Comparative Efficacy of an Organic Acid Blend and Bacitracin Methylene Disalicylate as Growth Promoters in Broiler Chickens: Effects on Performance, Gut Histology, and Small Intestinal Milieu

Table 4

Effect of feeding organic acid blend (OA) and bacitracin methylene disalicylate (BMD) at different dose levels on pH of different segments of the gastrointestinal tract, microbial counts in the digesta contents of the small intestine and length of the villi in different segments of the small intestine ^†.

	Dietary treatments					Pooled SE	Contrast $P$ value
Measurements	Control (Basal diet)	OAB		BMD			Dose effect		Between treatments
		1 g/kg diet	2 g/kg diet	0.5 g/kg diet	1.0 g/kg diet		OA	BMD
pH in different segments of the gastrointestinal tract
Crop	4.75	4.90	4.71	4.78	5.32	0.069	NS	NS	NS
Proventriculus	3.03	2.95	3.07	3.13	2.4	0.089	NS	^$	NS
Gizzard	3.23	2.63	2.61	3.15	2.52	0.059	^**LQ	^**L	NS
Duodenum	6.18	6.12	6.27	5.98	6.38	0.06	NS	NS	NS
Jejunum	6.32	6.29	6.28	6.35	6.34	.09	NS	NS	NS
Ileum	6.97	7.17	7.18	7.4	7.28	0.055	NS	^$	NS
Microbial counts of the digesta in different segments of the small intestine (log10 CFU/g digesta)
Escherichia coli	3.78	3.38	3.7	2.22	1.27	0.582	NS	NS	NS
Other coliforms	2.72	2.6	2.63	2.65	0.63	0.422	NS	NS	NS
Lactobacillus spp.	2.43	6.5	1.5	1.5	1.2	0.32	^**Q	NS	*
Height of villi ($\mu$m) in different segments of small intestine
Duodenum	1513	1524	1667	1197	1238	25.74	*L	^**LQ	^***
Jejunum	996	1049	1063	984	1287	16.37	*Q	^***LQ	*
Ileum	799	752	822	697	747	7.46	*LQ	^***LQ	*

^†Birds were harvested on d 35,  ${}_{}{}^{\text{L}}\text{s}$ignificant linear effect, ${}_{}{}^{\text{Q}}\text{s}$ignificant quadratic effect, *at $P<.05\text{,}$^**at $P<.01$, *at ^$$P<.001\text{,}$$P<.1$.
 Tests for Salmonella and Clostridium were negative and hence the results are not shown.