1) The document discusses various natural alternatives that can replace antibiotics in poultry feed, including probiotics, prebiotics, plant extracts, essential oils, and organic acids. 2) Probiotics are live microorganisms that can improve gut health, inhibit pathogens, and enhance immune function as alternatives to antibiotics for growth promotion. 3) Plant extracts contain active compounds with antioxidant, antimicrobial and anti-inflammatory properties that have shown benefits for poultry performance and health when used as feed additives.

1. Different ways to replace Antibiotics
By
Qasim Mahmood khan
BASF16M023
Submitted to: Sir Abd Ur Rehman
Department of Animal Sciences, University college of Agriculture
University of Sargodha
In partial fulfillment of the requirement for the course of
PS-402 Bsc. (Hones) Animal Sciences (session 2016-2020

2. Introduction
Antibiotics are used in poultry feed for growth promoters that enhance the growth rate as well
as efficiency of feed. But commonly used antibiotics and growth promoters have been banned
by European Union because the residues of antibiotics in poultry meat are also produce
resistance against the same antibiotics that are used for the curing of disease in humans. After
this incidence European and other countries have started work on the removal of antibiotics
residue and find the substitute that would be replaced with antibiotic. They find Natural
replacement includes probiotics, Prebiotics ,Plant Extracts , Etheric oils, organic acid and
immune stimulators have been used as an feed additives for maximize the performance ,
productivity , prevention and controlling of disease use in poultry in recent years .
Probiotics :
Probiotics are live micribioms known as good bacteria when consumed in equal amount. The
word probiotic is rubricate in 1980. Many kind of microbes used as proboitics , but the most
common group is bacteria like Lactobacillus spp., Bifid bacterium spp., Pedococcus
spp.,Streptococcus spp., and some strains of yeast based group Sacharomyces cerevisiae and
Kluyveromyces [6]. Each group has different species and every species have different strains.
Probiotics use for gastrointestinal health which develop the resistance against disease in the
digestive system like timpani and diarrhea [7]. Ability for the action of probiotics is directed
related with gut microbes equilibrium and immunomodulation. Most the studies shown that
lactobacilli spp., Bacillus spp., and some Straptococcus spp., are similar to the antibiotics but
the scientists can’t find the mode of action. But these species are suggested a) Beneficial
change in gut micro flora that reduce the population of E.coli: b) lactate production with
subsequent change in intestine pH: c) production of antibiotics like substance: d) reduction
of toxin release (suppression of E.coli). A lot of works with different poultry breeds lead to
positive impact on using probiotics in poultry diets [21]. As the probiotics are called
beneficial bacteria it has positive effect of broiler performance [22]. Substantial betterment in
daily feed intake and weight gain for broiler-chicks were ascertained [23]. Probiotics improve
feed efficiency in poultry [24]. Lower serum cholesterol and triglyceride level [9]. It’s
improved the gut microbioms and inhibits the pathogens [25] and immunomodulation [22]
opposition by Emeria acervalina as reflected by decreased oocyst shedding [26]. Overall the
studies shows result that the proboitics can replace the antibiotics and act as growth
promoters in poultry feed.

3. Table no-1 Effects of probiotics on poultry performance
S+, significantly increased; S −, significantly decreased; NS, non-significant, -, not studied, FCR, Feed
conversion rate.
Plant Extracts:
Plant extracts are composite compounds comprising different compositions and containing
active compounds. Plants are mainly consisting of proteins, peptides, oligosaccharides, fatty
acids, vitamins and micro minerals. Plant extracts have a broad variety of behaviors and their
significant secondary function. Biological processes of plant usually belong to the class of
isoprene and flavonoids [27]. They have a lot of activities. Most plants extract contain
compounds that exhibit antioxidants [28]. Antimicrobial [29], anti-inflammatory [30]
anticoccidial [31] and anti-helmanthatic [32] properties [table no 2]. There have been several
studies of the benefits of plant extracts for poultry result in animal feeding, beneficial
activities of herbal extracts or there active compounds can involve enhancement of appetite
and feed consumption , improvement of endogenous digestive enzyme secretion[34]. Adding
black pepper in broiler’s diets at 4-6 weeks of age that increased weight gain [35]. It was
stated that the introduction of plant extracts and essential oils (EOs) into diet will also play
role in enhancing animal’s growth efficiency and health status [36]. When black cumin was
Growth rate/final body weight FCR Histomorphology
Microorganisms Commercial
product
Pre-
starter
Grower
finisher
Overall Feed
intake
Overall Villas
height
Villas
height/crypt
depth ratio
Source
B. coagulans - NS NS NS NS S− NS NS Hung et al.
[16]
E. faecium - S+ S+ s+ - - S+ S+ Cao et al. [17]
L. acidophilus Primalac S+ S+ S+ S+ S− - - Landy and
Kavyani [18]
B. subtilis
E. faecium
Bifidobacterium
bifidium
Bacillus subtilis Gallipro
PrimaLac
NS – S+ S+ - S+ S+ Afsharmanesh
and Sadaghi
[19]
B. amyloliquefaciens - S+ S+ S+ S+ S− S+ S+ Lei et al. [20]

