NUTRITIONAL MANAGEMENT

Llamas and alpacas have three compartments in the forestomach that are referred to simply as compartments C1, C2, and C3. C1 and C2 contain 85% to 90% of the total stomach volume and function as fermentation vats, similar to the rumen and reticulum of cattle, sheep, and goats.^3,4 The first compartment contains numerous saccules lined with glandular epithelium that aid in the absorption of water and solutes³ and will retain fibrous feedstuffs longer (up to 60 hours) than in sheep (up to 40 hours).⁵ The cranial portion of C3 also functions as a fermentation vat, whereas the caudal portion of the compartment is “abomasum-like.”⁴ Llamas and alpacas appear to have greater salivary production relative to foregut volume, and a faster liquid flow rate from the forestomachs, than are reported for sheep.⁵ This faster liquid passage may result in quicker forestomach removal of soluble minerals, vitamins, and microbial protein.⁵ Llamas and alpacas are capable of thriving on a diet that contains less dry matter on a body weight basis (1.2% to 1.8%) than has been recognized for many other herbaceous animals (greater than 2.5%). Llamas and alpacas may have a 10% to 25% greater efficiency in digestion and assimilation of nutrients than that in true ruminants, but when they are fed nutritionally good- to excellent-quality feedstuffs, this advantage appears to be lost.^3–6 Llama and alpaca nutrition has been discussed elsewhere, and interested readers should refer to those publications for further information.^3–6

The llama is a browser by nature but will graze, whereas the alpaca is a grazer that shows a preference for succulent forages. Both species appear to be very adaptable to many types of feeding systems.^3,4 Cereal grains or pelleted supplements are rarely indicated except in older, chronically thin or ill animals, during prolonged periods of cold stress, or to ensure adequate intake of specific nutrients (e.g., selenium, zinc, protein).⁴ The assessment of body condition helps in determining long-term nutritional intake, particularly with respect to energy. A 10-point scoring system is most commonly used in which 1 is very thin, 10 is extremely obese, and 5 is ideal.³

Body condition in llamas and alpacas is best assessed by palpating the transverse processes of the lumbar vertebrae, around the shoulders, and over the ribs. A convex or concave plane from the dorsal spine to the tip of the transverse processes would be considered to indicate condition scores greater than 5 and less than 5, respectively. If the ribs are easily palpated, the condition score is less than 5, but if the ribs are difficult to feel and if fat cover over the lumbar vertebrae is bulging and slightly soft, body condition for that animal is scored at 6 or greater.⁴ The lateral aspects of the transverse processes of the lumbar vertebrae should not be sharp but should be easily palpable. The shoulder structures also should be palpable, with the bones and joint edges not sharp but appearing to have a slight smoothness. With weight gain, subcutaneous fat accumulates over the brisket, between the rear legs, and around the perineum. If the brisket is flat or soft between the front legs, then the body condition is 8. If the sternum is sharp and easily palpated, the condition score would be closer to 3. The pelvic bones can be easily palpated in all but obese llamas and alpacas.⁴ When possible, body weights should be evaluated on a continuous basis, and steps should be taken to minimize body weight changes. Llamas and alpacas naturally gain weight in spring and early summer and tend to lose weight in late summer, fall, and winter. If they are weighed at 60-day intervals, adults that do not show this seasonal pattern, but continue to gain (or lose) weight, should be examined, and appropriate dietary changes made.⁴

Llamas and alpacas that are healthy, parasite-free, nonpregnant or nonlactating, and mature may have their nutritional requirements met by being fed 1.2% to 1.8% of their body weight daily of a diet that has an average of 55% total digestible nutrients, 8% to 10% crude protein, 25% crude fiber, 0.6% to 0.8% calcium, and 0.3% to 0.5% phosphorus.^4,5 These maintenance requirements usually are met by good-quality grass or grass-legume pastures or hay. All llamas and alpacas should have free access to fresh, clean water. Modification in energy intake may be needed during extremes in weather. In most instances, the mineral needs are met by offering a well-formulated trace mineral supplement as the only source of salt in a granulated form. Salt blocks do not permit adequate intake of trace minerals and are not recommended. In areas in which forages are badly deficient in phosphorus, selenium, zinc, or other minerals, diets may be designed to supplement such deficiencies. The clinician can aid in dietary management of the herd by nutritional analysis of pasture, hay, grain, and, when indicated, water. In cases of suspected mineral deficiency, adequacy can be assessed by tissue analysis (e.g., whole blood for selenium level, serum or plasma for copper and zinc levels).⁴

The requirements of adult males can be met by the recommendations previously discussed, with the exception that energy content be increased or decreased, depending on body condition. Male fertility can be depressed during periods of extreme high temperature and humidity.⁴ To help minimize the incidence of heat stress, males should be shorn, fed highly digestible feeds (to avoid the increased heat of digestion associated with high-fiber feeds), fed to meet but not grossly exceed protein requirements, fed in the late afternoon or early morning, offered free-choice clean water, and maintained at a body condition score of 5 to 6. The hemostatic mechanisms used to dissipate heat (panting, sweating, and increased heart rate) may result in greater energy, mineral, and water requirements, and animals should be fed appropriately. Very aggressive males may lose excessive amounts of body weight and condition during a heavy breeding season.⁷

During the first two trimesters of gestation, dietary requirements will be met by feeding for maintenance. In the final trimester of gestation, mature females should be fed 1.5% to 1.8% of body weight of a good-quality forage, with a crude protein content of 10%. Energy requirements may increase to 1.5 times maintenance during the final trimester.⁵ These requirements can be met by feeding a good-quality legume-grass pasture or hay with supplemental grain.⁵ Overfeeding and obesity are common problems in llamas and alpacas in North America. Obesity should be avoided in breeding females because it may be associated with a higher incidence of heat stress, poor milk production, and dystocia.

During lactation, nutrient needs may increase by as much as 2 to 2.5 times maintenance requirements, particularly in heavy-milking females.⁵ To meet these demands, total digestible nutrients and crude protein content of the ration should be increased to 60% to 65% and 12% to 15%, respectively,^4,5 Intake of some excellent milk-producing alpacas may approach as much as 2.2% to 2.5% of their body weight. These requirements can be met by good-quality legume-grass hay, fed on a free-choice basis, with some supplemental grain. The dam’s diet can be reduced at the time her young are weaned (usually 3 to 5 months) to avoid obesity. Moderate energy restriction can be used for weight reduction in middle to late lactation for obese females; however, diets severely restricted in energy and protein should be avoided in late gestation because they may result in the formation of poor-quality or decreased quantities of colostrum, or in fatty liver syndrome.⁴