Effect of feeding regime on feed intake of cattle exposed to heat

The effect of high temperature and feeding regime on dry matter intake (DMI), metabolizable energy intake (MEI), respiration rate (RR), pulse rate (PR) and rectal temperature (RT) of 6 Hereford steers was examined. Three feeding times 0800 h (am; 14% roughage fed), 1600 h (pm; 14% roughage fed) or a split feeding (sp; 30% roughage diet fed at 0900 h and 6% roughage fed at 1600 h) were imposed on the cattle housed in either a thermoneutral (TNL) or a hot environment (HOT). Steers fed under HOT had a greater mean and range in RT and respiratory rate (RR) than steers fed under TNL. In general, PR was more indicative of DMI than of heat load. Afternoon (pm) feeding was not found to be an effective method of maintaining DMI under HOT. As a percentage of body weight, steers fed pm under HOT had significantly lower MEI than other treatments, while steers fed am or sp under HOT were able to maintain DMI at a level equal to or greater than steers fed under TNL. In the HOT treatment, sp fed steers had lower minimum RT than am and pm fed steers and tended to have lower 1600 and 2000 h RT than am fed steers. Managing heat load during periods of high ambient temperature by altering feeding regime may be effective in maintaining intake for feedlot cattle.