This study was conducted to determine the effects of dietary pennyroyal (Mentha pulegium L.) levels (0, 0.25 or 0.50%) on the growth performance and Escherichia coliand lactic acid bacteria count in the jejunum of broilers. A total of 150 broiler chicks (Ross 308), obtained from a commercial hatchery at 1 day of age, were allocated to 3 dietary treatments (5 replicates each), each treatment with 10 birds per replicate in a completely randomized experimental design. All the birds were housed in batteries from 1 to 21 days, then in grower broiler pens from 21 to 42 days under standard conditions. The average final body weights and body weight gains were similar in all groups. The addition of pennyroyal to the broilers' feed led to a decrease (P < 0.05) in the feed intake. The gain-to-feed ratios for 0, 0.25, and 0.50% dietary pennyroyal were 1.50, 1.50 and 1.41, respectively. The addition of pennyroyal reduced E. coli count and increased the lactic acid bacteria count of the jejunum (P < 0.01). In conclusion, dietary supplementation of pennyroyal improved feed conversion ratio and lactic acid bacteria count, as well as decreased E. coli count, of the jejunum in broilers.
Lactic acid bacteria;
Mentha pulegium L.;
It has been reported that the essential oils improved growth performance in poultry because of their ability to enhance digestibility, balance the gut microbial ecosystem and stimulate the secretion of endogenous digestive enzymes (Williams and Losa, 2001;Cross et al., 2007). Some researchers have shown that essential oils are most active against strains of E. coli ( Dorman and Deans, 2000 and Hammer et al., 1999).
Mentha, the genus of Labiatae family, includes 20 to 25 species that spread all over the world. Plants belonging to the Labiatae family are rich in polyphenolic compounds and a large number of them are well known for their antimicrobial properties ( Oumzil et al., 2002). Pennyroyal (Mentha pulegium L.) is one of the Mentha species. Some researchers reported that pennyroyal had antimicrobial actions in vitro ( Sivropoulou et al., 1995; Mahboubi and Haghi, 2008).
There are no studies in literature that explore antibacterial effects of pennyroyal in broilers. This experiment was conducted to determine the effects of the dietary supplementation of pennyroyal derived from herbs growing wild in Turkey on the growth performance and E. coli and lactic acid bacteria count in the jejunum of broilers.
2. Material and methods
A total number of 150 one-day-old broilers (Ross 308) were randomly allocated to 3 treatments with 5 replicates and each replicate contained 10 birds (5 male and 5 female). All the birds were housed in batteries from day 1 to 21, and, then in grower broiler pens from day 21 to 42 under standard conditions of temperature, humidity, and vantilation. Feed and water were offered for ad libitum consumption. All chicks were fed a starter diet from day 1 to 21, and a finisher diet to day 42 (Table 1).
Pennyroyal plant was harvested from its natural habitat (Erzurum, Turkey) in early July of 2010. The plant material was cleaned and then dried at at room temperature. Then, pulverized pennyroyal-supplemented diets were offered to broilers. Chemical compositions of the pennyroyal essential oil was analyzed by gas chromatograpy–mass spectrometry. The pennyroyal oil contained 38.3% p-menthone, 7.8% menthol, 3.6% isomenthone, 2.1% pulegone, 45.7% cis-piperitone oxide, 1.4% piperitenone oxide, 1.4% caryophyllene, 0.9% l-limonene, and 0.8% thymol.
Body weights of the chickens were recorded on day 1 and 42, and feed intake was recoreded over this period. Ten birds (5 females and 5 males) selected randomly from each treatment were slaughtered under laboratory conditions. The liver and heart were dissected from the viscera. All of the aforementioned components were weighed individually. The carcass yield was calculated. The carcasses of the birds were opened, and 2 g of intestinal contents from jejunum was transferred to sterile plastic bags. A total of 15 samples from the feed of all groups were also taken. All samples were processed within the same day for enumeration of microbial populations. E. coli and lactic acid bacteria counts were determined by using the methods reported by Peeler et al. (1992)and Baumgart et al. (1986), respectively.
All data were analyzed by analysis of variance with a completely randomized design—using one-way ANOVA procedure of SPSS/package (SPSS, 1999). Orthogonal polynomials contrasts were used to examine the response (linear and quadratic) to dietary pennyroyal levels.
Pennyroyal supplementation did not affect body weight and weight gain. Feed consumption decreased linearly (P = 0.003) with increasing levels of pennyroyal supplementation (Table 2). Increasing levels of pennyroyal supplementation linearly decreased (P = 0.023) feed conversion ratio in for broilers. There were no differences in hot carcass, hot carcass yield, and liver and heart weights among the treatment groups.
