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In the spring of 2019, adult (75 wk 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, four birds from each of six discrete sites (northwest, northcentral, northeast, southwest, southcentral, and southeast) in one production barn were obtained on two occasions, 8 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 for 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 (Choanotaenia infundibulum). The greatest 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 using both intestinal contents and overnight soaks. Immediately before the mapping study outlined above, birds were obtained from the east end of the source barn and used for the nematocidal evaluation of fenbendazole in the water (5 mg/kg body weight [BW] for 1 day), levamisole in the water (8 mg/kg BW for each of 2 days), herbal mixture in the feed (1 gm/4.5 kg BW each day for 5 days), diatomaceous earth (2% of total feed for 10 days), and a nutraceutical mixture feed supplement (2% of feed for 7 days). Based on arithmetic means for adult forms, control trial efficacies for A. galli and H. gallinarum were 0% and 12% for the nutraceutical feed additive, 0% and 22% for the diatomaceous earth feed additive, 0% and 26% for dietary herbals, 87% and 63% for levamisole, and 82% and 84% for fenbendazole, respectively. Only adult burdens of A. galli and H. gallinarum for fenbendazole- and levamisole-treated birds were significantly different from control bird levels (P ≤ 0.05).

Trials were conducted in Arkansas, Idaho, Illinois and Wisconsin using a common protocol to evaluate effectiveness and safety of a long acting (LA), oil-based injectable formulation of moxidectin in beef cattle grazing spring and/or summer pastures. At each site, 150 cattle (steers and/or heifers) were blocked based on pretreatment fecal strongyle egg counts (EPG) and then randomly assigned to treatments within blocks. Presence of naturally acquired parasitic infections, confirmed by presence of parasite eggs in feces, was a prerequisite for study enrollment. Within each block of three animals, two received moxidectin LA injectable on day 0 at a dosing rate of 1.0 mg moxidectin/kg b.w. into the dorsal aspect of the proximal third of the ear, and one received a placebo control treatment. Cattle were weighed before treatment and on day 55 or 56 (55/56) after treatment. Fecal samples were also collected from 10 randomly selected blocks of animals at each site on days 14, 28 and 55/56 for EPG quantification. Average daily gain (ADG) was computed over the posttreatment period. Data pertaining to ADG and EPG were combined across sites and analyzed by mixed model analysis of variance to assess the fixed effect of treatment and random effects of site, block within site and the treatment by site interaction. Compared to placebo-treated controls, the geometric means of fecal EPG counts from cattle treated with moxidectin LA injectable were reduced 99.8% 14 days after treatment, 99.1% 28 days after treatment and 96.7% 55/56 days after treatment. Rate of weight gain by cattle treated with moxidectin LA injectable was 0.59 kg/day, or 23% (0.11 kg/day) more than placebo-treated controls (P<0.05). None of the cattle treated with moxidectin LA injectable exhibited signs of macrocyclic lactone toxicosis. Summarized across all study sites, proportions of cattle that received concurrent therapeutic treatments were similar among treatment groups. Study results demonstrate that moxidectin cattle LA injectable administered at a dosing rate of 1.0 mg moxidectin/kg b.w. to grazing beef cattle was effective and safe.