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Field Breeding and Alpaca Ethology

A desire to eliminate adverse outcomes such as physical injuries or endometritis from overbreeding, plus a desire for a definitive conception date, has led many alpaca breeders to adopt a hand breeding management system. I initially followed the generally accepted standard of care for US alpacas in practicing hand breeding, separate housing for males and females, and grouping herds of intact males together. However, my commencement to field breeding alpacas began years ago when we purchased a partial interest in a proven breeding male. I remember the confusion I felt when he showed no libido whatsoever with his first female encounter at my farm. After several unsuccessful attempts at hand breeding females, I learned that he field bred within a harem. Thus my interest in alpaca ethology and the backdrop for writing this article.

My objective in writing this column is to challenge the generally held belief that hand breeding techniques should be the only method to mate alpacas. My literature review includes studies about camelid herd dynamics, socialization, mating, and behavior qualities of camelids and alpacas and reviewing research from other domestic livestock models.

Livestock Breeding Systems

Natural cover (Pasture Breeding) is the pasturing of animals together and allowing them to do the mating on their own. Pasture breeding is the easiest and least expensive of the breeding options for livestock. Pasture mating reduces labor and human exposure to injury, affords convenience to the owner, can catch breeding problems caused by social issues, and creates an opportunity for a high settling percentage. It has the disadvantage of obscuring breeding dates and offers some risk to either or both animals through injury, especially in smaller pastures and confined areas. It is worth noting that gestation lengths for alpacas vary greatly. In my opinion knowledge of the actual breeding date is not as relevant for alpacas as in other species.

Hand Breeding involves the placement of an estrous or receptive female in an area where she is mated to a particular male with supervision by a person working in the breeding area. Disadvantages include added time management requirements and potential for farm-related injuries that involve caregivers who manage controlled or hand breeding systems.  Advantages include supervision of the mating and known breeding date.

Assisted Reproductive Breeding includes artificial insemination, embryonic transfer, in vitro fertilization, fertility medication use, and other interventions. Obvious disadvantages include added cost for the procedure plus veterinarian care and management for some techniques.

Camelid Ethology

Alpacas no longer live like wild animals, so much of the research is observed from their wild counterpart, the vicuna and guanacos herds. Researchers have studied the establishment and maintenance of vicuna and guanacos herds in a natural environment. Many have described the social or­ganization as a year-round system for obtaining vegetation and water, providing defense, practicing polygyny, and a system with permanent feeding, sleeping, and neutral territories. Observations of vicuna demonstrated natural mating groups of one male for twenty females.

Studies of male and female cohabitation year-long showed that the mating activities are seasonal and last from December to March. Alternatively, when females are kept separately from males and copulation is allowed only once a month, both sexes are sexually active throughout the year. Continuous association of females and males can have an inhibitory effect on their sexual activity and, indeed, can cause male libido to disappear altogether (Sumar, 1996). "Sexual activity in these males is almost immediately resumed if introduced to a new herd of females." (Fernández-Baca et al., 1972) Factors controlling the onset of sexual activity under conditions of natural breeding, or the inhibitory effect on male libido resulting from continued exposure to females, are unknown.

Non-pregnant females are essentially in continuous estrus, and with a male introduction to a herd, they will attempt to mate with the first receptive female they encounter. Courtship begins with the male actively pursuing receptive females and trying to mount them. According to England et al. (1971), courtships lasting longer than about four minutes usually result in no mating or forced mating. However, the level of libido of individual males may influence the length of courtship. Conversely, the pursuit of a female by males of high libido may last for up to 10 min before the males give up (Fowler, 1989)

"The intense sexual activity of both sexes during the first week of breeding can result in over 70% of females being mated at least once (Fernández-Baca and Novoa, 1968). The sexual activity of males in breeding herds decreases with time (as short as three days) despite the presence of estrous females. Large Peruvian farms practice "male rotation" to better ensure libido and conception rates. As a result of this practice, birth rates of 57–81% have been reported" (Novoa et al., 1970)

As in all animals, some males may dislike certain females and refuse to mate with them (or vice versa), and periodically, males will show reduced libido, especially when running with a group of females. (McDonnell)

“Repeated insults of the uterus due to improper mating practices can lead to inflammation and loss of the ability to resist infection. Many breeders rely on “receptive” behavior for breeding. However, studies have shown that receptivity is not necessarily correlated with ovarian activity.  This results in multiple matings that have little chance of achieving pregnancies, but cause damage to the endometrium and cervix.” Thus, the female confined to a small paddock area may show submissiveness which is interpreted as receptivity by the breeder.

