title: Effect of calcium oxide inclusion in beef feedlot diets containing 60% dried distillers grains with solubles on ruminal fermentation, diet digestibility, performance, and carcass characteristics.
abstract: Two experiments were conducted to determine the effect of increasing dietary CaO on ruminal fermentation, diet digestibility, performance, and carcass characteristics of feedlot steers fed 60% dried distillers grains with solubles ( DDGS: ). In Exp. 1, 120 steers were allotted by weight (355 ± 7.9 kg) to 1 of 4 treatments containing 60% DDGS, 20% corn silage, 13.5 to 14.4% ground corn, 4% supplement, and 0 to 2.5% limestone on DM basis to determine the effects of CaO on performance and carcass characteristics. Treatments consisted of 0, 0.8, 1.6, or 2.4% CaO inclusion in the diet (DM basis), with CaO replacing limestone. Steers were slaughtered at a target BW of approximately 641 kg. In Exp. 2, 4 steers (initial BW = 288 ± 3 kg) were randomly allotted to the same diets in a 4 × 4 Latin square design (14-d periods) to determine the effects of CaO on ruminal pH, VFA, and nutrient digestibility. Statistical analyses were conducted using the MIXED procedure of SAS. Inclusion of CaO at 0.8, 1.6, and 2.4% increased ADG by 5.0, 3.9, and 0%, respectively, compared to 0% CaO (quadratic; P = 0.03). Intake was linearly decreased (P = 0.04) and G:F was linearly increased (P = 0.02) by CaO inclusion. Dressing percentage increased as CaO increased from 0 to 1.6% and then decreased for 2.4% CaO (quadratic; P < 0.01). In Exp. 2, steers fed 0% CaO had the greatest prefeeding ruminal pH, steers fed 0 and 0.8% CaO exhibited the most rapid postfeeding decline in ruminal pH, and steers fed 2.4% CaO exhibited a relatively stable ruminal pH throughout the 24-h period (treatment × time; P ≤ 0.01). Acetate, butyrate, and total VFA concentrations increased linearly (P ≤ 0.05) at 0, 3, 6, and 12 h postfeeding with increasing CaO. Propionate at 3 h postfeeding increased from 0 to 1.6% CaO and decreased from 1.6 to 2.4% CaO (quadratic; P = 0.10). Urine pH increased linearly (P ≤ 0.01) while urine output and urine ammonia decreased linearly (P ≤ 0.05) as CaO inclusion increased. Apparent NDF digestibility tended to increase (P = 0.07) and ADF digestibility did (P = 0.01) increase linearly with increasing concentrations of CaO. In conclusion, CaO improved ruminal pH variation, increased fiber digestibility, and decreased metabolic acid load in cattle fed 60% DDGS-based diets. Inclusion of CaO up to 1.6% was effective in improving performance of feedlot cattle.
authors.affiliation: Department of Animal Science, Purdue University, West Lafayette, IN 47907.
authors.forename: A J C
authors.initials: AJ
authors.lastname: Nuñez
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801.
authors.forename: T L
authors.initials: TL
authors.lastname: Felix
authors.affiliation: Department of Animal Science, Purdue University, West Lafayette, IN 47907.
authors.forename: R P
authors.initials: RP
authors.lastname: Lemenager
authors.affiliation: Department of Animal Science, Purdue University, West Lafayette, IN 47907 jschoonm@purdue.edu.
authors.forename: J P
authors.initials: JP
authors.lastname: Schoonmaker
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D017610:Calcium Compounds / Q000032:analysis / Q000494:pharmacology*; D002417:Cattle / Q000254:growth & development / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D004043:Dietary Fiber / Q000378:metabolism; D004068:Digestive System Physiological Phenomena / Q000187:drug effects*; D002523:Edible Grain; D005285:Fermentation / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects*; D010087:Oxides / Q000032:analysis / Q000494:pharmacology*; D011897:Random Allocation; D012417:Rumen / Q000502:physiology; D003313:Zea mays
chemical_list: D017610:Calcium Compounds; D004043:Dietary Fiber; D010087:Oxides; D000641:Ammonia; C016538:lime
keywords: beef; calcium oxide; digestibility; distillers grains; rumen pH