Letteratura scientifica selezionata sul tema "Merino sheep Breeding Australia"

Sheep Farming for Meat and Wool contains practical, up-to-date information on sheep production and management for producers throughout temperate Australia. It is based on research and extension projects conducted over many years by the Department of Primary Industries and its predecessors and the University of Melbourne. 
 The book covers business management, pasture growth and management, nutrition and feed management, drought management, reproductive management, disease management, genetic improvement, animal welfare and working dog health. It also gives seasonal reminders for a spring

Reproductive wastage is a major economic burden in sheep production globally, especially within Australia as livestock production systems face increased pressure from climatic variability (e.g. prolonged droughts or flooding). Sheep are sensitive to acute changes in their environment such as heat stress, which if not adequately monitored will result in significant production losses such as reproductive failure, increased parasite and worm burden, morbidity and mortality risks. Through basic and applied research in the areas of stress and reproductive physiology our team has made significant advancements in the understanding of sheep behaviour and physiological responses to acute and chronic stressors. Using minimally invasive hormone monitoring technology in combination with field based assessment of sheep health and productivity traits, our team has delivered new knowledge on how sheep react to acute environmental stress and how it impacts on sheep reproduction. In this chapter, we evaluated the fertility rates and embryo quality of Merino ewes under AI breeding program. We discuss factors such as heat stress that can impact on ewe and offspring quality.

This chapter examines the fraught attempts to acclimatize Spanish merino sheep in Britain in the early nineteenth century. Proponents of the merino were motivated by the commercial value of merino wool, which is and was exceptionally fine, but the debate over the merino’s place in Britain ultimately came down to its flesh. The breed’s opponents argued that merino mutton was inferior to that of British breeds like the New Leicester, and further that the fineness of merino wool was dependent upon Spain’s climate and environment. The long and acrimonious controversy which attended the merino’s attempted naturalization in Great Britain revealed the degree to which competing understandings of the relative influence of climate or environment and anthropogenic selection in sheep-breeding unsettled the very category of breed itself. Ultimately, attempts to acclimatize merino sheep in Britain failed, as its wool (although finer than that of “native” British breeds) grew coarser under Britain’s damper climate, and its leaner carcass offended the proud palates of British diners.

Succeeding phases of British economic growth prompted strikingly different imperatives for expansion, for natural resource exploitation, and for the social organization of extra-European production. In the eighteenth century, sugar, African slaves, and shipping in the Atlantic world provided one major dynamic of empire. But in the nineteenth century, antipodean settlement and trade, especially that resulting from expanding settler pastoral frontiers, was responsible for some of the most dramatic social and environmental transformations. Plantations occupied relatively little space in the new social geography of world production. By contrast, commercial pastoralism, which took root most energetically in the temperate and semi-arid regions of the newly conquered world, was land-hungry but relatively light in its demands for labour. The Spanish Empire based in Mexico can be considered a forerunner. By the 1580s, within fifty years of their introduction, there were an estimated 4.5 million merino sheep in the Mexican highlands. The livestock economy, incorporating cattle as well as sheep, spread northwards through Mexico to what became California by the eighteenth century. Settler intrusions followed in the vast landmasses of southern Latin America, southern Africa, Australia, and New Zealand. Australia was one of the last-invaded of these territories, and, in respect of the issues that we are exploring, was in some senses distinctive. Unlike Canada and South Africa, there was no long, slow period of trade and interaction with the indigenous population; like the Caribbean, the Aboriginal people were quickly displaced by disease and conquest. The relative scale of the pastoral economy was greater than in any other British colony. Supply of meat and dairy products to rapidly growing ports and urban centres was one priority for livestock farmers. Cattle ranching remained a major feature of livestock production in Australia. Bullock-carts, not dissimilar to South African ox-wagons, were essential for Australian transport up to the 1870s. But for well over a century, from the 1820s to the 1950s and beyond, sheep flooded the southern lands. Although mutton became a significant export from New Zealand and South America, wool was probably the major product of these pastoral hinterlands—and a key focus of production in Australia and South Africa. The growth in antipodean sheep numbers was staggering.

The purposes of this project were: 1) to introduce the FecB gene to the Awassi and Assaf breeds in Israel and the Rambouillet breed in the U.S.A. aiming in the long run to establish Awassi, Assaf and Rambouillet nucclei breeding flocks homozygous for the F gene in which the contribution of the Booroola Merino genetic background will be less than 10%; (In the U.S., Booroola crosses with Suffolk and Targhee were also studied. 2) to evaluate the effect of the FecB gene and different proportions of Booroola Merino genetic background on lamb survival, growth, milk production and wool production in