Effect of breed on response to foot rot treatment in mature sheep and lambs

Our objective was to determine whether breed differences existed in response to exposure and treatment of virulent foot rot. orset (DS), 1/2 Dorper (DX), 3/4 or greater Dorper (DO), Gulf Coast Native (GC), Katahdin (KA), and St. Croix (SC) mature heep and lambs were exposed to virulent foot rot in spring 2003. Treatment for foot rot was initiated in 132 lambs and 262 mature heep in late July. There were eight pasture groups treated, two of which were minimally exposed to foot rot. Treatment included oof paring, foot bathing with 10% zinc sulfate with surfactant, allowing the zinc sulfate to dry on the foot and moving to a small addock that had not been exposed to small ruminants for more than 14 d. Foot bathing was repeated every 7 d for a maximum of five reatments. Animals that had not responded (odor or any indication of persistent infection) by then were culled from the flock. As n indication of severity of foot rot for each animal, the number of areas on the foot (interdigital and two digits for each foot), a foot core (0 = no infection found; 1 = infection of digits only; 2 = infection of interdigital area and could include digits), and presence f characteristic odor was recorded. Least squares means for number of areas infected were greater for mature than growing sheep 2.07± 0.16 versus 0.88± 0.31; P< 0.001), for highly than minimally exposed groups (2.89± 0.17 versus 0.05± 0.29; P< 0.001), nd DX compared with other breed types (P< 0.03). Percentage of sheep with odor was similar between age groups, was greater n the highly exposed groups (11.4± 1.9 versus 2.1± 3.4; P< 0.02), and greater in DO compared with DS, KA, and SC breeds P< 0.001). Foot score was similar among breeds and greater in the highly exposed groups (age by group, P< 0.05). Percentage f sheep culled for failure to respond to foot bath treatment was greater for the highly than minimally exposed group (22.9± 2.3 ersus 0.0± 3.9; P< 0.001) and greater for mature sheep compared with lambs (P< 0.001) and similar among breeds. In November, our ewes in a large group and two lambs in a small group were determined to have foot rot and were immediately culled. The two roups containing these ewes were re-treated for 2 weeks and were determined to be free of foot rot (no further signs of lameness). esponse to foot rot eradication appeared to be similar among breeds examined. ublished by Elsevier B.V.