title: Effects of a dexamethasone implant on deposition of intramuscular fat in genetically identical cattle.
abstract: Administration of exogenous glucocorticoids has been shown to enhance deposition of intramuscular fat in cattle. In this study, six pairs of genetically identical (cloned) steers were used to determine the effects of an implant containing 100 mg of dexamethasone on intramuscular fat deposition and on other carcass and meat quality traits. One steer in each pair served as a negative control (CON), whereas the other steer received a dexamethasone implant 30 to 60 d from slaughter (DEX). Treatment with dexamethasone did not (P > .05) enhance intramuscular fat deposition. However, DEX steers had greater (.33 cm; P < .05) thickness of external fat, larger (5.94 cm2; P < .05) longissimus muscle areas, and higher (1.9 percentage points; P < .05) dressing percentages than did CON steers. In addition, treatment with dexamethasone increased (P < .01) serum insulin concentrations. Dexamethasone had no effect (P > .05) on cooked beef palatability traits or on 24-h calpastatin activity. Although the DEX implant tested in this study was not effective for improving carcass quality grade, use of the implant increased external fat thickness and was effective for increasing carcass muscularity and dressing percentage.
authors.affiliation: Department of Animal Sciences, Colorado State University, Fort Collins 80523, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Corah
authors.forename: J D
authors.initials: JD
authors.lastname: Tatum
authors.forename: J B
authors.initials: JB
authors.lastname: Morgan
authors.forename: R G
authors.initials: RG
authors.lastname: Mortimer
authors.forename: G C
authors.initials: GC
authors.lastname: Smith
mesh_terms: D000273:Adipose Tissue / Q000254:growth & development*; D000818:Animals; D001823:Body Composition / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D002417:Cattle / Q000235:genetics* / Q000502:physiology*; D003907:Dexamethasone / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004343:Drug Implants; D005938:Glucocorticoids / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D008297:Male; D008460:Meat / Q000592:standards; D018482:Muscle, Skeletal; D011897:Random Allocation
chemical_list: D004343:Drug Implants; D005938:Glucocorticoids; D003907:Dexamethasone