Review of Other Livestock Pasture Breeding Systems

Pasture breeding can achieve 100% success rates in horses, versus 50%–60% for "in hand" or controlled breeding. This success is probably because of familiarity between the horses, higher fertility of the mare, and less aggression between horses. Aggression while breeding can occur when stallions are overused, used out of season, or with forced breedings to mares that they otherwise would not choose. (Campbell et al., 2015).  

In most species, the sire’s mating capacity has shown that the male can mate with fewer females in a breeding season under pasture mating systems versus hand breeding systems. Consequently, in cattle, bull libido is a measurable trait with a large genetic component and is given significant weight in evaluating pasture mating potential.

Except for stallions, many livestock pasture systems will run more than one male at a time with a female herd under certain conditions. For example, if rams are accustomed to each other, several may run with the same flock of sheep.  

A literature review did not reveal a preponderance of evidence for over/excessive breeding, pregnant female copulation, non-estrous, or a high incidence of female submissiveness in pasture mating systems. Instead, many research studies identified decreased male libido in pasture breeding systems as a not uncommon consequence. 

Our Narrative

The females selected for a single breeding male harem are run together as a group long enough to establish the herd hierarchy before the male pastures with them. Since we breed February through April while alpacas are in full fleece, we shear the female rump area and tail area and wrap the tail in vet wrap to avoid entanglement with the male's penis. 

After a month of cover breeding, we rotate out the breeding male and ultrasound the females. Any females who remain open are then pastured with a new male or will wait for another field breeding month. Males return to their prior territory, which might or might not be living with other males depending on their temperaments.

Below are a few of my observations that could make for interesting discussion and research studies.

  • Young male alpacas that remain longer with their dams and in a female herd learn their place in the alpaca society, especially if the females have been rebred and are nonreceptive to the males.  
  • Males that are field breeders know how to "read" females and are less aggressive.  
  • The male libido is reduced after several weeks with one group of females, requiring removal from the harem.
  • Some males are inherently flawed field breeders for a variety of reasons. Some are overprotective of their harem to exclude breeding activities. Others never learn to "read" female alpacas.
  • Some breeding males will not live safely with other males. They may live "better" singularly but within a clear view of other alpacas.  
  • Pasture Breeding does not mean Paddock Breeding. The area  needs to be a large and safe range for cohabitation and mating to avoid injuries and submissive cornering.

Alpacas in the US live in a controlled environment. We manage their feed and water, their groupings, separation or "weaning" from adults, and their choice in matings. We decide whether a dam with new cria should remain with the herd or be fielded separately for a few days. We decide when we should introduce the female and male to each other. The notion that males should never pasture or field breed females is one that this author questions as a standard of practice within our US alpaca farming industry. I speculate that some of the problems we have in attempting natural mating of males and females are the consequence of our intervention and socialization control. As always, more research is necessary.

Pasture breeding can be a good option for some alpacas. Breeders should seek guidance from experienced breeders and a veterinarian before embarking on a pasture breeding program.



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Campbell, MLH, Sandoe, P.  Welfare in horse breeding. The Veterinary Record. 2015 Apr 25; 176(17): 436–440.

Pollarda, J.C. Littlejohn, R.P. Moore, G.H. Seasonal and Other Factors Affecting the Sexual Behaviour of Alpacas. Animal Reproduction Science Volume 37, Issues 3–4, February 1995, Pages 349-356

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Bowyer, R. Terry, Whiting, Jericho C,   McCullough, Dale R. Rachlow, Janet L.  Ciuti, Simone.  Evolution of Ungulate Mating Systems: Integrating Social and Environmental Factors. Ecology and Evolution Wiley, 2020

Tomka, Steve A. Vicuiias and Llamas: Parallels in Behavioral Ecology and Implications for the Domestication of Andean Camelids Human Ecology, Vol. 20, No. 4, 1992 

McDonnell, PhD, Reproductive Behavior of the Stallion.  vet.upenn.edu/docs

Bosch, Paul C. and Svendsen, Gerald E. Behavior of Male and Female Vicuna as It Relates to Reproductive Effort.  Journal of Mammalogy  Vol. 68, No. 2 (May, 1987), pp. 425-429

Brown,  Bruce W.  A Review on Reproduction in South American Camelids

Animal Reproduction Science Vol 58, Issues 3–4, 15 March 2000, Pages 169-195

Sumar, Julio B Reproduction in Llamas and Alpacas.   Animal Reproduction Science 42 (1996) 405-415

Fernández-Baca, S, Novoa, C. And Sumar, J. Actividad Reproductiva en la Alpaca Mantenida en Separación Del Macho.  Mem. ALPA (1972) 7, 7-18.

England, BG, Foote, WC, Cardozo, AG, Matthews, DH, Riera, S.  Oestrous and Mating Behavior in the Llama.  (1971). Animal Behaviour, 19, 722-726.

Fowler, ME, Medicine and Surgery of South American Camelids.  (1989)  Iowa University Press

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