PSXIV-12 Evaluation of an Ensiled, Self-Fed Diet for Backgrounding Beef Cattle

Abstract

Abstract Self-feeding of ensiled forages consists in allowing the animals to feed from the silo face through a physical barrier. Energy, protein, and mineral supplements are offered separately in free-choice portable feeders. Compared with offering a total mixed ration, the self-feeding system could result in differences in ensiled forage and supplement intake and may increase animal performance variability. Ensiling a complete diet may contribute to overcome these drawbacks. This study compared the performance of calves that consumed an ensiled backgrounding diet from a silo-bag face (self-feeding, SF) with that of calves fed a diet mixed and delivered daily in a feed bunk (TMR). A single forage sweet sorghum crop was harvested and bagged to be used in the TMR treatment, or harvested and added a dry supplement (45% finely-ground corn grain, 50% extruded soybean meal, and 5% vitamin-mineral premix without ionophore) during bagging, using an adjustable-discharge hopper mounted above the bagger’s packing rotor, to be used in the SF treatment. Regardless of treatment, the diet consisted of 61% forage sorghum and 39% dry supplement (DM basis; 9.9 and 11.6% CP, 42.3 and 43.8% NDF, and 9.8 and 9.5% starch for TMR and SF diets, respectively). Bagged feeds were allowed to ensile for 50 d before experiment began. Two hundred fifty-two, non-implanted Angus calves (224 ± 4.6 kg) were blocked by body weight (BW) and coat color resulting in 6 blocks and 1 pen/block per treatment with 12 or 30 animals per TMR or SF pen, respectively; more animals were required in the SF pens to maintain feed fresh and reduce spoilage, though BW was measured on 12 calves. Pens assigned to SF treatment were each equipped with a silo bag blocked off with an iron fence. The TMR animals were fed ad libitum once a day. In SF pens, feed was carved from the silo-bag face manually twice daily using a pitchfork onto a pile on the fence’s bag side. Cattle were fed for 70 d and held off feed and water for 16 h to record initial (day 1) and final BW (day 70). Data were analyzed as a randomized complete block design. Rate of BW gain, DMI, and DMI relative to BW were greater (P < 0.01; Table 1) for SF calves compared with TMR, resulting in greater (P = 0.03) final BW but similar (P = 0.36) ADG:DMI. Coefficient of variation (CV) of final BW and ADG and the increase in CV of BW did not differ (P ≥ 0.93) between treatments. Similar feed efficiency and animal performance variability were achieved by feeding an ensiled ration offered in a self-feeding system or a traditional TMR. The former might represent a simple and feasible feeding alternative for small-size beef cattle operations.