Effects of dietary pennyroyal on the growth performance and some carcass characteristics of broilers.
Broilers fed the diet with pennyroyal had reduced E. coli in the jejunum ( Table 3). The control group had the highest average concentration of E. coli in the jejunum, and the count of E. coli in the jejunum linearly decreased linearly (P = 0.001) as the dietary pennyroyal increased. Control group had the lowest average count of lactic acids bacteria in the jejunum (linear, P = 0.001) compared with diets supplemented with pennyroyal.
Lactic acid bacteria and E. coli counts in jejunum of broilers.
The results of this experiment showed that supplementation of the diet with pennyroyal had no effect on body weight and weight gain. Similar to the present findings, some researcher reported that supplementation of 4 or 8 g peppermint/kg (Toghyania et al., 2010), 1 g mint powder/kg (Demir et al., 2008), or 2 g pepermint/kg (Ocak et al., 2008) did not increase final body weight in broilers. Al-Ankari et al. (2004) reported that the addition of different levels of mentha longigolia (habek mint) increased final body weight of broilers compared to those which fed the control diet. Al-Kassie (2010) noted that mentha piperita supplementation in the diet of broilers increased weight gain.
The addition of pennyroyal to the basal diet decreased feed intake compared to control group. Also, feed conversion ratio was improved by the supplementation of 0.50% pennyroyal. In contrast, Al-Ankari et al. (2004) and Al-Kassie (2010) found that the addition of habek mint and mentha piperita to the basal diet, respectively, increased feed intake in broilers. It was reported that dietary supplementation of mint powder and pepermint to broilers had no beneficial effect on feed intake and feed efficiency (Demir et al., 2008 and Ocak et al., 2008). Similar to our study, some researchers reported that supplementation of the diet with several Mentha species has improved feed conversion ratio ( Al-Ankari et al., 2004; Al-Kassie, 2010).
Dietary factors did not affect the hot carcass, hot carcass yield, and weight of liver and heart. Our findings are in agreement with those of Demir et al. (2008) who reported that the supplementation of mint powder to a diet had no beneficial effect on weight of liver and heart.
The addition of pennyroyal to the broiler's feed led to an increase in the lactic acid bacteria count in the jejunum. Also the supplementation of pennyroyal resulted in a lowerE. coli count in jejunum compared to the basal diet. Therefore, pennyroyal antimicrobial substances may inhibit intestinal pathogenic organisms and improve digestion and absorption, thus, acting as growth promoter.
Microbiologically, Mentha species had powerful antimicrobial activities against certain microorganisms known to be pathogenic to broiler chickens ( Oumzil et al., 2002 and Saeed and Tariq, 2005). Pulegon, menthone, menthole, piperitone oxide and piperitenone oxide (compounds identified in Mentha species) showed strong antimicrobial activity ( İşcan et al., 2002 and Oumzil et al., 2002). Mahboubi and Haghi (2008) found that pennyroyal essential oil exhibited bactericidal effect againstStaphylococcusaureus, Staphylococcus epidermidis, Bacillus cereus, and E. coli.
The phytobiotic growth promoter stimulated proliferation of Lactobacilli in the gastrointestinal tract. In this study, pennyroyal supplementation in diet of broilers increased lactic acid count in the jejunum, improved the microflora balance, decreasedE. coli count and stimulated the lactic acid population. In accordance with the present findings, Tucker (2002) reported that blends of essential oils increased numbers ofLactobacillus spp. in broilers. In contrast to our study, other studies showed that supplementation of some essential oil to diet had no effect on lactic acid bacteria of broiler ( Cross et al., 2007 and Kırkpınar et al., 2011).
In conclusion, supplementation of 0.50% pennyroyal into diet reduced feed intake and improved feed conversion ratio. The addition of pennyroyal to the broiler feed led to a decrease in the E. coli count in the jejunum. It was also found that a number of lactic acid bacteria in the jejunum of broilers were increased by dietary inclusion of pennyroyal. Based on the results of this study, it can be recommended to supplement broiler feed with pennyroyal. These findings justify further research on the pennyroyal in diverse dosages and situations to fully explore its effect.
Conflict of Interest Statement
We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.
Tucker, L.A., 2002. Maintaining poultry performance in antibiotic-free diets by supplementation with commercial botanical feed ingredients. Proceedings of the 7th WPSA Asian Pacific Federation Conference, Gold Coast, Australia, pp. 227–230.