The four members of the South American camelids (SACs) are the llama, alpaca, guanaco, and vicuña. Although their progenitors originated in North America,these species evolved in the South American Andes, with the wild guanaco and vicuña serving as the foundation stock for the domesticated llama and alpaca, respectively.
Mature, average alpacas weigh 60–80 kg and stand 76–97 cm at the withers. Alpacas are primarily used as fiber-producing animals. The fiber grows rapidly and ideally requires shearing every 12–24 mo. Mature llamas are significantly larger animals, weighing an average of 120–200 kg and standing 102–127 cm at the withers. Llamas were primarily developed as pack animals and can carry loads of 25–40 kg. Both domestic SACs are meat staples for indigenous peoples. Males and females of both species have approximately similar mature weights. Guanacos are similar in size to llamas but weigh somewhat less. Unlike llamas and alpacas, in which coloration patterns vary markedly, guanacos and vicuña have a “wild pattern” characterized by a light brown or tan coat over the neck, back, and outside of the legs, with white on the underbelly and medial surface of the legs. Vicuñas are slightly taller than alpacas, with a longer neck, much shorter fiber, and a characteristic “bib” of long fibers in the chest region. Vicuñas have extremely fine fiber and are managed and protected in much of South America.
All SACs have 74 chromosomes and can interbreed, producing fertile F1 progeny. The most common, naturally occurring cross is a llama-alpaca mating, producing a “huarizo” that is intermediate in size, body characteristics, and fiber quality. Recent attempts to increase fiber quality and quantity have involved alpaca-vicuña crosses resulting in paco-vicuñas. Intact male llamas and alpacas are called studs (machos in Spanish), whereas castrated males are referred to as geldings. Females are called females (hembras in Spanish). The neonates and young up to 6 mo of age are called crias, whereas juveniles are called tuis in the local Quechua language.
Most llamas have characteristic “banana-shaped” ears, a level back, and a high tail set. There are no distinct llama breeds, but several types based on fiber length and crimp have emerged. A “suri-style” llama has recently been introduced into the North American market.
In contrast, there are two morphologically distinct types of alpacas: the Huacaya and Suri. The more common Huacayas have a lofted fiber coat with variable coverage down the legs and around the face. Suri have a flat-lying corded fiber structure (“dreadlocks”) with less coverage on the head. Alpacas have shorter “spear-shaped” ears, a lower tail set, slightly more humping to the back, and a sloping rear end that results in a slight sickle hock appearance.
SACs are most closely related to the Old World camelids (Bactrian and Dromedary), having the same number of chromosomes, similar anatomy and physiology, and general patterns of disease susceptibility. Although conventional ruminants are frequently used as reference points for drug dosage extrapolation, disease susceptibility, and management decisions, it is important to remember that SACs and common domestic ruminants are not the same.