The survival of Salmonella Montevideo and Salmonella heidelberg in dry milk, cocoa powder, poultry feed, and meat and bone meal was studied at three water activities (aw) in the range of 0.4 to 0.75. S. montevideo was more resistant to the various dry environments than S. heidelberg. Salmonellae were enumerated immediately after inoculation, after 2 d, and after 1, 3, 7 and 14 wk. Survival was greater at aw of 0.43 and 0.52 than at 0.75 aw. Based on these findings and due to the marked differences in survival observed in the different products equilibrated at a specific aw value, it is concluded that the survival of salmonellae in a dry product cannot be predicted on the basis of the aw alone.
The effects of Ca source (limestone or a mixture of one-third limestone and two-thirds oyster shell), NaHCO3 (0 or .5%) and feeding photoperiod (16 or 24 hr) were studied in a 16-week experiment involving 240 Hy-Line W-36 Leghorn hens, 25 weeks of age. Neither egg production (percent hen-day and egg mass, kg egg/bird per 16 weeks) nor feed conversion ratio (kg feed per kg egg) were significantly (P greater than .05) affected by dietary treatment or photoperiod. However, extending the photoperiod to 24 hr significantly (P less than .05) increased feed consumption with a consequent increase in egg weight (P less than .01). Feeding oyster shell in combination with limestone significantly (P less than .05) improved specific gravity of eggs, whereas dietary NaHCO3 significantly (P less than .01) improved elasticity of the egg shell as measured by deformation. Eggshell quality was improved by increasing the photoperiod to 24 hr and was most pronounced when hens were fed diets supplemented with .5% NaHCO3 and limestone as the only source of Ca.
The efficacy of four preenrichment media (lactose broth, lactose broth with Tergitol, buffered peptone and M-9) and of direct enrichment in selenite cystine and modified tetrathionate broths for recovering two Salmonella serotypes from dry poultry feed was determined. The salmonellae, artificially inoculated and stored for 7 wk in the dry feed (1.5 to 2.2 cells of salmonellae/g of feed analyzed), were recovered from significantly more samples after preenrichment with M-9 or buffered peptone than with any of the other procedures tested.
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