Resumen

KOKNAROGLU, H.; LOY, D.D.  y  HOFFMAN, M.P.. Effect of housing, initial weight and season on feedlot performance of steers in Iowa. S. Afr. j. anim. sci. [online]. 2005, vol.35, n.4, pp.282-290. ISSN 2221-4062.

Feedlot information, submitted by Iowa cattle producers to the Iowa State University Feedlot Performance and Cost Monitoring Program, was examined to determine the effects of housing, initial weight and season interactions on beef steer performance. Feedlot information, consisting of 1225 pens of steers, contained information including starting and ending dates, cattle per pen, sex, housing type, days on feed, initial and sale weights, feed efficiency, proportion of concentrate in diets, average daily gain (ADG) and certain economic variables. Starting date on feed was assigned to seasons and, since the steers were fed an average for 160 days, an overlapping of seasons occurred. Thus, cattle started in feedlots in spring, autumn, summer and winter were finished in summer, spring, autumn and spring, respectively. Cattle started in spring, autumn, summer and winter were exposed to hot, cold and warm portions of the year, respectively, and were classified as hot, cold and warm season cattle. Cattle housed in open lots with overhead shelter had higher ADG than those housed in confinement and in open lots in the warm season. In general, cattle in confinement had lower daily dry matter intake (DDMI) than those housed in open lots and open lots with overhead shelter, regardless of season. Light cattle had higher ADG in the hot season, whereas, heavy cattle had higher ADG in the cold season. Heavy cattle housed in confinement had lower ADG than those housed in open lots with overhead shelter and in open lots. Heavy cattle were less efficient than light and intermediate weight cattle regardless of housing system. These results indicate that the time of year cattle are started on feed and selection of cattle with starting weights most adaptable to the housing system provided, may contribute to improved production efficiency.

Palabras clave : Feedlot cattle; performance; housing; season; initial weight; interaction; Iowa.

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