Effect of Supplementation of Diets with L-Carnitine and Methionin on Broiler Chicken Productive Performance

1. Introduction

The poultry industry is one of the pillars of food security in the world, as it is relied upon to provide meat and eggs to meet the increasing food demands. Both chicken eggs and meat have been known as desirable food since their contain high levels of vital protein, good metabolic energy, as well as their short production period, and ease of management ( 1 ). Recently, the search began for finding new strategies to improve the productive performance of broiler chickens, such as L-Carnitine and methionine supplementation to the broiler diets. Carnitine is a by-product of the breakdown procedures of the essential amino acids methionine and Rebouche ( 2 ), which is referred to as an amino acid for its vital role in the synthesis of several amino acids. Also, carnitine had a biological function in metabolism and oxidation of polyunsaturated fatty acids ( 3 ). As well as its antioxidant activity and tissue protection from oxidative damage. Carnitine is also a generator of the essential amino acid methionine and vitamin B6. The great importance of carnitine has been proven in improving the productive performance in poultry ( 4 , 5 ).

Using natural substances in poultry production with antioxidant activity that do not have negative effects on consumer health, improve the antioxidant system, and protect cell membranes from oxidative damage would be the prefered strategy for improving the production performance in broiler chickens ( 6 , 7 ).

Therefore, this study was designed to investigate the effect of L-carnitine and methionine supplementation to the standard diets of broiler chickens in productive performance of broiler (Ross 308).

2. Materials and Methods

2.1. Study Design

One Hundred- fifty broiler chicks unsexed (Ross 308) with an initial weight with 43 g, were obtained from Al-Habbaniya hatchery (commercial hatchery). All the animals were within an average weight of 40 g (one-day old chicks).

The animals were randomly distributed to five different group (n=50) with three replicates (10 chicks/repeat) placed in 48 floor pens, inside a closed farm containing ground cages with an area of 1 m².

The light-dark cycle used in this study was adjusted to 23 hours light/day from the first day of experiment to the end of the research. The ambient temperature was controlled by thermostat and decreased gradually from 35°C at the first day to 22°C at 21^th day of age. Feed were formulated to be meet requirements of bird as guide with all nutrients for broilers as described by Nutrient requirements of poultry guideline ( 8 ). Birds were fed a three diets as follows : starter (0-10) days , grower (11-23) days and finisher (24–42) days. Water and feed were provided ad libitum. The experimental groups were as follows: the animals in T1 group received basal diet without any addition, the animals in T1 group received basal diet supplemented with lead acetate 400 mg/kg feed , the animals in T3 group received diet supplemented with carnitine 300 mg + lead acetate 400 mg, the animals in T4 group received basal diet supplemented with methionine 100 mg + lead acetate 400 mg, the animals in T5 group received basal diet supplemented with methionine 100 mg + carnitine 300 mg + lead acetate 400 mg.

All the animals were weekly weighed and feed consumption was recorded. Based on recorded measurement data, feed consumption, feed conversion ratio and live body weight gain were calculated during the experiment.

The ingredients and chemical composition of diets were presented in table 1.

2.2. Chemicals

The Carnitine was purchased from Vero Universal company (England), The Methionine pure was purchased from Agricultural Research Authority station in Baghdad.

2.3. Statistical Analysis

Statistical analysis of the data of this study was carried out using the steps of the general linear model of the statistical program SAS ( 9 ), where the effect of the coefficients for the studied traits was determined using a complete random design and the differences between means were tested using Duncan ( 10 ) 's multinomial test. A significant level of (P<0.05) was implemented.

3. Results

Table 2 showed effect of adding carnitine and methionine to broiler diets. Results of statistical analysis indicated significant differences were observed between different treatments in average weekly body live weight, a significant superiority (P<0.05) for T5 was observed comparison with other treatments, while T1, T2, T3 and T4 did not show any significant differences between them during first week of study, at second weeks, it was noted that superiority for T4 which recorded a significant increase (P<0.05) as comparison with treatments T1, T2 and T3. At third week table 2 shows T5 recorded highest live body weight with (762,66) gm with significant difference comparison with treatments T1, T2 ,T3 and T4. At fourth and fifth weeks T5 recorded significant difference. Results indicated superior increase for T5 comparison with T1, T2, T3 and T4. No significant difference between treatments T1, T2 and T4. While T3 recoded lowest live body weight (2119,13) gm.

