Impact of increasing dietary energy on fattening steers growth performance, feed efficiency, and metabolic traits

This study aimed to evaluate the effects of a high-energy supplement (XE), as a high-energy nutritional supplement, on the growth performance and feed efficiency of fattening steers. The XE consisted of glycerol, propylene glycol, and a single-cell protein formula. Sixty Brazilian steers, with an initial body weight of 300 kg, were randomly assigned individually into three treatment groups with the addition of XE at 0% (control), 0.5% (XE1) and 1.0% (XE2) to the diet. Average daily gain, total weight gain, nitrogen balance, feed intake, and blood metabolites were measured. The daily gain was increased (P < 0.05) in XE1 and XE2 steers (1.13 and 1.23 kg/day, respectively) compared to control steers (1.04 kg/day), indicating improved feed efficiency due to the enhanced energy density provided by the supplement. Total weight gain showed a significant increase (P < 0.05) in XE2 (147.0 kg) compared to XE1 (136.5 kg) and the control steers (124.5 kg). Feed efficiency rose by about 17% (P < 0.05) in XE2 compared to the control group. Nitrogen intake, excretion, and retention patterns also provided insight into the effect of XE on protein utilization. Blood metabolite analysis revealed that XE supplementation enhances metabolic efficiency, nutrient utilization, and overall health in fattening. The study demonstrates that energy-dense diets can improve growth rates in fattening beef by improving feed efficiency and increasing the rate of weight gain without increasing dry matter or nutrient intake. The XE as a feed supplement can enhance the growth performance and metabolic profiles of fattening steers.