21 Effect of increased time spent on a high-forage receiving ration on growth performance, carcass characteristics, and liver abscess prevalence in Angus × Holstein steers.

Abstract An increase in the population of beef × dairy crossbreds in the fed-beef supply in recent years has posed questions regarding appropriate management of these calves. We evaluated the effects of increasing time spent on a high-forage diet on growth and carcass performance in newly-received Angus × Holstein steers. Steers (n = 144; initial shrunk BW = 193 ± 17.2 kg) were procured from a grower yard in IA and were previously fed a 16% CP texturized calf starter. Steers were allotted by BW to one of 18 treatment pens (n = 8 steers/pen). Treatments consisted of a 30% roughage equivalent (RE; 60% DM basis) corn silage based-diet fed for either 28 (REC28), 56 (REC56), or 84 d (REC84) post-feedlot arrival before transitioning to a 12% RE finishing diet (six replicate pens per treatment). Steers were individually weighed every 28 d to calculate interim growth performance. No differences (P ≥ 0.10) were observed for entire-period growth performance outcomes among treatments. Rate of change (slope) in BW, ADG, and DMI during both the first 97 days and cumulative feeding period was evaluated. During the initial 97 days, BW, DMI and ADG were all negatively influenced by greater days spent on a high-forage diet (P ≤ 0.04; -0.2683, -0.0044, and -0.0028/d, respectively). However, entire feeding period rate of change was not influenced (P ≥ 0.19) by duration of time spent on a high-forage receiving diet. A tendency for less fat thickness (P = 0.07) was observed in REC84 steers, but no other differences (P ≥ 0.19) in carcass performance outcomes among treatments were noted. A numerical reduction in total liver abscessation was observed and was driven by a tendency (P = 0.06) for a linear reduction in minor abscesses with increasing time spent on a 30% RE receiving diet. Greater time spent on a high-forage receiving ration did not alter entire-feeding performance or carcass characteristics, including prevalence of liver abscesses, but did numerically reduce final BW by 2.4%.