Technical Note: Daily variation in intake of a salt-limited supplement by grazing steers

A pilot study was conducted to characterize the daily variation in supplement intake by group-housed, self-fed grazing steers. Supplement intake was measured by an automated supplement intake measurement system (SmartFeed; C-lock Inc., Rapid City, SD). For 61 d, 15 steers (256 ± 31 kg mean BW) tagged with radio frequency identification grazing dormant native range pasture had ad libitum, 24-h access to the automated feeder. During a 14-d test period within, the supplement was 55% concentrate (80% soybean meal, 20% soybean hulls, as-fed basis) and 45% fine mixing salt. Supplement (including salt) intake was 1.21 ± 1.15 kg/d per animal (as-fed basis). The high CV (95%) indicated that there is considerable variation in daily supplement intake among group-supplemented steers. However, within animals, weekly intakes were correlated (r = 0.84, P < 0.01), indicating that supplement intake of individual animals is somewhat predictable. Over the entire 61-d trial, salt inclusion in the supplement varied. Over the 61-d trial, steers visited the feeder 5.4 ± 2.1 times/d (SD). Salt intake averaged 0.17% of BW per day but was also highly variable among and within animals. Additional research is needed to describe effects of animal-to-animal competition on behavior at these automated feeders.