The "Halo Effect"

The "halo effect" refers to the look of a fleece in which there are a number of apparently longer fibers protruding beyond the majority of fibers within the fleece. This halo may be present over most of the animal, as may be the case with a cria, or it may be evident only in some areas, as is often the case on the chest or bib of an adult alpaca. In adult alpacas, a halo is often indicative of guard hair. The halo effect is a topic of much debate at shows and breeder gatherings. Is a halo a good thing or a bad thing? It can depend on many factors. Not only is each alpaca different genetically, but nutrition and environmental factors can also play a big part in how and when blanket fiber develops. 

A halo on a cria’s blanket is generally not the result of guard hair, but simply primary fibers that are longer than secondaries. On a crias, primaries are frequently longer because they start to grow in utero earlier than the secondaries. In addition, a cria's primary fibers may appear even longer because they may lack the crimp that is produced as a result of a group of fibers growing together in close proximity. Once the secondary fibers begin to grow, the entire group or bundle of closely clustered fibers will begin to exhibit crimp, both primaries and secondaries alike. Finer and more densely packed fibers, primaries and secondaries together, will tend to produce more highly defined crimp. Finer fibers bend more easily than thick and the more densely packed they are, the greater the pressure for them all to grow in the same fashion. A cria has the densest fleece per unit of skin area that it will ever have. As the alpaca grows and matures, the skin will expand like a balloon, forcing the skin follicles farther and farther apart. Because of these variables, both in the initial growth rates of primary versus secondary fibers and in the changing follicular density as the cria matures, experienced breeders often say that the quality of an alpaca's fleece cannot be fully evaluated until after its second shearing.

In adult alpacas in particular, a halo of primary fibers may be indicative of an alpaca that lacks density. When fiber is not densely packed, the primary fibers are not under pressure to perform like the secondaries. In contrast, when many fibers are growing together in a relatively small area they must conform to a like growth pattern, and primary fibers, especially fine ones, will tend to exhibit the same crimp character as the surrounding secondary fibers. A densely fibered alpaca, therefore, will tend to have highly organized fleece architecture in terms of bundling, staple and micro staple size, and crimp style.