Citrus Peel Oils Supplementation in Broiler Diet : Effects on Performance , Jejunum Microflora and Jejunum Morphology

This study was carried out to determine citrus peel oils (orange, lemon, bergamot) as food supplementation in different levels on performance, microflora and morphology in broilers. The trial consisted of 1-day-old male and female Ross 308 chicks (250 male 250 female). The study consisted of 10 groups in total and each group was replicated five times. Experimental diets were prepared by adding orange, lemon and bergamot peel oil levels (1,2 and 3 mL/kg) to basal diet. It was observed that the supplementation of citrus peel oils to the diet improved significantly the feed conversion rate. Especially the lowest feed intake and the best feed conversion ratio were received from broilers which were fed 3 mL/kg of orange peel oil. The study shows that the count of Escherichia coli (E.coli) and lactic acid bacteria in the jejunum decreased significantly with the supplementation of bergamot peel oil to broilers diets. Citrus peel oil, in contrast to bergamot peel oil, significantly increased lactic acid bacteria count. The highest lactic acid bacteria count was determined in birds fed 3 mL/kg with orange peel oil. In the result of this study, both the length and density of villi and the density of blood and lymphatic capillary in the jejunum increased significantly by dietary 3 mL/kg orange peel oil supplementation. Finally, our results indicate that, especially 3 mL/kg orange peel oil has positive effects on performance, jejunum microflora, and jejunum morphology. It could be advised to supply broilers feed with 3 mL/kg orange peel oil as feed additives.


IntRoduCtIon
In the present decade, antibiotics as an alternative in feed, has been researched by many scientists.It is known that the essential oils extracted from spices and herbs can be used as replacement for antibiotic feed additives.It is reported that herbal extracts or active substances may increase feed intake and may improve secretion of endogenous digestive enzymes (Craig, 1999;Jamroz et al., 2003).Besides that, it has been reported that essential oils have antibacterial effects in chickens (Cowan, 1999;Faleiro et al., 2003;Bölükbaşi et al., 2008Bölükbaşi et al., , 2009;;Giannenas et al., 2014;Skoufos et al., 2016).
Orange (Citrus sinensis), lemon (Citrus lemon) and bergamot (Citrus bergamia) aromatic herbs, are members of the Rutaceae family.By using a cold-pressing or steam distillation method, the essential oil is extracted from the peel of the fruit.Citrus essential oils contain high amounts of limonene and linalool.It is reported that the chemical composition of these oils was strongly influenced by harvesting time (Kırbaşlar et al., 2001;Zantar et al., 2015).
Some researchers recorded that the supplementation of the mixture of herbs (thyme, bay, sage, myrtle leaf, fennel and citrus essential oil) to the broiler´s diets, significantly improved live weight, feed efficiency Citrus Peel Oils Supplementation in Broiler Diet: Effects on Performance, Jejunum Microflora and Jejunum Morphology and carcass characteristics of the broilers (Alçiçek et al., 2003(Alçiçek et al., ,2004)).
It is reported that citrus sinensis peel mixtures of organic acid and essential oils (thyme, bay leaf, fennel, sage, myrtle and orange peel oils) increased live body weight and feed conversion ratio in broilers (Bozkurtet al., 2007).
It was determined that feed conversion rate significantly improved when laying hens were supplemented 1.5 mL/kg bergamot oil (citrus bergamia) in their feed (Bölükbaşı et al., 2010).
In some studies, different essential oils such as thyme, sage, rosemary and nigella sativa were seen to be more active against strains of E. coli in layers (Bölükbaşı et al., 2007(Bölükbaşı et al., , 2008(Bölükbaşı et al., , 2009) ) and broilers (Erhan et al., 2012).Jamroz et al. (2003) found that plant extracts decreased the number of E. coli and Clostridium perfringens in total in the intestines of broiler chickens.Pourhossain et al. (2012) reported that dried citrus sinensis peel increased lactic acid bacteria count in ileum of broilers at 14 d.
Antioxidative and antimicrobial features of plant oils have been well documented by many researchers.However, a few studies have been conducted on supplementing diets with plant extracts to investigate the action mode of active plant oils, morphologically and histologically in animals (Hassan et al., 2011;Murakami et al., 2014).Therefore, the present study was carried out to determine the effects of citrus peel oils (bergamot, orange, lemon) in different levels on performance, jejunum morphology and intestinal microflora in broilers.