4. added in the feed of layer at the level of 1, 2, or 3% show no effects on weight gain, FCR or
feed intake [37]. Similarly the efficiency was mildly impaired by supplementary broiler diets
EO extract from oregano cinnamon and pepper but the impact was not significant [38].
Results of the majority of the studies demonstrated beneficial behavior of plant extracts in the
production and wellbeing of the poultry. Some studies however stated that some additives of
plant extracts had no impact on poultry growth efficiency or health status. Using thyme oil to
broiler greatly improved body weight gain [39] and feed intake compared with the controle
group [40]. In the other side a combination of EO derived from saga, thyme and rosemary
improved the digestibility of dry metter and crude oil [38]. Use plant extracts as feed
additives in poultry may be useful as they optimize the overall efficiency and boost the
poultry nutrients digestibility. Many of the plant extracts examined in poultry studies had
beneficial results on profitability, and no adverse effect on animal welfare and agricultural
goods, and they can be used as substitute feed additive in the processing of poultry (Table 4).
Table 3. Common plant extracts, their utilized parts, main active substances and reported properties
Plant name Utilized parts Main compounds Reported properties
Aromatic spices
Clove Flower Eugenol Appetite enhancer, digestive stimulant, antiseptic
Cinnamon Leaf Cinnamaldehyde Appetite enhancer, digestive stimulant, antiseptic
Coriander Leaf, seed Linalool Appetite enhancer, digestive stimulant
Cumin seed Cuminaldehyde Digestive, carminative, galactagogue
Anise Fruit Anethol Digestion stimulant, galactagogue
Celery Fruit, leaf Phthalides Appetite and digestion stimulant
Pungent spices
Capsicum Fruit Capsaicin Anti-diarrheic, anti-inflammatory, stimulant, tonic
Pepper Fruit Piperine Digestion stimulant
Ginger Rhizome Zingerone Gastric stimulant
Aromatic herbs and spices
Garlic Bulb Allicin Digestion stimulant, antiseptic, antimicrobial
Rosemary Leaf Cineol Digestion stimulant, antiseptic, antioxidant
Thyme Whole plant Thymol Digestion stimulant, antiseptic, antioxidant, anticoccidial
Sage Leaf Cineol Digestion stimulant, antiseptic, carminative
Peppermint Leaf Menthol Appetite and digestion stimulant, antiseptic
Source: [33].

5. Table 4. Effects of dietary plant extracts used as feed additives on poultry performance
Plant extract Dose (%) Effects on performance Source
Chinese herbal medicine 0.5–1 Better growth performance from 7 to 21 days Guo et al. [41]
Thyme EO 0.2 Improved growth performance Denli et al. [36]
Plant extract consisting of capsaicin,
cinnamaldehyde and carvacrol,
capsaicin, cinnamaldehyde and
carvacrol
0.1 Live weight no affected, feed efficiency was
improved at 4.2%
Jamroz et al. [42]
Red pepper extract 0.1 No effect on growth performance or in organ
morphometrics
Barreto et al. [43]
Cinnamon 0.2 Higher growth performance Al-Kassie [44]
Black cumin seeds 1 Increased live weight, improved feed efficiency Khalaji et al. [45]
Thyme extracts 3–6 No improvement in growth performance and
carcass traits
Amouzmehr et al.
[46]
Source: [5].
Organic Acid:
Basic organic acids includes Formic, acetic, butyric, lactic and citric acids used in poultry
feed. Lactic, citric fumaric and ascorbic acids and their salts (e.g. calcium type and calcium
propionate) are included in feed preservative group [47] in the European Union (EU). In
addition the EU has approved the use of organic acids and their salts in poultry feeds as these
are usually safe for health [48]. These compounds have been used for so many years in
poultry diets with beneficial results (table 5). Organic acids have been used as replacements
for antibiotics growth promoters in poultry feeds in recent years owing to concern of
antibiotics tolerance and the entailment for human safety [49]. The acid has been shown to
have antimicrobial capacity, resulting in alteration of the micro flora consumption in the gut.
Organic acids and their salts are used in poultry feeds as substituted antibiotics which can
have beneficial effects on result. Organic acids have some functional effects other than
antimicrobial ones, including lowering in digesta pH, decreased pancreatic secretion and
metabolic impact on the gastrointestinal mucosa [50]. Mixing of acid in drinking water is a
way to increase the efficiency in broiler production [49]. The action of organic acid in
bacteria is through competitive exclusion [51] minimize the pH of digesta maximize the
pancreatic secretion [50]. Improve the feed conversion efficiency [24]. Reduction in the
manufacturing of the toxic bacteria in the intestinal tract, thus hindering damage to epithelial

