Effect of breed on response to foot rot treatment in mature sheep and lambs
Abstract Our objective was to determine whether breed differences existed in response to exposure and treatment of virulent foot rot. Dorset (DS), 1/2 Dorper (DX), 3/4 or greater Dorper (DO), Gulf Coast Native (GC), Katahdin (KA), and St. Croix (SC) mature sheep and lambs were exposed to virulent foot rot in spring 2003. Treatment for foot rot was initiated in 132 lambs and 262 mature sheep in late July. There were eight pasture groups treated, two of which were minimally exposed to foot rot. Treatment included hoof paring, foot bathing with 10% zinc sulfate with surfactant, allowing the zinc sulfate to dry on the foot and moving to a small paddock 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 treatments. Animals that had not responded (odor or any indication of persistent infection) by then were culled from the flock. As an 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 score (0 = no infection found; 1 = infection of digits only; 2 = infection of interdigital area and could include digits), and presence of 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 P P P P P P P
Prediction of the benefits of selection for resistance to footrot in sheep
The aim of this thesis is to quantify the benefits of selection for resistance to an important sheep disease in Britain. Specific aspects addressed are i) the choice of the specific disease based on economic costs and potential savings from selection, ii) genetic parameters for the disease, such as the heritability (h2) and the genetic and phenotypic relationships with production traits, iii) prediction of the response to selection on a trait that is measured in only two classes (healthy or diseased), accounting for variable exposure and prevalence, and iv) modelling of the combined effect of increased genetic resistance and reduced pathogen burden as a result of selection. It is shown that the major sheep diseases in Britain, in terms of annual costs to the British sheep industry are gastro-intestinal parasites, footrot, Chlamydial abortions (enzootic abortions of ewes) and Toxoplasmosis, with estimated annual total (variable) costs of £84M (f 84M), £24M (E12M), £20M (E1M) and £12M (9M). A commercial service for selection against gastro -intestinal parasites already exists in Britain and elsewhere, and footrot is identified as an opportunity to make substantial savings to the industry. Footrot is a highly contagious disease, caused by the bacteria Dichelobacter nodosus, which is influenced by environmental factors. It affects the skin between the digits Of a hoof resulting in lameness. Vaccines exist, but are expensive and have short protection periods. Resistance to footrot has been reported to show additive genetic variability, and this is confirmed in this thesis. A total of 4340 Scottish Blackface on 5 farms and 726 mule ewes in 3 flocks were scored repeatedly for lesions that are indicative of footrot by a team at SAC. Results showed that in these adult sheep lesion scores are heritable, with the h2 typically around 0.2 (for footrot 0.19 in SBF, 0.12 in mules; for severe footrot 0.26 and 0.19 respectively). This simple binary score turned out to be as effective as more complex criteria that considered the severity of lesions. Phenotypic correlations between successive scores in the same animals were generally close to 0, but genetic correlations were higher. The repeatability of footrot
Using Infrared Thermography to Detect Moisture in Historic Masonry: A Case Study in Indiana
Nondestructive testing mapped water infiltration in the decoratively painted interior of a Masonic Temple in Muncie, Indiana.