Abstract
Ergot alkaloids are vasoconstrictors frequently detected in low concentrations in livestock feed. The Canadian Food Inspection Agency permits up to 3,000 μg ergot alkaloids per kg cattle feed. The objective of this study was to examine the effects of feeding low concentrations of ergot alkaloids over 9-weeks on vascular dynamics in the caudal and internal iliac arteries of beef cows. A relationship between ergot alkaloid concentration in feed and hemodynamic changes in the caudal and internal iliac arteries was hypothesized. Periparturient beef cows were randomized into four groups and group fed mixed rations containing <15 μg ergot alkaloids per kg of dry matter intake (Control, n = 9), 48 μg/kg (Low, n = 9), 201 μg/kg (Medium, n = 8), and 822 μg/kg (High, n = 6). Three experimental periods comprised the study: pre-treatment (2 weeks), treatment (9 weeks), and post-treatment (3 weeks). B-mode and Doppler ultrasonography was performed weekly to measure hemodynamic endpoints. Plasma prolactin concentrations and rectal temperatures were measured weekly. Caudal artery diameter decreased (Treatment*Experimental Period i.e., Tx*EP, p < 0.001) by 14% in the High group during the treatment period. Reductions (Tx*EP, p < 0.001) in caudal artery blood flow (37%, 29%) and blood volume per pulse (29%, 11%) were recorded during the treatment period in the High and Medium groups. Internal iliac artery diameter and blood flow decreased (Tx*EP, p ≤ 0.004) by 13% and 40% during the treatment period in the Medium group. Moderate reductions (Tx*EP, p ≤ 0.042; 12–25%) in the mean blood velocity during the treatment and post-treatment periods and decreases (Tx*EP, p ≤ 0.01; 12–17%) in the peak systolic velocity of both arteries during the post-treatment period were also detected. Prolactin did not change in any group during the treatment period (p = 0.462). Rectal temperatures were within the normal physiological range for beef cows. In conclusion, we documented moderate vasoconstriction in the caudal artery and the internal iliac artery in cows fed 201–822 μg ergot alkaloids per kg of dry matter intake for 9-week period near parturition. The pattern of alterations was similar between the caudal and internal iliac arteries. Results of this study suggest that feeding up to 822 μg/kg produce reversible pharmacological changes in beef cow vasculature and warrant reconsideration of current regulations for cattle.
Highlights
Ergot alkaloid mycotoxins are secondary metabolites produced by the plant fungus Claviceps purpurea that infects cereal crops including rye, wheat, barley, triticale, and oats
This study evaluated the effects of prolonged low-concentration ergot alkaloid exposure on hemodynamic responses in the caudal and internal iliac arteries of beef cows around the time of parturition
The three concentrations of ergot alkaloids (48, 201, 822 μg total ergot alkaloids per kg of dry matter intake offered) were chosen to be well below the Canadian permissible levels of 2,000–3,000 μg/kg of feed [3] and lower limit was decreased compared to our previous work [20] in order to more accurately represent and examine an on-farm feeding scenario
Summary
Ergot alkaloid mycotoxins are secondary metabolites produced by the plant fungus Claviceps purpurea that infects cereal crops including rye, wheat, barley, triticale, and oats. The principle mechanism of vasoconstriction appears to be through the agonistic activity of ergot alkaloids on smooth muscle serotonin and adrenergic receptors [6, 14,15,16,17,18,19] resulting in decreased blood flow to tissues. Despite this well-accepted pathogenesis, there is a lack of research studying the effects of subclinical low concentrations of ergot alkaloids in cattle feed within the permitted tolerance limits on the peripheral vascular system in cattle, under Canadian climatic conditions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