6. cell [48] and improve the nutrients absorption [52]. The usage of organic acid in poultry diets
has improved the productivity of poultry processing considerably and has also supplied
citizens with safe and notoriously balanced poultry [54].
Table 5. Effects of organic acids on poultry performance
Organic acid Dose (%) Performance effect Source
Fumaric acid 0.5–1 Increased body weight, but did not affect feed efficiency Patten and Waldroup [55]
Formic acid 0.5–1 Improve apparent ileal digestibility of crude protein and
dry matter
Garcia et al. [56]
Butyrate 0.4 Increased body weight, improved feed efficiency Panda et al. [57]
Fumaric, formic
and acetic acid
0.75–2 Improved metabolizable energy, crude protein and crude
fibre digestibility
Ghazala et al. [58]
Propionic acid
and
sodium bentonite
0.2 Increase in digestibility and availability of nutrients
(such as calcium and total phosphorus)
Ziaie et al. [59]
Citric acid 3 Improvement in ileal nutrient (crude protein, apparent
metabolizable energy, calcium and total phosphorus)
digestibility
Nourmohammadi et al.
[60]
Prebiotics :
Prebiotics are classified as non-digestible constituents offered which selectively stimulate the
growth and metabolism of healthy microbes in the intestinal tract [61]. This impress the
microbial balance in an organisms’ intestine prebiotics consist of Fructooligosacharides
(FOS), Mannanooligosacharides (MOS), Glactooligosacharides (GOS), Transgalacto-
oligosacharide (TGOS), lactose and inulin [62]. MOS is acquired from the yeast cell wall and
TOGS are famous prebiotic substance. Prebiotics are derived from the cell wall of specific
plants or yeast cells, and many of theprobiotics are carbohydrates, primarily short-chained
oligosaccharides containing 3-10 carbohydrates units. Major source of prebiotics are proteins
lipids, some peptides and non-digestible carbohydrates (oligo or poly sacharides). Lactose is
a disaccharides and prebiotics for poultry especially for chicks. The absence of lactase
enzyme in chicken contributes to lactose reached in the ileum, cecum and intestinal bacteria
hydrolyzed is [63]. If a nutrient follows some requirements it may be called a prebiotic: first
it can readily hydrolyze or absorbed in stomach or in small intestine and secondly: is
fermentation should lead to beneficial effects in the digestive system [64]. Infect the diet
production dose not change different prebiotic clearance, rendering their usage even easier
than utilizing medicines or chemicals [65]. Prebiotics are helpful substances for gastro-

7. intestinal microbes which may be used as possible alternatives to antibiotic that encourage
development. A large deal of gastrointestinal bacteria may use indigestible carbohydrate to
generate energy [62]. They have been shown to alter gut micro flora, strengthen the immune
system, and avoid colon cancer, decrease pathogen invasion, cholesterol rates and odoud
compounds [66]. Studies have also shown that they have the potential to enhance gut health
through intestinal microbial equilibrium, boost animal’s efficiency, increase nutrient
consumption, minimize emissions and reduce production costs [67]. Prebiotics action
pathways are: reducing the pH of intestine via the development of lactic acid[68], inhibiting
pathogenic bacterial colonization [69], altering the function of the intestine micro flora and
activating animal efficiency , reduce dangerous enzymes and toxic metabolites, lower blood
pressure and cholesterol rates, and avoid the cycle of carcinogenesis[71]. Commonly used
oligosaccharides are presented in (table 6).
Table 6. Major oligosaccharides as prebiotics
Oligosaccharides Structure Linkages Process Origin
Xylo-oligosaccharides (Glu)n β-1,4 Hydrolysis Cereals
Lactulose Gal-Fru β-1,4 Isomerization Lactose
Isomalto-oligosaccharides (Glu)n α-1,6 Hydrolysis Algae
Gluco-oligosaccharides (Glu)n α-1,2 and α-1,6 Synthesis Sucrose
Galacto-oligosaccharides (Glu)n-Glu β-1,4 and β-1,6 Synthesis Lactose
Fructo-oligosaccharides (Fru)n-Glu (β-2,1)-(α-1,2) Synthesis Synthesis
Oligofructose (Fru)n-(Fru)n-Glu (β-2,1) Hydrolysis Inulin
Source: [62].
Essential oils:
EOs are derived from different material of plants (buds, flowers, seeds, laves, fruits, wood,
roots, twigs, bark and herbs). EOs is a blend of the fragrant volatile compounds [72]. EOs as
feed additives are becoming common in poultry feed as replacer of antibiotic growth
promoters (which are prohibited in the EU since 2006). EOs includes flavonoids, terpenoids
and phenolic compounds. Cell membrane can be disrupting by terpenoides and phenolic
substances flavonoids and phenolic substances may cause matel-iron chelation and
especially, coumarin and alkaloids inhibit growth ofmicro-organisams [73]. EOs increase the
development of digestive secretions and absorption of nutrients , minimize pathogenic stress

