The Impact of Time on Feed and Partial Replacement of High-Moisture Corn with a High-Lipid High-Fiber Pellet on Steer Performance, Visceral Organ Weight, Fat Deposition, and Carcass Composition.

The objective of this experiment was to determine the impact of time on feed and the partial replacement of starch with a high-fat, high-fiber by-product based pellet. Angus crossbred steers (n = 97; initial BW 469.3 ± 45.8 kg) were randomly assigned to one of two isocaloric dietary treatments: control (CON;  n = 48) steers were fed a finishing diet consisting of 10% haylage, 77% high-moisture corn, 11% soybean meal, and 2% of a salt, vitamin, and mineral pre-mix including monensin; or high-fat, high-fiber pellet (HLHF; n = 49). The HFHF contained 29.8% wheat shorts, 26.2% corn DDGS, 18.8% soy hulls, 19.2% corn gain, and 6% tallow and replaced 30% (DM basis) of the high moisture corn in CON. Steers were randomly assigned to pens equipped with Insentec feeders to record individual feed intake. Steers were randomly split into two blocks in order to facilitate sample collection at the abattoir. On d 1 of the feeding period and every 6 wk thereafter, 10 steers from each treatment were selected at random and slaughtered. Organ and visceral fat weights were recorded, and rib sections were cut into muscle, fat, and bone in order to estimate carcass composition. Data were analyzed as a randomized complete block using PROC MIXED in SAS and included the fixed effects of diet, time on feed, and random effects of pen and block. Contrasts between diet and linear effects of time on fed were used for mean separation and significance was declared at P ≤0.05. Steer initial BW did not differ (P ≥ 0.43); however, final BW increased linearly (P < 0.001), but did not differ with dietary treatment (P = 0.55). Overall ADG did no differ with dietary treatment (P = 0.63), but decreased linearly with increasing time on feed (P = 0.015). Empty rumen mass was 12.4 and 11.4 ± 0.24 for CON and HLHF (P = 0.004). Abomasum weight tended to be heavier for HLHF than CON steers (P = 0.06). Carcass traits did not differ with dietary treatment (P > 0.51). Rib dissection indicated that rib section weights of lean, bone, intermuscular, body and subcutaneous fat did not differ with dietary treatment (P ≥ 0.24). Overall these data indicate that partially replacing starch with a high-lipid, high-fiber pellet had limited impacts on growth performance and carcass traits and energy partitioning in steers.