What is alpaca fibre?
As we all know, alpaca fibre is a textile fibre that fits into the group of fibres produced by a follicle on the surface of the animal’s skin. This process is not unique to alpacas. It is not even unique to fibre producing animals. A study of the skin of the hair seal will reveal that it, too, has fibre producing follicles virtually identical to those of the alpaca.
The process of cell division that produces the fibre at the base of the follicle is also identical across species.
What then creates this alpaca fibre?
The genetic imprint in each species ensures that the follicles produce a fibre with the structure and properties that are specific to that particular species. So that, although the basic structure of all fibres is the same, the minor variations in the chemistry and physical structure differentiate the fibres from different species. These differences create variations in the textile properties of the fibres which cause each of these types of fibres to be unique.
The commonality of fibre producing principles allows a sharing of knowledge between species which becomes important in an emerging breed like alpacas. Research conducted for sheep and goats in Australia must give us guidelines to the expected performance of alpacas under Australian conditions. This will be particularly relevant when the Australian alpaca industry progresses from an intensive industry to a viable extensive industry. It would be foolish for this enormous bank of knowledge to be disregarded.
But I digress from the fascination of the alpaca fibre. The fascination of the alpaca fibre is that it is an enigma. It is promoted as a fibre that is fine, that possesses softness combined with strength, excellent thermal insulation combined with light weight compared to similar fibres, high durability and a soft silky texture. Handling both fibre and textiles confirms this perception.
Fibre Fineness
Alpaca is classified as a wool fibre in the textile industry. This means alpaca fibre is currently processed on machines developed for wool. On these machines, the average fibre diameter determines the diameter of the spun yarn and this, in turn, determines the fineness of the cloth.
From the testing of alpaca fibre at Sydney Institute of Technology, where over 400 mid-side samples were tested on a CSIRO Laser scan, it was found that only four samples were less than 21 µm and the average fibre diameter was 26.2 µm. These samples were sourced from the Southern Highlands, the Blue Mountains, the Hills district and the central west of New South Wales and also from Southern Queensland. This average fibre diameter exceeds the average fibre diameter of most merino wools produced in Australia and makes it difficult for alpaca fibre to compete directly with wool on a fineness basis.
Very few wools greater than 27 µm are used in apparel fabrics. Consequently, with an average fibre diameter of 26.2 µm, almost half the fibre samples were from fleeces outside this range.
The choice for alpaca growers is to either develop speciality fabrics to utilise the current unique properties of the alpaca fibre as is occurring in the craft industries or to modify the current fibre production to produce a finer fibre by changes in management, genetics and/or flock structure.
Fibre growth
To understand appropriate management adaptations it is necessary to outline factors that affect fibre growth in an alpaca.
Previously, the mechanism of fibre production was described. It is now necessary to relate this mechanism to the practical situation.
The concept of fibre growth from a follicle is analogous to the growth of a pot plant. The more the pot plant is fed, the more vigorously it grows. The height of the plant increases (equivalent to fibre length), the thickness of the stem increases (equivalent to fibre diameter) and the ‘bushiness’ increases (equivalent to crimp size in the case of crimped fibres). The converse occurs with a reduction in nutrition and, although this reduction in these features is not obvious Fain the pot plant, in the follicle where the fibre is being continuously produced by the papilla at the base of the follicle, the reduction in fibre diameter and length of fibre and, in the case of crimped fibres, the size of the crimp is obvious and measurable.
The nutrition for the creation of the fibre is carried from the digestive system to the papilla in each follicle by the circulatory system. As this is a closed system, (each papilla is being serviced by the same network of arteries and veins) any change in nutrition will be reflected in all follicles and therefore all fibres over the surface of the animal. However the rate of change in each follicle, although in proportion, will not necessarily be the same.
Factors affecting fibre growth
The question arises: what is the relationship between genetics and nutrition and other environmental influences on the growth of the alpaca fibre?
The characteristics of the fibre or any other features of the animal that are visible (the phenotype) have resulted from two influences, the genetic make-up of the animal (the genotype) inherited from its parents and the environment in which the animal has been run. The environmental influences include available nutrition, pregnancy, lactation, health status and level of internal parasites. For some of the features of fibre growth, the genetics of the animal has exclusive influence, e.g. colour of fibre pigmentation. However, in other areas, the genetics sets the limits for production but the environment determines whether those limits are achieved.
