Non-gonadal linear type traits can discriminate reproductive ability of breeding dairy bulls

Linear type traits are easily measurable phenotypic characteristics that help breed characterization, selection of animals for breeding and found to be associated with animals' performance. Unlike cows, there have been limited studies linking body linear traits with male reproductive ability and semen cryo-preservability of breeding bulls. Present study reported the age-related changes in body linear type traits in Frieswal (N = 378) dairy bulls and its relevance with reproductive potentials of breeding bulls. Our results indicated that body frame size traits were significantly and positively correlated with gonadal linear traits. Among the selected body mophometric parameters body length, chest girth and head circumference were the important body linear type traits having capability to discriminate between bulls of frozen semen doses (FSD) and non-FSD categories. Discriminant function has been developed based on body linear traits of crossbred dairy bulls to find out males of superior reproductive potentials. Our finding provided evidence that body length (humerous tuberosity to tuber ischii) was the most powerful linear body trait associated with breeding bulls' reproductive ability and semen quality.