was calculated, and Feed Conversion  
Ratio (FCR) was calculated. On 35 days, two birds were  
randomly selected from each replicate to measure carcass  
quality and collect the small intestine.  
100.00 100.00 100.00 100.00  
Nutrient values (%)  
Metabolizable energy  
(kcal/kg)  
3050  
3050  
3050  
3050  
Crude protein (%)  
Crude fat (%)  
Crude fiber (%)  
18.87  
8.55  
3.46  
18.82  
8.59  
3.46  
18.87  
8.55  
3.46  
18.82  
8.59  
3.46  
Calcium (%)  
0.89  
0.89  
0.89  
0.89  
Morphology of small intestine  
Available phosphorus (%)  
Digestible lysine (%)  
0.40  
1.03  
0.40  
1.03  
0.40  
1.03  
0.40  
1.03  
The procedure of gut morphology was conducted  
based on the described method by Alshelmani, et al.  
(2016). The villi height and crypt depth were measured in  
the duodenum, jejunum, and ileum. Briefly, samples were  
taken from the middle part of the duodenum loop, the  
midway between the duodenum and Meckel’s  
diverticulum for jejunum and the midway between  
jejunum part and ileocecal junction for ileum. The samples  
were flushed with 10% (v/v) formalin buffer and kept in  
formalin for further analysis.  
Digestible methionine (%)  
0.50  
0.42  
0.50  
0.42  
Digestible methionine+  
cysteine  
0.77  
0.69  
0.77  
0.69  
Digestible threonine (%)  
Digestible tryptophan (%)  
Digestible arginine (%)  
a Mineral premix provided per kilogram of the diet: Fe 100 mg; Mn 110  
mg; Cu 20 mg; Zn 100 mg; I 2 mg; Se 0.2 mg; Co 0.6 mg. Vitamin mix  
provided per kilogram of the diet: retinol 2.00mg; cholecalciferol  
0.03mg; α-tocopherol 0.02mg; menadione 1.33 mg; cobalamin 0.03 mg;  
thiamine 0.83 mg; riboflavin 2 mg; folic acid 0.33mg; biotin 0.03 mg;  
pantothenic acid 3.75 mg; niacin 23.3 mg; pyridoxine 1.33 mg. T1 =  
0.260% DL-methionine; T2 = 0.179% DL-methionine; T3 = 0.260% L-  
methionine; T4 = 0.179% L-methionine  
0.67  
0.20  
1.14  
0.67  
0.20  
1.14  
0.67  
0.20  
1.14  
0.67  
0.20  
1.14  
b
Statistical analysis  
The experimental design was applied based on a 2 x  
2 factorial completely randomized design following GLM  
procedures of statistical analytical system (SAS, 2003).  
Each pen considered as an experimental unit for feed  
intake and FCR, whereas individual BWG was considered  
as the experimental unit. When significant effects were  
found, comparison among the treatments was applied by  
Tukey’s test with a probability of 5% (p< 0.05). The  
statistical model was: Yijk = µ + αi + βj + αβij + Eijk .Where  
Yijk is dependent variable; µ is general mean; αi is effect of  
Met form; βj is effect of Met level; Eijk is experimental  
error; αβij is effect of the interaction between Met form  
and Met level.  
RESULTS AND DISCUSSION  
Growth performance  
Table 2 shows the growth performance of broiler  
chickens fed diets supplemented with different levels and  
forms of Met. The BWG, feed intake and FCR were not  
significantly (p>0.05) different among the dietary  
treatments, regardless of the forms and levels of Met used.  
The findings are consistent with Shen et al. (2015) who  
reported no significant difference was found between  
181  
Abdulla et al., 2020  
broilers fed diets fortified with DL-Met compared to birds  
increase in villus height compared with group of chickens  
fed a basal diet.  
fed diet fortified with L-Met. The results are also in  
agreement with the findings obtained by Lim (2015) who  
investigated the bioavailability of L-Met on nursery pigs.  
The previous study evaluated the DL-Met and L-Met on  
broiler or pigs and indicated that availability of L-Met was  
better than DL-Met only at the first seven days of age. The  
literature attributed findings to the expression of DAAO  
which found to be very low in the young birds. This  
enzyme is responsible for converting the D-form of Met to  
L-form to be utilized by the animal. The expression of this  
enzyme increase after the first week of age. Therefore, it  
seems that bioavailability of DL-Met and L-Met are  
similar to each other regarding growth performance and  
carcass quality. Another point to consider is that DL-Met  
supplementation provided a significant improvement in  
body weight and BWG compared to herbomethione in a  
comparable study by Kaur et al. (2013).  
Table 2. Growth performance of finisher broiler chickens  
fed diets fortified with different levels and forms of  
methionine.  
Body weight  
Feed intake b  
(g/bird)  
FCR b  
Dietary  
treatments  
gain a (g)  
15–35 days  
15–35 days  
15–35 days  
1.688  
T1  
T2  
T3  
1459.19  
1452.41  
1459.97  
2458.42  
2518.14  
2500.57  
1.734  
1.712  
T4  
SEM c  
1470.31  
7.11  
2565.28  
25.71  
1.744  
0.01  
p-value  
Methionine Form  
0.51  
0.40  
0.49  
Methionine  
levels  
Form x Levels  
0.90  
0.54  
0.24  
0.96  
0.13  
0.77  
a n = 140 b n = 7 replicates (pens) with 20 birds each. T1 = 0.260% DL-  
Met; T2 = 0.179% DL-Met; T3 = 0.260% L-Met; T4 = 0.179% L-Met in  
the finisher phase. c Pooled standard error of the means.  
