Table 2.
Summary of results for 547 studies investigating Salmonella in animal feeds by sector of animal feed production.
| Number of studiesa | ||||||
|---|---|---|---|---|---|---|
|
Field/Pasture
(N = 15) |
Plant
(N = 106) |
Transport
(N = 11) |
Retail
(N = 15) |
Farm
(N = 226) |
Not specified
(N = 204) |
|
| Species for which the feed was intendeda | ||||||
| Not reported (N = 189) | 6 | 53 | 2 | 5 | 10 | 113 |
| Poultry or chickens, not further specified (N = 105) | – | 23 | 1 | 8 | 24 | 49 |
| Swine (N = 103) | – | 29 | 2 | 2 | 44 | 26 |
| Broiler chickens (N = 84) | – | 17 | 2 | 2 | 43 | 20 |
| Laying hens (N = 76) | – | 13 | 3 | 3 | 42 | 15 |
| Cattle, not further specified (N = 42) | 4 | 8 | – | 3 | 14 | 13 |
| Dairy cattle (N = 37) | 2 | 3 | – | – | 28 | 4 |
| Turkeys (N = 28) | – | 3 | 1 | 1 | 20 | 3 |
| Beef cattle (N = 19) | 2 | 2 | – | – | 12 | 3 |
| Fish/Shellfish (N = 19) | – | 4 | 1 | 2 | 7 | 5 |
| Sheep (N = 15) | 2 | 2 | – | – | 3 | 8 |
| Ruminant, not further specified (N = 11) | 1 | 3 | 1 | – | 1 | 5 |
| Goats (N = 8) | 1 | – | – | 1 | 2 | 4 |
| Other farmed poultry (N = 5) | – | – | – | 1 | 2 | 2 |
| Domestic ducks (N = 3) | – | – | – | – | 2 | 1 |
| Buffalo/Bison (N = 1) | – | – | – | – | 1 | – |
| Meat rabbits (N = 1) | – | – | – | – | 1 | – |
| Source(s) tested for Salmonella a | ||||||
| Feed (N = 537) | 11 | 101 | 10 | 15 | 199 | 201 |
| Feed environment (N = 81) | 8 | 30 | 1 | – | 40 | 2 |
| Feed equipment (N = 41) | – | 20 | 2 | – | 16 | 3 |
| Not specified (N = 6) | 1 | – | – | – | – | 4 |
| Other (N = 5) | 1 | 4 | – | – | 1 | – |
| Study design | ||||||
| Single group observational (descriptive only) (N = 169) | 5 | 36 | 6 | 6 | 98 | 18 |
| Analytical observational (N = 139) | 5 | 35 | 4 | 3 | 74 | 18 |
| Laboratory study with experimental manipulation (N = 101) | 1 | 8 | – | 2 | 10 | 80 |
| Diagnostic test assessment (N = 74) | – | 10 | – | 4 | 14 | 46 |
| Molecular characterization, previously obtained isolates (N = 66) | – | 15 | 1 | – | 12 | 38 |
| Trial with natural exposure to Salmonella (N = 23) | 1 | 2 | – | – | 17 | 3 |
| Challenge trial in natural setting (N = 5) | 3 | – | – | – | 1 | 1 |
| Purpose of the Salmonella in feed component of the studya | ||||||
| Estimating prevalence of Salmonella (N = 372) | 9 | 68 | 10 | 9 | 187 | 89 |
| Determining serovars of Salmonella (descriptive) (N = 195) | – | 45 | 8 | 1 | 100 | 41 |
| Evaluation of interventions to reduce Salmonella (N = 121) | 3 | 19 | – | – | 36 | 63 |
| Molecular characterization (descriptive) (N = 115) | 1 | 28 | 2 | 2 | 49 | 33 |
| Determining antimicrobial resistance (descriptive) (N = 111) | – | 16 | 4 | 2 | 55 | 34 |
| Estimating concentration of Salmonella (N = 98) | 6 | 15 | 1 | 2 | 22 | 52 |
| Identifying risk factors for prevalence or concentration (N = 85) | 5 | 19 | 4 | 1 | 36 | 20 |
| Development/Validation of detection methods (N = 82) | – | 9 | – | 5 | 17 | 51 |
| Estimating survival time for Salmonella (N = 54) | – | 4 | – | 1 | 8 | 41 |
| Outbreak investigation with animal feed component (N = 20) | – | 5 | – | – | 12 | 3 |
| Comparing serovars between sectors (N = 16) | – | 11 | 1 | – | 4 | – |
| Comparing prevalence of Salmonella between sectors (N = 15) | – | 11 | – | – | 3 | 1 |
| Comparing molecular characteristics between sectors (N = 10) | – | 4 | – | 1 | 2 | 3 |
| Comparing antimicrobial resistance between sectors (N = 7) | – | 4 | – | – | 1 | 2 |
| Evaluation of conditions associated with survival times (N = 4) | – | 1 | – | – | 1 | 2 |
| Development or validation of surveillance methods (N = 4) | – | 1 | – | 1 | 2 | – |
| Evaluation of linkages between Salmonella in feed and human illness (N = 3) | – | 1 | – | – | 1 | 1 |
| Salmonella outcomes reporteda | ||||||
| Serovar(s) in food/Food environment/Food equipment (N = 292) | 5 | 64 | 7 | 6 | 97 | 113 |
| Prevalence/Proportion positive (N = 283) | 5 | 62 | 7 | 9 | 135 | 65 |
| Molecular characteristics (N = 93) | – | 24 | 2 | 3 | 34 | 30 |
| Concentration (N = 92) | 6 | 12 | 1 | 3 | 16 | 54 |
| Reported Salmonella absent, no denominator (N = 81) | – | 8 | 1 | 2 | 33 | 37 |
| Antimicrobial resistance (N = 68) | – | 15 | 2 | 1 | 28 | 22 |
| Survival time (N = 59) | 3 | 3 | – | 1 | 9 | 43 |
| Reported Salmonella present, no denominator (N = 55) | – | 8 | – | 2 | 25 | 20 |
| Reported number of positive samples, no denominator (N = 18) | – | 4 | – | 1 | 6 | 7 |
| Odds ratios/Risk ratios (N = 5) | – | 3 | – | – | 2 | – |
| Incidence (N = 2) | – | – | – | – | 2 | – |
| Results were combined among sample types (N = 102) | 2 | 11 | 3 | 1 | 63 | 22 |
| None of the above (N = 18) | – | 3 | – | – | 3 | 12 |
| No results presented (N = 3) | – | 1 | – | – | 2 | – |
a
More than one response could be selected for a study, so the total may exceed the total number of studies characterized.