Influences of short-term pre-slaughter dietary manipulation in sheep and goats on pH and microbial loads of gastrointestinal tract

Sheep (BW=39.9kg, n=16) and goats (BW=32.8 kg, n=16) were used in a completely randomized design to determine the effect of short-term pre-slaughter diet and feed deprivation (FD) time oil pH and microbial loads in the gastrointestinal tract (GIT) contents. In a 2 x 2 x 2 factorial treatment arrangement, the main effects of species, diet, and FD time prior to slaughter and their interactions were studied. Animals were fed either a hay or concentrate diet for 4d and then feed deprived for either 12 or 24-h prior to slaughter. The pH of rumen and colon contents as well as weight of GIT was measured. The contents of rumen and rectum were also sampled for microbial analysis. The GIT of sheep (1.82 kg) was heavier (P < 0.05) than that of goats (1.46 kg). The 12-h FD group (1.74 kg) had a higher (P < 0.05) GIT weight than the 24-h FD group (1.53 kg). Hay-fed animals had higher (P<0.05) rumen (7.08 vs. 6.43) and colon pH values (7.02 vs. 6.56) than those of the concentrate-fed animals. The 24-h FD group (3.39+/-0.272 log(10) CFU/g) contained more (P < 0.05) Escherichia coli in the rumen than did the 12-h FD (2.17+/-0.272 log(10)CFU/g) group. The concentrate-fed animals (3.49+/-0.289 log(10)CFU/g) had higher (P< 0.05) coliform counts in the rumen than the hay-fed animals (2.43+/-0.289 log(10)CFU/g). The 24-h FD group (3.42+/-0.289 log(10)CFU/g) had a higher (P< 0.05) concentration of coliform than did the 12-h FD group (2.50+/-0.289 log(10)CFU/g). The 24-h FD group (3.31+/-0.259 log(10)CFU/g) also had higher (P<0.05) Enterobacteriaceae counts in the rumen than did in the 12-h FD group (2.47+/-0.259 log(10C)FU/g). Goats (5.71+/-0.158 log(10)CFU/g) had lower (P < 0.05) total plate counts in the rumen compared to sheep (6.27+/-0.158log(10)CFU/g). The concentrate-fed animals had higher (P < 0.05) E coli (6.44 vs. 4.01+/-0.468 log(10) CFU/g), total coliform (6.74 vs. 4.16+/-0.469 log(10)CFU/g), Enterobacteriaceae (6.93 vs. 3.83+/-0.651 log(10) CFU/g), and total plate counts (7.79 vs. 7.28+/-0.170 log(10)CFU/g) in the rectum than the hay-fed animals. The results indicate that microbial loads in the GIT of small ruminants may be reduced by either feeding hay for 4 d or depriving feed for 12-h prior to slaughter. (C) 2008 Elsevier B.V. All rights reserved.