Producing Quality Mohair - Some Options For Growers
Mohair producers have five main methods of manipulating mohair quality and production. These are;
Live weight manipulation
As goats grow and become heavier they generally grow coarser mohair. In Australian mohair goats, for every 10 kg increase in mean live weight, mohair fibre diameter increases 3.5 micron. Thus with groups of goats, increasing mean live weight from 15 to 45 kg would be expected to increase mean mohair diameter 10 micron.
Producers wanting to produce fine mohair need to develop a production system that excludes heavy goats that produce coarse mohair. For example, a producer may wish to exclude all goats producing mohair 32 micron or stronger. This would require stringent examination of goats heavier than 38 kg and extensive culling of goats producing coarse mohair. This is no easy task as most mature does reach this live weight and so careful culling would need to be done over many years.
Live weight, age and mohair fibre diameter. It is common to hear that mohair fibre diameter increases as Angora goats age. This concept is not very reliable as has been demonstrated when Angora goats were grazed under a variety of conditions in Australia. Age and mean live weight of Angora goats are reasonably correlated with each other, and with mohair fibre diameter, under conditions of good nutrition. However under poor nutritional conditions, such as high stocking rates and long periods of drought, mean live weight was much more reliable than age in accounting for the variation measured in fibre diameter. Over all nutritional conditions, mean live weight was still much better than age in predicting fibre diameter.
Practical applications. There are two important applications of the knowledge that live weight is strongly related to mohair fibre diameter;
The following nutritional and environmental factors can be managed by mohair producers; stocking rate, supplementary feeding and doe nutrition.
1. Stocking rate influences the quality and production of mohair. The effects are large and commercially significant (Table 1).
Table 1. The main effects of stocking rate of grazing Angora goats in southern Australia on mohair production and mohair quality parameters.
Mohair producers need to graze Angora's at relatively low stocking rates in order to minimise internal parasitism. Such goats will grow relatively rapidly, grow more mohair which will be longer and coarser than heavily stocked goats but the greasy mohair is likely to have lower levels of medullation and higher yields. High stocking rates usually lead to severe health and welfare problems.
2. Supplementary feeding of energy is usually provided in droughts, dry summers, at weaning and during late pregnancy and lactation. Energy supplementation directly effects live weight change and therefore mohair fibre diameter. Goats that lose live weight grow less mohair (-15 to -40%) and the mohair is commonly 2 to 3µm finer than mohair from goats which maintain their live weight. Goats fed to gain live weight grow more mohair (up to +100%) that has increased fibre diameter (often 2 to 3µm coarser) compared to goats fed to maintain their live weight.
Feeding at levels to produce live weight gain has also reduced the incidence of medullated fibres in Australian kid mohair compared to feeding goats to maintain live weight. This response could be economic depending on the discount prevailing for kempy mohair and the way the fibre was classed before selling.
3. Doe nutrition can influence the production of mohair from both the doe and her kids, see Table 2. The other main benefits from supplementary feeding energy to does are to obtain high reproductive rates resulting from increased doe live weight at weaning and increased survival rates for kids resulting from increase lactation performance of does. There is also a benefit from an increase in the quality of kid mohair later in life.
Table 2.The main effects of improved nutrition of pregnant and lactating does on the production and quality of mohair grown by does and their kids.
The energy intake of Angora does grazing low quality pasture can be increased by low levels of energy supplementation but as energy supplementation increases the intake of forage by does will decrease.
Generally the costs of feeding energy supplements far outweigh the direct benefits of increased mohair production. Supplementary energy usually increases mohair fibre diameter of non breeding goats and consequently reduces the value of the entire fleece. Supplementary energy is indicated when the welfare of the goats is at risk (droughts, pregnancy) and large benefits to reproductive performance can arise when energy is fed to pregnant and lactating does.
