Effect of Ascophyllum nodosum on alleviation of heat stress in dairy cows

Abstract

A study was conducted to evaluate the effect of Tasco (Ascophyllum nodosum; Acadian Seaplants Limited, Dartmouth, Nova Scotia, Canada) on alleviation of heat stress in dairy cows. Thirty-two cows were randomly assigned (randomized complete block design) to 4 treatments: control-1 (C-1); control for period 2 and 0.50% Tasco for period 3 (C-.5T); 0.25% Tasco (0.25T); 0.50% Tasco (0.5T). The study was divided into 3 periods: period 1 (7 d; adaptation to Calan Gate system); period 2 [28 d; C-1 and C-.5T representing the control (CON)]; period 3 (28 d; C-.5T was changed to 0.50% Tasco to evaluate duration of feeding Tasco and other groups remained unchanged). Respiration rate and rump and ear skin temperatures were measured at 0700, 1600, and 1900 h. Core body temperature was recorded every 20 min with telemetric temperature transmitters in the reticulum. Tasco had no effect (P > 0.10) on milk production, but DMI was occasionally less (P < 0.05) for 0.25T cows than for CON cows in period 2. The rump skin temperature of 0.25T cows was reduced (P < 0.05) for some hours in period 2 and for some days in period 3. Linear regression of core body temperature and rump skin temperature versus ambient temperature in period 3 revealed less (P < 0.05) increase for 0.25T than for the control as ambient temperature increased. These results suggest that inclusion of 0.25% Tasco reduced body temperature response to increasing ambient temperature and sustained milk production, even with reduced DMI. No benefit of 0.50% Tasco was seen when fed for 28 or 56 d. Limited benefits of Tasco were observed in this study.