Sires can be selected for '''ease of calving''' and estimated birth weights. Many non-genetic factors influence birth weight, such as age of the dam and environment, and so genetic selection is not a fool-proof method of avoiding dystocia. | Sires can be selected for '''ease of calving''' and estimated birth weights. Many non-genetic factors influence birth weight, such as age of the dam and environment, and so genetic selection is not a fool-proof method of avoiding dystocia. |