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Roughage removal from feedlot diets improve feed efficiency in feedlot cattle
Our objective was to compare how feeding systems (FS) used to feed finishing cattle affects feed efficiency within the feedlot. Feeding systems were traditional (TRAD), no roughage (NR) and balanced matched (BM).We hypothesize matching steers to diets formulated to match actual growth potential in addition to removal of roughage from the diet will result in greater efficiency of gain compared to steers fed a traditional feedlot diet. Steers (n=90; 276.1±3.0kg) purchased through regional livestock markets were randomly placed into two separate feedlots. Within feedlot steers were stratified by BW, frame size, muscle score, color and source and randomly assigned to FS. TRAD FS received a diet formulated to meet NRC requirements for a desired ADG. Diets fed to NR and BM FS were formulated to meet estimated effective energy (EE) and amino acid (AA) requirements for a desired ADG without the inclusion of roughage. For the initial 28 d all BM steers were fed a diet formulated to achieve an ADG of 2.2 kg. BM steers were blocked within feedlot by 28 d ADG into high (2.53 to 1.86 ± 0.21 kg), mid (2.07 to 1.61+0.14 kg) and low (1.69 to 1.04 +0.21 kg) ADG groups. Overlap in ADG range between ADG blocks was a result of blocks being assigned within feedlot. TRAD, NR and low BM (LBM) FS remained on their respective diets for the entirety of the experiment. High BM and mid BM FS were transitioned to LBM diet once it met estimated EE and AA requirements for each FS average ADG and BW. Completion of trial occurred prior to slaughter on d 157. Data was analyzed using PROC MIXED with feedlot serving as a random effect. Over a 157 d finishing period initial BW, final BW, ADG and DMI were not different (p > 0.10) between FS. Feed conversion ratio (FCR) was not different (p > 0.10) between NR and BM or between TRAD and BM FS. However, the NR FS improved FCR by 9.8 percent compared to TRAD (4.6 vs 5.1 ± .18; p ≤ 0.05) FS. In conclusion, more descript information on prior nutrition, health status, environment and genetics on cattle entering the feedlot would benefit diet formulation to match actual growth performance. Furthermore, roughage free diets formulated to balance EE and AA requirements for growth improve feed efficiency compared to traditional feedlot diets.
Keywords: beef, feed efficiency, feedlot