Effect of coconut oil on growth performance, carcass criteria, liver and kidney functions, antioxidants and immunity, and lipid profile of broilers

The aim of this study is to evaluate the beneficial effects of coconut essential oil on growth performance, carcass criteria, antioxidant status, and immune response of broiler chicks. A total of 192 un-sexed 7-days broiler chicks were divided into six treatment sets with four copies of 8 chicks per set. The groups were as follows: (1) basal diet (without additive), (2) basal diet plus 0.5 ml coconut essential oil/kg, (3) basal diet plus 1 ml coconut essential oil/kg, (4) basal diet plus 1.5 ml coconut essential oil/kg, (5) basal diet plus 2 ml coconut essential oil/kg and (6) basal diet plus 2.5 ml coconut essential oil/kg. The results showed that the most prevalent compound in coconut oil is 6-Octadecenoic acid (oleic acid) representing 46.44% followed 2(3H)-Furanone, dihydro-5-pentyl- (CAS) (11.36%), Hexadecanoic acid (CAS) (4.71%), and vanillin (2.53%). Dietary 1 and 1.5 ml of coconut oil improved significantly the body weight and gain of broiler chickens. Dietary supplementation of 1 ml of coconut oil improved significantly liver function compared to control and other treatment groups. The supplementation with 1 ml coconut oil significantly reduced TG and VLDL compared to control and other treatment groups, while no significant differences in TC, HDL, and LDL due to dietary coconut oil. The present findings showed that dietary coconut oil with 1 and 1.5 ml/kg feed improved significantly antioxidants status through increased antioxidant enzymes like SOD and GSH while decreasing significantly MDA levels compared to control and other treatment groups. Therefore, it was concluded that the diets of broiler chickens could be fortified with coconut oil with 1 or 1.5 ml to improve the growth, feed utilization, and antioxidant status of broiler chickens.

In recent years, there is great attention to the use of natural feed additives in poultry production as a global demand.The successful application of herbal growth promoters increases the profitability of the poultry industry by enhancing feed efficiencies and health conditions 1,2 .The secondary metabolites of herbal plants, including phenolic compounds, saponins, and essential oils, are linked to some of the health benefits 3,4 .
Coconut oil is saturated oil, and medium-chain fatty acid (MCFA) represents about 60% of its total fatty acid composition that contains a chain length of 6 to 12 carbon atoms, which are absorbed directly into the portal circulation without re-esterification in the intestinal cells 5 .The antibacterial properties, antioxidant activity, and anti-inflammatory effect of coconut oil make it a valuable feed additive in poultry feed 6,7 .The main natural antioxidants found in coconut oil include capric acid, tocotrienols, and lauric acid.
In broiler chickens, coconut oil significantly increased the growth through the 1-21-days period (9.9%) compared the fish oil-diet 8 .The supplementation with coconut oil significantly increased superoxide dismutase (SOD) activity compared to the fish oil group.Besides, coconut oil-supplemented rations significantly decreased plasma malondialdehyde (MDA) compared to the fish oil diet 8 .While, Wang et al. 9 stated that a coconut oil -supplemented diet has no impact on body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR).In addition, coconut oil improves the digestion of fats and the performance index during coccidiosis infection 9 .
It is hypothesized that the dietary addition of coconut oil is expected to exert beneficial effects on broiler chicks.Thus, this study aimed to determine the impact of coconut essential oil on growth performance, carcass criteria, liver and kidney function, antioxidant and immunity, and lipid profile of broiler chicks.Animals, design and diets.One hundred ninety-two broiler chicks were divided into six groups sets with four replicates of 8 chicks per set.The groups were as follows: (1) basal diet (control), (2) basal diet plus 0.5 ml coconut essential oil/kg, (3) basal diet plus 1 ml coconut essential oil/kg, (4) basal diet plus 1.5 ml coconut essential oil/kg, (5) basal diet plus 2 ml coconut essential oil/kg and (6) basal diet plus 2.5 ml coconut essential oil/kg.We provided standard broiler rations (National Research Council, 1994).Water and food were available freely.Two phases of commercial diets were administered: the beginning (0-3 weeks) and the finishing phase (4-5 weeks).Table 1 indicates the form and structure of trade broiler rations.

