Phenotypic factor and image analysis of type traits of holstein cows in the masstock Saudi herds

Abstract

Factor and image analysis were carried on 13,642 type traits records collected from Masstock dairy farms in Saudi Arabia. Principal component analysis showed that only 5 principal components (PC) were to be retained for factor analysis. These 5 principal components accounted for 59% of the total variance in all type traits. Factor 1 included udder traits, factor 2 included capacity traits, factor 3 included leg characters, factor 4 included angularity and rump angle, and factor 5 included teat characteristics. Factors computed from correlation matrix adjusted for discontinuity, or image correlation matrix, described similar type traits. Cows with well-developed fore and rear udders and with deep and strongly supported udders produced more milk than cows with opposite udder traits. Rear legs as viewed from the side and foot angle had no significant effect on milk production in first and second lactations. Pair-wise image correlation (ri), correlation between the predictable part of the phenotypic value of type traits, was high between fore udder attachment and other udder characteristics (ri>.60). Fore udder angle had a high image correlation (ri) with rear udder width, udder support and udder depth (ri= .78, .73 and .73 respectively).