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Summary of full report
March 2004
RIRDC Publication No 04/027 RIRDC Project No KKN-1A
Project Title
Investigation into the Basis
of Down Production in Cashmere Goats and its Improvement by Genetic Means.
Objectives
1. To establish an understanding
of the fleece growth patterns of individual Cashmere animals with high
annual down production.
2. To identify if possible,
the genetic basis of some, or all, of the components that contribute to
inherited down production in Cashmere goats.
3. To view these findings
in the context of molecular genetics and available genomic data.
4. To identify and suggest
areas with commercial implications for the Australian Goat Industry.
Background
Low annual cashmere down
production (per head) is a major constraint to industry profitability.
While the production average is similar to that of other countries, some very high production animals do exist in the Australian herd. The animals used in this project were selected from the Karakan herd in Victoria, Australia. This herd is one of the oldest ‘bred-on’ cashmere herds in Australia tracing its origins in part to the original CSIRO herd founded in 1972, (See Appendix B).
Analysis of data in the Karakan herd has identified a number of very high performing phenotypes (VHPP) for fleece production. Further analysis suggested that a number of individually inherited components contribute to overall performance.
This research project was made possible by the prior existence of a privately financed venture called Project KKN. Project KKN was originally established to develop the technology to produce Cashmere under housed conditions, similar to ‘Sharlea’ sheep (Reynolds 1969); and to select and multiply suitable animals for housed Cashmere production.
The opportunity to combine the selection of superior animals with a controlled environment led to the formulation of this project.
Research
A group of 120 females and
3 males that exhibited VHPP characteristics were selected and the females
introduced into controlled environment conditions in Sept. 1997. These
animals were made available for this project, which commenced in 1998 and
ran for three years.
Given the limitations of the small number of animals involved and the short time frame, it was also considered necessary to draw heavily on the complementary knowledge available from a wide range of outside sources.
While the primary objectives of the project have been achieved, a full understanding of the biomechanisms involved provides a challenge for the future. The report suggests some possible future areas of exploration.
Outcomes
The Report has some elements
of a specialist review and some elements of original work. The authors
believe it to be the most complete work, yet published, on ‘Inherited Down
Production’ in goats.
Some new techniques to examine the contributing components to fleece production in the subject animals were developed, and are described. One of these, the ‘Ofdagram’ is recommended for on farm use.
A range of inherited production characteristics, which appear to be discrete and repeatable between animals were identified. Of primary importance is the suggestion that an animal’s commercially saleable cashmere fleece is the product of contributions from a number of individual fibre populations. These overlay each other on the animal. The major populations are identified and a naming convention proposed. Fibre populations that cover the full-body have been called ‘Garbs’.
The overlay regional populations have been called ‘Garblets’. The genetic and production implications of these findings are discussed.
It is demonstrated that commercial gains not only involve increasing down production, but also the manipulation of the guard hair coat to optimum levels This improves returns to growers by reducing downstream fibre processing costs.
The key discovery of this
report is that Fibre Growth Rate and Fibre Diameter are independently inherited.
It is an undisputed and well known fact, that within an individual animal
fleece, there is a strong relationship between down fibre length, the product
of growth rate for a given time and given mean fibre diameter (mfd). This
has led to the general industry assumption that, selecting for one, changes
the other. This is not the case between animals and the production implications
of this are considerable.
Implications
The Cashmere goat
Measured fleece production
figures for the Australian Cashmere Growers Association, National Fleece
Competition, have been published annually for over 20 years. This database
provides a striking illustration of production variation, even in selected
goats, and the high levels of production achievable in superior individuals.
This report demonstrates that, taken individually, the characters responsible
for this ‘production variation’ can be manipulated with considerable effect.
The findings of this project are just a “beginning”, something parallel to exploring the world using a 17th Century map. However the age of biological discovery is upon us. The explosion of Genomic Research in the last few years has generated a mass of fundamental information on goat genes.
Genomic studies deal with the very biochemistry of genes and the chemical mechanisms used to build observable genetic characteristics. This report breaks inherited down production into contributing components. This is a necessary first step in linking commercial gains with fundamental discovery.
Some of the techniques developed could be incorporated in on-farm breeding programs. The report provides some guidance to practical breeders choosing to make a start. Appendix A, for example, explains in detail, how to extract additional information from OFDA fleece test data that could be useful in assessing potential breeding sires.
The Mohair goat The findings of this report also have some relevance to the Mohair goat. (The term Mohair goat is used throughout this report in preference to Angora goat. An Angora goat is a “breed”, a Mohair goat is a “type”. The distinction is important, and fundamental to understanding the approach taken in this study.) There is an emphasis on different fibre population elements, but the principles are inherently the same.
Also in sheep The report draws attention to the great underlying similarities between fleece production in sheep and goats. A study of the genetic basis of fleece production in one - becomes a study of fleece production in the other – displaced in time. The Australian cashmere goat of today, represents a “genetic snapshot” of the “Australian sheep” of around 1805, before the creation of the modern Australian Merino. The relevance to the improvement of Merino Wool is covered in discussion.
Other fleece bearing animals The authors believe the same mechanisms and principles as discussed in this report, may apply to a wide range of fleece bearing animals, extending at least as far as the Family Camelidae.
From an Industry perspective,
a framework now exists which may be useful in establishing future research
priorities.
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