Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 4/21/2011
Publication Date: 7/10/2011
Citation: Shappell, N.W., Lenneman, E.M., Mostrom, M.S. 2011. Estrogenicity of sugar beet by-products used as animal feeds [abstract]. American Society of Animal Science and American Diary Science Association, July 10-14, 2011, New Orleans, LA. p. 252. Interpretive Summary:
Technical Abstract: A veterinarian observed a reduction in embryo transfer success rates on beef and dairy farms in Minnesota, which were both feeding sugar beet by-products. Beet tailings and pelleted post-extraction beet pulp, associated with the affected farms were analyzed for estrogenicity by E-Screen (proliferative assessment of non-transfected MCF-7 BOS cells). Samples contained estrogenic activity; with pelletized beet pulp containing ~ 4 fold the estradiol equivalents of the tailing sample (3.8 and 1.2 E2 Eq µg/kg DM, respectively). Whole beets, beet pellets and shreds from several Midwest US locations, were dried, extracted, and assessed for estrogenicity. All pellets examined were found to be estrogenic (range 0.1 – 2.0 µg E2 Eq /kg dry matter) with a mean of 0.46 µg/kg dm and median of 0.28 µg/kg dm (n=9). Relative E2 Eq for the other sample types ranked as follows: pellets > shreds (n=3) > most unprocessed plant material (n=7). Beet by-products are sold both within the United States and abroad, and are used as feed predominantly for cattle (both beef and dairy), but also for horses and elk. Using the recommended feeding guidelines, cattle could consume 0.3 – 6.8 µg E2 Eq per day, however, maximal feeding guidelines are often exceeded when feed prices favor the use of beet by-products. Possible E2 Eq blood concentrations assuming the consumption of by-product containing 5 µg/kg E2 Eq, 10% absorption, and 500 kg body weight, would be 12.5 pg/ml E2 Eq, a value similar to the 10 pg/ml of estradiol typical of cows during estrus.