To all our cooperators from across California. be they ranchers, growers, or regulators, activists, resource managers, and the public THANK YOU!

Transcription

1 Managing Rangeland sheds for Agricultural Production, Quality, and Food Safety To all our cooperators from across California be they ranchers, growers, or regulators, activists, resource managers, and the public THANK YOU! Rob Atwill, D.V.M., Ph.D. University of California-Davis California feeds the nation, every day California beef cattle Juxtaposition of plant agriculture and grazed rangeland Salinas Valley example Produce outbreaks traced back to California Many outbreaks occur in late summer to early fall Year Food Vehicle Pathogen Cases Reference Produce Fields raw food always safe Chaparral wildlife habitat Salinas River riparian corridors wildlife habitat water Rangeland cow-calf & stockers wildlife habitat 199 Mesclun lettuce E. coli O157:H7 1 Hilborn et al., Unpasteurized apple juice Alfalfa or clover sprouts ( outbreaks) E. coli O157:H7 7 CDC, 199; Cody et al., 1999 E. coli O157 Salmonella -1 Raw almonds Salmonella Enteritidis PT3 Mohle-Boetani et al., 1 18 Isaacs et al., 5 Romaine lettuce E. coli O157:H7 9 CDHS, -4 Raw almonds Salmonella Enteritidis PT9c 47 CDHS, 4 3 Baby spinach E. coli O157:H7 1 Reiss et al., 7 Baby spinach E. coli O157:H7 5 CDC, Iceberg lettuce E. coli O157:H7 77 CDPH, 7 Iceberg lettuce E. coli O157:H7 8 CDPH, 8 Recalls and outbreaks continue to present day 1

2 Are these produce outbreaks the result of livestock grazing on rangeland (cattle or sheep)? GAPs & BMPs proximity to livestock, rangeland runoff, irrigation water, wildlife intrusion borne pathogen BMPs for grazing borne pathogen BMPs for grazing Key processes driving waterborne contamination 1. animal loading (who done it). microbial transport (how did it get there) 3. microbial inactivation (is it still alive) Key processes driving waterborne contamination 1. animal loading (who done it). microbial transport (how did it get there) 3. microbial inactivation (is it still alive)

3 Rangeland buffers appear to retain 95% of key pathogens in winter and spring; >99.9% achievable under certain conditions Sierra Foothill Research & Extension Center, University of California Buffer width (m).1, 1.1,.1 Land slope (%) 5,, 35 RDM (kg/ha) 5, 5, 9, 45 Rangelands and timing of grazing Match onset of rainy season to exclusion dates Summer riparian grazing Rotational grazing timelines Irrigated rangeland/pasture BMPs exclude cattle before irrigation, reduced tailwater flows, retention basins, constructed wetlands, etc. 1 technical reports on waterborne pathogens and BMPs Ken Tate s website (California Rangeland shed Laboratory) all are FREE! NRCS, USDA Riparian habitat removal WHO Bare ground buffers 3

4 Are livestock and wildlife infected with key food pathogens? E. coli O157:H7 in central California wildlife and cow-calf operations E. coli O157:H7, 8-1 Feral pig 1/ (5%) Coyote /95 (%) Am. crow 5/93 (5%) Cowbird / (3%) Rabbit /18 (%) Skunk /3 (%) Tule elk 3/15 (%) Deer /447 (%) Cow-calf herds 8/715 (.5%) Cow-calf herds, 8-1 E. coli O157 infection ranged from % to 1% Salmonella was <1% Herd A B C D E F G H I Total pos n prev (%) Would vaccination for E. coli O157:H7 make sense? 11 & 1 field trials of romaine lettuce, Salinas Valley Prevalence of pathogens in wild rodents in produce fields, central California <1% infected with E. coli O157:H7 3-4 % infected with Salmonella Rodent species Cryptosporidium Giardia CA parasitic mouse 11% 13% Deer mouse 33% 7% Dusky-footed wood rat 17% 17% Total 8% 5% Preliminary data: Crypto appears human infectious, Giardia mostly not Add in hours of irrigation to 3% heads of lettuce contaminated with E. coli O157:H7 4

5 Statewide livestock survey E. coli O157:H7, Salmonella, Cryptosporidium, Giardia Sheep infection with Cryptosporidium spp. - sheep and cow-calf - lambs 31% ewes 3% 9% not human infectious 1% human infectious Surface water distance from raw manure 1 ft for sandy soil, ft for loamy or clay soil (slope <%) Increase distance to 3 feet if slope >% Edge of crop >3 feet from grazing lands; use vegetated buffers, fencing, berms, etc. 5

6 Irrigation water that contacts produce: E. coli 1 MPN / 1 ml (geometric mean n=5) 35 MPN / 1 ml for any single sample Microbiological of irrigation water E. coli concentrations in California irrigation water, (n=44,; all seasons: wells,canals,on-farm reservoirs) Exceedance 77% 11% % 1, 1% %.8%.5%.4%.1% 1 4% 1 % 1 % % % 4% % > No. of feed lots in 5Km radius E. coli concentration (MPN/1mL) Often poor correlation between generic E. coli and pathogens -- Example: Sacramento/San Joaquin Delta-- Correlation between indicator bacteria and pathogens in water 35 cfu/1 ml 1 1 Salmonella (mpn / 1 ml) Pathogen (number / 1 ml) Frequency 8% 8% Probability of E. coli > 1, Imperial country, CA Irrigation canals adjacent to feedlots 1% Proportion 1, Indicator bacteria (number / 1 ml) E. coli (cfu / 1 ml)

7 E. coli -most are beneficial -million or more per gram feces Enterohemorrhagic E. coli outbreak strain CVRWQCB From Red Bluff to Sacramento, Sonora to Modesto E. coli O157 / = 3% E. coli O157:H7 Salmonella 1/ = 35% Salmonella (MPN/1 ml) Average: E. coli 4 mpn/1 ml Salmonella.1 mpn/1 ml ~3 more E. coli than Salmonella E. coli (MPN/1 ml) CCRWQCB From Rincon Creek up to Aptos Creek 3 rivers, creeks or their estuaries April 9 to April 1 E. coli O157 /51 =.4% Salmonella 78/51 = 35% 1.3 MPN/1 ml Recall <1% cow-calf shed Salmonella; -% in wildlife Any questions 7