Evaluation of Alternatives to Antibiotic Feed Additives in Broiler Production

INTRODUCTION

Feed additives are substances that have the potential to enhance production performance without significantly altering the composition of feed. Broiler chicken requires high dietary energy and protein with balanced amino acid profile in the compound feed (Boling and Firman, 1998). Feed costs approximately about 70% of total production expenditure and nutrient lost in the feces either undigested or unabsorbed due to intestinal microbial population by parasitic action or occupation of receptors on the surface of intestinal epithelium could result in the economic loss (Lu and Walker, 2001). Therefore, dietary energy and protein in the feed and their utilization have significant effects on growth performance of broiler and overall production cost.

Growth enhancing effects of antibiotics were also explored soon after (ten years) their discovery in the mid-twentieth century. Initially animals were fed with dried mycelia of Streptomyces aureofaciens containing chlortetracycline residues, which resulted in improved growth (Castanon, 2007). The mechanism, by which antibiotics act as growth promoters, operates through inhibiting pathogenic bacteria (Dibner and Richards, 2005; Niewold, 2007), decreasing competition between host and bacteria and thus making available nutrients for the host, otherwise consumed by bacteria for their propagation (Hardy et al., 2013). However, the concerns about the use of antibiotics as growth promoters were expressed within ten years of their use in the poultry feed industry (Mathew et al., 2007). Later, discovery of antibiotic resistant bacteria (Aarestrup et al., 2001) from different parts of the world resulted in a ban on the use of certain antibiotics as feed additive (FAO, 2003) and it resulted in increased disease outbreak in different countries (Casewell et al., 2003).

In order to find alternative to antibiotic feed additives to control diseases and increase production efficiency in poultry different types of additive alternative including probiotics, prebiotics, synbiotics, organic acids, enzymes and herbs (Cabuk et al., 2006; Dahiya et al., 2006; El-Latif et al., 2013) have been used, which exhibited encouraging results. Medicinal herbs and culinary spices have been used in different parts of the world for centuries to cure diseases in human and animals. Herbs are known to have a wide range of activities such as antibacterial, antiparasitic, antioxidant, antifungal, immune enhancer properties, feed intake stimulation, and enhanced endogenous enzyme secretions. Many of these effects are associated with different types of secondary metabolites like isoprene, flavonoids and tannins (Shin et al., 1995).

Garlic (Allium sativum) of the family Amaryllidaceae is used for both culinary purposes and medicine. It has major bioactive compounds g-glutamyl-S-allyl-Lcysteines and S-allyl-L-cysteine sulfoxides which have antibacterial (Andleeb et al., 2014) and immune enhancing effects (Amagase, 2006). The studies have also revealed that garlic consumption reduces risk for heart diseases and cancer. It is also reported that garlic consumption reduces cholesterol and hypertension (Dorhoi et al., 2006; Zeybek et al., 2007). Jir or Bootae (Artemisia scoparia) (Family Asteraceae) is an indigenous local medicinal herb contains monoterpenoids, sesquiterpenoids, β-pinene, capillin, limonene and murcene in the oil (Negahban et al., 2006; Singh et al., 2009) and its decoction or tea is used to treat indigestion, cold, and fever (Tareen et al., 2010) and have hepato-protective effects (Gilani and Janbaz, 1993). Sanna Makki (Cassia angustifolia) (Family Leguminosae) has different bioactive compounds such as galactomannan, epimelibiose, galactobiosylylmannose, mannobiose and galactobiose in water soluble fraction (Alam and Gupta, 1986). Its antipyretic, laxative, and diuretic effects are documented (Sultana et al., 2012). The purpose of this study was to find out the effect of indigenous culinary and medicinal herbs as feed additive on growth performance and enumeration of intestinal microflora.

MATERIALS AND METHODS

Management of the birds

A total of 320 one day-old Hubbard broiler mixed sex chicks were randomly divided into eight treatment groups (40 chicks for each treatment) with four replicates of ten chicks respectively, reared in littered floor pens. Standard managerial conditions were maintained with 24 h lighting. Controlled feeding program was selected and measured feed at morning and evening was offered to the birds with slight modification in accordance with Hubbard guide for altitudes. Water was provided ad libitum. Vaccination against Newcastle, Infectious Bronchitis, and Infectious Bursal disease was carried out. The experiment lasted for six weeks (42 days).

