Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/30/2003
Publication Date: 3/15/2004
Citation: Soto-Navarro, S.A., T.L. Lawler, J.B. Taylor, L.P. Reynolds, J.J. Reed, J.W. Finley, and J.S. Caton. 2004. Effect of high selenium wheat on visceral organ mass, and intestinal cellularity and vascularity in finishing beef steers. J.Anim. Sci. 82:1788-1792. Interpretive Summary: The practicality of producing high selenium beef products and the impact of selenium on rapidly growing body tissues is not defined. Therefore, the objective of this study was to determine the effect of selenium supplementation, through the provision of high selenium wheat, on rapidly growing body tissues (e.g., small intestine). Twelve finishing steers received either a high selenium wheat diet or a control diet. Provision of high selenium wheat increased the weight and decreased the amount of blood vessels across the jejunum portion of the small intestine.
Technical Abstract: Twelve crossbred steers (351 ± 24 kg initial BW) were used to determine effects of high selenium (Se) wheat on visceral tissue mass, intestinal cell growth, and intestinal cellularity and vascularity. Steers were allotted randomly by weight to one of two treatments consisting of 75% concentrate diets that supplied: 1) adequate Se level (7 to 12 µg·kg-1 BW·d-1) or 2) high Se level (60 to 70 µg·kg-1 BW·d-1). Diets were similar in feedstuff composition (25 % grass hay, 25 % wheat, 39 % corn, 6 % desugared molasses, and 5 % wheat middlings supplement, DM basis). In the Se treatment, high-Se wheat (10 ppm) was exchanged for commodity wheat (0.35 ppm). Diets were formulated to be similar in nitrogen and energy (14.0% CP, 2.12 Mcal NEm·kg DM-1, and 1.26 Mcal NEg·kg DM-1) and were offered once daily (1500) individually to steers in an electronic feeding system. After 126 d, steers were slaughtered and individual visceral tissue weights determined. In addition, intestinal tissue protein, DNA, and RNA concentrations, cell proliferation and vascularity were determined. Concentrations of DNA, RNA, and protein of duodenum, ileum, and total small intestine were unaffected (P > 0.05) by treatment. Rations of RNA:DNA and Protein:DNA in duodenum, jejunum, ileum, and whole small intestine were not (P > 0.10) affected by high Se wheat. Conversely, jejunal weight was greater (P < 0.002) in steers fed high Se-wheat compared with controls (916 vs. 1427 ± 84 g). Jejunal DNA was increased (P < 0.04) in high Se steers (2.95 vs. 3.56 ± 0.19 mg/g) suggesting increased cell number. Concentrations of jejunal RNA and protein were not altered (P > 0.59) by treatment; however, since jejunal weight increased in high Se steers, DNA, RNA, and protein contents (g) were greater (P < 0.05). Vascularity of jejunal tissue decreased (P < 0.10) with high Se-wheat. However, since jejunal mass was higher for the high Se-wheat treatment, total microvascular volume was not affected (P > 0.10) by treatment. Percentage of jejunal crypt cells proliferation was unaffected (P > 0.10) by treatment; however, total number of cells proliferating within the jejunum was increased in high Se steers. These data indicate that the lower jejunal vascularity in the diet high in Se (provided from wheat) may have resulted in increased jejunal mass in order to meet physiological nutrient demand.