Effect of enzyme supplementation and plant extracts on villus height and microbial counts in broilers

Abstract

Due to issues concerning antimicrobial resistance, the use of antibiotics in poultry and pigs has been restricted in many countries. The research  focus is now on suitable and readily available alternatives to antibiotic growth promoters. Alternatives such as probiotic, prebiotic, synbiotic, enzymes and acidifiers are being utilized while Phyto biotics (plant extracts) are also considered as viable alternatives. In this study, leaf extracts of  Azadirachta indica (neem) and Vernonia amygdylina (bitter leaf) were administered through drinking water, while enzyme (Roxazyme G2 G ®) was supplemented in the feed of different groups of broiler birds which were randomly allocated to three treatments and a control in triplicates of ten birds per replicate. The control group did not receive either plant extract in water or enzyme in their diet. On day 42, the chickens were slaughtered;  the digesta was gently collected from the ileum and caecum for microbial analysis, while histological analysis was carried on the empty ileum for the determination of villus height. Data collected for microbial analysis was log transformed before statistical analysis and was stated as Log colony forming unit/g of digesta sample (Log cfu/g). The highest villus height was recorded for enzyme treatment (0.955mm) followed by bitter leaf  (0.717mm), and least for neem leaf (0.592 mm) with 0.656 mm for the control. Enzyme supplementation, bitter leaf and neem leaf extract administration had no significant effect (p>0.05) on villus height. However, villus height recorded for enzyme supplementation and administration of  bitter leaf extract wa  numerically higher than the control group. The population of total heterotrophic bacteria (THB) in the ileum was significantly higher (p<0.05) in the control group (9.28 Log cfu/g) than enzyme supplementation (8.52 Log cfu/g) and administration of leaf extract.  The least value was recorded was recorded with bitter leaf (7.94 Log cfu/g). A value of 8.14 Log cfu/g was recorded with neem extract in drinking water. Total coliform was significantly higher (p<0.05) in the control (7.33 Log cfu/g) than in enzyme (6.00 Log cfu/g), neem leaf (4.74 Log cfu/g) and bitter leaf (4.84 Log cfu/g) treatments. The population of enteropathogenic bacteria (Escherichia coli and Salmonella) was also significantly reduced (p< 0.05) by enzyme supplementation and administration of neem leaf and bitter leaf extracts in the ileum. The THB and total coliform counts (Log  cfu/g) was significantly (p<0.05) reduced by enzyme supplementation, neem leaf and bitter leaf extract in the caecum also. In conclusion, the results of the current study showed that the leaf extracts and enzyme supplementation significantly decreased the number of enteropathogenic bacteria in
the ileum and caecum. Although there was no significant impact on villi height, but numerical difference in villi height were recorded.

Keywords: Broilers, enzyme, Phyto biotic, intestinal villi height