Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 7/22/2002
Publication Date: 7/22/2004
Citation: Van Kessel, J.S., Nedoluha, P.C., Williams-Campbell, A., Baldwin, Vi, R.L., Mcleod, K.R. 2004. Effects of ruminal and post ruminal infusion of starch hydrolysate or glucose on the microbial ecology of the gastrointestinal tract in growing steers. Meeting Abstract. p.236. Interpretive Summary:
Technical Abstract: Forty steers fitted with ruminal and abomasal infusion catheters were used to determine the effects of site of carbohydrate supply on gastrointestinal tract bacteria. Steers were assigned randomly to one of 8 groups in a complete randomized block design with a 36 d experimental period. Treatments included: 1.) a pelleted basal ration fed at 0.163 Mcal ME · (kg BW.75)-1 · d-1 (LE), 2.) the basal ration fed at 0.215 Mcal ME · (kg BW.75)-1 · d-1 (HE), 3.) the basal ration fed at 0.163 Mcal ME . (kg BW.75)-1 · d-1 plus ruminal infusion of starch hydrolysate (SH) (RSH), 4.) the basal ration fed at 0.163 Mcal ME · (kg BW.75)-1 · d-1 plus abomasal infusion of SH (ASH), and 5.) the basal ration fed at 0.163 Mcal ME · (kg BW.75)-1 · d-1 plus abomasal infusion of glucose (AG). Glucose and SH were infused at 14.35 and 12.64 g/kg BW.75/d, respectively. Ruminal, intestinal, and fecal samples were obtained on d 36. Ruminal pH was low (5.79) in LE steers and unaffected (P > 0.10) by increased energy intake or carbohydrate infusions. Intestinal and fecal pHs were 6.93 and 7.00, respectively for LE steers. Energy intake (P < 0.10) and carbohydrate infusions (P < 0.01) decreased intestinal and fecal pH compared with LE. Ruminal counts of anaerobic bacteria in LE steers were 8.99 Log10 cells/g. ASH and AG steers had approximately 1.5 Log10 cells/g higher (P < 0.01) intestinal and fecal anaerobic populations. There were 40, 22, and 23%, respectively, fewer aerobic than anaerobic ruminal, intestinal, and fecal bacteria. Less than 1% of the anaerobic bacteria enumerated in the rumen, intestines and feces were coliforms, and 97% of the coliforms were Escherichia coli. Carbohydrate infusions resulted in only numerical increases in fecal coliform and E. coli concentrations (P > 0.10). Fecal E. coli were highly acid-sensitive in all steers with less than 1% surviving a 1 h exposure to low pH (2.0). This suggests that intestinal or fecal pH is not a good indicator of acid-resistance and supports the concept that there are other factors that may induce acid resistance.