Growing Longer Mohair
Mohair producers can improve the prices they receive for mohair if they shear when fibre length is between 10 and 15 cm. Harvesting longer mohair can be achieved by developing flexibility in shearing practices, good kidding management and appropriate nutritional management. In some areas of Australia during the winter half year it is hard to produce mohair fleeces of these lengths. This article discusses some of the biological and management issues relating to mohair length. But first there is a discussion regarding the market discount for mohair length.
Market discounts for mohair length
Historic South African prices
Based on the 10-year average of prices in the South African market up to 1982, mohair of 5 to 7.4 cm in length was discounted by an average of 10% compared to mohair 7.5 to 15 cm in length. There was little difference in average prices between mohair of 7.5 to 10 cm and mohair of 12.5 to 15.0 cm in length. While evidence from South Africa suggests that markets discount less against length than against fibre diameter many Australian producers believe otherwise and the prices received in recent years support this view.
Recent Australian prices
Using the average prices from a typical mid year auction at a leading Australian broker the following discounts were observed:
In recent years there are instances were there was no reduction in price by selling the shorter B length fibre but there are cases when A length fibre sold for 80% more than B length fibre.
When fibre diameter was exactly the same only two quotes were available at this sale with:
It has been possible in some years, to achieve price increases of between 20 and 80% for fine kid fibre, which may have been of B or C length, by ensuring that this fibre was shorn when A length. Why then are growers risking large discounts in price for their best mohair?
Seasonal patterns of mohair growth.
Mohair growth is affected by the length of the day, called the photoperiod. During mid winter mohair growth can be reduced by as much as 60% compared to peak growth rates in mid summer. Many fibre producing follicles in the skin of older goats stop growing for short periods during the winter period. As a consequence of this cessation of fibre growth many Angora goats exhibit a seasonal shedding of mohair fibres during mid spring (September). These shed fibres show up as cross fibres in the staple. Fleeces that have shedded fibres can exhibit matting and cotting (natural felting) making shearing, fibre classing and processing difficult.
Effects of nutrition.
Provision of adequate highly digestible pasture will maximise fleece growth. Mohair growth is usually greatest in Australia during spring, particularly if goats are grazing temperate pastures. In regions where annual pastures die in late spring and do not grow until autumn, mohair growth will be least in summer and autumn. In regions with perennial pastures, which grow over summer and autumn, mohair growth is least during winter. Nutritional effects can override photoperiod effects but in some districts they are additive.
Cold wet winters significantly increase the energy requirements for maintenance of Angora goats, particularly weaner yearling goats. Many farmers do not provide enough pasture for young goats believing that as they are small they do not need much. This approach is a very BIG mistake. Yearling goats require additional feeding and shelter from the wind. The best form of energy is growing grass and plenty of it. Growing weaned goats have an energy requirement greater than that of mature wether goats. Supplementary feeding of energy will increase mohair growth, particularly when pasture quality or quantity is limited during wet cold winters or hot dry summers.
Trace mineral deficiencies, particularly during winter, will result in ill thrift of animals, lack of vigor and reduced mohair growth. Any such deficiency requires direct treatment of all affected goats.
Nutrition also affects the development of secondary follicles in the skin of kids up to the age of about 5 months. Excellent feeding of pregnant and lactating does is recommended to maximise follicle development.
The length:diameter relationship
Experimental results show that the ratio of fibre length (L) to fibre diameter (D) from an animal remains relatively constant over a wide range of fibre growth rates caused by normal fluctuations in nutrition. In particular the L/D2 ratio is virtually constant for animals. This happens as D2 more closely represents the cross-sectional area of a fibre than does D. Thus shorter mohair tends to be finer and longer mohair tends to be coarser. Too much feeding will increase the length of the mohair and also the diameter.
It is possible to select goats to increase mohair length. Staple length has a relatively high heritability of about 0.3 in Texan Angoras but heritability of staple length in South African goats is regarded as low ( < 0.2). Any selection for increased mohair length must ensure that mohair fibre diameter does not increase.