The importation of Peruvian alpacas is expected to influence the Australian alpaca population by providing both a source of finer genetic material to mate with existing alpacas and a critical mass of animals expected to produce finer fibre. The unknown factor will be the ability of these animals to adapt to Australian conditions in terms of the final fibre diameter that they will produce.
The expression of the environmental influences is usually in the form of nutrition or the amount of nutrition that is available to the individual animal in relation to the nutritional requirements of the animal at any particular time. This can be best demonstrated by the following chart:
Distribution of nutrition in animal
Available food— Maintenance of body systems: (nervous, circulatory, digestive, immune etc)
• Body growth
• Fibre growth
• Pregnancy
• Lactation
• Fat deposition
The available food is absorbed from the system in descending order of priority with the maintenance requirement being withdrawn first and then, as or if required, the food is distributed to the other areas.
If the nutrition level falls so that there is not enough nutrition to satisfy all the requirements of the animal, the system starts to shut down from the bottom. Fat is absorbed instead of deposited; levels of lactation decrease; foetal growth and reproductive performance are reduced; fibre growth and body growth are reduced; and finally, if the level of nutrition falls low enough, the animal’s body systems will start to close down and the animal will die.
Nutrition
As already indicated, the level of nutrition at the follicle base is responsible for the amount of fibre that is produced by the cell division at the papilla. This volume of fibre is represented by both the fibre diameter and the fibre length. As nutrition increases, both fibre diameter and fibre length increase and as the nutrition decreases, both decrease. This leads to a variation in fibre diameter along the fibre over the year and this seasonal variation is common to all animal fibres produced by grazing animals.
If the fibre diameter is reduced enough, the fibre will become weak and will break at that point during processing. Normally this tendency to break or ‘tenderness’ only occurs as the result of rapid changes in nutrition and not as the result of a gradual reduction in feed as occurs in a drought. If the conditions are appropriate for tenderness, then this weakness will occur on all fibres and at the same point because the follicle system is integrated by being connected to the circulatory system.
The other ramification that must be considered as a result of the change in nutrition is the relationship between the fibre diameter in alpaca fibres and the level of medullation. The level of medullation tends to decrease with reductions in fibre diameter and to increase with increases in fibre diameter.
The dominance that nutrition has over the genetic make-up of the animal is demonstrated by the difference in fibre diameter from the same animal in a good season compared with a bad season. Although the animal will maintain its ranking in the flock when compared with the other animals, (the genetic effect or control) the mean fibre diameter is capable of varying considerably. Although the natural conditions for alpacas are in sparse, stony ridges, most Australian alpaca growers appear to be running their high priced animals on good quality pastures and then are concerned that the animals are not producing the fine fibre. There is too much quality feed!
Health and Disease
The effect of sickness and disease is probably best explained by the chart above. Sickness or disease has the effect of reducing the amount of nutrition that is available for conversion into fibre. This occurs in a number of ways: reduced appetite as a result of the sickness leading to less available nutrition; extra nutrition required by the body systems to overcome the effect of the disease; and reduced effectiveness of the digestive system as a result of the disease or the effect of toxins released by the disease. Sometimes, as in the case of a fever, the level of cell division at the papilla will cease or be considerably reduced, leading to adramatic reduction in fibre production.
Pregnancy and Lactation
Pregnancy and lactation have the effect of diverting available nutrition away from the wool follicle causing reductions in wool growth.
In pregnancy, this reduction is greatest towards the end of pregnancy when the growth of the foetus is greatest. In sheep, the foetus triples in size over the last third of pregnancy. This is probably also true of the alpaca and this extra growth requires extra nutrition. In sheep also, at the time of lambing there is a cessation of fibre production leading to a dramatic reduction in fibre diameter and resulting lack of tensile strength.
This phenomenon occurs in response to hormonal changes within the ewe at birth and it would be logical to assume a similar situation occurs with alpacas. Although, theoretically, hormone levels could be artificially controlled to prevent this happening, birth would also be prevented from occurring. The only option available to the producer, if this tenderness is a problem, is to ensure that shearing is either just before or just after the birth which means the weak spot in the fibre is at the end.
Lactation provides a great drain on the nutritional levels in the dam, as she must process a lot of feed to produce the necessary amount of milk. In a sheep the required level of nutrition increases by up to three times over the level required by a non-pregnant, non-lactating sheep. It would be reasonable to expect similar ratios for alpacas.
Parasites
Internal parasites are found in the digestive tract of the animal and rely on the animal to convert the pasture into a form that the parasite can absorb (usually the same form required by the host animal). The parasite exerts three forms of influence.
