title: Effects of Added Zinc on Skeletal Muscle Morphometrics and Gene Expression of Finishing Pigs Fed Ractopamine-HCL.
abstract: Finishing pigs (n = 320) were used in a 35-day study to determine the effects of ractopamine-HCl (RAC) and supplemental Zinc (Zn) level on loin eye area (LEA) and gene expression. Pens were randomly allotted to the following treatments for the final 35 days on feed: a corn-soybean meal diet (CON), a diet with 10 ppm RAC (RAC+), and RAC diet plus added Zn at 75, 150, or 225 ppm. Sixteen pigs per treatment were randomly selected for collection of serial muscle biopsies and carcass data on day 0, 8, 18, and 32 of the treatment phase. Compared to CON carcasses, RAC+ carcasses had 12.6% larger (P = 0.03) LEA. Carcasses from RAC diets with added Zn had a tendency for increased (quadratic, P < 0.10) LEA compared to the RAC+ carcasses. Compared to RAC+ pigs, relative expression of IGF1 decreased with increasing levels of Zn on day 8 and 18 of treatment, but expression levels were similar on day 32 due to Zn treatments increasing in expression while the RAC+ treatment decreased (Zn quadratic × day quadratic, P = 0.04). A similar trend was detected for the expression of β1-receptor where expression levels in the RAC+ pigs were greater than Zn supplemented pigs on day 8 and 18 of the experiment, but the magnitude of difference between the treatments was reduced on day 32 due to a decrease in expression by RAC+ pigs and an increase in expression by the Zn pigs (Zn quadratic × day quadratic, P = 0.01). The ability of Zn to prolong the expression of these two genes may be responsible for the tendency of Zn to increase LEA in RAC supplemented pigs.
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: D D
authors.initials: DD
authors.lastname: Burnett
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: C B
authors.initials: CB
authors.lastname: Paulk
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Tokach
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Nelssen
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Vaughn
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Phelps
authors.affiliation: b Department of Diagnostic Medicine/Pathobiology , Kansas State University , Manhattan , Kansas , USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Dritz
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: J M
authors.initials: JM
authors.lastname: DeRouchey
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Goodband
authors.affiliation: c Elanco Animal Health , Greenfield , Indiana , USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Haydon
authors.affiliation: a Department of Animal Sciences and Industry , Kansas State University , Manhattan , Kansas , USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Gonzalez
mesh_terms: D000821:Animal Feed; D000818:Animals; D019587:Dietary Supplements; D015870:Gene Expression / Q000187:drug effects*; D036341:Intercellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D010627:Phenethylamines / Q000008:administration & dosage*; D011506:Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D034421:Sus scrofa; D013552:Swine; D015032:Zinc / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010627:Phenethylamines; D011506:Proteins; C060897:ractopamine; D015032:Zinc
keywords: Finishing pig; Muscle Hypertrophy; Ractopamine-HCl; Zinc