Prevalence of Giardia and Cryptosporidium andersoni and their effects on performance in feedlot beef cattle

Abstract

Sixty individually housed Charolais crossbred steers originating from one ranch source had a 12-d (days 0–12) adaptation period in their pens to adjust to their ration and surroundings, followed by two consecutive backgrounding periods (85.5% roughage, 12% concentrate rations) with durations of 84 d (days 13–97) and 63 d (days 98–153), respectively. Steers had a 21-d adaptation period (days 154–174), followed by a 77-d (days 175–257) finishing period (20% roughage, 75% concentrate ration). Fecal samples and animal weights were collected from each steer every 28 d initially, then every 21 d during a test duration of 257 d. Feed weigh-backs were performed weekly for each steer. Fecal samples were processed, and Giardia duodenalis cysts and Cryptosporidium andersoni oocysts were counted. ADG, DMI and FE were calculated for each of the periods (Backgrounding Period 1, Backgrounding Period 2, Finishing Period 3 and Overall). Overall prevalence of C. andersoni and G. duodenalis was 85 and 82%, respectively. There was a decrease (P < 0.05) in the percentage of G. duodenalis infected steers from day 132 to the completion of the trial. The percentage of C. andersoni infected steers decreased (P < 0.05) from day 97 to the completion of the trial (day 257). Shedding of G. duodenalis cysts and C. andersoni oocysts in the feces was intermittent throughout the trial period. A comparison between the ADG, DMI and FE of G. duodenalis infected and non-infected steers demonstrated no overall differences (P > 0.05). A similar comparison between C. andersoni infected and non-infected steers showed no overall difference (P > 0.05) with the exception of a lower (P < 0.05) DMI for infected steers. The degree of Giardia or C. andersoni infection observed in the present study did not effect DMI, ADG or FE of feedlot steers. Key words: Giardia, Cryptosporidium andersoni, feedlot performance, cattle