Feeding and treatments

Two-phase feeding regime was applied and for this purpose, a basal diet was formulated (Table I). The dietary treatments were Allium sativum 1.0% (T1), Allium sativum 0.5% (T2), Cassia angustifolia 1.0% (T3), Cassia angustifolia 0.5% (T4), Artemisia scoparia 1.0% (T5), Artemisia scoparia 0.5%, (T6) Control (Basal diet) (T7) and Positive control (Oxyfeed @ 2g/kg) (T8). The powdered herbs were initially mixed in small amount of feed and later in the total required feed thoroughly. The nutritive value of the herbs was considered as negligible.

Weekly data of body weight (BW) and feed intake (FI) per replicate were recorded and weight gain (WG) and feed conversion ratio (FCR) were calculated. At the end of the trial, one bird was randomly picked from each treatment of each replicate, weighed before being slaughtered by severing jugular vein.

Evaluation of Alternatives to Antibiotic Feed Additives in Broiler Production - Image 1

Immediately the intestine was removed and samples of the digesta from Ileum were collected in sterile falcon tubes for bacterial enumeration. Briefly, 1 g digesta was added to 9 ml physiological saline and vortexed to make homogeneous slurry. Subsequently, homogenate was serially diluted up to 10^-8. Total aerobe bacteria were counted on brain heart infusion agar (LAB) plates. Coliform bacterial enumeration was carried out by using MacConkey agar (Oxoid) and lactic acid bacterial count was made using MRS agar (Oxoid) plates in duplicate for 24 to 48 h at 37°C. The results expressed log₁₀ colony forming units (log₁₀ CFU) per gram.

Statistical analysis

The data were statistically analyzed by using analysis of variance technique and, general linear model (GLM) procedure in SPSS-16 for windows and the results were presented as mean±standard error. In order to determine the difference between treatments, Duncan’s Multiple Range (DMR) test was applied at 95% confidence interval.

RESULTS

At the start of the experiment, the chicks were randomly divided into the respective replicates and no difference (P>0.05) was observed in the weight of the chicks was observed and overall mean was 39.24g/chick. The dietary supplementation of the herbs as additive indicated a significant (P<0.05) effect on performance parameters compared to control (T7) (Table II). The highest weight gain was observed in T1, T2 and T8 (P>0.05), which was followed by T4, T3, T6 and T5 which was insignificant with each other (P>0.05). The supplementation of the Allium sativum @ 1.0 and 0.5% in the feed exhibited results comparable to antibiotic. There was no significant difference (P>0.05) in feed intake between treatment groups (Table II).

In the present study, treatment groups supplemented with additives, showed improved feed efficiency and average daily gain (Table II). The use of garlic at both (0.5 and 1%) levels exhibited better feed conversion and daily weight gain compared to the other herbal treatments (P<0.05). However, feed efficiency and daily gain of garlic treatment group was not significantly different from antibiotic treatment group (P>0.05). Similarly other herbal additive groups showed better feed efficiency and daily gain compare to control (P<0.05). The carcass and internal organ characteristics are shown in Table III.

Evaluation of Alternatives to Antibiotic Feed Additives in Broiler Production - Image 2

Evaluation of Alternatives to Antibiotic Feed Additives in Broiler Production - Image 3

Evaluation of Alternatives to Antibiotic Feed Additives in Broiler Production - Image 4

Evaluation of Alternatives to Antibiotic Feed Additives in Broiler Production - Image 5

The relative weights of carcass and various organs were found to be insignificant between treatment groups (P>0.05). However, numerical differences were observed in the relative weight of the organs in the study. The prominent features of the intestinal segments observed in the study are given in Table IV. There was no significant difference (P>0.05) found between treatment groups in the length of duodenum, jejunum, ileum and intestine. But the relative length of the different segments and intestine of treatment groups revealed a significant difference (P<0.05). The highest relative length (9.37±0.28) of the intestine was observed in T7 and lowest (8.08±0.14) was in T1 (P<0.05). Supplementation of the additives to the broiler diets caused a reduction (numerical) in the length of the intestine.

