The effect of feeding non-heat treated, non-pelleted feed compared to feeding pellited, heat treated feed on the salmonella-seroprevalence of finishing pigs

摘要

Epidemiological studies indicated, that a major risk factor for high seroprevalence of Salmonella in finishing pigs in Denmark is the use of purchased feed compared to home-mixed feed. In Denmark all purchased feed is heat treated and generally pelleted, whereas in home-mixed feed is served as meal, and at least the cereal part is never heat treated. It is believed, although not documented, that home-mixed feed is more coarse ground than purchased feed. A clinical trial was performed to investigate, whether the epidermological results could be explained by the differences between heal treated pellets and non-heat treated meal. Six finishing sections with 12 pens in each were used for the trial. Some sections were used several times, giving a totalof 150 pens. The feed of all groups were based on the same standard recipe for finishing pigs in Denmark, but the physical characteristics drffered. Characteristics of each feed is described in table 1. Shortly before slaughter 6 pigs were bled in eachpen, and the blood samples were analysed using the Danish Salmonella-Mix-ELISA. To account for the effect of different infection levels in different units, a measure for the infection level for each unit was defined as the average OD percent of all sampled pigs in the unit. Method 1. Results were analysed using a cut-off of OD percent=40. OD percent=40 is the cut-off used in the Danish Salmonella Surveillance Programme.