Abstract:
Increasing knowledge of bacterial resistance to antibiotics used in both human and
veterinary medicine has contributed to development of perceptions in consumers that
suitable alternatives to antibiotics must be identified. Probiotics have been recently
documented to have beneficial effects on animal health and thus stand for a better
alternative to antibiotics. Therefore, the aim of the study was to evaluate the effect of
drinking water supplementation of locally isolated probiotics on broiler growth
performance, organ development, hematological profile and cecal microbial composition
in replacing antibiotic growth promoters (AGPs). A total of 320 one day old mixed sexed
“Cobb 500” broiler chicks were allocated to 4 treatment groups in a complete randomized
design (CRD) and each treatment was replicated 4 times with 20 chicks in each replicate.
Treatments included (T1) the basal diet as a negative control; (T2) basal diet +
doxycycline antibiotic via drinking water (2g/L) as a positive control; (T3) basal diet +
probiotic I (Lactobacillus spp); (T4) basal diet + probiotic II (Bifidobacterium spp.). The
results revealed that supplementation of probiotic I (Lactobacillus spp.) increased
(P<0.05) body weight and decreased FCR but had no significant difference (P>0.05) in
feed consumption, dressing percentage and survivability percentage. None of the weights
of the heart, gizzard, spleen, bursa, and abdominal fat were influenced by supplemental
probiotics (P>0.05), although improved liver weight was found by supplemented with
probiotic I (P<0.05). Significant (P<0.05) improvements were also observed in Hb, RBC
and WBC counts in probiotic supplemented group than the antibiotic and control group.
In addition, DLCs, PCV, MCH, MCHC were not affected (P>0.05) by the treatments.
The microbiological analysis indicated that the lactic acid bacterial population boosted
predominantly. The total coliform and Salmonella counts were significantly reduced and
Lactobacillus spp was significantly (P<0.05) increased supplemented with probiotic I and
probiotic II compared with antibiotic and control group in the cecal contents of birds at
day 28. The best performance was detected in birds of probiotic I group followed by the
probiotic II, antibiotic and control group. Because of its remarkable efficacy it is
concluded that, the use of mixed culture of Lactobacillus spp. could be considered as a
good potential probiotic for broiler chickens and viable alternative to antibiotics in broiler
diet at finisher stage and its benefits should be further evaluated on a commercial scale.
Description:
A Thesis
Submitted to the Faculty of Animal Science & Veterinary Medicine
Sher-e-Bangla Agricultural University, Dhaka,
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE (MS)
IN
POULTRY SCIENCE
SEMESTER: JAN-JUNE, 2019