The composition of bacterial enumeration of ileum at the end of the experiment on the day-42 is shown in Table V. Different treatments had a significant (P<0.05) effect on CFU count of aerobe, coliform, and lactic acid bacteria. The lowest aerobe CFU count was noted in T1 (6.25) and T8 (7.25), respectively. The highest count was recorded in T7 (8.25). The other herbs also exhibited a reduction in aerobe numerically compared to the control (P>0.05). Coliform bacterial CFU count was lowest in T1and T3, which were followed by T8. Lactic acid bacterial enumeration showed no significant difference (P>0.05) between treatments. Least (4.75±0.25) lactic acid bacterial count was observed in T8 followed by (5.25±0.47) in T7 and highest count (6.00±0.40) log10 CFU/g digesta was in T1, respectively.

DISCUSSION

In the present study, body weight gain and feed conversion, which were broiler performance indices, increased in additive supplemented groups compared to control. The effect of herbal additive and antibiotic additive was found to be insignificant (P>0.05). The use of antibiotic as growth promoter has previously been reported in addition to their drawback resulting in antimicrobial resistance (Aarestup et al., 2000). The beneficial effects of herbs in the present study are in line with studies of Elagib et al. (2013) and Lukanov et al. (2015), suggesting that supplementation of herbs to broiler diet increased performance indices. This increase in weight gain and feed conversion efficiency could be due to beneficial effects of the herbs in terms of change in gut environment, decreased microbial metabolites, competitive elimination of the pathogenic bacteria and their toxic metabolites from the intestinal tract (Chrubasik et al., 2005; Kabir, 2009; Ramiah et al., 2014).

In the present study, the control feeding system was opted to neglect the effect of height as the study was undertaken at about 1635meter above sea level. However, in other studies, even though ad libitum feed was offered, no significant difference was observed between control and additive supplemented groups in terms of feed intake (Choi et al., 2010). Supplementation of the antibiotic and herbs as additive resulted in better FCR. The improved feed conversion could be due to better digestion, increased absorption, of nutrients (Kabir, 2009). The reduced number of pathogens in the intestinal tract could also result in nutrient sparing effect, available for the host bird otherwise utilized by the bacteria or lost in the feces unabsorbed (Wenk, 2003).

The length of the intestine could be affected by the type of ingredients used in the feed (Wang et al., 2005) and wheat based diet has been reported to cause an increase in the length of intestine due to the presence of arabinoxylans (Annison and Choct, 1991). In the present study, difference in length of intestine might also be due to the changes in the digesta characteristics like viscosity.

The result of the present study indicated that it affected the microbial composition of the ileum. The use of antimicrobial as additive had the most profound effects on microbial population and caused the reduction in the all kinds of bacterial population. The results are in agreement with the study of Engberg et al. (2000) showing that antibiotic additive reduced intestinal microbial load. Similarly, there are reports suggesting phytogenic feed additives also act as antimicrobial agents under in-vivo conditions as synthetic antibiotics with different mode of action and beside exclusion of pathogenic bacteria they act as prebiotic (Jamroz et al., 2003; McReynolds et al., 2009) and support the enumeration of the lactic acid bacteria thought to be beneficial bacterial population (Wati et al., 2015). In general, the improved performance of the treatment groups supplemented with herbs used as feed additive are due to different bioactive ingredients present in herbs and exhibiting their activities in different ways.

CONCLUSION

In conclusion, the result of the present study revealed that culinary and medicinal herbs had multiple additional potentials compared to antibiotic feed additives and can be used as alternative to antibiotic feed additives. The inclusion level of herbs used in the present study was observed to be beneficial. Moreover, supplementation of feed with A. sativum in particular and C. angustifolia and A. scoparia to some extend had beneficial effects on performance parameters and gut microbial population.

Statement of conflict of interest

Authors have declared no conflict of interest.

This article was originally published in Pakistan Journal of Zoology, vol. 49(3), pp 1063-1069, 2017. DOI: http://dx.doi.org/10.17582/journal.pjz/2017.49.3.1063.1069. This is an Open Access article licensed under the Creative Commons Attribution License.