Effect of lasalocid on fall-calving beef cows.

Abstract

The effects of lasalocid on fall-calving beef cows were examined in a 196-d trial that began October 12, 1983. Forty-two crossbred cow-calf pairs were stratified to six groups by breed, calving date and sex of calf. Three replications of each of two treatments, 0 and 200 mg lasalocid X head-1 X d-1, were used. The cows were fed a combination of haylage and grass hay ad libitum. The cow-calf pairs were allowed access to pasture at all times, except during the breeding season. At this time they were kept in confinement to facilitate heat detection and artificial insemination. Cow weight changes and body condition (0 = very thin, 9 = very fat) were unaffected (P greater than .10) by feeding lasalocid to the cows. Twelve-hour milk production per cow, percent fat and percent protein were each determined three times during the trial. A slight increase in milk yield was observed in treated cows (P greater than .10). Percent milk fat and protein were also unaffected by treatment (P greater than .10). Lasalocid supplementation of cows did not affect calf gain or 205-d adjusted weaning weight (P greater than .10). Average days open was evaluated for the cows. There were no differences between treatments for actual average days open (P greater than .10). No detrimental effects were observed in long-term feeding of lasalocid to fall-calving beef cows.