The body weight gains were significantly (P < .05) improved
by dietary supplementation of organic acids when compared
with the control group (Table 2). The highest weight gains
were achieved in the birds fed 3% fumaric acid, followed
by the group fed diet supplemented with 3% lactic acid.
The 3% inclusion levels were found better in promoting
the weight gains when compared with the groups fed diets
supplemented with the 2% levels. The results of the present
study regarding weight gains coincide with the other workers
[11–14] who reported that the supplementation of organic
acids in broiler chicken improved the body weight gain when
compared with the unsupplemented group. The improved
body weight gain is probably due to the beneficial effect
of organic acids on the gut flora. The organic acids may
affect the integrity of microbial cell membrane or cell
macromolecules or interfere with the nutrient transport and
energy metabolism causing the bactericidal effect [6]. Use
of organic acid mixture decreases the total bacterial and
gram negative bacterial counts significantly in the broiler
chicken [15]. Besides, the butyric acid has been reported
to reduce the virulent gene expression and invasiveness in
Salmonella Enteritidis, leading to its decreased colonization
in the caeca of broiler chicken [16–18]. Furthermore, organic
acids supplementation has pH reducing property, although
nonsignificant, in various gastrointestinal segments of the
broiler chicken [19]. The reduced pH is conducive for the
growth of favourable bacteria simultaneously hampering the
growth of pathogenic bacteria which grow at a relatively
higher pH. However, it is worth mentioning that the
effects of organic acids down the digestive tract diminish
because of the reduction in concentration of acids as a
result of absorption and metabolism [20]. Thus, it can be
hypothesized that the effect of organic acids in the distal
segments of gastro-intestinal tract could be due to the
reduced entry of pathogenic bacteria from the upper parts
of gastro-intestinal tract as a compensatory mechanism but
no valid literature regarding such mechanism was found.
The beneficial microbiological and pH-decreasing abilities of
organic acids might have had resulted in the inhibition of
intestinal bacteria leading to the reduced metabolic needs,
thereby increasing the availability of nutrients to the host.
This also had decreased the level of toxic bacterial metabolites
as a result of lessened bacterial fermentation, causing
an improvement in the protein and energy digestibility,
thus ameliorating the weight gain and performance of
experimental birds. Moreover, the organic acids improve
the villus height in the small intestines (Table 3) and also
have a direct stimulatory effect on the gastro-intestinal cell
proliferation as reported by Tappenden and McBurney [21]
that short chain fatty acids increase plasma glucagon-like
peptide-2 (GLP-2) and ileal proglucagon mRNA, glucose
transporter (GLUT2) expression, and protein expression,
which are all signals which can potentially mediate gut
epithelial cell proliferation. These histological changes in
small intestines probably had increased the intestinal surface
area, facilitating the nutrient absorption to a greater extent
and, thus boosted the growth promoting effect of organic
acid supplementation.
The feed consumption was found statistically nonsignificant
(P > .05) among all the treatment groups
(Table 2). These results are in agreement with Hernandez
et al. [22] who found no difference in the cumulative feed
consumption between the groups fed organic acids and
the control group. Chicks fed the diets supplemented with
organic acids showed a significant (P < .05) improvement in
the FCR as against the chicks fed the control diet (Table 2).
The improvement in the FCR could be possibly due to better
utilization of nutrients resulting in increased body weight
gain (Table 2) in the birds fed organic acids in the diet.
These results are in concordance with the reports of earlier
researchers [23, 24] who reported that the supplementation
of organic acids improved the feed conversion ratio in
broiler chicken. The carcass characteristics of broiler chicken
fed diets supplemented with the organic acids showed no
significant differences (P > .05) between various treatment
groups (Table 2), confirming the earlier findings [25].
