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

Table 7 Effect of essential oils on cecal bacterial populations of broilers on day 28

Item ^a	Total bacteria	Lactobacillus	Escherichia	C. perfringens
Treatment
Basal diet, unchallenged	11.18	9.14	8.83	2.68
60 mg/kg EO, unchallenged	11.19	9.10	8.66	2.54
120 mg/kg EO, unchallenged	11.31	9.16	8.80	2.55
240 mg/kg EO, unchallenged	11.00	8.99	8.55	2.42
Basal diet, challenged	11.18	9.22	9.24	2.79
60 mg/kg EO, challenged	11.24	9.30	9.01	3.24
120 mg/kg EO, challenged	10.89	9.19	8.77	2.78
240 mg/kg EO, challenged	10.81	9.02	8.42	2.47
SEM	0.046	0.056	0.092	0.077
P-value
Challenge	0.126	0.473	0.428	0.078
EO	0.076	0.624	0.269	0.205
Challenge × EO	0.220	0.951	0.685	0.406
Linear ^b	0.026	0.255	0.060	0.112
Quadratic ^b	0.399	0.509	0.928	0.437

^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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