Case Study: Frequency of visits to a mineral feeder by steers grazing wheat pasture1

Supplemental minerals are routinely offered ad libitum to grazing cattle for the correction of major and trace mineral deficiencies of forages relative to the requirements of various classes of cattle and their expected performance. These mixes are often used as carriers for prophylactic feed additives, which normally have recommended intervals of consumption for them to be effective. However, adequate information is not available on the frequency that cattle visit free-choice mineral feeders. The objective of this study was to determine the frequency with which stocker steers grazing wheat pasture visit a feeder containing a free-choice mineral supplement. Steers were tracked during 53 d using radio-frequency identification ear tags and a custom built, computer monitored mineral feeder. Wheat pasture was grazed by 45 stocker steers (starting weight, 257 ± 4 kg). Individual steers visited the mineral supplement feeder 44.3% of the days monitored (24.5 to 69.8%). Daily weight gain averaged 1.03 ±  kg/head. The correlation between frequency of mineral feeder visits with weight gain was 0.40 (P < 0.01). Daily mineral disappearance for the grazing period averaged 72 ± 15 g/head, slightly less than the median recommended intake range. It is concluded that the frequency of individual consumption of a free-choice mineral is variable. Average consumption and average herd performance were within projected ranges; however, the great variation in frequency of individual animal intake may result in some cattle that are vulnerable to disease or nutritional maladies if consumption of a feed additive supplied in a mineral supplement is not frequent and consistent.