Threshold Models Applied to Holstein Conformation Traits

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Abstract
Threshold animal models were applied to five conformation traits of Canadian Holsteins. The estimated breeding values for sires from the threshold model allowed the calculation of predicted percentages of daughters in the desirable categories. Results were compared with those from a linear animal model in terms of their ability to predict future percentages of daughters in the desirable categories using an independent set of data. There was no advantage in a threshold model compared with a conventional linear animal model in its ability to predict future daughter performance. This was likely due to the 18 categories used in the classification of major type traits in Canada and the nearly normal distribution of observations across categories.