In vitro antibacterial activity of thymol and carvacrol and their effects on broiler chickens challenged with Clostridium perfringens

Table 6 Effect of essential oils on cecal bacterial populations of broilers on day 21

Item ^a	Total bacteria	Lactobacillus	Escherichia	C. perfringens
Treatment
Basal diet, unchallenged	11.16	8.52	9.77	3.05
60 mg/kg EO, unchallenged	11.50	8.86	9.53	2.38
120 mg/kg EO, unchallenged	11.41	9.16	9.51	2.83
240 mg/kg EO, unchallenged	11.42	8.69	9.41	2.41
Basal diet, challenged	11.28	8.60	9.28	3.68
60 mg/kg EO, challenged	11.43	9.02	9.42	3.63
120 mg/kg EO, challenged	11.40	9.06	9.46	3.30
240 mg/kg EO, challenged	11.37	8.70	9.34	3.39
SEM	0.041	0.068	0.085	0.110
P-value
Challenge	0.973	0.785	0.316	<0.001
EO	0.190	0.022	0.952	0.327
Challenge × EO	0.842	0.916	0.783	0.466
Linear ^b	0.299	0.673	0.566	0.270
Quadratic ^b	0.129	0.002	0.927	0.606

^a Values are means of eight replicates per treatment, and expressed as log₁₀ (copy/g digesta). EO, essential oils; unchallenged, birds without challenge of C. perfringens; challenged, birds challenged with C. perfringens from day 14 to 20; SEM, pooled standard error of the mean; Challenge × EO, interaction between C. perfringens challenge and EO supplementation
^b When interaction between C. perfringens challenge and EO supplementation was not significant, linear and quadratic polynomial contrasts were performed on the main-effect means to EO dosages

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