Document Type

Honors Thesis

Publication Date

Spring 5-2016

Abstract

Lobster shell, a chitin-based material, was applied to the ova, and to the L3 and L4 larval stages of the ruminant nematode Haemonchus contortus to assess its nematicidal effects on the parasite. Methods were developed to more accurately characterize and quantify larvae, including a formalin-kill technique to establish larval viability and a procedure for culturing L3 stage larvae into L4s in AF. Larval cultures containing 80g of fecal matter, 30g vermiculite and 100ml water were treated with various proportions of crushed lobster shell (medium or fine crush) to assess the affect of lobster shell on the maturation of H. contortus ova into L3 stage larvae. Fourth stage larvae in AF were treated with lobster shell conditioned media, chitin, chitosan, or Ivermectin and live:dead counts were obtained to compare larval viability.

Larvae incubated in AF developed anatomical characteristics analogous to functional L4 structures, although no consistent larval growth was evident from body length measurements over time. On average, cultures incubated with medium-sized (filtered through sieve No.400, between 38-212μm) lobster shell had total larval counts of 242.5, fine-sized (filtered through sieve No.400, 38μm) lobster shell had 499, and lobster shell-free cultures had 1,253.5 larvae. Overall, lobster shell exhibited nematicidal effects on H. contortus development from ova to L3 stage, but no clear comparison of larval viability could be obtained from any of the L4 treatment groups. Further studies may reveal that lobster shell is effective as a supplemental treatment in conjunction with standard anthelmintics, to decrease exposure of sheep to infective larvae on pasture.

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