title: Effect of grain type and processing index on growth performance, carcass quality, feeding behavior, and stress response of feedlot steers.
abstract: One hundred sixty crossbred steers (538 ± 36 kg BW) were used in an 84-d experiment with a randomized block design to study the effects of wheat or barley grain processed to 2 different indices on growth performance, feeding behavior, carcass characteristics, stress, and temperament of finishing beef cattle. Treatments were a wheat-based diet (88.4% of diet DM; WH) and a barley-based diet (89% of diet DM; BA), processed to an index of either 75% (HI) or 85% (LO) of their original volume weight. Cattle were allocated to 16 feedlot pens (10 animals per pen, 4 pens per treatment), 8 of which were equipped with the GrowSafe system for monitoring feeding behavior. Flight speed, hair, and saliva samples were collected on d 1, 28, 56, and 84 to determine temperament, acute, and chronic stress. All steers were slaughtered at the end of the experiment, and carcass quality was evaluated. Cattle fed WH had a lower (P < 0.05) meal length and frequency of visits per meal and tended (P = 0.10) to have a lower DMI, meal size, and feeding time than those fed BA. The LO processing index increased (P = 0.05) DMI and reduced (P < 0.05) the G:F and the percentage of saleable meat of the carcass compared to HI. There was a trend (P = 0.09) for a grain × processing index interaction, where cattle fed BA-LO had a lower incidence of severe liver abscesses compared with cattle fed other treatments. Cattle fed WH had greater hair cortisol concentrations (P = 0.01) and flight speed (P < 0.01) than those fed BA. There was a trend (P = 0.07) for a grain × processing index interaction, where heifers fed WH-LO had a lower salivary cortisol than those fed other treatments. Results suggest that a LO processing index had a negative effect on feed efficiency and carcass performance and that the WH diet caused a range of effects on feed intake and behavior indicative of steers with greater excitability and chronic stress.
authors.forename: D
authors.initials: D
authors.lastname: Moya
authors.forename: M L
authors.initials: ML
authors.lastname: He
authors.forename: L
authors.initials: L
authors.lastname: Jin
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: G B
authors.initials: GB
authors.lastname: Penner
authors.forename: K S
authors.initials: KS
authors.lastname: Schwartzkopf-Genswein
authors.forename: T A
authors.initials: TA
authors.lastname: McAllister
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001823:Body Composition / Q000502:physiology*; D002417:Cattle / Q000254:growth & development / Q000502:physiology* / Q000523:psychology; D004032:Diet / Q000662:veterinary; D004435:Eating / Q000502:physiology; D002523:Edible Grain; D005247:Feeding Behavior / Q000502:physiology*; D063427:Food Quality; D001467:Hordeum; D006854:Hydrocortisone / Q000378:metabolism; D008099:Liver / Q000473:pathology; D008297:Male; D008460:Meat / Q000592:standards; D013315:Stress, Psychological / Q000523:psychology*; D014908:Triticum; D015430:Weight Gain / Q000502:physiology
chemical_list: D006854:Hydrocortisone