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S U M M A R YWhen salmonella organisms were put into the rumen of cattle their subsequent growth or elimination depended on the dietary intake before and after the organisms were ingested. When the animals were receiving a regular daily ration of 6.8 kg. lucerne hay the organisms were rapidly eliminated from the rumen and viable organisms in the faeces were rarely detected. Decreasing the daily food intake to 2-3 kg. or interruption of feeding for one or more days retarded the elimination of salmonellas and Escherichia coli or permitted their growth in the rumen. Growth of salmonellas and E. coli type I occurred during starvation, and resumption of feeding after starvation caused further multiplication. Starvation for 2 or 3 days was generally followed by infection of the intestine, with salmonellas persisting in the faeces for at least a week.

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SUMMARY Salmonella spp. were detected commonly in railway wagons, saleyards and abattoir holding pens through which cattle pass from farm to slaughter. The salmonellae population in the rumen and faeces of cattle at slaughter depended on the previous treatment of the animal. The percentage of animals with salmonellae in the rumen was greater the longer the period between leaving the farm and slaughter; feeding once during this period increased the incidence and numbers of salmonellae in the rumen and at least the incidence in the faeces.

Campylobacter jejuni was commonly detected in both rumen (74%) and faecal (54%) samples obtained at slaughter from calves which were about 4-weeks old but was much less frequently found in adult cattle. However there was a high incidence (47–88%) of C. hyointestinalis in intestinal tract samples from both calves and cattle. While C. jejuni occurred in ruminal material at only low counts (less than 100/g), C. hyointestinalis was often present at high counts (above 105/g). Lot-fed cattle were more likely to have both organisms in their intestinal tracts and on their carcasses than were pasture-fed cattle. Chilling cattle carcasses for 20–24 h significantly reduced the incidence of both Campylobacter species on the carcasses. In contrast campylobacters were found on almost all calf carcasses examined after chilling. The mean count of C. jejuni on calf carcasses before chilling was about 16/cm2 and decreased by about 10-fold after 20 h of chilling.