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Management strategies to reduce heat stress in feedlot cattle
Three feedlot trials and one trial conducted in a semi-controlled environmental facility were used to determine the impact of various feeding and microclimatic modification schemes on physiological and behavioral responses of feedlot cattle to environmental heat stress. Additionally, panting scores (an indicator of heat stress) were used to examine relationships between environmental measures and level of heat stress, and were also used to determine adjustment factors to the temperature-humidity index based on wind speed (WSPD) and solar radiation (RAD). In the feedlot trials, altering feeding time and(or) reducing total feed intake reduced tympanic temperature (TT) during the period in which these strategies were employed. Additionally, reductions in TT of steers on limit-feeding regimens were maintained following realimentation. Providing water via sprinklers to the surface of feedlot mounds for two hours in the morning or afternoon and intermittently throughout the day reduced soil temperature of the mound and TT of steers. Feed conversion of cattle sprinkled intermittently throughout the day were improved compared to non-sprinkled cattle, and feed efficiency of cattle sprinkled in the morning was superior to those provided afternoon sprinkling. Experiments conducted in the semi-controlled environmental facility under heat stress conditions resulted in decreases in TT, pulse rate and respiration rate during water application. Dry matter intake and rate of intake was increased in sprinkled versus non-sprinkled animals. Inconsistent duration of sprinkling resulted in alterations in respiration rate and TT. Measurements of panting scores in the feedlot experiments suggest level of heat stress is inversely related to WSPD and proportionally related to RAD. Based on these observations, adjustment factors based on WSPD and RAD to the temperature-humidity index used by the Livestock Weather Safety Index to determine risk of heat stress were determined. In summary, management strategies examined in these trials effectively altered the animal's susceptibility to heat stress with marginal effects on feedlot performance. ^
Agriculture, Animal Culture and Nutrition
Davis, Michael Shane, "Management strategies to reduce heat stress in feedlot cattle" (2001). ETD collection for University of Nebraska - Lincoln. AAI3028655.