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La poblacion de Merino australiano ha disminuido de forma significativa a lo largo de los ultimos 15 anos como respuesta a una bajada del precio de las prendas de lana, tanto en terminos absolutos como en lo relativo al precio de su carne. Durante el mismo periodo de tiempo, se ha presentado un sistema nacional de evaluacion genetica basado en los metodos BLUP, cuya aceptacion por parte de los criaderos va creciendo de forma progresiva. Los parametros geneticos estimados para la poblacion indican una importante diversidad genetica para todos los rasgos registrados, proporcionando una gran oportunidad para la mejora genetica. Mas recientemente, determinadas pruebas han puesto de manifiesto un progreso, cada vez mas rapido, con respecto a las caracteristicas del vellon, asi como a una serie de caracteristicas relacionadas con la adaptacion y la produccion de carne. La poblacion de Merino esta evolucionando hacia dos grandes grupos � uno centrado en la produccion de lana para ropa de alta calidad cuya seccion de fibra es inferior a las 19 micras y utilizadas en empresas con unos ingresos en la proporcion lana-carne a razon de 3 a 1 respectivamente, y otro mas centrado en la cria de un animal de doble proposito que produce una fibra de lana cuya seccion se encuentra entre 19 y 21 micras y utilizadas en empresas cuyos ingresos corresponden a la proporcion lana:carne a razon de 1.5 a 1:1 respectivamente. Detras de estas tendencias existe un creciente enfoque en las caracteristicas de adaptacion que incluyen una resistencia a parasitos, una menor necesidad de intervenciones por veterinarios, y un mayor crecimiento en edades tempranas, asi como un aumento de la fertilidad y de la capacidad maternal. Juntas, estas tendencias apuntan hacia un ganado ovino cuyos cuidados son cada vez mas sencillos, asi como a la explotacion de la diversidad genetica disponible para aumentar rapidamente la rentabilidad.

Genetic parameters were estimated using uni- and bi-variate random regression models for weight, eye-muscle depth and fat depth measures between 60 and 360 days of age. Each trait was measured up to five times in 50-day intervals following weaning on approximately 4000 Australian Poll Dorset Sheep. The model accounted for rearing type, dam age, management group and age of recording. The model used for analysing weight included quadratic, orthogonal polynomials for direct genetic and environmental effects, a linear polynomial for maternal genetic effects and heterogeneous error variance across ages. The fat and muscle analysis used linear orthogonal polynomials for direct genetic and environmental effects and heterogeneous error variance. Throughout the 300-day trajectory heritability for weight traits ranged from 0·20 to 0·31, while heritability for fat depth ranged from 0·24 to 0·34 and heritability for eye-muscle depth ranged from 0·24 to 0·40. Genetic correlations between repeated measures of the same trait at different ages were positive and declined as the age interval increased, to minimum values of 0·60, 0·31 and 0·50 for weight, fat and muscle respectively between 60 and 360 days of age. Genetic correlations between weight and fat and weight and eye muscle were moderate to high (0·6 to 0·8) and positive but decreased slightly with age. The genetic correlations between fat and muscle were moderate to high (0·5 to 0·7) throughout the 300-day trajectory. In all cases, the estimates produced in this study were reasonably consistent with the limited number of studies that exist in the reported literature. This study demonstrated the relationships that exist between repeated measures of weight, fat and muscle measures over time, which is of interest to prime lamb producers looking to select for specific breeding objectives or market end points requiring precise weight, fat and muscle combinations at certain ages.

A genetic algorithm (GA) was used to find optimal male and female age distributions in a natural mating system that maximizes cumulative response to mass selection over a 20-year time horizon for the case where inbreeding affects reproduction at 0·0 (F-0) and 0·1 (F-10) per 0·1 inbreeding coefficient. Twenty breeding female population sizes were considered ranging from 25 to 500 breeding females distributed across five age groups. Loss of response due to inbreeding effects on reproduction ranged from 19.4% and 15.5% in small breeding female populations to 2.5% and 5.2% in large breeding female populations when number of males was fixed (FX) or optimized (OP), respectively. OP resulted in an increase in response over FX ranging from 0·0 % to 69.3% for F-0 and 0·0 % to 77.6% for F-10. The potential loss of genetic gain that resulted from ignoring the inbreeding effects upon reproduction when they really existed ranged from 0·1 % to 44.6%. The potential loss of genetic gain that resulted from including inbreeding effects upon reproduction when they did not exist ranged from 0·1% to 3.9%. Optimal male and female age structures depended upon breeding female population size, the number of breeding males and inbreeding effects. Ignoring inbreeding effects upon reproduction may result in over estimation of response to selection. Use of a GA allowed accounting for complex relationships in the optimization.

To mount a critique of Freud's views on any polemical issue is almost always a risky business. This is partly because one remembers the fate of so many of his earlier critics. As Phillip Rieff so delightfully puts it, ‘much of Freud's polemical writing is so superior to that of his opponents, that it takes on the character of a totem feast in which the most powerful sons are carved up with swift clean strokes, the father, meanwhile, justifying his action at every stroke’. There is also the possibility that exposure to psychoanalytic theory of one's own presuppositions and views will result in their being transformed into something quite different or to their being quite psychoanalysed away. Nevertheless the task must be undertaken. Freud's approach to religion has had too pervasive an influence upon modern thought to be ignored. Also, its complexity and potential have not always been sufficiently discerned by those who, especially from a Christian point of view, have sought to grapple with it.