The mean values regarding the histomorphological alterations
in the broiler chicken fed organic acid based diets
are given in Table 3. Dietary supplementation of organic
acids significantly (P < .05) increased the villus height
in the duodenum, jejunum, and ileum but the values
were significant (P < .05) only in the duodenum and
jejunumwhen compared with the control group. The highest
duodenal, jejuna, and ileal villus heights were recorded in
the birds fed diets supplemented with 3% butyric acid, 3%
The body weight gains were significantly (P < .05) improvedby dietary supplementation of organic acids when comparedwith the control group (Table 2). The highest weight gainswere achieved in the birds fed 3% fumaric acid, followedby the group fed diet supplemented with 3% lactic acid.The 3% inclusion levels were found better in promotingthe weight gains when compared with the groups fed dietssupplemented with the 2% levels. The results of the presentstudy regarding weight gains coincide with the other workers[11–14] who reported that the supplementation of organicacids in broiler chicken improved the body weight gain whencompared with the unsupplemented group. The improvedbody weight gain is probably due to the beneficial effectof organic acids on the gut flora. The organic acids mayaffect the integrity of microbial cell membrane or cellmacromolecules or interfere with the nutrient transport andenergy metabolism causing the bactericidal effect [6]. Useof organic acid mixture decreases the total bacterial andgram negative bacterial counts significantly in the broilerchicken [15]. Besides, the butyric acid has been reportedto reduce the virulent gene expression and invasiveness inSalmonella Enteritidis, leading to its decreased colonizationin the caeca of broiler chicken [16–18]. Furthermore, organicacids supplementation has pH reducing property, althoughnonsignificant, in various gastrointestinal segments of thebroiler chicken [19]. The reduced pH is conducive for thegrowth of favourable bacteria simultaneously hampering thegrowth of pathogenic bacteria which grow at a relativelyhigher pH. However, it is worth mentioning that theeffects of organic acids down the digestive tract diminishbecause of the reduction in concentration of acids as aresult of absorption and metabolism [20]. Thus, it can behypothesized that the effect of organic acids in the distalsegments of gastro-intestinal tract could be due to thereduced entry of pathogenic bacteria from the upper partsof gastro-intestinal tract as a compensatory mechanism butno valid literature regarding such mechanism was found.The beneficial microbiological and pH-decreasing abilities oforganic acids might have had resulted in the inhibition ofintestinal bacteria leading to the reduced metabolic needs,thereby increasing the availability of nutrients to the host.This also had decreased the level of toxic bacterial metabolitesas a result of lessened bacterial fermentation, causingan improvement in the protein and energy digestibility,thus ameliorating the weight gain and performance ofexperimental birds. Moreover, the organic acids improvethe villus height in the small intestines (Table 3) and alsohave a direct stimulatory effect on the gastro-intestinal cellproliferation as reported by Tappenden and McBurney [21]that short chain fatty acids increase plasma glucagon-likepeptide-2 (GLP-2) and ileal proglucagon mRNA, glucosetransporter (GLUT2) expression, and protein expression,which are all signals which can potentially mediate gutepithelial cell proliferation. These histological changes insmall intestines probably had increased the intestinal surfacearea, facilitating the nutrient absorption to a greater extentand, thus boosted the growth promoting effect of organicacid supplementation.The feed consumption was found statistically nonsignificant(P > .05) among all the treatment groups(Table 2). These results are in agreement with Hernandezet al. [22] who found no difference in the cumulative feedconsumption between the groups fed organic acids andthe control group. Chicks fed the diets supplemented withorganic acids showed a significant (P < .05) improvement inthe FCR as against the chicks fed the control diet (Table 2).The improvement in the FCR could be possibly due to betterutilization of nutrients resulting in increased body weightgain (Table 2) in the birds fed organic acids in the diet.These results are in concordance with the reports of earlierresearchers [23, 24] who reported that the supplementationof organic acids improved the feed conversion ratio inbroiler chicken. The carcass characteristics of broiler chickenfed diets supplemented with the organic acids showed nosignificant differences (P > .05) between various treatmentgroups (Table 2), confirming the earlier findings [25].The mean values regarding the histomorphological alterationsin the broiler chicken fed organic acid based dietsare given in Table 3. Dietary supplementation of organicacids significantly (P < .05) increased the villus heightin the duodenum, jejunum, and ileum but the valueswere significant (P < .05) only in the duodenum andjejunumwhen compared with the control group. The highestduodenal, jejuna, and ileal villus heights were recorded inthe birds fed diets supplemented with 3% butyric acid, 3%
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