Growth parameters.
Live body weight and weight gain data are presented in Table 3.The supplementation with 1 and 1.5 ml of coconut oil improved significantly body weight and gain (quadratic p < 0.01).In contrast, 2.5 ml of coconut oil impaired significantly body weight and gain.With the same trend, dietary supplementation of 1 ml of coconut oil improved significantly FCR (Table 4) while 2.5 ml level increased FCR compared to other levels and control groups.Feed intake increased significantly due to dietary supplementation of 2.5 ml of coconut oil (Table 4).

Carcass measurements.
No significant changes were seen among all the carcass parameters examined (dressing, liver, gizzard, and giblets) in response to coconut oil (Table 5).
Liver and kidney functions.Regarding liver function (Table 6), dietary supplementation of 1 ml of coconut oil improved significantly (linear p < 0.01) liver function in comparison to the control and other treatment groups.The addition of coconut oil to broiler diets has no significant effect on total protein, albumin, globulin, and creatinine.The supplementation with coconut oil linearly increased ALT compared to the control group  Lipid profile.The supplementation with 1 ml coconut oil significantly reduced TG and VLDL compared to control and other treatment groups (Table 7) while no significant differences in TC, HDL, and LDL due to dietary coconut oil.
Antioxidant status and immunity.Regarding immune response and antioxidants status (Table 8), the present findings showed that dietary coconut oil with 1 and 1.5 ml/kg improved significantly antioxidants status through increased antioxidant enzymes like SOD and GSH while decreasing significantly MDA levels compared to control and other treatment groups.However, coconut supplementation has no significant effect on immune response.

Discussion
Our findings showed that dietary coconut oils up to 1.5 ml/kg significantly improved body weight and weight gain compared to a control group, this might be due to the bioactive compounds in coconut oil 13,14 .On the same context, use of coconut oil in broiler diets increased the growth rate during the 1-21-days period (9.9%) compared the fish oil-diet 8 .Moreover, it is suggested that that plant-derived essential oils can increase appetite.The digestion and absorption of nutrients in the gut are also improved by herbal supplements 15 .Several studies demonstrated the promotional effects of dietary coconut oil on growth performance in broilers 13 , and Japanese quail 16 .www.nature.com/scientificreports/Moreover, dietary 2% coconut oil improved growth performance in broiler chicks challenged with coccidiosis 17 .However, dietary coconut has no effect on weight gain of broiler chickens 18 .In the same line dietary coconut at 1% had not negative effect in European quail performance 19 .These discrepancies in the results may be due the dietary level or the extraction process.The present findings showed that the best FCR was obtained by 1 ml of coconut , while the worst level was 2.5 ml level, the reason for that might due to increase the level of caprylic acid supplementation that affect feed conversion in broiler chickens 20 , however the mode of action of caprylic acid in affecting FCR is not clear .Inclusion of 1 ml coconut oil in to broiler diets improved liver function.It could be due to the medium-chain fatty acids (MCFA), particularly lauric acid, in coconut oil's components, which have antioxidant and antiinflammatory characteristics 21 .These findings point to a protective effect of PUFA on the integrity of hepatic cell membranes, which may be caused by increased phospholipids, which are a crucial component of cell membrane integrity and contain two hydrophobic long-chain fatty acids LCFA 22,23 .
Regarding to lipid profile, our findings showed that coconut oil inclusion at 1 ml coconut oil reduced significantly TG and VLDL.Our results agree with Attia et al. 8 who found that dietary coconut oil has a positive effect on lipid profile in broiler chickens.Our finding showed that the lack of an impact on HDL cholesterol, demonstrated that MCFA in the form of coconut oil didn't lower cholesterol by bringing LDL cholesterol to the liver where it could be processed again, but rather by some other mechanisms 18 .Due to their effect on raising HDL-C while lowering LDL-C, the hazardous lipoprotein segment, UFA and beneficial PUFA have been shown in previous research to have desirable and healthful effects on plasma lipids [24][25][26] .
The present findings showed that dietary coconut oil with 1 and 1.5 ml /kg improved significantly antioxidants status through increased antioxidant enzymes like SOD and GSH while decreasing significantly MDA levels in comparison to the control and other groups.These results agree with Attia et al. 8 who found that dietary supplementation of coconut oil decreased plasma MDA compared to the fish oil diet in broiler chickens.The main natural antioxidants found in coconut oil include capric acid, tocotrienols, and lauric acid.It has been reported that coconut oil as a source of lauric acid has an antioxidant activity in broilers diet 27 .Moreover, dietary coconut oil in rabbit diet improved GSH and SOD 12 , improved the antioxidant status in coconut oil supplemented diets might due to the bioactive ingredients that existing in coconut like higher saturated fatty acids and polyphenolic compounds, that have antioxidant properties 28 .Boosting the secretion of digestive enzymes, endocrine function, immune function, and antioxidant status are just a few of the multiple ways that phytogenic supplements may perform 29,30 .Our results indicated that broilers' growth performance and health condition could be improved in the future by using coconut oil as a natural antioxidant.
In the present study, dietary supplementation with coconut oil has not significant effect on immune response; these results disagree with previous one in broilers 24 they found that the coconut-enriched diets in broiler chickens significantly increased α1-globulin.Moreover, El-Abasy et al. 21suggested that including dietary coconut (2%) in rabbit diets may have a positive impact on the animals' health and immunological functions.With the same trend, El Kholy et al. 31 found that dietary supplementation of 1.5 or 2% of coconut oil in Domyati ducklings diets increased plasma immunoglobulin levels, which collectively suggested that the immunological response had improved.The non-significant effect of coconut oil as immune stimulator in our study may be due to unstressed condition that birds reared in.

