Feeding Behavior Changes of Cattle during Introduction of Monensin with Roughage or Concentrate Diets

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Abstract
To assess the nature of the aversion frequently shown by cattle for feed containing Rumensin, cattle were prepared with rumen cannulas and adapted to either a 93% ground alfalfa hay diet (n=12) or an 85% concentrate diet (n=12) They were assigned to one of three treatments for 6 hr/day for 7 days: 1) Basal feed and continuous intraruminal injection of a total of 50 ml alcohol (Control); 2) 250 mg monensin sodium as Rumensin/4 kg feed and continuous intraruminal injection of a total of 50 ml alcohol (Rumensin); or, 3) Basal feed and continuous intraruminal injection of a total of 250 mg monensin sodium in 50 ml alcohol (Monensin). All groups were offered basal feed the following 18 hours. Cattle fed Rumensin in the concentrate diet showed reduced intake within the first .5 hr of the first day (1.36 vs .13 kg, P<.05), while cattle fed Rumensin in the alfalfa diet ate as much feed as controls the first day but decreased intake the second to seventh days. On the first of five recovery days, cattle previously fed Rumensin ate the same amount as control cattle with both alfalfa and concentrate diets. Cattle fed Rumensin in both diets for 7 days, even after a 5-day recovery period, showed an immediate and marked aversion when offered feed containing Rumensin. Cattle injected with monensin ate less concentrate but not roughage diet during the 6-hr treatment period. Cattle continuously injected with monensin sodium showed an aversion to feed containing monensin sodium (not Rumensin), but responded to feed containing Rumensin similarly to Rumensin cattle with both diets on the first treatment day. It is postulated that with the concentrate diet the Rumensin flavor is sufficient to cause an immediate aversion, while with the roughage diet Rumensin flavor becomes a conditioned stimulus for development of a postinjection aversion associated with a nonconditioned stimulus. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.