The diagnosis of zygosity in bull twins by means of the discriminant function for body conformation

Body conformation of monozygous twin bulls was considered as a variate, depending on single body measures. With the aid of a discriminant function, between-pair differences were maximized relative to within-pair differences. Two pairs of bull twins with identical blood types, which, nevertheless, gave rise to doubt of their monozygosity, could be discriminated unambiguously. Their within-pair variances for body conformation were at the between-pair level and half the between-pair level, respectively. The method was superior to a comparison of single body measures. The diagnosis of dizygosity reinforced arguments for dizygosity on the basis of behavioral and biochemical differences. The exact approach to body conformation is discussed in relation to multiple-factor analysis.175th Communication of the Research Institute of Animal Husbandry Schoonoord.