Abstract
The influence of dietary L-carnitine and lysine (Lys)-methionine (Met) levels on productive performance, haematology and triiodothyronine hormone levels of broilers was investigated. Dietary treatments included different L-carnitine (0, 50 and 100 mg/kg) and Lys-Met (0%, 10% and 20% over National Research Council (NRC) (1994) recommendation levels), under a 3 × 3 factorial design arrangement. From the findings, the body weight (BW) gain, feed intake and feed conversion ratio (FCR) of broilers were significantly (p < 0.05) influenced by dietary treatments in the different growing stages. Conversely, carcass yield and organs did not differ (p > 0.05) among treatments, whereas meat-cuts varied significantly when broilers were fed experimental diets. Moreover, the dietary inclusion of the highest levels of amino-acids (L-carnitine (100 mg/kg) and Lys-Met (+20%)) produced a reduction (p < 0.05) of blood uric acid, also leading to the highest triiodothyronine (T3) hormone levels. Based on the obtained results, it can be concluded that the combination of extra levels of L-carnitine associated with Lys-Met positively influenced the performance traits in broiler chickens.
1. Introduction
Essential amino acids (AA) are critical for the proper development of poultry. As feed efficiency is crucial factor for intensive rearing systems of poultry, it is imperative to formulate diets that improve and maximize animal production [,].
The importance of utilizing the correct amount of balanced dietary AA for poultry is a high priority issue due to its significant impact on broiler growth and meat yield. Therefore, defining dietary AA needs for optimum production is of utmost importance. Essential AA recommendations currently used for broilers by the National Research Council (NRC) Nutrient Requirements of Poultry of 1994 are largely based on results of trials conducted several decades ago [], and time has passed and scientific advancement has been made since 1994; thus, there is the need for an update poultry NRC guidelines for modern poultry production [].
L-carnitine (3-hydroxy-4-N-trimethylaminobutyrate) plays a key-role in long-chain fatty acid oxidation by enabling its transport from the cytoplasm to the mitochondrial matrix [,]. In broilers, fed diets supplemented with L-carnitine facilitate the beta-oxidation of fatty acids from fat sources, and thus improving productive performance [,]. With regard to Lys, it was even reported that Lys in excess of an animal´s requirement reduces the concentrations of free and total L-carnitine in tissues. This is most likely explained by the fact that only protein-bound—not free—Lys can be methylated in mammals and avian species. In fact, a large body of evidence has been provided that proves L-carnitine biosynthesis is limited by the availability of free Nε-trimethyllysine [,], which serves as the initial L-carnitine precursor being enzymatically converted into γ-butyrobetaine. Both Lys and Met appear to be the significant limiting amino acids in poultry nutrition, and therefore they must be included in diets [,]. The immune role of both amino acids has been studied in many livestock species, involved directly or indirectly in regulatory actions. According to Derballa et al. [], the deficiency of Lys and Met in fish diets significantly decreased blood lymphocytes, monocytes, basophils and eosinophils levels. Nevertheless, the effect of simultaneous feeding of L-carnitine levels and excess Lys-Met has not been deeply studied.
Therefore, the objective of the present study was to evaluate the effect of different dietary levels of L-carnitine and Lys-Met on productive performance, haematology and the triiodothyronine hormone levels of broilers.
2. Materials and Methods
This experiment was conducted at the poultry farm facilities of the Chukam village, Khomam, Iran and all the procedures were assessed and approved by the Institutional Animal Care and Ethics Committee in Rasht Branch, Islamic Azad University (Rasht, Iran).
Prior to bird allocation, facilities and equipments were disinfected. Five hundred and forty male Ross-308 chicks (Aviagen, Newbridge, Scotland, UK) were assigned randomly to nine different dietary treatments diets with four replications per treatment. Each replication group of 15 mixed birds was reared in 1 × 2 m wire mesh pen. The initial body weight (BW) was similar (44.2 ± 0.8 g) for all broilers. Each cage was equipped with automatic drinkers and a pan feeder. Feed and water were offered ad libitum. A light schedule, temperature, humidity, vaccination, and general management were performed according to the Ross broiler manual [].
Dietary treatments included: a control treatment (T1) having the levels of Lys-Met according to NRC [] recommendations (Table 1); whereas the other treatments included extra levels of Lys-Met as: L-carnitine 0, 50 and 100 mg/kg, and Lys-Met 0%, 10% and 20% over the recommendations [] (T2–T9), under a 3 × 3 factorial design arrangement (Table 2).
Table 1.
Ingredients and nutrient composition of basal diets fed to broiler chickens.
Table 2.
Levels of L-carnitine, lysine and methionine of the experimental dietary treatments.
