The research flock consists of St. Croix White and Dorper x St. Croix White sheep. The St. Croix White breed is the most common local breed of sheep and is known for being prolific, cycles year round and has a high degree of parasite tolerance. Both males and females reach puberty at about 8-10 months of age and are polled. Mature ewes weigh 100-120 lbs (45-54 kg) and rams weigh 150-175 lbs (68-79 kg). Ewes average 1.8 lambs/ewe lambing and can lamb at 8-month intervals. The St. Croix White sheep are selected to be solid white in color and have a slick coat, although the rams tend to develop a beard as they mature.
The Dorper x St. Croix White sheep are varied in color ranging from solid white to a preponderance of black or brown hair. They also tend to have a heavier coat with some clumps of hair along the topline. Rams may have scurs but females tend to be polled. Mature ewes weigh 110-130 lbs (50-59 kg) and rams weigh 160-180 lbs (73-82 kg).