133 Feeding Behavior of High-Risk Steers Newly Received for Backgrounding

Abstract There is a need to understand the feeding behavior ontogeny of newly received high-risk steers. Understanding how calves learn to eat out of a bunk will facilitate the implementation of management practices that expedite this process and allow animal managers to exploit this information to monitor individual animal health. To address this knowledge gap, the feeding behavior of high-risk steers that were received for backgrounding was quantified and characterized using electronic feedbunks in this context. To create this paradigm, crossbred steers (n = 20) were purchased in two groups (Group: n = 64 steers; Group 2: n = 56 steers) from a local auction market, transported 800 km to the Prairie Research Unit in Prairie, MS, and immediately weighed (shrunk body weight, BW). Steers were purchased according to research unit space availability. Therefore, purchases occurred 133 days apart. The subsequent day, steers were ranked by shrunk BW (227 ±.3 kg) and allocated to 1 of 8 drylot pens (n = 8 steers/pen) with two GrowSafe automated feeding systems per pen. Steers were fed a total mixed ration ad libitum for a 28-day period and steer BW was recorded on d 0, 2, 6, 10, 13, 21 and 28. Daily feeding behavior [e.g., meal duration (sec), intake (g/d), meal frequency (count/d), bunk visit frequency (count/d), head down duration (sec), maximum non-feeding interval (NFI,s), ratio of head down duration to bunk visit duration)] were calculated using Meal Criterion Calculation Software. The impact of time on feeding behavior and performance was analyzed using a mixed linear model (PROC MIXED). To determine when steers had established consistent dry matter intake (DMI), consistency was defined as when the DMI of a steer remained within one standard deviation of the 7-day average DMI of the steer. Latency to first bunk attendance (d), first feed consumption, attainment of NEm requirement, and latency (d) to establish consistent feed intake levels were analyzed using a generalized linear mixed model (PROC GLIMMIX) for binomial data. Steer BW increased across days (P < 0.01), whereas average daily gain was.48 ± 0.4 kg/d. All feeding behaviors changed across days (P < 0.01). Meal and bunk visit (duration and frequency), meal intake (mean and sum), head down duration, and maximum NFI increased over time. All steers visited the bunk and consumed their first meal by day 4 (P < 0.01). All steers achieved NEm requirements by day11 (P < 0.01). These results quantify the acclimation period of steers to a new environment and characterizes the learning and development of novel modes of eating. These results inform the development of behavioral expectations for newly received high-risk calves that can be used to monitor cattle health, understand cattle perception, and promote cattle welfare.