MAteRIAl And MethodS
Materials: Ross 308 broiler chickens were used in the study which were 1-day-old and 500 (250 male 250 female) in total.The chicks were randomly assigned to 10 treatment groups; five replicates with ten chicks in every cage.Ten treatments consisted of a control (basal diet), 1 mL/kg orange peel oil, 2 mL/kg orange peel oil, 3 mL/kg orange peel oil, 1 mL/kg lemon peel oil, 2 mL/kg lemon peel oil, 3 mL/kg lemon peel oil, 1 mL/kg bergamot peel oil, 2 mL/kg bergamot peel oil, 3 mL/kg bergamot peel oil (citrus oils were purchased from a commercial company, in Turkey).
Experimental procedures: Body weights of the chickens were recorded on days 1 and 42, and feed intake was measured over this period on day 42.The research protocol was approved and conducted in accordance with the Animal Ethics Committee Guidelines of Atatürk University (protocol number: 2009/55).
Five birds selected randomly from each treatment were slaughtered (neck cutting).The carcasses were plucked and the heads, necks, shanks as well as feet were removed.The liver and heart were dissected from the viscera.The carcass yield was calculated.
The carcasses of the birds were opened, and 2 g of intestinal contents from jejunum were transferred to sterile plastic bags.All samples were processed within the same day for enumeration of microbial populations.The number of lactic acid bacteria and E. coli were determined by using the methods reported by Merck (1998) and Baumgart et al. (1986), respectively.
Dissecated jejunum was sent to the laboratory for histopathologic analyses by putting into the tubes with 10% formalin.Jejunum tissues were rapidly kept in 10% buffered formalin for 24-48 hours for histopathological examination.After fixation, each liver-tissue sample was then routinely processed and embedded in paraffin.After embedding, 5-μm sections were taken from the tissue´s blocks and then stained with hematoxylin-eosin (H&E).These sections were stained with H&E and all jejunums were examined by light microscopy for histological evaluation of the following parameters in Table 1 (Pellegrino et al., 1979).
To analyse the data, one-way analysis of variance (ANOVA) was applied by using the statistical package SPSS for Windows (SPSS, 1999).