Supplementary feeding of protein and non-protein nitrogen is not usually warranted in Australia as feed wheat used to overcome energy deficiencies usually has 12 to 14% crude protein. Results in Australia and the USA have shown that the costs feeding protein supplements usually far outweigh the benefits with one exception. Results in the USA have shown that the most strategic use of protein is to enable young female goats to reach mating liveweight by 17 months of age when their base diet is very low quality grazing.
Changing flock type
Many wool producers maintain specialist flocks of wethers. Some wool growers only have wether flocks. Why is this so? The main reasons are related to management and labour. Breeding flocks are subject to major nutritional stresses in autumn and winter which results in reduced wool quality and tender low strength wool. Wether flocks are less susceptible to such stresses. Wether flocks also require no labour at lambing!
With Angora goats, the stresses of pregnancy and lactation often result in reduced fibre growth and in fibre shedding. The resulted cotted fleece is less valuable and mohair may be lost prior to shearing.
Slaughtering unwanted Angora males wastes their potential to produce fine mohair. It is surprising that so few Angora wethers are retained to produce top quality mohair. Without careful nutritional management wethers will grow rapidly and produce coarser types of mohair that is less valuable.
Running wether flocks is an easier way to be introduced to mohair production, requires less labour and if managed correctly, wether flocks could always be producing mohair less than 30 mm by instituting rigorous culling and replacement programs.
4. Changing flock structure
Within a breeding flock the proportion of adult does to kids can be altered. These changes can have important effects on the type, quantity and value of mohair produced.
To illustrate this point let's take a property that can run only 500 Angoras with a feed requirement of 620 dry sheep equivalents (DSE's). Should the does be managed to have a weaning % of 70 or at more intensive levels say 160%? The flocks will be managed to achieve a culling rate of 33% of adult does to enable;
In this simplified example I have assumed typical production levels and fibre diameters for Australian mohair goats. The relative value of mohair has been derived from market information that shows the price of mohair declining by 5% for each increase of 1 mm in mean fibre diameter between 26 mm and 34 mm mohair. Mohair coarser than 34 mm has a relative value of 0.55. To calculate the total relative value of mohair the weight of mohair produced has been multiplied by the market relative value. No death rates are included and selling costs have also been excluded.
The results show that below 70% weaning it is not possible to replace 33% of the adult does each year as too few doe kids are born. The following flock structures are possible (Table 3). The table also provides the production of fibre and cull goats for sale.
Table 3.Flock structure and production at different weaning rates. See assumptions given in the text
There are three major outcomes;
This example shows the benefits of seeking higher kidding performance from does in order to alter the structure of the mohair flock with the aim of selling higher quality mohair. In practice seeking 160% weaning would be difficult, requiring significant labour inputs and many other skill. However the current management of does under field conditions results in weaning rates of 80 to 90% and a lower production of higher value mohair.
It is easily possible to change mohair characteristics by genetic selection and/or changing mohair strains. All the economically important mohair traits are heritable. These issues are discussed elsewhere in Goat Notes and will not be discussed here.
Genetic selection is used to select for finer mohair, reduce the incidence of medullated fibres and to increase clean fleece weight. Australia has a national mohair breeding plan called Moplan. More detailed information can be obtained from Mohair Australia. Moplan is used to provide breeding indexes and progeny testing results to fully evaluate potential bucks and to provide weightings of various traits prior to selection.
Strain Selection refers to using mohair goats of different breeding origin. There are many strains of mohair goats including Australian, Texan, South African and numerous crosses of these strains of Angora goats. There is significant variation within strains providing an enormous opportunity to select sires for crossbreeding programs to exploit superior characteristics.
Genetic improvement is slow but cumulative.
Australian mohair producers can influence the quality of their mohair by
Irrespective of environmental and genetic conditions, mohair producers will need to be increasingly concerned about the quality of their mohair as changes in the clothing and textile industries and consumer preferences are occurring. Consumer preferences are for easy case, comfortable and casual clothing. Increasing emphasis on the production of mohair with mean fibre diameter of less than 30 micron will lead to mohair which will be more marketable.
© 2000 B.A.McGregor