title: The effects of feeding increasing concentrations of corn oil on energy metabolism and nutrient balance in finishing beef steers.
abstract: The use of an added lipid is common in high-concentrate finishing diets. The objective of our experiment was to determine if feeding increasing concentrations of added dietary corn oil would decrease enteric methane production, increase the ME:DE ratio, and improve recovered energy (RE) in finishing beef steers. Four treatments were used in a replicated 4 × 4 Latin square ( = 8; initial BW = 397 kg ± 3.8). Data were analyzed using a Mixed model with the fixed effects of period and dietary treatment and random effects of square and steer within square. Treatments consisted of: (1) 0% added corn oil (Fat-0); (2) 2% added corn oil (Fat-2); (3) 4% added corn oil (Fat-4); (4) 6% added corn oil (Fat-6). Dry matter intake or GE intake did not differ across diets ( ≥ 0.39). As a proportion of GE intake, fecal energy loss, DE, and urinary energy loss did not differ by treatment ( ≥ 0.27). Additionally, methane energy produced decreased linearly as corn oil increased in the diet ( < 0.01). No differences were detected in ME loss as a proportion of GE intake ( ≥ 0.98). However, the ME:DE ratio increased linearly ( < 0.01; 93.06, 94.10, 94.64, and 95.20 for Fat-0, Fat-2, Fat-4, and Fat-6, respectively) as corn oil inclusion increased in the diet. No differences in RE or heat production as a proportion of GE intake were noted ( ≥ 0.59) and dry matter digestibility did not differ across diets ( ≥ 0.36). Digestibility of NDF as a proportion of intake responded quadratically increasing from 0% corn to 4% corn oil and decreasing thereafter ( = 0.02). Furthermore, ether extract digestibility as a proportion of intake responded quadratically, increasing from 0% to 4% corn oil inclusion before reaching a plateau ( < 0.01). As a proportion of GE intake, RE as protein decreased linearly as corn oil was increased in the diet ( < 0.01). As a proportion of total energy retained, RE as protein decreased when corn oil increased from 0% to 6% of diet DM ( < 0.01). Similarly, RE as fat and carbohydrate as a proportion of GE intake increased linearly as corn oil increased in the diet ( = 0.05). From these data, we interpret that adding dietary fat decreases enteric methane production and increases the ME:DE ratio, in addition to increasing the amount of energy retained as fat and carbohydrate.
authors.forename: K E
authors.initials: KE
authors.lastname: Hales
authors.forename: A P
authors.initials: AP
authors.lastname: Foote
authors.forename: T M
authors.initials: TM
authors.lastname: Brown-Brandl
authors.forename: H C
authors.initials: HC
authors.lastname: Freetly
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D003314:Corn Oil / Q000008:administration & dosage / Q000494:pharmacology*; D004032:Diet / Q000662:veterinary*; D004041:Dietary Fats / Q000378:metabolism; D004063:Digestion; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects*; D005243:Feces; D008297:Male; D008697:Methane / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D003314:Corn Oil; D008697:Methane