Broilers BW and feed intake were evaluated weekly and feed conversion ratio (FCR) was calculated by dividing total feed consumption by BW gain. Carcass measurements were carried out as reported by Jahanpour et al. []. Briefly, at 42 days of age, three representative chicks per replicate were selected and sacrificed; then, after slaughter, broilers were eviscerated, and the carcass and different organs and meat-cuts were weighted.
Blood constituent evaluations were carried out following Shabani et al. []. Briefly, at day 42, three broilers per group, for a total of 12 subjects per treatment, were selected. Blood was collected from the wing veins into EDTA tubes and immediately transferred to the biochemical and hematological laboratory for analysis. Biochemical analysis, including the levels of plasma glucose, cholesterol, triglyceride, and uric acid were determined using diagnostic kits (Teif-Azmoon Pars Co, Tehran, Iran). The triiodothyronine (T3) hormone determination was carried out according to Seidavi et al. [].
Analysis of variance under a 3 × 3 factorial design with three L-carnitine treatments (0, 50, and 100 mg/kg in diet) and three Lys-Met treatments (0%, 10% and 20% over NRC recommendations) [], using a one-way procedure of analysis of variance (ANOVA) was performed. The general linear model (GLM) procedure was used to analyse data (SPSS software version 17.0). Means among groups were compared by using least significant difference (LSD). The significance level was set at p < 0.05. Results are reported as mean ± standard error of the means (SEM).
3. Results
Based on the different levels of L-carnitine and Lys-Met supplied, significant differences among dietary treatments were found in broiler BW gain (Table 3), where supplementing L-carnitine (50 mg/kg) and Lys-Met (+20%) during the grower period led to the best gains (p < 0.05). The average feed intake and FCR was significantly affected by treatments, especially during the starter rearing period (1–14 days of age). The feeding of high levels of amino-acids favourably regulated the efficiency of broilers; however, during the grower and finisher periods, feed efficiency was not significantly modified by diets (Table 4 and Table 5, respectively). As reported in Table 6, broiler carcass components showed a substantial reduction liver percentage (p < 0.05) when fed L-carnitine (50 mg/kg) and Lys-Met (+20%). Supplementing extra levels of L-carnitine and Lys-Met improved (p < 0.05) the yield of meat-cuts (breast, drumstick and wings); conversely, no effect was detected in eviscerated carcass yield, heart, pancreas, gizzard and abdominal fat (Table 6).
Table 3.
Average body weight gain (g/day) of broilers fed different levels of L-carnitine and lysine-methionine (Lys-Met).
Table 4.
Average feed intake (g/day) of broilers fed different levels of L-carnitine and lysine-methionine (Lys-Met).
Table 5.
Feed conversion ratio (g/g) of broilers fed different levels of L-carnitine and lysine-methionine (Lys-Met).
Table 6.
Carcass traits (%) of broilers fed different levels of L-carnitine and lysine-methionine (Lys-Met).
On day 42, some blood parameters were affected by dietary treatments (Table 7). The lowest blood total cholesterol level was found in the control group, whereas the highest was found in broiler fed L-carnitine (100 mg/kg) and Lys-Met (+20%). Furthermore, the feeding of the same diet showed the highest blood uric acid concentration (p < 0.05). Blood glucose and triglycerides were not affected by dietary treatments. As reported in Table 8, the blood triiodothyronine (T3) hormone concentration varied significantly among groups, where the highest levels were detected in broilers fed L-carnitine (100 mg/kg) and Lys-Met (+20%) compared to the other treatments; conversely, no difference in spleen percentage was found among dietary groups.
Table 7.
Blood constituents (mg/dl) of broilers fed different levels of L-carnitine and lysine-methionine (Lys-Met).
Table 8.
Immunity and hormonal parameters of broilers fed different levels of L-carnitine and lysine-methionine (Lys-Met).
4. Discussion
Evaluating the different combinations of dietary L-carnitine and Lys-Met, we found considerable differences of broiler performances. In particular, the grower period demands a high synthesis of protein which could explain the significant broiler body weight gain increase by the experimental groups. The greatest improvement in feed intake and feed conversion ratio, was obtained broilers fed the highest levels of L-carnitine and Met-Lys treatments. This is in agreement to a recent study conducted by Ghoreyshi et al. []. Conversely, it was suggested that concentrations of Lys and Met above NRC [] recommendations improve broiler productive traits, such as breast meat yield, body weight gain and feed conversion ratio [].
