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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Publications at this Location » Publication #214999
Title: Technical note: comparison between two tracing methods with ultrasonography to determine lumen area of the caudal artery in beef cattle

Author
item Aiken, Glen
item Klotz, James
item Kirch, Brett
item Strickland, James
item Boykin, Deborah

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2008
Publication Date: 9/12/2008
Citation: Aiken, G.E., Klotz, J.L., Kirch, B.H., Strickland, J.R., Boykin, D.L. 2008. Technical note: Comparison between two tracing methods with ultrasonography to determine lumen area of the caudal artery in beef cattle. Journal of Animal Science. 87:371-374.

Interpretive Summary: Cattle grazed on endophyte-infected tall fescue pasture will consume ergot alkaloids that cause constriction of blood flow to peripheral tissues. Consequently, cattle on tall fescue diets are vulnerable to severe heat stress when there are high ambient temperatures and humidities. Doppler ultrasonography has potential use as a non-invasive technique to study the effects of ergot alkaloids on vascular circulation in cattle. Mean blood flow velocity, heart rate, and cross-sectional area of the targeted artery or vein are measurements taken with Doppler ultrasound to measure blood flow rate through the blood vessel. Accurate and precise measurement of artery lumen area is critical in quantifying vasoconstriction responses to ergot alkaloids and other toxins. Vessel lumen area can be determined by tracing either the inner boundary of the layer of connective tissue in the artery wall or the outer boundary of the Doppler flow signal. Two experiments were conducted to compare variation between the two tracing methods in measuring lumen area of the caudal artery in heifers and to compare the two tracing methods in detecting changes in artery lumen area after heifers were switched from a diet containing non-endophyte infected tall fescue to a diet containing endophyte-infected tall fescue. There was no difference in variation between the two tracing methods and both methods were similar in detecting declines in lumen area after cattle were switched from non-endophyte infected to endophyte-infected tall fescue diets. Results indicated that lumen area of the caudal artery can be measured to the same degree of precision by tracing either the inner boundary of the connective tissue in the artery wall or the outer boundary of the Doppler flow signal.

Technical Abstract: Doppler ultrasonography has potential use in studying the effects of ergot alkaloids on vascular circulation in cattle. Accurate and precise measurement of artery lumen area is critical in quantifying vasoconstriction responses to ergot alkaloids and other toxins. Lumen area can be determined by tracing either the inner boundary of the layer of elastin connective tissue in the artery wall (i.e. intima) or the outer boundary of the Doppler flow signal. An experiment was conducted to compare variation between the two tracing methods in measuring cross-sectional lumen area of the caudal artery in five beef heifers on three different dates. Another experiment compared the two tracing methods in detecting changes in artery lumen area after five heifers were switched from a diet containing non-endophyte infected tall fescue (0 µg ergovaline/g of dry matter in diet) to a diet containing endophyte-infected tall fescue (0.85 µg/g of dry matter in diet). Lumen area determined by tracing the Doppler flow signal in experiment 1 was 25% lower than that determined by tracing the connective tissue, but there was no difference (P > 0.10) in the variation of measures between the two methods. Declines in lumen area were detected at the same level of significance (P < 0.05) for both tracing methods after cattle in experiment 2 were switched from non-endophyte infected to endophyte-infected tall fescue diets; however, variation in lumen areas differed (P < 0.05) between non-infected and infected diets for both tracing methods. Results indicated that lumen area of the caudal artery can be measured to the same degree of precision by tracing either the connective tissue in the artery wall or the outer boundary of the Doppler flow signal.