Lighting during grow-out and Salmonella in broiler flocks

Table 1 Odds-ratios of detecting Salmonella in broiler flock and house litter depending on parameters of grow-out lighting.

		Parameter/its association with the outcome
Outcome sample type	n	Parameter	Mean (range)	OR (Wald-type 95% CI)	P
Feathered carcass rinsates 1 week before the end of rearing	58	10% increase of the hours of full lights during grow-out	25.5% (6.5%-81.2%)	1.38 (0.98, 1.95)	0.061
	58	10% increase of the hours of black-out during grow-out	12.4% (0%-23.9%)	0.32 (0.09, 1.05)	0.060
Post-harvest drag swabs of litter from grow-out house	50	Day of grow-out when dim lights for ≥18 hours per day started	15 (3-29)	0.89 (0.78, 1.01)	0.065
Feathered carcass rinsates at arrival for processing	50	Day of grow-out when dim lights for ≥18 hours per day started	15 (3-29)	0.93 (0.85, 1.01)	0.098
Post-chilling carcass rinsates	54	10% increase of the hours of full lights during grow-out	25.5% (6.5%-81.2%)	1.31 (0.99, 1.74)	0.062
	54	10% increase of the hours of dim lights during grow-out	62.1% (3.2%-77.8%)	0.77 (0.56, 1.05)	0.091

Association between a parameter of grow-out lighting and an outcome was tested in a multi-level mixed logistic regression model that accounted for variation in the Salmonella burden among grow-out farms within a broiler complex, complexes within a company, and between companies. The lighting parameter was tested in this model as a single fixed-effects factor, and was considered to be associated with the outcome if P ≤ 0.100; only such parameters are presented. In all these models, the variation among grow-out farms within a complex significantly (P ≤ 0.100) contributed to variability in the outcome, but not the variation among complexes within a company or between companies (all P > 0.500). n - number of flocks.

ISSN: 1751-0147