Evaluation of two-stage weaning and trace mineral injection on receiving cattle growth performance and behavior

Rauch, Jordan C; Stokes, Rebecca S; Shike, Daniel W

Due to the segmented nature of the beef industry, calves are often abruptly weaned and then transported directly to a feedlot or backgrounding facility. These calves exhibit increased behavioral stress, with excess walking and vocalization (Veissier and Le Neindre, 1989 ) that can lead to an increased susceptibility to respiratory tract infections (Loerch and Fluharty, 1999) . In addition, even with an adequate TM status (though this is often unknown), due to this additional stress, these animals may also have a greater TM requirement. Therefore, the authors hypothesized that an ITM may be most beneficial in the more stressed, abruptly weaned calves. Steers were housed in two identical barns that were adjacent to each other and were separated by weaning strategy. The authors acknowledge that weaning strategy is potentially confounded by barn; however, calves were segregated by weaning strategy to minimize the impact of calf behavior from one weaning treatment on calf behavior in the other treatment. There were no weaning strategy × ITM interactions for BW or ADG throughout the experiment. In contrast, experiments by Arthington et al. (2014) and Genther-Schroeder and Hansen (2015) showed that stressed calves that received an ITM actually had decreased ADG initially following stress compared to calves receiving saline injections. Genther-Schroeder and Hansen (2015) then followed those calves' performance for the remainder of a 78-d growing period and noted no effect of an ITM on calf ADG. This is also in contrast to this experiment, where there was a tendency for ITM to improve overall (day 0 to 124) ADG. Arthington et al. (2014) also reported a trend for ITM to increase ADG in growing heifers.