Abstract
One hundred ninety-two Continental × British steers [initial body weight (BW) = 420 kg (standard deviation = 24.7)] were used in a randomized complete block design finishing study to evaluate the effects of feeding two types of silage germplasm at two inclusion rates. A 2 × 2 factorial arrangement of treatments was used with either a conventional hybrid (Golden Harvest G07B39-311A, Syngenta Seeds LLC, Minnetonka, MN; CON) or a hybrid with increased expression of alpha-amylase (Syngenta Enogen Feed corn, Golden Harvest E107B3-3011A-EVT5, Syngenta Seeds, LLC; ENO) fed at either 12% (12SIL) or 24% (24SIL) of diet dry matter. Steers were blocked by source and location (source 1: first three pen replicates, n = 10 steers per pen with a fourth pen replicate of six steers per pen; source 2: one pen replicate, n = 12 steers per pen) and assigned randomly within block to treatments, resulting in five pens and 48 steers per treatment. Steers were harvested after 126 (12SIL) or 140 (24SIL) days on feed (DOF). There were no silage hybrid by inclusion rate interactions detected for live growth performance (P ≥ 0.15). Silage hybrid did not affect average daily gain (ADG), gain-to-feed ratio (G:F), or final BW (FBW; P ≥ 0.35). Feeding 24% silage reduced ADG (P = 0.04) and increased G:F (P = 0.01) but increased FBW (P = 0.02) because of greater DOF compared with 12SIL. A hybrid by inclusion rate interaction was detected (P = 0.04) for calculated yield grade (YG) with steers fed 24SIL having increased YG within CON but not ENO. Hot carcass weight and rib fat were unaffected by silage hybrid (P ≥ 0.81) but were increased by feeding 24SIL (P = 0.03 and P = 0.02, respectively). Feeding increased amounts of silage increased beef produced per hectare (P = 0.05). Source of silage did not affect feedlot growth performance of cattle but, because of slight differences in estimated silage yield, conventional silage produced more kilograms of beef per hectare (P < 0.01). Feeding increased amounts of silage reduced G:F on both a live and carcass-adjusted basis but increased kilograms of beef produced per unit of land, which is paramount to cattle feeders who grow their own feedstuffs.
Highlights
Corn silage is a cornerstone feed ingredient for beef production in the Midwest
The objective of this study was to evaluate the effects of levels of corn silage inclusion [on a dry matter (DM) basis] with or without alpha-amylase on the growth performance and carcass characteristics of finishing yearling steers and to determine differences in efficiencies as measured on both a per animal and per unit of cropland basis
The lack of response in this experiment to silage expressing the alpha-amylase trait contrasts with the positive effects observed when Enogen Feed corn silage was fed to growing steers (Johnson et al, 2019) or finishing yearling steers (Baker et al, 2019)
Summary
Corn silage is a cornerstone feed ingredient for beef production in the Midwest. It is a versatile source of readily digestible energy and neutral detergent fiber (NDF) and can be an effective option for marketing home-raised feedstuffs through cattle. The most effective use of corn silage is in growing cattle diets. Corn silage is typically limited to the minimum amount required for sufficient scratch factor to maintain ruminal health (Samuelson et al, 2016). Increased inclusion rates of corn silage in finishing diets may be economically beneficial, depending upon the business and marketing strategies of the enterprise and the degree of integration between crops and livestock (Goodrich et al, 1974; DiCostanzo et al, 1997; Klopfenstein and Hilscher, 2018). Measuring the efficiency of beef production both on a unit of cropland and on a per animal basis is important in an integrated crop–livestock system
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