PSI-25 - Associations between feeding behavior, Residual Feed Intake, and Residual Average Daily Gain in Performance Tested Yearling Angus Bulls and Heifers

Abstract: The objective of this study was to evaluate relationships among feeding behaviors, off-test Residual Feed Intake (RFI), and Residual Average Daily Gain (RADG) EPD for performance tested cattle. Eighty-seven angus bulls and thirty-two angus heifers (n=119) were fed a high forage diet consisting mainly of ground hay and corn silage for fifty-seven days using the Vytelle feed system. The variables evaluated were; time spent visiting the bunk, time with headdown, number of visits, RFI, average DMI, DMI, RADG, ADG, and quadrant location of RFI and ADG. RFI and ADG are plotted for each individual animal, which places that individual into one of four quadrants (1= Favorable RFI/ Below average ADG, 2= Favorable RFI/ Above average ADG, 3= Unfavorable RFI/ Below average ADG, 4= Unfavorable RFI/ Above average ADG). The data analyzed by gender, using non-parametric Spearman’s Rho in JMP to determine variable relationships. A very strong positive correlation was observed in yearling bulls for the time spent with headdown and the length of time spent at the bunk (0.8331, < .0001^*). Also, a moderate correlation for the animals individual RFI and total number of visits (0.4924, < .0001^*). A very strong negative correlation was observed for yearling bulls in the average amount consumed and the total number of visits to the bunk (-0.8380, < .0001^*). Also, a weak negative correlation was observed in the animals individual RADG and RFI (-0.2777, < .0001^*). Similarly, a strong positive correlation in yearling heifers was observed in headdown and length of time spent at the bunk (0.9457, < .0001^*). A strong negative correlation was observed in yearling heifers for the total number of visits and the average amount of feed consumed per each visit (-0.5293, < 0.0018^*). Also, a moderate negative correlation in each animals individual RADG and RFI (-0.4822, 0.0052^*). While a moderate positive correlation of individual animal RFI and the total number of visits was observed for the yearling bulls, the yearling heifers showed no significant correlation between the two. Our studies show that feeding behavior on a high forage diet is similar to that of behaviors shown on a high concentrate diet by others. Although there was a significant but weak relationship between RFI and RADG, the strength of the relationship is such that one cannot be used predict the other and they are measuring different components of the animal’s efficiency.