Fm. Nattress et Ac. Murray, Effect of antemortem feeding regimes on bacterial numbers in the stomachs and ceca of pigs, J FOOD PROT, 63(9), 2000, pp. 1253-1257
Three groups, each of 45 pigs, were either not fasted, fasted for 15 h duri
ng lairage at the abattoir, or fasted for 15 h before dispatch from the pig
gery to the abattoir. Three subgroups, each of 15 pigs from each group, wer
e held at the abattoir for additional times of either 0 to 1 h, 2 to 3 h, o
r 4 to 5 h. Immediately after slaughter, stomach and cecal contents were co
llected for pH measurement and enumeration of coliforms, Escherichia coli b
iotype 1 and lactic acid bacteria (LAB). Stomach pH changed from 4.1 to 3.1
as additional abattoir holding time increased from 0 to 1 h to 4 to 5 h bu
t was unaffected by feed withdrawal (mean pH, 3.5). Cecal pH (range 6.4 to
7.2) increased in response to both treatments. Coliform and E. coli biotype
1 numbers in the stomach, means 4.6 and 4.5 log CFU/g, respectively, were
not affected by feed withdrawal but decreased 0.8 log units as additional a
battoir holding time increased from 0 to 1 to 4 to 5 h. LAB in the stomach
decreased in response to both feed withdrawal and holding at the abattoir.
Cecal numbers of coliforms and E. coli biotype 1 increased 0.8 and 1.0 log
units to 7.8 and 7.6 log CFU/g, respectively, as a result of feed withdrawa
l, and 0.6 log units to 7.6 and 7.5 log CFU/g, respectively, as additional
abattoir holding time increased to 4 to 5 h. The LAB in the cecum (mean 9.4
log CFU/g) increased slightly with increasing abattoir holding time. In th
e event of release of stomach or cecal contents onto the meat during carcas
s dressing, larger numbers of E. coli per g would be released from the ceca
and fewer per g from the stomachs of pigs that have had feed withdrawn as
compared to pigs not subjected to feed withdrawal.