Distribution of four parasitic helminth species in one, pen-free, egg laying housing facility and the corresponding efficacy of nutraceutical and pharmaceutical administrations

In the spring of 2019, adult (75 weeks old) brown laying hens from a commercial, pen-free, egg-laying facility (11,000 birds per house) located in Northwest Arkansas were obtained for the purposes of sourcing robust and evenly dispersed cestode infections for anticipated anthelmintic evaluations. To that end, 4 birds from each of 6 discrete sites (northwest, northcentral, northeast, southwest, southcentral, southeast) in one production barn were obtained on two occasions, 10 days apart, and necropsied for helminth counts. A definite, repeated, location to location variation in infection incidence and magnitude was seen for each of the two cestode parasite species present, and one of the two nematode parasite species present. Burdens of Ascaridia galli were generally similar regardless of bird location, with site-specific mean totals per bird over both sampling days between 31 and 80. For the remaining helminths, infections were greatest for birds from the southern half of the building as opposed to the northern, and from the western end of the barn as opposed to the central or eastern portions. Location specific, mean worm burdens over both sample dates ranged from 340 to 1133 ( Heterakis gallinarum ), 14 to 277 ( Raillietina cesticillus ), and 1 to 35 ( Choanataenia infundibulum ). Highest, individual bird infections were 299 ( A. galli ), 3575 ( H. gallinarum ), 1015 ( R. cesticillus ) and 102 ( C. infundibulum ). The above counts are for all developmental stages combined ( A. galli and H. gallinarum ) and for scolexes only ( R. cesticillus and C. infundibulum ); as determined via standard collection and quantification procedures utilizing both intestinal contents and overnight soaks.