Among carcass components evaluated, there were no significant differences, although liver mass displayed a significant increase. The high bioavailability of Lys-Met by diet could intensify the liver functionality to produce L-carnitine. The biosynthesis of L-carnitine takes place in the kidneys and liver from Lys and Met []. Both Lys and Met tend to stimulate pancreas function for the further secretion of insulin into the blood. Especially in broilers, insulin promotes the lipoprotein metabolisms and amino-acid release from different bodily sources []. A high concentration of insulin and glucagon on plasma had been found in broilers with considerable body weight and fat content [,]. The current study showed no significant dietary effect on glucose and triglycerides, whereas the feeding of highest levels of amino-acids (L-carnitine (100 mg/kg) and Lys-Met (+20%)) produced significant less amount of blood uric acid. In this regard, there is a direct relationship of plasma uric acid and excreta uric acid as dietary nitrogen intake increases []. As the primary end product of nitrogen metabolism, uric acid, and not urea, is generated in broilers []. When daily Lys increased in the broiler diet, plasma uric acid and excreta uric acid decreased []. Another investigation has reported no changes in plasma uric acid concentrations after dietary Lys supplementation []. Broilers fed the highest levels of L-carnitine and Lys-Met showed a significantly high T3 hormone concentration. Thyroid hormones play a significant role in controlling bird oxidative metabolism; therefore, any pronounced functional changes are expressed in an altered metabolic rate [].
5. Conclusions
Based on the obtained results, our study demonstrated that the addition of a combination of amino acids (L-carnitine and extra level of Lys-Met) to the diet affected the performance and health status of the broilers chickens positively.
Author Contributions
A.S., H.M.-G. and M.B. conceived and designed the experiments; H.M.-G., M.B., A.Q. and H.A. performed the experiments; A.S., H.M.-G., M.B., E.P. and V.T. analyzed the data; A.S., H.M.-G., V.T., V.L. wrote the paper. All authors have read and agreed to the published version of the manuscript.
Funding
Financial support by Rasht Branch, Islamic Azad University, grant number 17.16.4.6457 is gratefully acknowledged.
Acknowledgments
The Authors would like to thank the support of technicians of the Institutions.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Laudadio, V.; Tufarelli, V. Dehulled-micronised lupin (Lupinus albus L. cv. Multitalia) as the main protein source for broilers: Influence on growth performance, carcass traits and meat fatty acid composition. J. Sci. Food Agric. 2011, 91, 2081–2087. [Google Scholar] [CrossRef]
- Alagawany, M.; El-Hack, M.E.A.; Laudadio, V.; Tufarelli, V. Effect of low-protein diets with crystalline amino acid supplementation on egg production, blood parameters and nitrogen balance in laying Japanese quails. Avian Biol. Res. 2014, 7, 235–243. [Google Scholar] [CrossRef]
- Applegate, T.J.; Angel, R. Nutrient requirements of poultry publication: History and need for an update. J. Appl. Poult. Res. 2014, 23, 567–575. [Google Scholar] [CrossRef]
- Corduk, M.; Ceylan, N.; Ildiz, F. Effects of dietary energy density and L-Carnitine supplementation on growth performance, carcass traits and blood parameters of broiler chickens. S. Afr. J. Anim. Sci. 2007, 37, 65–73. [Google Scholar] [CrossRef]
- Rehman, Z.; Naz, S.; Khan, R.U.; Tahir, M. An update on potential applications of L-carnitine in poultry. World Poult. Sci. J. 2017, 73, 823–830. [Google Scholar] [CrossRef]
- Farrokhyan, P.; Bouyeh, M.; Lartey, F.; Seidavi, A.R. The effects of dietary L-carnitine and gemfibrozil on performance, carcass characteristics, cholesterol and triglycerides in broiler chicks. Avian Biol. Res. 2014, 7, 160–166. [Google Scholar] [CrossRef]
- Zhang, Y.; Xu, B.Y.; Zhao, L.; Zhu, L.Y.; Batonon-Alavo, D.; Jachacz, J.; Qi, D.S.; Zhang, S.J.; Ma, L.B.; Sun, L.H. Increased consumption of sulfur amino acids by both sows and piglets enhances the ability of the progeny to adverse effects induced by lipopolysaccharide. Animals 2019, 9, 1048. [Google Scholar] [CrossRef]
