Factors affecting variation of udder traits of dairy ewes.

Udder depth, width, and circumference; cistern height; teat position, angle, length, and width; and milk yield at 120 d were studied in 113 Churra sheep from three flocks. Means were 9.30, 12.18, and 46.55 cm, respectively, for udder depth, width, and circumference; 1.48 cm for cistern height; 3.64 (scored from 1 to 5) for teat position; 50.39 degrees for teat angle; 3.83 and 1.93 cm, respectively, for teat length and width; and 132.39 L for milk yield. Analysis of variance showed significant effects for lactation month, flock, parity number, and milk yield. The traits related to udder size (depth, width, and circumference) were significantly influenced by lactation month, flock, and milk yield and showed low repeatability (.17 to .18). The traits related to cistern morphology (cistern height, teat position, and angle) were significantly influenced by flock and parity number. These traits, together with teat length and width, had high repeatabilities (.45 to .77). Cistern height, teat position and angle, and size of teats are related to aptitude of the udder for mechanical milking. This association, as with cattle, would justify focusing genetic improvement on these traits.