title: Effects of organic selenium supplementation on growth performance, carcass measurements, tissue selenium concentrations, characteristics of reproductive organs, and testis gene expression profiles in boars.
abstract: The objective was to compare growth and physiological responses in boars fed diets supplemented with organic or inorganic sources of Se. At weaning, crossbred boars (n = 117; 8.3 kg of BW) were placed in nursery pens (3 boars/pen) and assigned within BW blocks to receive on an ad libitum basis 1 of 3 dietary treatments: I) basal diets with no supplemental Se (controls), II) basal diets supplemented with 0.3 mg/kg of organic Se, and, III) basal diets supplemented with 0.3 mg/kg of sodium selenite (13 pens/dietary treatment). Average daily gain (470 g/d), ADFI (896 g/d), and G:F (0.54) were similar among groups. Blood Se concentrations were greater (P < 0.01) for boars consuming organic Se (107.5 ± 4.8 µg/L) or sodium selenite (114.7 ± 4.8 µg/L) compared with controls (28.4 ± 4.8 µg/L). Intact pens of boars (11 pens/dietary treatment) were moved to a grow-finish barn and continued to receive appropriate diets on an ad libitum basis. Average daily gain (1,045 g/d) and ADFI (2,716 g/d) were similar among groups. Gain:feed was affected by treatment (P = 0.02) and was greater (P < 0.06) for boars fed organic Se (0.378 ± 0.004) compared with boars fed sodium selenite (0.368 ± 0.004) or controls (0.363 ± 0.004). Blood Se concentrations were greater (P < 0.01) in grow-finish boars consuming organic Se (198.9 ± 5.5 µg/L) than boars consuming sodium selenite (171.4 ± 5.4 µg/L) or controls (26.7 ± 5.4 µg/L). Treatment did not affect (P > 0.15) HCW, dressing percent, carcass length, LM area, standardized fat-free lean, lean percentage, backfat thickness, visual color, firmness, marbling, or Minolta loin color scores. Selenium supplementation did not affect (P > 0.17) testis or accessory sex gland sizes. Concentrations of Se in loin, liver, kidney, testis, cauda epididymis, and accessory sex glands were greatest (P < 0.01) in boars receiving organic Se, intermediate in boars receiving sodum selenite, and least in control boars. Microarray analysis of testis gene expression did not detect differences (P > 0.05) due to dietary treatment. Testis gene expression of glutathione peroxidase 4, as determined using quantitative PCR, was increased (P < 0.01) in boars fed organic Se compared with those fed sodium selenite. In summary, dietary supplementation of boars with organic Se failed to alter ADG or ADFI but enhanced G:F during grow-finish. More research is needed to discern the mechanism by which organic Se improves feed efficiency in boars.
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg 24061, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Speight
authors.forename: M J
authors.initials: MJ
authors.lastname: Estienne
authors.forename: A F
authors.initials: AF
authors.lastname: Harper
authors.forename: C R
authors.initials: CR
authors.lastname: Barb
authors.forename: T D
authors.initials: TD
authors.lastname: Pringle
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D008297:Male; D008460:Meat / Q000592:standards*; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D012313:RNA / Q000737:chemistry / Q000235:genetics; D011897:Random Allocation; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012645:Selenomethionine / Q000097:blood / Q000494:pharmacology*; D018038:Sodium Selenite / Q000097:blood / Q000494:pharmacology*; D013552:Swine / Q000378:metabolism*; D013737:Testis / Q000187:drug effects / Q000378:metabolism*
chemical_list: D012313:RNA; D012645:Selenomethionine; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D018038:Sodium Selenite