Huarizo (cross of a male Alpaca and a female Llama) will be
fertile. Each of the parent species have 37 pairs (74) of
chromosomes so the offspring can 'match up' with other haurizos,
other alpacas, or other llamas. Your question likely arises because
a cross between a horse and a donkey (a mule) is sterile. The
reason is that a horse has 64 chromosomes, and a donkey has 62.
Thus then offspring (Mule) have 63, an odd number, meaning it
cannot breed back as there are not 'pairs' to match up. and NO, you
cannot breed a mule to a mule, because even though both have 63
chromosomes, the cannot 'split the pairs' and then recombine.. as
that off chrimosome is paired, and cannot split by itself!