Comparison of Single- and Multiple-Trait Selected Sires — Response of Heifer Growth

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Abstract
Body weights and linear body measurements were determined for 386 heifers whose sires were selected according to 2 criteria: yield, selection only on milk yield Predicted Difference from daughters'' 1st lactations; and merit, selection on a combination of milk yield Predicted Difference (all daughters), udder type, and percentage of daughters leaving herd in 1st lactation. Yield and Merit heifers did not differ significantly in body weight at various ages through 1st calving or in heart girth or withers height through 18 mo. of age. Heifers born to dams 1st parity were lighter at birth but did not differ significantly from other parities of dam for weight, withers height, or heart girth at later ages. Differential selection for milk yield as in this study did not change body weight of heifers.