title: The value of creep feeding during the last 84, 56, or 28 days prior to weaning on growth performance of nursing calves grazing endophyte-infected tall fescue.
abstract: To evaluate limiting the number of days that calves are creep fed, 84 crossbred cows (frame score 4) nursing steer calves were randomly assigned to three replicates over 2 yr to receive one of four lengths of creep feeding (0, 28, 56, or 84 d) for cows and calves grazing endophyte-infected tall fescue. There were no differences in cow performance due to treatments. Calf daily gain increased (P < .001) as the length of time exposed to creep increased. In yr 1, creep intake increased (P < .05) as the length to time exposed to creep increased. In yr 2, there was no difference in intake by period among 28-, 56-, and 84-d treatments. Supplemental feed efficiency was best for 56 and 84 d, and the 28-d treatment was extremely poor. During the feedlot phase, there were differences in performance between the 2 yr and there were no differences in carcass composition due to length of time receiving creep feed. Overall, creep feeding calves for 56 or 84 d improved performance, and the 56-d calves had the most efficient gain. Creep feeding calves for 28 d showed no advantage during the creep feeding period or in the feedlot. Four ruminally fistulated nursing steer calves were used in a 4 x 4 Latin square design to receive treatments of forage alone or .68 kg, 1.13 kg, or 2.27 kg/d of creep plus high-quality, freshly harvested forage available on an ad libitum basis. Forage OM intake and NDF digestibility tended (P = .11) to decrease as intake of creep feed increased. The pH decreased (P < .001), molar proportion of propionate tended to increase (P = .06), and acetate tended to decrease (P = .07) as the level of creep feed intake increased. Higher levels of creep feed tended to cause a decrease in ruminal fiber digestibility and forage intake. Creep feeding calves for 56 or 84 d improved gain; 56 d had the most efficient supplemental gain. Creep feeding calves for 28 d showed no advantage during the creep feeding period or in the feedlot.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801.
authors.forename: S L
authors.initials: SL
authors.lastname: Tarr
authors.forename: D B
authors.initials: DB
authors.lastname: Faulkner
authors.forename: D D
authors.initials: DD
authors.lastname: Buskirk
authors.forename: F A
authors.initials: FA
authors.lastname: Ireland
authors.forename: D F
authors.initials: DF
authors.lastname: Parrett
authors.forename: L L
authors.initials: LL
authors.lastname: Berger
mesh_terms: D000273:Adipose Tissue / Q000254:growth & development; D000641:Ammonia / Q000032:analysis; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000833:Animals, Suckling / Q000254:growth & development* / Q000502:physiology; D002417:Cattle / Q000254:growth & development* / Q000502:physiology; D004063:Digestion; D004435:Eating; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D006863:Hydrogen-Ion Concentration; D008297:Male; D009752:Nutritional Status; D006109:Poaceae / Q000382:microbiology; D011897:Random Allocation; D012417:Rumen / Q000737:chemistry / Q000502:physiology; D013997:Time Factors; D014886:Weaning; D015430:Weight Gain
chemical_list: D005232:Fatty Acids, Volatile; D000641:Ammonia