Effects of repeated-low level sodium chlorate administration on ruminal and fecal coliforms in sheep

The objective of this study was to evaluate the efficacy of oral sodium chlorate administration on reducing total coliform populations in ewes. A 30% sodium chlorate product or a sodium chloride placebo was administered to twelve lactating Dorper X Blackbelly or Pelibuey crossbred ewes averaging 65kg body weight. The ewes were adapted to diet and management. Ewes were randomly assigned (4/treatment) to one of three treatments which were administered twice daily by oral gavage for five consecutive days: a control (TC) consisting of 3g sodium chloride/animal/d, a T3 treatment consisting of 1.8g of sodium chlorate/animal/d, and a T9 treatment consisting of 5.4g sodium chlorate/animal/d; the latter was intended to approximate a lowest known effective dose. Ruminal samples collected by stomach tube and freshly voided fecal samples were collected daily beginning 3days before treatment initiation and for 6days thereafter. Contents were cultured quantitatively to enumerate total coliforms. There were no significant differences in total coliform numbers (log(10) cfu/g) in the feces between treatments (P = 0.832). There were differences (P < 0.02) in ruminal coliform counts (log(10) cfu/mL) between treatments (4.1, 4.3 and 5.0 log(10)/mL contents in TC, T3 and T9 Treatments, respectively) which tended to increase from the beginning of treatment until the 5th day of treatment (P < 0.05). Overall, we did not obtain the expected results with oral administration of sodium chloride at the applied doses. By comparing the trends in coliform populations in the rumen contents in all treatments, there was an increase over the days. The opposite trend occurred in the feces, due mainly to differences among rumen contents and feces in ewes administered the T9 treatment (P = 0.06). These results suggest that the low chlorate doses used here were suboptimal for the control of coliforms in the gastrointestinal tract of ewes.