Carcass traits  
The effect of different levels and forms of Met on  
Table 3.  
Effect of different levels and forms of  
carcass and breast yield in broiler chickens is shown in  
table 3. No significant difference (p>0.05) was shown on  
carcass and breast yield among the dietary treatments  
irrespective of the forms and levels of Met used in the  
present study. The results are in agreement with Li, et al.  
(2017), who reported that no significant differences in  
carcass yield in pigs fed different levels of diet fortified  
with L-Met. The results are also consistent with El-Faham,  
et al. (2017), who reported that there was no difference  
among groups of broiler chickens fed diet fortified with  
different forms of Met. The results are also in agreement  
with Kaur et al., (2013), who mentioned that no significant  
difference in carcass or breast yields between  
herbomethione and DL-Met supplemented to the  
commercial broiler chickens.  
methionine on carcass and breast yield in finisher broiler  
chickens.  
Carcass Composition a  
Dietary treatments  
Carcass yield  
(%)  
Breast yield  
(%)  
T1  
70.18  
69.58  
69.94  
69.40  
0.25  
36.68  
35.20  
35.74  
36.01  
0.26  
T2  
T3  
T4  
SEM b  
p-value  
Methionine Form  
Methionine levels  
Form x Levels  
0.690  
0.275  
0.945  
0.904  
0.244  
0.095  
a
n = 14 T1 = 0.260% DL-Met; T2 = 0.179% DL-Met; T3 = 0.260% L-  
Met; T4 = 0.179% L-Met in the finisher phase. b Pooled standard error of  
the means.  
Table 4. Effect of different levels and forms of  
methionine.  
Morphology of small intestine  
Dietary treatments  
T2 T3  
p-  
value  
There was an interaction between the form and level  
of methionine on villus height in the jejunum and crypt  
depth in the ileum (Table 4), whereas the interaction was  
observed on crypt depth in jejunum. The higher villus  
height was shown on birds fed diet supplemented with  
0.179% L-Met in the finisher phase in comparison with  
the other groups. The increase of villus height could be  
attributed to the low levels of methionine. The  
observations corroborate with Sterling, et al. (2005) who  
referred that broiler fed low methionine diet showed an  
Parameter  
T1  
T4  
SEMc  
Villus height b  
Duodenum  
Jejunum  
921.38 968.59 747.27 803.53 74.17 0.069  
775.14 707.57 431.32 675.92 47.86 0.002  
475.68 351.54 488.47 530.93 28.52 0.006  
Ileum  
Crypt depth  
Duodenum  
Jejunum  
65.79  
79.52  
74.97  
71.20  
68.56  
77.54  
69.39  
73.24 103.59 6.43  
85.59 75.79 4.12  
74.59  
4.87  
0.493  
0.104  
0.303  
Ileum  
a T1 = 0.260% DL-Met; T2 = 0.179% DL-Met; T3 = 0.260% L-Met; T4  
= 0.179% L-Met in the finisher phase. b n = 14 c Pooled standard error of  
the means.  
182  
 
J. World Poult. Res., 10(2S): 180-183, 2020  
interactions on carcass tissue distribution and chemical  
composition. Egyptian Poultry Science Journal. 37 (1): 155-167.  
CONCLUSION  
Kaur D, Nagra SS, Sodhi S and Dwivedi P (2013). Comparative  
performance of commercial broilers fed herbomethione® as a  
replacement for dl-methionine in diet. Journal of Applied Animal  
Based on the current findings, no significant differences  
between the methionine forms were found, it can be  
concluded that the DL-Met can be utilized by broiler  
chickens likewise the L-Met.  
Research.  
41  
(4):  
410-416.  
DOI:  
https://doi.org/10.1080/09712119.2013.792731.  
Li Y, Zhang H, Chen YP, Ying ZX, Su WP, Zhang LL and Wang T  
(2017). Effects of dietary l-methionine supplementation on the  
growth performance, carcass characteristics, meat quality, and  
muscular antioxidant capacity and myogenic gene expression in  
low birth weight pigs1. Journal of Animal Science. 95 (9): 3972-  
3983. DOI: http://dx.doi.org/10.2527/jas.2017.1652.  
Authors’ contributions  
All authors participated equally in designing,  
sampling, analyzing of results and writing the paper.  
Lim J (2015). Evaluation of l-methionine bioavailability in nursery pigs.  
MSc.Thesis, University of Kentuky, USA.  
Competing interests  
The authors declare that there is no conflict of  
interest.  
Ojano-Dirain C and Waldroup P (2002). Evaluation of lysine, methionine  
and threonine needs of broilers three to six week of age under  
moderate temperature. International Journal of Poultry Science. 1  
(1): 16-21.  
SAS. 2003. Statistical analytical system. SAS Institute Inc., Cary, NC,  
USA.  
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