Abstract
Our objective was to determine the effect of calf-fed (CF) or yearling-fed (YF) finishing systems on performance and carcass characteristics of dairy-beef (DB) crossbred steers compared to native beef (NB) steers. The NB steers were acquired from Capitol Land and Livestock in Schwertner, Texas. The DB steers were acquired from 5-Star Dairy in Hart, Texas. The NBCF and DBCF steers were transported directly to commercial feedyard (Buffalo Feeders, Buffalo, OK) from the source. Yearling fed steers grazed mixed grass prairie for 144-d before finishing. At feedlot processing, steers were implanted with 100 mg of trenbolone acetate and 14 mg of estradiol benzoate (Synovex Choice, Zoetis Animal Health, Parsipanny, NJ). Steers were reimplanted with either 200 mg of trenbolone acetate and 28 mg of estradiol benzoate (Synovex One Feedlot, Zoetis Animal Health) or 200 mg of trenbolone acetate and 28 mg of estradiol benzoate (Synovex Plus, Zoetis Animal Health). The NBCF steers were fed a 26% roughage growing ration (15% CP and 1.2 Mcal NEg/kg) for 97 d then transitioned through a series of step-up diets (13% CP and 1.3 Mcal NEg/kg) for 13 d to a 7% roughage, finishing diet (13% CP and 1.6 Mcal NEg/kg). The CFDB were fed a series of step-up diets for 19 d each before transitioning to a finishing diet at d 64. The YF steers were fed a series of step-up diets for 29 d before transitioning to the finishing diet. For CF, initial BW did not differ for DB and NB (P=0.11). The initial BW of YFNB was 21 kg greater (P< 0.01) than YFDB. Yet at reimplant, YFDB and YFNB did not differ and both YF groups were greater than CF group which did not differ (P=0.73). The YFDB compensated for 114% of the previous difference in initial BW from YFNB. The DBYF steers had the greatest overall ADG (P< 0.01) with NBCF having the least ADG (P< 0.01) and NBYF and DBCF being intermediate. There was a finishing system by breed interaction for back-fat thickness (P=0.03) where NBCF had the greatest back-fat thickness, and DBYF having the least BFT, while DBCF and NBYF were intermediate. Yield grade was greater (P< 0.01) in YF than CF, but there was no breed effect (P=0.12). Overall liver abscesses had a breed (P< 0.01) and finishing system effect (P=0.01) with DB and YF steers having a higher incidence of liver abscesses. Dairy-beef yearling-fed steers exhibited compensatory gain from grazing within the first 83 d of being in the feedlot. Breed and finishing system had an impact of performance but exhibited minimal impact on carcass quality or liver abscesses.