Search

Data collected from 2011 until 2017 on a South African Dohne Merino flock were used for the estimation of genetic parameters for parasite resistance indicator traits. Nine to twelve recordings of faecal egg count (FEC), Famacha© score (FAM) and body condition score (BCS) were done annually from January (after weaning) until the end of June on all the lambs in the flock. Monthly body weight, as well as fleece traits at selection age (14 months of age), were also recorded. Various animal models were applied to estimate genetic parameters for and correlations among the resistance traits (FAM, BCS, FEC), as well as correlations between the resistance and production traits. Moderate univariate model heritabilities of 0.29 ± 0.05, 0.29 ± 0.05 and 0.26 ± 0.05 were estimated for FAM, BCS and log transformed faecal egg count (LFEC) respectively, when all data recordings were included. Heritabilities obtained for FAM, BCS and LFEC averaged for the 1 st, 6th and 9th recordings were much lower than the heritabilities obtained under univariate analyses where all available data were included. Considering the variance components and genetic parameters for the resistance traits over 1 to 12 recordings, it is evident that direct heritability increased with 10% to 15% for all the traits when data from all 12 available recordings were included. Direct heritabilities estimated with repeatability animal models for all the traits were lower than those obtained with the univariate models. FAM had a high genetic correlation and moderate phenotypic correlation with LFEC, while body weight, fleece weight and the coefficient of variation of fibre diameter had favourable genetic correlations with FAM. BCS had a moderate genetic correlation with LFEC and significant favourable genetic correlations with body weight, fleece weight and coefficient of variation of fibre diameter. Body weight, fleece weight and coefficient of variation of fibre diameter had favourable genetic correlations with LFEC, while fibre diameter and staple length was unfavourably correlated with LFEC. Standard errors of these correlations were, however, high and more data need to be collected to confirm these correlations. The genetic parameters estimated for this flock will be used to design the most suitable protocol incorporating FAM, BCS and FEC for the selection of sires and dams resistant to H. contortus.

The subfield of anthropology and education has developed differently in Canada from the path it followed in the United States, even though the discipline of anthropology shared individuals and research topics across the border. Anthropology and education in Canada is distinctly Canadian and is a peripheral version of the central subdiscipline found in the United States.

The authors show that results from previous research in the area of machining economics may be used to obtain good solutions to the problem of planning the production of parts which have machined volumes which intersect one another. The basic problem involves the determination of methods of subdividing the total machined volume so that cost is minimized; the method derived is based upon cost per unit volume, the major advantage being that a good solution may be obtained without conducting an exhaustive evaluation of the costs for each feasible volume combination.

The histological response of bone to freezing is described and it is suggested that there are three overlapping phases: necrotic, osteogenic and remodelling. Different methods of freezing bone are evaluated using thermographic data and conclusions are made regarding the clinical application for each in the region of the jaws. The use of cryosurgery is described in the treatment of a group of patients with odontogenic keratocysts. It was used in an attempt to eliminate residual cellular rests and reduce the tendency to recurrence.

Two cases are described of intra-bony cavities occurring in areas of tibro-osseous abnormality. The criteria for the diagnosis of solitary bone cyst are stated and applied to each case. The possible aetiology of such cysts is discussed and a suggestion made about a possible pathogenesis.

The effect of cryosurgery on the mechanical properties of bone has been studied by freezing rats' mandibles. The mandibles of laboratory rats were subjected to cryosurgery and tested at 2, 4, 8, 16 and 26 weeks. In comparison to the control contralateral sides, a reduction in strength was recorded at four and eight weeks, the difference being highly significant at eight weeks. This indicates the susceptibility of bone treated by cryosurgery to pathological fracture and suggests that preventive measures may need to be undertaken to minimise this possibility.