Studies on the digestion of ryegrass species and the regulation of food intake by sheep : a thesis submitted for the degree of Doctor of Philosophy in the Massey University of Manawatu

Abstract

The economy of New Zealand is dependent largely on the export of products of the livestock industry. While there has lately been an upsurge in secondary industry, a basic lack of raw materials and cheap labour curtails New Zealand's ability to compete economically with other countries as a manufacturing nation. If New Zealand's position as one of the world's leading agricultural exporters is to be maintained or expanded then increased primary production must be achieved. Such an increase is also necessary to maintain or improve the high standard of living of a rapidly growing internal population. Three general factors are important when the problem of increasing livestock production is considered. 1. Nutrition 2. Breeding 3. Diseases and Pests The interest of the author lies with nutrition but the other two factors are clearly important if animal production is to be improved. Breeding is important particularly in relation to raising fertility and producing types of animals that will give optimum returns in particular environments. It must be remembered however, that genetic improvement by selection of livestock, though essential, is usually slow because of the low heritability of many productive characteristics. Pests and diseases can limit animal production, particularly at high stocking rates, so the prevention of epidemics and the eradication of persistent diseases such as footrot, brucellosis and tuberculosis must continue to be actively pursued. At a symposium entitled, "Problems of Increasing Sheep Production", held in February 1964 by the NewZealand Society of Animal Production, it was evident that the most effective short-term method of increasing animal production would be by increasing stocking rate. This infers increases in both animal numbers and the food to support them. Thus to increase the carrying capacity of the present farming area there must be an increase in the quality and quantity of pasture produced. This can be achieved in two ways: by techniques of pasture management and by breeding improved strains of pasture plants. It must also be remembered that considerable advances may be obtained with improved management of existing strains of pasture plants.