Changing the interval between shearing is easy. Instead of having almost fixed 6 monthly intervals between shearing, the time can be changed to ensure mohair length is always 10 cm or more. This manipulation of mohair length costs almost nothing other than good organisational skills and the use of a ruler. The are 2 ways of manipulating shearing to alter mohair length.
i) Make the winter period longer (Static method)
This method allows for the fact that mohair growth is least during the winter half year as a result of short days (photoperiod) and nutritional effects (limited pasture availability and colder wetter conditions). The actual adjustment depends on the environment but could involve an interval of 61/2 or 7 months between shearing in winter and 51/2 or 5 months for summer.
Another approach is to put shearing out of synchrony with the seasons so that the "winter half" year includes more of the period when mohair is growing rapidly in spring. It still may be necessary to have shearing periods of 61/2 months for winter and 51/2 months for summer. It is best to shear before any fleeces become matted or cotted as a result of shed fibres becoming entangled. Usually this matting occurs around September and with does around kidding time in spring. Shearing as late as October/November could present problems for fleece quality and significant reduction in fleece value if fleeces become cotted.
ii) Measure the fleece and shear at the correct length (Dynamic method)
This involves using a ruler to measure staple length and arranging shearing when the correct length has been achieved. This method is recommended when shearing young kids. When kids are young they have low live weights and grow the finest but potentially shortest mohair. To maximise prices for the finest mohair, harvested in the first 3 shearings, it is essential that mohair length is at least 10 cm. For this approach it is essential to manage mating so that kidding is not spread out over more than 6 to 8 weeks. It may be necessary to have shearing spread so the younger kids are shorn 4 to 6 weeks after the earlier born kids to ensure that their finest mohair is long enough.
Second cuts must be avoided at shearing. This occurs when the shearer cuts the staples twice in removing the fleece. Second cuts reduce the effective staple length for processing. Mohair fleeces must be placed onto a fleece table and gently shaken to allow the short locks and second cuts to separate away from the main fleece and fall underneath the table.
Once the fleece has been shorn it is necessary to also remove the short edges. This process is called skirting the fleece. Skirting also removes stained fibre, skin pieces, coloured fibres and any other non scourable impurities with the objectives of making the fleece as even as possible and as long as possible. Mohair grown underneath the body, around the inside of the legs and around the britch needs to be separated from the main body of the fleece. This fibre is usually shorter than the main fleece because of rubbing and wearing during everyday walking, and often contains coarse fibres and medullated fibres. Lack of careful skirting is a major cause for downgrading of kid fleeces into shorter length lots for sale.
While it is possible to increase mohair length and weight by supplementary feeding it has never been shown to be economic to provide supplementary energy or protein just to grow additional mohair. The best use of supplementary feeding is during pregnancy and early lactation (see article on this topic). The only other exception would be if additional feeding allowed B length fine kid mohair to reach A length without being penalised into less valuable kid or young goat fibre diameter grades. The reason for the generally uneconomic response is that as length growth rate increases fibre diameter also increases, as the L/D2 ratio remains constant. Generally increases in fibre diameter result in greater reductions in the price of mohair than the price reductions due to reduced length of mohair.
The ideal is to grow the maximum amount of fine mohair that achieves the ideal length. This requires nutritional management that allows young mohair goats to grow continually during their first year. Ideally weaned kids will have access to green pasture throughout the year. Growers need to prevent trace mineral deficiencies and severe internal parasite infestations to ensure live weight growth is possible. In cold and wet environments shelter from wind during winter is strongly advised.
Serious breeders need to be involved in MoPlan or a similar performance recording scheme if they are going to make any long-term impact on the genetics of fibre length growth. There will be some bucks that can grow longer mohair, which is fine, but unless you measure these characteristics carefully and manage the goats in a consistent manner you will never be able to properly identify these goats. If growing sufficient length of mohair during winter is a major constraint then bucks and does should be selected on their ability to grow sufficient mohair during the winter half year. Progress is likely to be slow in this regard but progress will be cumulative.
When you purchase bucks do you ask for data on fibre diameter, mohair staple length and fleece weight? If not you need to have a good hard think about your objectives.
Growing long fine mohair is not easy. It involves a range of management skills including flexibility in shearing practices, good kidding management, nutritional management to allow weaned kid to grow and careful buck selection. Mohair producers should use these management skills to develop a production system suitable for their environment that maximises the harvest of their principal product, high value mohair.
© 2000 B.A.McGregor