ReSultS And dISCuSSIon
The growth performance, total feed intake, carcass yield, weight of liver and hearth of the broilers are shown in Table 3.The supplementation of citrus peel oil (bergamot, lemon, orange) in the diet had no effects on weight gain, carcass yield or weight of liver and hearth.But, total feed intake of the chicks (p<0.05)reduced significantly with bergamot, lemon and orange peel oil.Dietary citrus peel oil suplementation significantly (p<0.01)improved feed conversion rate.The best feed conversion rate was obtained in the group fed the diet containing 3 mL/kg orange peel oil.
The results of this study showed that supplementing the diet with citrus peel oil had no effect on gaining weight.In contrast to the present findings, Alçiçek et al. (2004) reported that adding a mixture of herbal essential oils to the diet, increased body weight gain of the broilers.Dietary supplementation of citrus peel oil significantly improved feed conversion rate and decreased feed intake.Similarly, Çabuk et al. (2006) reported that the feed conversion rate improved and feed intake was decreased by the mixture of herbal essential oil supplements in breeder flocks.Erhan et al. (2012) found that the supplementation of pennyroyal to broiler diet decreased feed intake and improved feed conversion ratio.They also say that pennyroyal antimicrobial substances may inhibit intestinal pathogenic organisms and improve digestion and absorption, thus, acting as a growth promoter.The improvement in feed conversion rate in this study was in accordance with results which were reported by Alçiçek et al. (2003).However, in contrary to these findings, Botsoglou et al. (2004), Demir et al. (2003), Eclache & Besson (2004) and Hernández et al. (2004) found that the addition of an essential oil isolated from oregano to broiler diet, had no beneficial effect on feed conversion ratio.The reason of this can be the fact that the level of active ingredients of the citrus peel oil was different and it was added to the feed in different levels, and also the fact that different races were used.
There is no beneficial effect of the citrus peel oils in the liver and hearth weight of the broiler chicks in this study.Likewise, Lee et al. (2003) reported that thymol did not influence liver weight.This, however, contradicts the findings of Bölükbaşı et al. (2006) who reported that thymol resulted in reduced liver weight.
Broilers fed the diet with citrus peel oil had significantly (p<0.05)decreased E. coli in the jejunum (Table 4).3 mL/kgbergamot and 1mL/kg lemon group had the lowest average number of E. coli in the jejunum.The addition of orange and lemon peel oils to the broiler's diet led to a significant (p<0.01)increase in the lactic acid bacteria count.Supplementation of bergamot peel oil resulted in a lower lactic acid bacteria, 2 and 3 mL/kg bergamot group had the lowest average count of lactic acid bacteria in the jejunum, compared to other groups.The highest lactic acid bacteria count was determined in bird feed 3 mL/kg orange peel oil.Besides, feed conversion rate was the best in this group.Therefore, we can say that citrus peel oil improved feed conversion rate by increasing the number of lactic acid bacteria.
There are many studies that show that essential oils might inhibit pathogenic bacteria in the small intestine.It is reported that herbal extract has antimicrobial effect againts E. coli in poultry and pigs (Bölükbaşı et al., 2007(Bölükbaşı et al., , 2009;;Bruggeman et al., 2002;Kamel 2001;Mitsch et al., 2004).The results of trials, which those researchers conducted, fit the findings which we carried out.Erhan et al. (2012) found that pennyroyal supplementation in the diet of broilers, increased the lactic acid count in the jejunum, improved the microflora balance, and decreased the E. coli count.Therefore, in this study, increased Lactobacilli counts could be due to antibacterial effect of citrus peel oils.Similar to the results of our study, Tucker (2002) reported that blends of essential oils increased the number of lactic acid in broilers.But, some researchers reported that herbal dietary extracts (Demir et al., 2003) and essential oils (Cross et al., 2007;Kırkpınar et al., 2011) have no effect on the population of microorganisms of broilers.The reason of this, is that essential oil was added to the feed in different levels.
The density of blood and lymphatic capillaries; and the length and density of villus of jejunum are shown in Table 5.It is observed that the density score of blood and lymphatic capillaries of the birds fed with the diet containing 3 mL/kg orange peel oil, was very dense.
The density score of blood capillaries and lymphatic capillaries of the groups consuming 1mL/kg citrus peel oil (bergamot, lemon and orange) were determined as rare.The increase of nutrient absorbtion surface and the amount of nutrient absorbtion is related to the increase of the density of blood capillaries.However, *:1: rare 2: dense 3: very dense.**: 1;short and rare, 2; long and dense, 3; very long and very dense.Citrus increasing the density of lymphatic capillaries causes the increase, both in the absortion surface and the amount of oil.The lowest density and length of villus was determined in birds fed with 1mL/kg of bergamot, lemon and orange peel oils.Density and length of villus of the control groups added 2mL/kg lemon and 2 mL/kg orange were found long and dense.Supplementation of broilers diets with a relatively high concentration of bergamot, lemon and orange peel oil (3mL/kg) increased the density and the length of the villus in the jejunum.The villi were found to be very long and dense in these groups.The increase of villi length and density is an indicator of increased intestinal absorbtion surface.Similar to our study, Hassan et al. (2011) found that the addition of 0.5 and 1% of essential oils to broilers diets, increased villus height significantly.Also, Murakami et al. (2014) reported that adding essential oil to the broiler´s ration increased villus height in the jejunum on day 14.In contrast, it was reported that supplementing essential oils to the broiler´s diets had no effect on villus height in the jejunum statistically, but it increased villus height numerically (Jamroz et al., 2006).In this study, the performance values such as feed consumption and feed conversion ratio were determined to be best in the 3 mL/kg of orange peel oil, depending on the increase, both in the length and density of villi and the density of blood and lymphatic capillary.Some researchers reported that the morphological feature of villius was corresponded to the increase of feed intake and rapid growth rate of the broilers, showing a possible relationship between intestinal function and intestinal villus histological alterations (Yamauchi & Isshiki, 1991).It was reported that the microvilli might be protected by some components of spice plants.Intrinsic antioxidative activity, at both cell and tissue levels, have had effects on these functions of the intestinal mucosa layer (Rhodes 1996;Best 2000;Tschirch 2000).It was reported that reducing intestinal microbial load, by antimicrobial agents, caused decrease of toxins associated with negative changes in the intestinal morphology (Xu et al., 2003).The highest total score was obtained from the group fed with the diet containing 3mL/kg orange peel oil.The supplementation 1 mL/kg level of bergamot, lemon and orange peel oil resulted in a lowest total score compared to the other groups.
Consequently, citrus peel oils had positive effects on the performance, intestinal micro flora and jejunum morphological properties.Supplementation of 3 mL/ kg orange peel oil improved feed conversion rate and increased amount of lactic acid bacteria and villus dense in jejunum compared to other groups.Based on the results of this study, it can be recommended to supply broiler´s feed with 3 mL/kg orange peel oil.

Table 1 -
Histopathological scoring system for tunica mucosa.

Table 4 -
Effects of dietary supplementation of citrus peel oils on microflora in jejunum of the broilers.
a, b, c,d,e,f : Column means with no common superscript differ significantly SEM: standarderrorofmeans.

Table 3 -
Effects of dietary supplementation of citrus peel oils on performance and some carcass characteristics of the broilers.
Citrus Peel

Table 5 -
Effects of dietary supplementation of citrus peel oils on in jejunum morphology of the broilers.