Genetic parameters for linear udder traits of dairy ewes.

An animal model was used to estimate the repeatabilities and genetic parameters of linear udder traits of Churra ewes (5265 records from 2015 ewes). In addition, the phenotypic correlations were examined between log SCC and udder traits. Heritabilities of udder depth (0.16), udder attachment (0.17), teat placement (0.24), teat size (0.18), and udder shape (0.24) were similar to those for dairy cattle, making it feasible to use data from the proposed linear system in a breeding program to improve the machine milkability of ewes. Genetic correlations among udder traits were generally favorable, implying that selection for improvement of one trait would result in improvement of others. A notable exception was the genetic correlation between teat placement and teat size of 0.62. Vertical placement of teats was associated with larger teats. Also, genetic correlations between udder and yield traits (milk and protein yields) were small, except for udder depth and teat placement. These exceptions predict worsening udder morphology from selection based solely on milk yield. Phenotypic correlations between udder traits and log SCC indicate that present handling routines led to a greater likelihood of infections for deep udders with large teats.