Submitted to: American Society of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2005
Publication Date: 6/22/2005
Citation: Obeidat, B.S., Loest, C.A., Thelen, T.M., Strickland, J.R., Sawyer, J.E., Taylor, J.B., Hallford, D.M. 2005. Effects of various exposure routes of swainsonine on serum constituents, rumen characteristics, and nutrient metabolism of sheep. American Society of Animal Science Proceedings. 56:378-382. Interpretive Summary: This study showed that administering swainsonine into the rumen, abomasum, and intravenously at 0.6 mg of swainsonine/kg BW/d caused intoxication of sheep based on serum concentrations of aspartate aminotransferase. However, serum concentrations of alkaline phosphatase responded only in those animals exposed to swainsonine via their rumen. Subacute ruminal, abomasal, and intravenous exposure to swainsonine had little impact on ruminal fermentation characteristics, total tract digestibility of nutrients, and nitrogen retention. Therefore, consumption of locoweek (o.e. swainsonine) by ruminants should have little, if any, negative effects on utilization of nutients by sheep.
Technical Abstract: Nineteen mixed breed wethers (42.6 +/- 1.5 kg initial BW) were used in a two period (14-d treatment period plus 8-d post-treatment period) experiment to determine the effects of swainsonine via subacute ruminal, abomasal, or intravenous exposure on ruminal characteristics, serum constituents, diet digestibility, and N retention. The animals were fed once daily at 1.8% of BW (DM basis) a diet of 95% fescue hay and 5% alfalfa hay (DM basis). Treatments were: 1) no (CON; n = 5), 2) ruminal (RUM; n = 5), abomasal (ABO; n = 4), and 4) intravenous (IV; n = 5)infusions of a locoweed extract to deliver 0.6 mg of swainsonine/kg BW/d on d 1 to 14 of the experiment (subacute exposure). Serum concentrations of aspartate aminotransferase werre greater (P < 0.15) for RUM, ABO, and IV versus COM on d 8, 12, 16, 18, and 20 of the experiment. Serum alkaline phosphatase was greater (P < 0.15) for RUM when compared to CON on d 2, 4, 8, 12, 16, and 18, but were not different (P > 0.11) among ABO, IV, and CON on d 4 to 20. No differences (P > 0.25) were observed for serum concentrations of glucose, non-esterified fatty acids, and serum urea N. Ruminal concentrations of VFA, pH, an ammonia collected on d 14 and d 23 of the study were not different (P > 0.15) among treatments. Nutrient intake and digestibility, and N retention were not affected (P > 0.11) by treatments. Results demonstrated that subclinical intoxication occurs when sheep are exposed by swainsonine, but appears to have little effect on ruminal fermentation, nutrient digestibility, and N retention.