|Obeidat, B - NMSU GRAD STUDENT|
|Vogt, M - NMSU GRAD STUDENT|
|Loest, C - NMSU|
|Sawyer, J - TAMU|
|Reed, M - NMSU GRAD STUDENT|
|Krehbiel, C - OSU|
|Halalsheh, R - NMSU GRAD STUDENT|
|Chen, L - NMSU GRAD STUDENT|
Submitted to: American Society of Animal Science
Publication Type: Proceedings
Publication Acceptance Date: April 13, 2004
Publication Date: June 1, 2004
Citation: Strickland, J.R., Taylor, J.B., Obeidat, B.S., Vogt, M.L., Loest, C.A., Sawyer, J.E., Reed, M.M., Krehbiel, C.R., Halalsheh, R.A., Chen, L. 2004. Effects of locoweed on serum constituents and rumen profiles of sheep. American Society of Animal Science. 55:410-414. 2004. Interpretive Summary: In locoweed infested rangelands, science based strategic grazing is required to minimize livestock production losses while optimizing nutrient intake. Current management strategies to minimize locoweed intoxication include: avoidance of locoweed infested areas, and removal of animals after visual observation of intoxication. Results of the current study indicate these types of management strategies may be safe if animals are not clinically intoxicated. However, additional research fully defining the effects of swainsonine on not only gross parameters of nutrient digestion and metabolism but also on nutrient transport and utilization is needed before a high degree of confidence can be obtained in recommending locoweed consumption at any level.
Technical Abstract: Thirteen mixed breed wethers (47.5 ' 9.3 kg), fitted with ruminal and duodenal cannula, were used in a randomized design experiment to evaluate the effects of locoweed on serum constituents and ruminal fermentation. Locoweed treatments supplied: 1) 0.2 mg, 2) 0.4 mg, and 3) 0.8 mg of swainsonine'kg BW-1'd-1. Data were collected during 3 periods: pre-locoweed treatment (d -19 to d 0), locoweed treatment (d 1 to d 20), and post-locoweed treatment (d 21 to d 40). Blood and rumen samples were collected throughout each period; nutrient digestion (in situ) was assessed during the pre- and locoweed treatment periods. Serum swainsonine was detected in all treatments when locoweed was consumed, and was highest (P < 0.05) for the 0.8 mg treatment. Serum alkaline phosphatase activity was elevated (P < 0.05) due to locoweed treatment, but immediately returned to pre-locoweed values during the post-locoweed period (P = 0.13). Locoweed concentration and duration of exposure increased (P < 0.05) serum aspartate aminotransferase (AST). However, serum AST did not return to pre-locoweed values during the post-locoweed treatment period. Concentrations of blood urea N, NEFA, and AA were not affected by treatments (P > 0.11). Although not affected when locoweed was fed, propionate was elevated (P = 0.05) for the 0.2 mg treatment during the post-treatment period. Ammonia concentrations, ruminal pH, and DM digestion were not different (P > 0.13) among treatments. Extent of ruminal DM, OM, and ADF digestion during the treatment period was greatest (P = 0.01) in the 0.4 mg treatment. Wethers consuming locoweed exhibited subclinical toxicity. However, effects on nutrient metabolism were dependent upon the amount of locoweed consumed. Further, research is needed to fully determine the effects of swainsonine on nutrient metabolism.