title: Effects of supplemental zinc concentration and source on performance, carcass characteristics, and serum values in finishing beef steers.
abstract: Three studies were conducted to examine the effects of zinc concentration or source in diets of finishing beef steers. In Exp. 1, 108 (British x Continental) beef steers were supplemented with concentrations of added zinc (as ZnSO4) at 20, 100, or 200 mg/kg of dietary DM. No differences (P > 0.10) were noted among treatments for ADG or gain:feed for the 112-d finishing period. However, a linear (P < 0.10) decrease was noted in daily DMI with increasing zinc concentrations for the overall finishing period. No differences (P > 0.10) were noted in hot carcass weight; dressing percentage; longissimus muscle area; percentage of kidney, pelvic, and heart fat; or marbling score. There were, however, quadratic increases in s.c. fat thickness (P < 0.05) and yield grade (P < 0.01) with added zinc. In Exp. 2, 12 beef steers were used to examine effects of added dietary zinc on serum concentrations of cholesterol and fatty acid profiles. No differences (P > 0.10) were observed in cholesterol or fatty acids among the supplemental zinc levels. In Exp. 3, 84 Brangus- and Angus-sired steers were fed a steam-flaked corn-based diet containing 30 mg of supplemental zinc per kilogram of dietary DM from one of the following sources: 1) ZnSO4, 2) Zn amino acid complex, or 3) a zinc polysaccharide complex. No differences (P > 0.10) were noted for the overall 126-d trial for ADG, DMI, or gain:feed ratio. Percentage kidney, pelvic, and heart fat was increased (P < 0.10) in steers supplemented with ZnSO4 vs the average of Zn amino acid and Zn polysaccharide complexes. However, s.c. fat thickness was greater (P < 0.10) in steers supplemented with Zn amino acid and Zn polysaccharide complexes vs ZnSO4. Serum zinc concentration did not differ (P > 0.10) among zinc sources. Supplemental zinc concentration in finishing diets did not seem to influence feedlot performance and had a minimal impact on carcass quality. Either the organic or inorganic source can be included in finishing diets without affecting feedlot performance.
authors.affiliation: Clayton Livestock Research Center, New Mexico State University, 88415, USA. kmalcom@nmsu.edu
authors.forename: K J
authors.initials: KJ
authors.lastname: Malcolm-Callis
authors.forename: G C
authors.initials: GC
authors.lastname: Duff
authors.forename: S A
authors.initials: SA
authors.lastname: Gunter
authors.forename: E B
authors.initials: EB
authors.lastname: Kegley
authors.forename: D A
authors.initials: DA
authors.lastname: Vermeire
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000097:blood*; D002784:Cholesterol / Q000097:blood; D019587:Dietary Supplements; D008460:Meat / Q000592:standards*; D015032:Zinc / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D002784:Cholesterol; D015032:Zinc