Survival of Indicator and Pathogenic Bacteria in Bovine Feces on Pasture

Lester W. Sinton; Robin R. Braithwaite; Carollyn H. Hall; Margaret L. Mackenzie

doi:10.1128/AEM.01620-07

DOI: 10.1128/AEM.01620-07

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FIG. 1.
Survival of E. coli (○), fecal streptococci (•), enterococci (▪), S. enterica (▵), and C. jejuni (▴) in cow pats deposited on pasture in the winter, as well as the water contents of the indicator (○) and pathogen (•) pats and rainfall (columns).
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FIG. 2.
Survival of E. coli (○), fecal streptococci (•), enterococci (▪), S. enterica (▵), and C. jejuni (▴) in cow pats deposited on pasture in the spring, as well as the water contents of the indicator (○) and pathogen (•) pats and rainfall (columns).
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FIG. 3.
Survival of E. coli (○), fecal streptococci (•), enterococci (▪), S. enterica (▵), and C. jejuni (▴) in cow pats deposited on pasture in the summer, as well as the water contents of the indicator (○) and pathogen (•) pats and rainfall (columns).
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FIG. 4.
Survival of E. coli (○), fecal streptococci (•), enterococci (▪), S. enterica (▵), and C. jejuni (▴) in cow pats deposited on pasture in the autumn, as well as the water contents of the indicator (○) and pathogen (•) pats and rainfall (columns).

Tables

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TABLE 1.

Initial, peak, and final counts of indicators and pathogens in cow pats placed on pasture in each season

Measurement	Concn (CFU/g [dry wt] of feces)^a
Measurement	E. coli	Fecal streptococci	Enterococci	C. jejuni	S. enterica
Winter
Initial	2.2 × 10⁶	6.9 × 10⁵	3.2 × 10²	6.7 × 10⁶	1.1 × 10⁷
Peak		1.0 × 10⁶ (21)	1.3 × 10³ (21)		2.4 × 10⁷ (7)
Final	91 (149)	1.3 × 10³ (149)	4.7 × 10² (149)	3.1 × 10² (76)^b	5.0 × 10² (140)
Spring
Initial	3.3 × 10⁵	7.2 × 10⁶	1.3 × 10⁵	6.3 × 10⁶	1.7 × 10⁷
Peak	5.0 × 10⁵ (7)	3.4 × 10⁷ (7)	3.5 × 10⁶ (7)
Final	1.4 × 10³ (148)	1.4 × 10³ (148)	71 (148)	46 (16)^b	40 (153)
Summer
Initial	3.0 × 10⁶	1.4 × 10⁶	2.8 × 10⁴	2.7 × 10⁷	1.7 × 10⁷
Peak	4.8 × 10⁷ (7)	5.0 × 10⁷ (7)	1.3 × 10⁵ (7)
Final	2.9 × 10⁴ (141)	1.3 × 10⁴ (141)	1.5 × 10³ (141)	4 (10)^b	1.5 × 10⁴ (146)
Autumn
Initial	2.2 × 10⁵	4.0 × 10⁶	99	6.1 × 10⁶	3.2 × 10⁷
Peak	1.9 × 10⁶ (14)		9.6 × 10² (7)		6.5 × 10⁷ (5)
Final	1.7 × 10³ (155)	1.6 × 10² (155)	1 (155)	54 (27)^b	1.6 × 10³ (153)

↵ a Each count is the mean for four samples (one sample from each cow pat). Peak counts are given only where they were greater than the initial count. The number in parentheses is the day on which the count was recorded.
↵ b Last day on which C. jejuni was detected.

TABLE 2.

Growth and decrease phase coefficients and T₉₀ values (calculated for both the total survival curve and for the decrease phase only) for indicator and pathogenic bacteria in cow pats^a

Season	Indicator or pathogen	Increase coefficient		Decrease coefficient		T₉₀ for decrease phase (days)^b	T₉₀ for deposition (days)
Season	Indicator or pathogen	Value (day⁻¹)	R²	Value (day⁻¹)	R²	T₉₀ for decrease phase (days)^b	T₉₀ for deposition (days)
Winter	E. coli			0.06	0.89	38	38
	Fecal streptococci	0.03	0.80	0.08	0.91	29	34
	Enterococci	0.06	0.85	0.04	0.98	58	62
	C. jejuni			0.14	0.97	16	16
	S. enterica	0.11	(1)^c	0.09	0.99	26	26
Spring	E. coli	0.06	(1)^c	0.06	0.89	38	39
	Fecal streptococci	0.23	(1)^c	0.07	0.92	33	30
	Enterococci	0.48	(1)^c	0.06	0.83	38	37
	C. jejuni			0.87	0.97	2.7	2.7
	S. enterica			0.08	0.96	29	29
Summer	E. coli	0.40	(1)^c	0.05	0.74	46	48
	Fecal streptococci	0.53	(1)^c	0.06	0.77	38	42
	Enterococci	0.25	(1)^c	0.03	0.82	77	69
	C. jejuni			1.91	0.99	1.2	1.2
	S. enterica			0.04	0.87	58	58
Autumn	E. coli	0.15	0.98	0.05	0.93	46	66
	Fecal streptococci			0.07	0.98	33	33
	Enterococci	0.33	(1)^c	0.05	0.94	46	57
	C. jejuni			0.49	0.99	4.7	4.7
	S. enterica	0.15	(1)^c	0.06	0.95	38	38

↵ a The coefficients (k) were derived from a regression of the natural logarithms: N = e^kt, where N is the count and t is time. T₉₀ values were calculated from T₉₀ = 2.303/k.
↵ b Same as the T₉₀ for deposition when there was no increase phase.
↵ c There were only two data points.

TABLE 3.

Monthly rainfall, drainage, and the percent loss of E. coli from undisturbed cow pat on the leachate collector^a

Month	Rainfall (mm)	Winter		Spring		Summer		Autumn
Month	Rainfall (mm)	Drainage (mm)	% E. coli loss from pat	Drainage (mm)	% E. coli loss from pat	Drainage (mm)	% E. coli loss from pat	Drainage (mm)	% E. coli loss from pat
July 2004	40.4	13.1	0.39
August 2004	136.8	31.3	0.43
September 2004	34.2	7.6	0.03
October 2004	25.4	3.1	0.13	0.1	0.002
November 2004	45	9.6	4.71	28.2	16.6
December 2004	131.6			84.3	57.8
January 2005	33.6			17.3	11.4
February 2005	18.6			32.5^b	6.13	35.7^b	26.5
March 2005	36.6					10.3	0.13
April 2005	52.4					30.1	5.95	32.4	0.25
May 2005	61					47.3	7.79	41.2	0.03
June 2005	19					7.0	1.74	5.7	0.005
July 2005	18.2							7.0	0.001
August 2005	13.8							6.0	0.92

↵ a The total number of E. coli CFU in the pat was estimated from the geometric mean of the counts in the other four pats.
↵ b Site flooded (drainage exceeded rainfall).