The efficacy of cleaning and disinfection on pig farms

Abstract

Little is known about the effectiveness of the cleaning and disinfection methods in use on commercial pig farms either in Ireland or worldwide. A National Salmonella Control Programme was implemented in Ireland in August 2002 to monitor and control infection with Salmonella spp. in pigs. In Ireland, all commercial pig herds must be categorised according to their Salmonella sta- tus. Herds in category 1, 2 and 3 have a serological Salmonella prevalence of infection of #10%, >10-#50% and >50-#100%, respectively. The aim of this study was to assess the efficacy of washing and disinfecting finisher units on category 1 and category 3 farms, in reducing or eliminating levels of Enterobacteriaceae. Enterobacteriaceae counts were used as indicators of the contamination of the environment with enteric bacteria, which could include Salmonella spp. Samples were taken from the pen floors and feeder/drinker units of four category 1, two high category 2 and 1 category 3 farms. Enterobacteriaceae and salmonellae were enumerated in each sample. Limited results available on enumeration suggest that there was a decrease in levels of Enterobacteriaceae on pen floors after cleaning and disinfection, regardless of category. However, significant residual contamination remained on the surfaces of the feeder/drinker units following cleaning and disinfection on all farms. Introduction A national programme to reduce Salmonella contamination in pork and pork prod- ucts should include monitoring and intervention from the farm to the factory. In Ireland, the national Salmonella control programme is based on the categorisation of all commercial pig herds according to their Salmonella status. Finishing pigs in herds in category 1, 2 and 3 have a serolog- ical Salmonella prevalence of #10%, >10-#50% and >50-#100%, respectively. The prevalence of Salmonella within a herd from farm to slaughter is governed by many fac- tors, one of the most important being an effective hygiene programme. Cleaning and disinfection have an important part to play in the control of this disease. It has been found that uninfected pigs, which remained in disinfected pens, usually stayed free of Salmonella (Linton et al. 1970). However, achieving a sufficient reduction in Salmonella levels by hygienic and management proce- dures alone can be quite difficult. In a study aimed at reducing Salmonella at farm level, Dahl et al. (1997) found that problem herds that improved hygiene combined with all in-all out measures did not achieve the same success as those that used organic acids in the water or feed. The objectives of this study were 1) to determine and compare the efficacy of cleaning and disinfection procedures in finisher units from ten category 1 and ten high category 2/category 3 farms, using Enterobacteriaceae counts as a marker for residual enteric bacteria, and 2) to deter- mine the prevalence of Salmonella spp. both before and after cleaning.