title: Roughage level and limited maximum intake regimens for feedlot steers.
abstract: Hereford steers (n = 280, BW = 371 +/- 29 kg; 40 pens) were used to evaluate two alternatives to ad libitum access to feed and constant roughage levels in finishing diets. The eight treatments were as follows: two treatments in which intake was limited to a multiple of the maintenance (MM) energy requirement (2.1, 2.3, 2.5, and 2.7, [2.7MM] and 2.3, 2.5, 2.7, and 2.9 [2.9MM] times maintenance for wk 1, 2, 3, and 4 and thereafter, respectively) and six roughage regimen and grain source treatments (10% roughage equivalent [RE] fed during the mid- and late-finishing periods [10/10], respectively, 2% RE followed by 10% RE [2/10], and 10% RE followed by 2% RE [10/2] fed with steam-flaked sorghum grain [SFSG] or whole-shelled corn [WSC]). The 2.7MM treatment tended to improve ADG (6%, P = .08) and gain efficiency (4%, P = .15) relative to ad libitum access to feed. The 2.9MM treatment was intermediate. Steers fed WSC diets consumed approximately 12% more DM (9.2 vs 8.2 kg/d) and gained 4% more (1.45 vs 1.39 kg/d, P < .05) but had lower gain efficiency (7%, 159 and 170 g/kg, P < .001) than steers fed SFSG diets. For SFSG diets, the 2/10 regimen resulted in similar gains, a 3.6% decrease (P = .10) in DMI, an 8.6% improvement (P < .01) in gain efficiency, and reduced roughage use (40 kg per steer) compared with the 10/10 regimen. With WSC diets, the 2/10 regimen did not (P > .2) affect gain efficiency but did reduce roughage use (48 kg) compared with the 10/10 regimen. The 10/2 regimen did not differ (P > .2) from the 10/10 regimen. Few differences in carcass characteristics were noted among treatments. Roughage use and cost of gain can be reduced by feeding 2% roughage during the mid-finishing period followed by a return to 10% roughage.
authors.affiliation: Department of Animal Science, Texas Tech University, Lubbock 79409.
authors.forename: S J
authors.initials: SJ
authors.lastname: Bartle
authors.forename: R L
authors.initials: RL
authors.lastname: Preston
mesh_terms: D000273:Adipose Tissue / Q000254:growth & development; D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000254:growth & development*; D002418:Cattle Diseases / Q000453:epidemiology; D004043:Dietary Fiber / Q000008:administration & dosage*; D004435:Eating; D002523:Edible Grain; D005069:Evaluation Studies as Topic; D005243:Feces / Q000737:chemistry; D015994:Incidence; D008100:Liver Abscess / Q000453:epidemiology / Q000662:veterinary; D008297:Male; D024510:Muscle Development; D013213:Starch / Q000032:analysis; D015430:Weight Gain; D003313:Zea mays
chemical_list: D004043:Dietary Fiber; D013213:Starch