First, it competes with the animal for the food that is available.
Secondly, the parasite often damages the gut lining by burrowing into it and reducing the effectiveness of the absorption of nutrition.
Thirdly, toxins can be produced by the parasites which affect fibre production.Parasites have a blocking effect between food and the areas where the food is required.
The overall effect of parasites is a reduction in the amount of fibre produced both in diameter and length.
Age
As with most fibre producing animals, there appears to be an increase in fibre diameter with age in alpacas.
Flock Structure
Fibre producers must balance all the above management factors to produce the desired fibre but there are also other considerations to complicate the issue.
To ensure successful breeding, the nutrition levels of the females must be kept high. The developing cria must also be given high levels of nutrition to ensure growth and development and also to develop the optimum number of secondary follicles. Although the physiological state of the hembra and the age of the cria will result in a fining of the fibre, in spite of the high levels of nutrition, the resulting fibre diameter will be unpredictable and variable.
The introduction of wethers will ensure a critical mass of fibre can be produced. Mature wethers require low levels of nutritional maintenance to produce good quantities of fine fibre, particularly if grazed on native pastures. Running wethers means producers can allocate their improved pasture to the females and developing cria while the wethers utilise the ridges in conditions more closely resembling those of their origins. The best fibre in terms of both fibre diameter and fibre properties tested at Sydney Institute of Technology in my time there was produced on a property at Queanbeyan where the alpacas were running on the top of a hill on native pastures.
The ideal flock structure for a permanent self-replacing flock, in the long term, must be one third breeding females, one third developing cria, and one third wethers. This allows a 60 per cent culling and rigid selection to ensure an improvement in quality.
All the above factors have directly influenced the fineness of the fibre. But, even with an understanding and application of these factors, alpaca fibre remains on the broad end of the range of apparel fibres. Are there any mitigating factors that overcome this lack of fineness?
The enigma of alpaca fibre
The illusion of fineness in textile fibres is created by our tactile response to the surface of the fibre and this property is perpetuated in the resulting fabric. Alpaca fibre feels fine and an examination of the surface structure of the fibre will explain this.
The outside layer of all follicle produced fibre consist of overlapping cuticle cells. These cells are overlapping so that the protruding extremities point to the outside tip of the fleece. It is these overlapping cells that allow fibres to spin together, as the elasticity of the fibres locks these cells together to form a permanent structure of many fibres.
The impression of fineness is created in alpaca fibre by its silkiness and apparent softness.
The silkiness is generated by the low scale height of the cuticle cells, allowing the hand to slide over the surface of the fibre but maintaining sufficient height for effective spinning to occur. This scale height varies with different species and alpaca is distinguished by possessing one of the lowest scale heights. The wool industry has managed to duplicate this effect by the using the process of superwash in which fibre is immersed in resin. This coats the fibre, effectively reduces the scale height and creates the illusion of a finer fibre.
The second part of this illusion is the apparent softness of the fibre. The alpaca fibre is not soft. The resistance to abrasion of the cuticle cells of alpaca is 368 compared to 172 for wool, over twice as much. Avery hard surface.
Alpaca fibre feels soft because of its springiness and its high resistance to compression. This ‘softness’ is also transferred to the yarn and fabric.
Alpaca fibres resist forming a solid mass under compression. This resistance results in other enigmatic features of the alpaca fibre, particularly its light weight compared to other fibres. This same effect occurs with scoured wool after the grease has been removed. Although the mass of alpaca fibres are very similar to other follicle-produced fibres, their springiness prevents them being compressed.
This is a positive that the alpaca industry could exploit. Wool processing aims to produce a tightly spun yarn, whereas alpaca fibre would be ideal for producing a loosely spun yarn which would produce a very light garment with high insulating properties.
The hardness of alpaca cuticle cells endows the fibre with high durability which, combined with relatively high fibre diameter, produces a strong fibre that is capable of withstanding the rigours of high speed spinning and weaving.
So where does that leave us?
We now have a fibre that appears fine but is not; that appears soft but is actually hard and strong; that has excellent thermal insulation, combined with apparent light weight, but one that is actually similar in weight compared with other fibres, and that has high durability and a silky texture. As a bonus, in many cases, we also have lustre.
This is the enigma that is alpaca fibre. This is the fascination. This is ‘the fibre of the gods’.
AUTHOR : Geoff Lenehan
