LAUSR

The integrity of a diet fed as a total mixed ration (TMR) in feedlot and backgrounding scenarios is essential to maintain animal performance and minimized digestive upsets. The objective of this study was to quantify crude protein (CP), dry matter (DM) and ash concentration of a backgrounding diet fed as a TMR in a GrowSafe feed intake monitoring system. Angus crossbreed heifers (n = 70; 360 ± 60 kg of BW; 470 ± 26 d of age) and steers (n = 20; 386 ± 65 kg of BW; 465 ± 30 d of age) were allocated to 18 concrete-floored pens (108 m2), equipped with two GrowSafe feed bunks each to receive a backgrounding diet fed ad libitum as a TMR. Diet was comprised of (DM basis): 35% cottonseed hulls, 34% cracked corn grain, 20% pelleted corn gluten feed, 5% cottonseed meal, 4% liquid supplement (molasses-based), and 2% limestone. Feed samples were collected from three segments of each bunk (top; TOP, middle; MID, and bottom; BOT).Samples from the TOP was collected immediately after feed was provided and further samplings were conducted when feed was consumed throughout the day to obtain the MID and BOT samples in a 24 h interval. Approximately 90 kg (as fed) of the TMR was provided at 0800 h in each clean feed bunk. Concentration of CP did not differ (P = 0.89) throughout the day. However, DM content decreased as feed was consumed (P < 0.001). Concentration of ash was greater for the MID and BOT portions compared to TOP (P = 0.04). In conclusion, CP concentrations in the backgrounding diet fed were not altered throughout the day as diet was consumed. Increased ash concentration towards the bottom of the feed bunk prior to the new feed delivery may result from vertical stratification of the TMR.