A preliminary study revealed that feeding Ascophyllum nodosum (Tasco meal) to beef cattle exposed to elevated ambient temperature lowered body temperature. Tasco meal may be utilized in beef and dairy cattle diets to enhance animal production in hot environments. As a result, another study was conducted to determine the long-term effects of feeding Tasco meal at 1 % of diet dry matter intake on body temperature and rumen parameters in beef cattle exposed to thermoneutral or elevated ambient temeperature. Twenty-four steers were randomly assigned to one of four trematments; those fed Tasco meal(TM) and those not fed Tasco Meal(NT), under thermoneutral(TN) and heat load (HL) conditions. The steers were placed in one of four environmental chambers (6 steers per chamber), maintained initially at thermoneutral level, with 3 steers in each room assigned to TM vs NT. Prior to the study, steers were ruminally cannulated (n=8) and transmitters (n=24) installed in the peritoneal cavity. Steers were acclimated to the chamber at TN (19 C) for seven days. After 7 days, steers were placed on the dietary treatments (TM and NT). At 0700, steers were fed a cottonseed hulls/ cracked corn diet ad libitum. Tasco meal was fed to steers prior to the meal in an alfalfa / ground corn premix to ensure complete intake. During period 1, steers were fed treatments for 10 days at 19 C. For period 2, two rooms were maintained at 19 C throughout while the other rooms were step-up increases in air temperature to 36 C for 10 days. For period 3, HL was applied with day-time high maintained at 36C but night-time low increased to 31 C in order to prevent adequate cooling. For period 4, animals previously exposed to thermoneutral were exposed to HL; those previously at HL were exposed to thermoneutral for 10 days.

During the four periods, core body temperature was continously recorded using telemetric transmitter, Additional measurements included feed intake, respiration rate, skin temperature,and body weight changes by period. An in situ study was conducted to determine the impact of TM on ruminal disappearance of ground tall fescue grass hay, as well as changes in rumen pH, volatile fatty acids, and N. Data will be presented at the meetings to demonstrate the effects of Tasco meal in cattle exposed to a heat load.