Loline Alkaloid Effects on Gastrointestinal Nematodes
2022
Kelly Ann Froehlich | Robin McAnulty | Andy Greer
Loline, an alkaloid with several derivatives, has suggested antimicrobial and anthelmintic properties. Therefore, loline was investigated as a natural anthelmintic against <i>Trichostrongylus colubriformis</i>, <i>Teladorsagia circumcincta</i>, and <i>Haemonchus contortus</i>. Preliminary in vitro studies had reduced L3 <i>T. circumcincta</i> establishment but no effect on L3 <i>T. colubriformis</i> larvae migration or <i>H. contortus</i> establishment. While loline-treated lambs had lower establishment of L4 and adult <i>T. circumcincta</i> and L4 <i>T. colubriformis</i>, L4 and adult <i>H. contortus</i> appeared unaffected. Following preliminary study, an in vivo experiment examined lambs infected with a mix of L4 <i>T. circumcincta</i>, <i>T. colubriformis</i>, and adult <i>H. contortus</i>. These lambs were treated with either a loline seed extract (LOL, <i>n</i> = 7), nothing (CON, <i>n</i> = 7), or a non-loline seed extract (NIL, <i>n</i> = 2). There were no differences in worm burdens, fecal egg counts, weight gain, or feed intake between treatments. However, an average growth efficiency (kg LWG/kg DM intake) was detected (<i>p</i> = 0.01) in CON (0.18) which was less than LOL (0.24) or NIL (0.23). There was limited evidence to support an in vivo anti-parasitic effect of loline despite in vitro studies indicating potential benefits. Discrepancies between in vivo and in vitro studies results were potentially a result of loline contact time with larvae, mode of ingestion or the forms of loline present.
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