Mineral nutrition studies of small ruminants in north-western and north-eastern China

• Chinese Academy of Agricultural Sciences, China

China has nominated increased animal production in the northern regions as a major research priority. Animal products currently comprise 15% of the total agricultural output, and includes about 200 000 tonnes of wool (from 120 million sheep), of which 40% is carpet wool and 30% semi-fine. This is one of three integrated projects, with shared resources, seeking to improve the quality of semi-fine wool in an attempt to meet the growing domestic demand. The semi-fine wool quality produced is not expected to compete with the fine wool currently imported from Australia.

This project seeks to establish seasonal growth cycles of the grazing sheep, relate those cycles to the animals' mineral nutritional status, and evaluate and identify any limiting trace elements. It will also determine the response to provision of such deficient elements, in terms of both wool and meat production.

Trials at three representative locations will establish the growth and production patterns of the sheep grazing there. Pasture, blood and tissue samples, collected concurrently with the growth measurements, will be analysed at the Beijing Institute of Animal Science for a range of elements.
Where possible, these will include sodium, potassium, calcium, phosphorus, magnesium, copper, zinc, manganese, selenium, molybdenum, iron, sulfur, nitrogen and cobalt. Apart from revealing any marked deficiencies, such data will define the present physiological levels of the elements in these animals and allow the team to design appropriate animal-house experiments for closer examination of possible interactions.

In the first year the work will be concentrated at one of the three designated locations. In the following year it will extend to the other two, where the work schedule will remain 12 months behind for the duration of the project in order to capitalise on the experience gained from the first location.

It may be possible to identify limiting trace elements from blood and tissue samples alone, but it is also proposed to use controlled-release devices and pattern analysis for this purpose. This technique is presently being developed at the CSIRO Division of Animal Production, and concurrent testing under field conditions in both China and Australia should assist that development.

Research workers will also fit controlled-release devices to sheep to supplement their diets with the trace elements identified as possible limiting factors for optimal development. Supplemented sheep will be compared with controls taken from the same group of animals. Initially, the response trials will concentrate on zinc and selenium, both of which are known to be deficient in some areas. Trials with zinc will take place in Shandong Province, where earlier work revealed very low levels of zinc (10 ppm) in both soil and pasture. Similarly, previous trials in the northeast have provided evidence of selenium deficiency in pastures, and the scientists will supply this element in controlled-release form to sheep in one of the three affected provinces there.

The project will accumulate a large volume of valuable data, and procedures used in the course of the project will also provide practical remedies, experience and training in a range of techniques for the younger Chinese members of the team. In this way strong contacts will develop between those members and the Australian scientists working with trace elements.