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Effects of source and level of zinc on feedlot performance and carcass characteristics in steers
Abstract
To determine the effects of source and level of dietary Zn on performance, carcass characteristics and tissue Zn concentration, Angus steers (n = 120; initial weight = 325 kg ︢2.57) were assigned to diets containing five levels of added Zn (5, 35, 95, 215, or 445 mg/kg) from Zn methionine (ZnMet) or ZnSO4 in a 2 x 5 factorial arrangement of treatments. Total dietary Zn was 30, 60, 120, 240 and 480 mg/kg. Within treatment groups, steers were assigned to one of two kill groups (kill group I = d 77; kill group 2 = d 126). Steers were housed four to a pen and fed ad libitum a 90% concentrate diet of primarily corn and cottonseed meal by electronic Calen gate feeders. At the time of slaughter, the right front metacarpal, a 150 g liver sample and the right kidney were obtained from each steer. Carcass cooler traits were determined 48 h post slaughter and soft tissue from 9-1 0-1 1 rib section was analyzed for water, protein and lipid content. Statistical models for carcass characteristics included carcass weight as a covariate. Steers fed ZnSO4 gained faster (P <.05) than steers fed ZnMet (2.01 vs 1.85 kg/d .︢048). However, feed intake and feed efficiency were similar for ZnSO4 and ZnMet supplemented steers (I 1.2 vs 10.9 kg/d and 178 vs 170 g gain/kg intake, respectively). There was no difference (P > . I 0) in ADG or feed efficiency due to level of Zn in the diet. Neither source nor level of Zn affected (P > . I 0) carcass characteristics. The composition of the 9-1 0-1 1 rib section was not affected (P > . I 0) due to dietary treatment. Zinc and Cu concentrations in the liver, kidney and bone were not affected (P > . 1 0) by source of Zn. Level of Zn, however, did affect tissue concentrations of Zn and Cu. Liver Zn was higher (P <.0007) in steers fed 480 mg/kg Zn compared to steers in any other treatment. Liver Cu decreased(P<.OOOI)as level of dietary Zn increased. Zinc and Cu content of the kidney was higher (P<.0001) in steers fed 480 mg/kg Zn than steers in any other treatment. Zinc concentration of the metacarpal was highest (P < .000 1) in steers fed 480 mg/kg Zn than steers receiving 30, 120 and 240 mg/kg Zn, but not different from steers fed 60 mg/kg Zn. Bone Cu was not affected (P > . I 0) by level of dietary Zn.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references: p.54-59.
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Citation
Nunnery, Greg Alan (1998). Effects of source and level of zinc on feedlot performance and carcass characteristics in steers. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1998 -THESIS -N86.
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