Conclusion
Our findings showed that dietary coconut oil with 1 and 1.5 ml improved significantly body weight, gain, and FCR in broiler chickens.Also, the antioxidant status of broiler chickens was improved due to dietary coconut oil.However, the immune response has not affected by coconut oil supplementation.The supplementation with 1 ml coconut oil reduced TG and VLDL compared to control and other treatment groups.Therefore, the diets The experiment was accepted by the Ethics Committee of the Local Experimental Animals Care Committee and performed under the guidelines of the Department of Poultry, Faculty of Agriculture, Zagazig University, Egypt (ZU-IACUC/2/F/56/2021).The study was conducted following ARRIVE guidelines.

Table 1 .
Composition and chemical analysis of the basal diets (starter and finisher diets).

Table 2 .
Bioactive chemical constituents assigned in coconut essential oil by GC-MS analysis.

Table 3 .
3ive body weight (LBW) and body weight gain (BWG) of broiler chicks as affected by dietary levels of coconut essential oil.Means in the same column significantly different (p < 0.05). 1 LBW live body weight, BWG Body weight gain.2SEMstandarderrormeans.3pvalue (Linear and quadratic).

Table 4 .
3eed intake (FI) and feed conversion ratio (FCR) of broiler chicks as affected by dietary levels of coconut essential oil.Means in the same column significantly different (p < 0.05). 1 FI feed intake, FCR feed conversion ratio.2SEMStandardErrorMeans.3pvalue (Linear and quadratic).

Table 6 .
3iver and kidney functions of broiler chicks as affected by dietary levels of coconut essential oil.Means in the same column significantly different (p < 0.05). 1 TP total protein, ALB albumin, Glob globulin, ALT alanine aminotransferase, AST aspartate aminotransferase.2SEMStandardErrorMeans.3pvalue (Linear and quadratic).

Table 8 .
3ntioxidants indices and immune parameters of affected by dietary levels of coconut essential oil.Means in the same column significantly different (p < 0.05). 1 SOD superoxide dismutase, MDA malondialdehyde, GSH Glutathione reduced, IgG immunoglobulin G, IgM immunoglobulin M.2SEM Standard Error Means.3pvalue (Linear and quadratic).