Table 3 shows effect of adding carnitine and methionine to broiler diets at different ages on body weight gain. Results indicated significantly differences between treatments in average weekly live body weight gain at 1 week for T5 which recorded highest weights (93,56 gm/bird). Results of second week indicated keeping T5 superior significantly as compare with T1,T2,T3 and T4 which observed significant differences comparison with T1, T2 and T3. Table 3 shows a significant superiority (P<0.05) for T1 comparison with T2 and T4 at 3 week. A significantly differences between treatments were showed for T5 as compare with experimental treatments, while T1, T2, T3 and T4 did not show any significant differences between them at fourth week of study. Also, it was noted from results that T1 recorded a significant increase (P<0.05) as comparison with treatments T2 and T4 during fifth week. Data of sixth week shows significant difference for T2 which recorded highest body weight gain (602,81) gm/bird comparison with treatments T1 and T2, while no significant difference between treatments T1,T3,T5 and T6. A significantly differences not observed between treatments in accumulative live body weight gain . Our finding were agreed with Farhan, Mousa ( 3 ) who mentioned that no significant differences between means of body weights gain of broiler fed diets supplemented with carnitine 300 mg/kg feed. On other hand results disagreement with Parsaeimehr, Farhoomand ( 11 ); Ardekani, Shevazad ( 12 ); Jalali, Rabiei ( 13 ) who reported there were significant differences between treatments in body weights gain of broiler fed diets supplemented with carnitine.

As shown in table 4 results of adding carnitine and methionine to broiler diets. At the first week, T1 (basal diet) and T2 (adding lead acetate) observed highest feed consumption with 150,43 and 151,22 gm/bird respectively, while no significant differences between treatments were recorded between T4 (adding of methionine 100 mg/ kg feed + lead acetate 400 mg/kg feed) and T5 (adding of methionine 100 mg/ kg feed with carnitine 300 mg/ kg feed + lead acetate 400 mg/kg feed). In second week of birds age there were a significant increase (P<0.05) in T5, which recorded highest mean of feed consumption compared to other experimental treatments, while T1, T2 and T3 did not indicate significant differences between them. Also, data in table 4 included significant increase (P<0.05) for T1 and T5 which recorded highest feed consumption 602,85 and 617,09 gm/bird respectively, while T2 recorded lowest 543,27 gm/bird at third week . In the fourth week birds of T5 (adding of methionine 100 mg/ kg feed with carnitine 300 mg/ kg feed + lead acetate 400 mg/kg feed) had highest mean of feed consumption as compare with treatments. Results of statistical analysis did not show significant differences between treatments at fifth week. During sixth week of birds age T5 recorded lowest mean feed consumption 1035,48 gm/bird , T2 recorded highest mean feed consumption 1172,23 gm/bird, no significant differences between treatments T1, T3 and T4 which recorded 1093,78, 1117,07 and 1085,21 gm/bird respectively. The accumulative feed conversion coefficient (1-42 days) showed significant differences between treatments T5 observed increase in feed consumption mean 4024,49 gm/bird without significant difference with T2 3954,04 gm/bird. No significant differences between treatments T1 and T4. Results of study were agreed with Jalali, Rabiei ( 13 ); El-Wahab, Aziza ( 14 ) who demonstrated that addition of 350 mg/kg of carnitine with methionine resulted significant increase (P<0.05) in feed intake as compared with experimental treatments. In contrast, data of results disagreed with Murali, George ( 15 ); Farhan, Mousa ( 3 ) found that addition of carnitine at 300 mg/kg to broiler diet did not had any effects on feed consumption.

Data of feed conversion ratio are shown in table 5, At the first week, significant differences between treatments were recorded for T4 and T5 which recorded best feed conversion ratio 1,66 and 1,36 (gm feed consumed/gm body weight gain) respectively. Second week a significant decrease (P<0.05) in T1 (basal diet) which recorded worst value of feed conversion coefficient compared to T4 did not differ significantly with T2, T3 and T5. At 21 days of age a significant decrease (P<0.05) for T5 (addition of methionine 100 mg/ kg feed with carnitine 300 mg/ kg feed + lead acetate 400 mg/kg feed) which recorded worst value of feed conversion ratio compared to T2 (addition of lead acetate 400 mg/kg feed) which differs significantly with treatments T1, T3 and T4. Results of statistical analysis did not show significant differences at fourth week between treatments. At fifth week of birds age T1 (basal diet) observed best feed conversion ratio 1,76 compare with T2, T3, T4 and T5 which recorded 2.00, 1.88, 1.88 and 2.03 respectively . Data of sixth week indicated no significant differences between T4 and T5 which recorded highest means compare with T1 and T3 which did not differ significantly between them. While T2 had best values 1,94 gm. feed consumed/gm. live body weight gain. The accumulative feed conversion ratio (1-42 days) showed that no significant differences between T4 and T5 which observed 1,74 and 1,73 respectively while T2 recorded worst feed conversion ratio 1,85 and did not differ significantly with T1.