- Hoppel, C.L.; Davis, A.T. Inter-tissue relationships in the synthesis and distribution of carnitine. Biochem. Soc. Trans. 1986, 14, 673–674. [Google Scholar] [CrossRef]
- Rebouche, C.J.; Lehman, L.J.; Olson, L. є-N-Trimethyllysine Availability regulates the rate of carnitine biosynthesis in the growing rat. J. Nutr. 1986, 116, 751–759. [Google Scholar] [CrossRef]
- Harms, R.H.; Russell, G.B. Adding methionine and lysine to broiler breeder diets to lower feed costs. J. Appl. Poult. Res. 1998, 7, 202–218. [Google Scholar] [CrossRef][Green Version]
- Ghoreyshi, S.M.; Omri, B.; Chalghoumi, R.; Bouyeh, M.; Seidavi, A.; Dadashbeiki, M.; Lucarini, M.; Durazzo, A.; Hoven, R.; Santini, A. Effects of dietary supplementation of l-carnitine and excess lysine-methionine on growth performance, carcass characteristics, and immunity markers of broiler chicken. Animals 2019, 9, 608. [Google Scholar] [CrossRef] [PubMed]
- Derballa, A.E.; Khalil, R.H.; Saad, T.T. Effect of lysine and methionine deficiency on immunity in fresh water fish. J. Arab. Aquacult. Soc. 2010, 5, 65–78. [Google Scholar]
- Aviagen. Ross 308 Broiler: Nutrition Specification; Aviagen Inc.: Scotland, UK, 2007. [Google Scholar]
- NRC (National Research Council). Nutrient Requirements of Poultry, 9th Revised ed.; The National Academies Press: Washington, DC, USA, 1994. [Google Scholar]
- Jahanpour, H.; Seidavi, A.; Qotbi, A.A.A.; Van Den Hoven, R.; Rocha e Silva, S.; Laudadio, V.; Tufarelli, V. Effects of the level and duration of feeding restriction on carcass components of broilers. Archiv. Anim. Breed. 2015, 58, 99–105. [Google Scholar] [CrossRef]
- Shabani, S.; Seidavi, A.R.; Asadpour, L.; Corazzin, M. Effects of physical form of diet and intensity and duration of feed restriction on the growth performance, blood variables, microbial flora, immunity, and carcass and organ characteristics of broiler chickens. Livest. Sci. 2015, 180, 150–157. [Google Scholar] [CrossRef]
- Seidavi, A.R.; Ebrahimi, A.; Qotbi, A.A.A.; Nieto, J.A.G. Effect of different levels of Citrus sinensis peel extract on broiler performance, blood parameters, thyroid gland activity and bone ash. Ind. J. Anim. Sci. 2015, 85, 1225–1228. [Google Scholar]
- Bouyeh, M. Effect of excess lysine and methionine on immune system and performance of broilers. Ann. Biol. Res. 2012, 3, 3218–3224. [Google Scholar]
- Parsaeimehr, K.; Afrouziyeh, M.; Hoseinzadeh, S. The effects of L-carnitine and different levels of animal fat on performance, carcass characteristics, some blood parameters and immune response in broiler chicks. Iran. J. Appl. Anim. Sci. 2014, 4, 561–566. [Google Scholar]
- Sturkie, P.D. Avian Physiology, 6th ed.; Springer Science & Business Media: New York, NY, USA, 2012. [Google Scholar]
- Dupont, J.; Chen, J.; Derouet, M.; Simon, J.; Leclercq, B.; Taouis, M. Metabolic differences between genetically lean and fat chickens are partly attributed to the alteration of insulin signaling in liver. J. Nutr. 1999, 129, 1937–1944. [Google Scholar] [CrossRef][Green Version]
- Baéza, E.; Le Bihan-Duval, E. Chicken lines divergent for low or high abdominal fat deposition: A relevant model to study the regulation of energy metabolism. Animal 2013, 7, 965–973. [Google Scholar] [CrossRef]
- Đaković, N.; Térézol, M.; Pitel, F.; Maillard, V.; Elis, S.; Leroux, S.; Lagarrigue, S.; Gondret, F.; Klopp, C.; Baeza, E.; et al. The loss of adipokine genes in the chicken genome and implications for insulin metabolism. Mol. Biol. Evol. 2014, 31, 2637–2646. [Google Scholar] [CrossRef]
- Donsbough, A.L.; Powell, S.; Waguespack, A.; Bidner, T.D.; Southern, L.L. Uric acid, urea, and ammonia concentrations in serum and uric acid concentration in excreta as indicators of amino acid utilization in diets for broilers. Poult. Sci. 2010, 89, 287–294. [Google Scholar] [CrossRef] [PubMed]
- Miles, R.D.; Featherston, W.R. Uric acid excretion as an indicator of the amino acid requirement of chicks. Proc. Soc. Exp. Biol. Med. 1974, 145, 686–689. [Google Scholar] [CrossRef] [PubMed]
- Abdel-Fattah, S.A.; El-Sanhoury, M.H.; El-Mednay, N.M.; Abdel-Azeem, F. Thyroid activity, some blood constituents, organs morphology and performance of broiler chicks fed supplemental organic acids. Int. J. Poult. Sci. 2008, 7, 215–222. [Google Scholar] [CrossRef]
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