By Dan Undersander
Centuries ago, the Inca began raising alpacas for their soft and luxurious fleece. They pastured their animals in the lowland meadows and marshlands called bofedales, at an elevation of about 4,000 feet above sea level. The alpaca’s native region has a very short growing season with 75% of the rainfall between December and March. During the dry season (May to October), native forage has relatively low nutritional value. Fortunately, alpacas are well adapted to this cycle of feast and famine. In fact, the primary feeding-related problem among North American alpacas is obesity.
Digestive Physiology
Alpacas are lamoids which is a group of South American camelids including the guanaco, vicuna, alpaca and llama. Camelids are not true ruminants like cattle, sheep and goats; their unique gastrointestinal anatomy designates them as “functional ruminants.” Their stomachs have three compartments, all with absorptive and secretory glandular areas which are characteristic of the camelid digestive system. Stomach motility is faster than that of true ruminants, with contractions of the first compartment occurring at three to four times every minute (even faster when eating). These factors facilitate nutrient absorption when forage quality is low. In such cases, camelids are 50% more efficient in extracting fiber than are sheep. In the first compartment (C-1), carbohydrates are converted into volatile fatty acids which are then absorbed with two to three times the efficiency of cattle and sheep. Apart from their nutritive function, these fatty acids aid in the camelid’s adaptation to low-protein diets; when nitrogen is metabolized into urea, the microfauna in the alpaca’s digestive tract use it to synthesize protein; these microbes are then digested and the protein absorbed. Though few reports exist on the exact species microbes present in the camelid stomach, it is evident that they also digest the cellulose from plant cell walls, as well as starches, sugars, acids, lipids, and protein. Some even synthesize vitamins. These bacteria are very sensitive to environmental shifts; sudden changes in an alpaca’s diet can cause stomach atony, a condition wherein the microorganisms die off and digestion is severely inhibited. Therefore, diet changes must occur gradually. Stomach microfauna are also hindered by excess lignin in overly mature forage, as well as nitrogen/mineral deficiency. Slowing down their facilitating effect on cellulose digestion will reduce the amount of forage an alpaca will voluntarily consume; and in terms of contribution towards an animal’s energy (84.5 kcal per kilogram0.75 of body weight) and nutritional requirements1, quantity is just as essential as quality.
The digestive system of lamoids has a noteworthy capability for digesting certain toxins.
Temperate Pastures
Now move the thousands of miles north to the Midwestern regions of North America, where alpaca ranching has been growing in popularity for the last few decades. Information on raising alpacas is most often obtained through the oral traditions within what might be termed a subculture of alpaca breeders, though there is very little in the literature pertaining to the actual practices involved. The ideal pasture, particularly with regards to alpaca fleece production, is nearly impossible. Studies with Australian sheep have shown that the particular amino acids of which wool is primarily composed (namely, cysteine and methionine) simply does not exist in grasses in sufficient quantities for feed-to-wool efficiency rate any greater than 0.115 (+0.018). Legumes are a necessary companion to grass. A pasture must have at least 40% legumes for adequate nitrogen fixation; otherwise nitrogen fertilization is required. Furthermore, legumes suffer less decline in digestibility and accessible protein as they mature.
As for specific types, numerous books have been written on the subject of forage. However, the question of what to include in a temperate pasture is not as daunting as all that. The myriad species can reasonably be trimmed down to a selection of a few of the more common forage crops. The University of Wisconsin Extension publishes forage variety updates and a booklet called Pastures for Profit: a Guide to Rotational Grazing. These list a number of grasses and legumes with the necessary information to plant a productive pasture. They are not ubiquitously appropriate, however, and only a few will succeed in southeastern Wisconsin. Timothy, for example, yields much high-quality forage and is quite compatible with legumes, but will not tolerate the heat and drought that typically occur in late July and August. Perennial ryegrass tolerates the drought, but not the winter cold. The spring rains and melt water tend to flood lower areas, and reed canarygrass is well-suited to these conditions; however, the presence of alkaloids in some varieties of this species makes it unpalatable if not toxic. It is also an invasive species which can easily displace native plants. Beyond climate concerns, there is the question of growing season and the distribution of a crop’s yield. These considerations make orchardgrass a good choice. With a long growing season, it produces a high yield with greater regeneration after the late-summer drought. It is highly competitive; any companion crops must be as well. Red clover is just such a legume to compete with orchardgrass. Meadow fescue is also resistant to high traffic (an individual alpaca is easy on the pasture, but they do like to travel in groups) and has good fall yield, especially if fertilized. It must be noted that the latter is slow to establish and must be planted in early spring.
Alfalfa is a popular legume; it tolerates drought more than flooding and has a long growing season. However, it is generally inappropriate for alpacas. Alfalfa has more crude protein (18 to 20% DM) and calcium than is necessary (requirements are 12-15% DM and 0.6-0.85%, respectively); excess dietary protein can potentially have adverse renal effects, while excess calcium can bind with other nutrients and/or form stones in C-1. A vigorous clover would be a better choice. Red clover is very competitive, but does not withstand dry conditions. It must also be replanted every three to four years. White clover is thus left as the best choice; it persists well, surviving even heavily-grazed pastures. It is also easy to establish.