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Optimum Monensin Levels In Feeder Calf Receiving Diets, R. H. Pritchard, J. U. Thomson
Optimum Monensin Levels In Feeder Calf Receiving Diets, R. H. Pritchard, J. U. Thomson
South Dakota Beef Report, 1993
Monensin was fed in the receiving diets of recently weaned calves at a rate of 0, 10, 20, or 30 g per ton (air dry basis) or 100 or 200 mg per head daily to determine effects on feed intake and coccidia control. The 240 steer calves used originated from western rangelands and had no previous exposure to milled feeds or confinement. During the first week in the feedlot, monensin fed at 30 g per ton depressed feed intake by 5% and the depression response was linear (P<.001) over the range of dosages tested. This reduction in feed intake did not affect average daily gain or calf health. Over 90% of these calves were shedding coccidia oocysts on the first day in the feedlot. Monensin began to suppress (P<.01) oocyst shedding after 10 days on feed and this effect persisted throughout the 84-day experiment. The percentage of calves within a treatment that were not shedding oocysts improved as monensin dosage was increased. These data indicate that intake sensitivity to monensin is primarily related to daily intake of the drug rather than drug concentration in the diet. Furthermore, monensin can be included in receiving calf diets at sufficiently high levels to reduce coccidia oocyst shedding without depressing performance.
Optimum Monensin Levels In Receiving Diets For Newly Weaned Calves, R. H. Pritchard, J. U. Thomson
Optimum Monensin Levels In Receiving Diets For Newly Weaned Calves, R. H. Pritchard, J. U. Thomson
South Dakota Beef Report, 1992
This research addressed the effects of dietary monensin on the performance and health of steer calves weaned and shipped directly to the feedlot. Feedlot receiving diets were based on corn silage and contained 0, 10, 20, or 30 g/ton monensin. Calves were allowed ad libitum access to feed for 85 days to determine the effects of monensin level on dry matter intake, average daily gain, and fecal shedding of coccidia oocysts. Higher levels of monensin caused decreases (P<.05) in dry matter intake during the initial feeding period. Gains were not affected by monensin during this period and as a result feed efficiency was improved (P<.05) when diets contained 20 or 30 g of monensin per ton. Cumulative 85-day feedlot performance was not affected by treatment. Over 90% of all calves were shedding coccidia oocyst when they arrived in the feedlot. The number of calves shedding oocysts was consistently reduced by monensin after 18 days postweaning.