4. Discussion

The improvement in body weight of L-carnitine supplementation treatments may be attributed to its role in transporting long-chain fatty acids across the mitochondrial membrane, controlling their oxidation, and its biological effect on energy metabolism ( 5 ). Carnitine plays a role in improving the utilization of dietary nitrogen through the availability of the two amino acids (methionine and lysine) from which carnitine is derived to complete the process of protein biosynthesis and other cellular functions ( 16 ). Kita, Kato ( 17 ) showed a significant superiority in live body weight of broilers during first weeks of study when L-carnitine was added with (50 mg/kg feed). The improvement may be due to L-carnitine increases the concentration of Insulin Growth Factor (IGF-1) and has the ability to increase weight ( 17 ). The results of study agreed with the results of Lien and Horng ( 18 ), which indicated that adding L-carnitine to broiler diets with (160 mg/kg) had no significant effect on live body weight at 42 days of age. Moreover, agreed with results of El-Wahab, Aziza ( 14 ) who reported significant differences in the average live body weight of birds at 42 days of age when carnitine and methionine were added to different energy diets. It also agreed with the results of Murali, George ( 15 ) when adding L-carnitine at a concentration (900 mg/kg) to broiler rations. The results of the study were in agreement with the findings of Arslan and Tufan ( 19 ) who mentioned that addition carnitine 100/kg feed enhanced growth performance of broiler. The addition of methionine works to balance the representation of amino acids, which leads to a rapid increase in protein synthesis and a reduction in deposited fat. Methionine plays a biological role as intermediate in reactions of methylation and it converted to Cystien which is required Taurine and Glutathione (GSH) for synthesis. Both Taurine and Glutathione peroxidase which considered important compounds in defense system against oxidative stress. Glutathione provides protection against free radicals. However, results of study showed that antioxidant status was influenced by methionine addition ( 20 ). Our results were consistent with Jankowski, Ognik ( 21 ) who reported that adding methionie to diets enhanced antioxidant status. Xie, Hou ( 22 ) mentioned that addition high Methionine levels resulted in high homocysteine levels, which is toxic and results in neurodegenerative disease by impeding endothelium functions and reactive oxygen species generation ( 23 ). L-Carnitine is vitamin-like natural, acts in cell as a receptor for activated fatty acids. The major metabolic role of L-Carnitine appears transporting of long-chain fatty acids (LCFA) to inner mitochondrial membrane for oxidation ( 24 ). The effects of L-carnitine on growth indicators were inconsistently. Some researchers mentioned useful effects of addition of L-carnitine to broiler diets, while some researchers reported no effects. Carroll and Cote ( 25 ) mentioned that carnitine has beneficial effects on animal productive performance by enhance resistant for metabolic diseases, preventing diseases, increase immune system and plays an important role in metabolism and physiological pathways. Moreover, Lettner ( 26 ) observed improving in live body weight gain, feed efficiency, decrease in serum triglycerides and cholesterol in broilers fed diets added with carnitine. However, not effect of carnitine on broiler productive performance was adverse in results of some studies ( 3 ). Recent studies have suggested that methionine in excess recommendations may result to enhance productive performance, especially body weight gain and feed conversion ratio ( 27 ). Carnitine is an endogenous substance that plays as a carrier for long chain fatty acids across through mitochondrial membranes which necessary for β-oxidation and ATP production. Gülçin ( 28 ) have demonstrated that carnitine represented a best antioxidant. Also, carnitine play role as scavenger against free radicals such as 1, 1- diphenyl-2-picryl-hydrazyl radical, superoxide anion radical (O:), hydrogen peroxide (OH). Carnitine might interfere with the reactive oxygen species (ROS) formation and chelate metal ferrous ions ( 28 ). Moreover, Lee, Lin ( 29 ) reported carnitine responsible for buffering fatty acids for exceed acetyl groups (buffer function) in mitochondria, decreasing mitochondrial free radicals production during hypoxia or substrate excess, especially in tissues.

Authors' Contribution

Study concept and design: A. M. A.

Acquisition of data: A. M. A.

Analysis and interpretation of data: A. M. A.

Drafting of the manuscript: A. M. A.

Critical revision of the manuscript for important intellectual content: A. M. A.

Statistical analysis: A. M. A.

Administrative, technical, and material support: A. M. A.

Ethics

The study design was approved by the ethics committee of the University Of Anbar, Baghdad, Iraq.

Conflict of Interest

The authors declare that they have no conflict of interest.

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