CHAPTER ONE
1.0 INTRODUCTION
Intensifying concerns about
the use of antibiotic growth promoters in meat and poultry production has
increased interest in the application of probiotics and prebiotics as natural
alternatives to antibiotic growth promoters, and for prevention of diseases in
food animals (Chinoy, 1997).
In
some developing countries, the traditional use of papaya is being investigated
as an alternative to conventional treatments for a range of ailments. C. papaya has a wide range of medicinal
properties including antiseptic, antimicidal, anti-parasitic, anti-inflamatory,
anti-hypertensive, and anti-hyper lipidenoids. It also contains saponins,
tannis, cardiac glycosides, anthraguinones, reducing sugars, steroids,
phenolics, and cartenoids. Papaya may exert a proteolytic effect on bacteria
resulting from the production of a coagulum that immobilizes micro-organisms
and protects the host against bacterial infections (Jernigan et al, 2009).
In
addition, papaya may improve the efficiency of phagocytic cells that destroy
bacteria. Papaya also contains the alkaloid, carpeine, which has anti-bacterial
properties. Prebiotics, non-digestible oligosaccharide chains, promote bacterial
health by acting as a substrate for probiotics bacteria in the gut.
Fructoliogosaccharide (FOS) is a short chain of glucose-fermented fructose
molecules, with a maximum length of five units. According to Japanese
researchers, FOS can be converted into short chain fatty acids in the colon to
improve immune function and the absorption of nutrients particularly minerals
(Onifade and Odunsi, 1999).
It
is known that the various types of micro-organisms are sensitive to the tracts of
its host. The digestive tract possesses a conducive environment for
micro-organisms to thrive, which include favorable temperature, a constant
supply of nutrient and essential fluids. In this situation the micro-organisms
benefit from the environment and the animal benefits by maintaining a
microflora that does not cause any disease condition (Jernigan et al, 2009).
The authors noted that, there are
generally two different types of bacteria population which can become
established in the digestive tract. The first is that which exists in close
association with the gut epithelium and the second is that which establish
themselves in the digestive tract, can be either beneficial or harmful to the
host. Not only are certain bacterial species pathogenic, but they can compete
with the host for essential nutrients. If beneficial bacteria establish
themselves, they promote metabolism and suppress other undesirable bacteria.
The term “probiotics” has been used to indicate micro-organisms which function
to create gut balance. Crawford (1979) defines probiotics as a culture of
specific living micro-organisms (primarily Lactobacillus
spp. which implants in the animal to which it is fed and ensures the
effective establishment of intestinal populations of both beneficial and
pathogenic organisms. The culture must consist of specific counts of the
bacteria present, be maintained in a dry form for storage purpose within a
specific dose range (Jernigan et al,
2009).
In the laboratory, extracts from
leaves, skin flesh and seeds of papaya showed in vitro anti-bacterial activity against Bacillus cereus, Bacillus, Enterobactes subtile cloacae, E. coli, Klebsiella pneumonia, Proteus vulgaris,
Pseudomina aeruginosa, Salmonella typii, Shigella flexrneri and Staphylococcus aureus. Attention has
been given to some tropical fruit that are of economic importance (Glombitza et al, 1993) among which is papaya (Carica papaya) as a source of
potassium, magnesium and fiber. They are
reported to promote the functions of cardiovascular system and provide
protection against colon cancer (Fisher, 1998, Franco et al, 1993). Papaya leaves contains active ingredients such as
caricacin inhibitor and oleanolic glycoside which had been found to cause
sterility in male albino rats (Das, 1980) .Papaya leaf is readily available in
the tropics because the fruits can be found all years round. They are source of
cheap feedstuff in animal nutrition. However, van Bell et al (1990) pointed out that most researchers considered prebiotics
to be selected and concentrated viable contents of lactic acid bacteria that is
Lactobacillus, Bifidobacterium, Staphylococcus.
Therefore the use of prebiotics or a fermentable sugar instead of antibiotics
in broilers has been shown to be helpful towards improving the beneficial
microbial population in broiler gut (Kermanshahi and Rostani, 2006). Prebiotics
have been shown to alter gastro-intestinal microflora, improve the immune
system, reduce pathogen invasion including pathogens such as Salmonella entritidis and E. coli and
reduce cholesterol levels (Comings and Mactarlone, 2002). Lactobacillus spp is capable
of producing large amounts of lactic acid from simple carbohydrates and
reducing the pH of the gut, which is usually fatal to other bacteria.
Fuller (1977), adjusted the pH of
agar medium to 4.5 with lactic acid or HCl. The growth of E.coli was inhibited by low pH. Lactic acid was shown to inhibit
the growth of E.coli and the
inhibitory effect of HCL acid was identical to that obtained with lactic acid
(organic acid). It was also reported that the inhibition of E.coli in the crop was dependent on the presence of sufficient
numbers of lactobacillus. Rantala and
Numi (1997), showed that a prebiotic culture had the ability to prevent the establishment of Salmonella infantis in the caeca of chicks although in this case Lactobacillus was not the only organisms
present. Since papaya leaves contain chemical components; papains and others
which aids in digestion and reduction and/or possible destruction of entheropathogens
in the gut of the animal. Micro-organisms like Staphylococcus, E. tenella,
E. coli, Shigelia and others can
be dislodged by the effect of the papaya leaves. Which will also act as a
growth promoter, enhancing the animals appetite hence promoting feed efficiency
.
1.2
Objectives of
the study were to:
·
determine
the effect of papaya leaf meal (PLM) on populations of the Lactobacillus spp and some enteropathogens in the gut of broilers.
·
establish
how the effect impacts on the counts of Lactobacillus
spp and the enteropathogens shed in the droppings of the broilers weekly
throughout the trial period.
1.3
Justification of
the study
Plant substances continue to serve as inclusive
sources of
drugs for the
majority of the world population and several plant based drugs are in extensive
clinical use (Roja and Rao, 2000) .
Therefore the use of papaya leaves
for medicinal purposes in the reduction of enteropathogens and in improving the
gut microflora of animals helps to
reduce the most risks encountered in the adipose tissues of animals after
slaughter which was fed or medicated with antibiotics. These papaya leaves will
also improve the guts ecosystem of these birds, enhance their growth and also
add some minerals to them since is of a natural origin.