8. in the intestine , exert antioxidant properties and improve the immune status of animal which
may help to understand the improved output observed in poultry[74]. Such a molecules can
have effects are antibacterial, antioxidant, antifungal, and anti-inflammatory simultaneously
they activate digestive enzyme enhance the histology of the intestine and contribute the
tranquilization. EOs is in essence very complicated, since they compose of compounds
mixtures. Their chemical composition and compound amounts are very complex.
Effectiveness of EOs has been documented to be based on pH chemical composition,
concentration or the specific bioactive compounds. Additionally the population and types of
micro organisms can alter efficiency of EOs. Most EOs promotes beneficial microbial growth
and reduces the amount of pathogenic poultry bacteria [75]. The combination of Thymol and
cinnimaldehyde can be used with specific antibacterial properties to effectively prevent the
development of yeast and fungi [76]. There have been studies of many plants and there EOs
processing antiphrastic effect on livestock. Carvacrol and Thymol are the major compounds
in oregano oil and are known to show action against Eimeria tenella [40] and Eimeria spp.
mixed illness [77]. EOs antioxidant functions are focused on both capacities to contribute
hydrogen is send free radical an electron, and their capacity to delocalize unpaired electrons
inside the aromatic framework [78]. EOs therefore guard against oxidation and chain reaction
with certain biological molecules. In broilers, EOs improve Trypsin, amylase and jejunal
chime secretion [79], and reduce pathogen colonization supplementing the diets with EOs
will improve broiler growth performance [80]. Using a mixture of lowrel, oregano, saga,
citrus, and anise EOs or combinations of EOs greatly increase the FCR in broiler [81].
Adding a mixture of basil, caraway, laurel, garlic, oregano, ginger, tea and thyme EOs to a
broiler diet increased the body weight and positive effect on feed to gain ratio [82]. The
precious functions of EOs are not explicit, but they tend to alter the faction of enzymes in the
intestine, enhance nutrient digestion and absorption, and minimize the intestinal micro flora.
Laboratory studies found that some EOs, including carvacrol, cinnamaldehyde and capsaicin
have shown to boost poultry efficiency.
Immunostimulants:
Immunostimulants are chemical compounds, medication and stressors that enhance the
immune reaction or defense system [83]. The immune system provides defense against
different micro-biomes, such as virus’s microbes fungi and parasites [84]. Animal feeding
experiments have shown that improvements in immune system constituents are responsive to

9. the intake of dieting amino acids [85]. Dietary methionine rates in broiler diets <0.50%
contributes to reduce immune cell reaction relative to higher amounts [86]. For safe poultry
only regular nutritonal amounts of amino acids are necessary. But cattles are held varying
kinds and doses of pressures and diseases in concentrated industrial farms. These animals
require dietary immunostimulants substances glucans derived from the yeast cell wall were
used to boost the growth efficiency of single stomach animals and to activate the immune
system. Recently the usage of complex carbohydrates has been a considerable importance in
disease prevention and the use of a therapeutically. Manonoligoscharide is a complex of
glucomannoprotiens derived from cell wall of the yeast. The deficiency of minerals
comprising vitamins A, C, and E, Cr and Se induces compromised immune system in both
human and animals. Using immunostimulants before a microbial infection can help the
animal’s mechanism of defense. The function of the immunostimulant compounds primarily
focus on the protection from pathogen infections. The intake of these substances thus
improves health and efficiency of the animals. Addition of an immunostimulant results in
improved beneficial intestinal changes such as villi elongation or narrowing of intestinal
crypts. Another possibility is the synthesis and releases of pro-inflammatory cytokines which
modulate adaptive immunity or intestinal microbes stabilization [87].
Conclusion:
For the poultry industry a number of substances have been identified as antibiotics. Many
studies revealed that probiotics and plant extracts in particular have close results to antibiotics
in poultry. Additionally sufficient doses and application methods for these alterative to
antibiotics are necessary to make them more efficient in poultry.
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