SINGLE AND MULTIPLE TRAIT SIRE SELECTION - 1ST LACTATION MILK-YIELD AND COMPOSITION, CONFORMATION, FEED-INTAKE, EFFICIENCY, AND NET INCOME

Daughters of sires selected on predicted difference milk of 1st lactations (yield) were compared with daughters of sires selected on an udder index from among artificial insemination bulls with < 10% of their daughters culled and with a predicted difference fat-corrected milk > 181 kg (merit). On latest proofs yield bulls were 425 kg higher than merit bulls for predicted differences of 1st lactations; merit bulls had an average predicted difference type which was 1 point higher than yield bulls. Data were from 1st calving interval. Yield daughters produced 685 and 51 kg more milk and solids-not-fat but were 0.28% and 0.12% lower in fat and protein percentages than merit daughters, respectively. Energy intake of the ad lib mix rations was nearly identical, but gross feed efficiency was significantly higher (0.73 vs. 0.69) for yield daughters. Mammary conformation score was significantly higher for the merit group. A significantly higher number of merit daughters were coded acceptable for descriptive udder traits in the udder index. Net income per day was significantly higher for the yield group than for the merit group. Much of this difference was due to the higher expense associated with a 21 day longer calving interval of merit heifers.