The Effect of Night-Time Feeding on Steer Performance After Terminal Sort

Heat stress occurs when total environmental and metabolic heat production is greater than an animal's ability to dissipate that heat. Heat stress negatively impacts feeder cattle performance and welfare. Limited research has been conducted to determine if feeding cattle in the evening, thereby shifting their metabolic heat production to a cooler period of the day, can help mitigate heat stress. This pen-level randomized controlled trial evaluated the effects of evening feeding (PM; feedings at 2000, 2300, and 0200 h; n = 24 pens) versus morning feeding (AM; feedings at 0500, 0800, and 1200 h; n = 24 pens) on terminally sorted steer performance in a commercial feedyard in the Pacific Northwest. Data collection included feed delivery, water consumption, health events, open mouth breathing prevalence, and carcass traits. Linear and generalized linear mixed-effects models were used to determine potential differences between treatment group and temperature-humidity index (THI; <80 versus ≥80). Only 14% of the total study days had a THI ≥ 80, indicating little to no heat stress impacts. There were no differences found between PM and AM for any outcome (p < 0.05). Regardless of treatment group, water consumption tended (p = 0.07) to increase, and open mouth breathing significantly (p < 0.05) increased on days with THI ≥ 80. Further research is warranted to assess evening feeding as a heat stress mitigation strategy in a feedyard setting.