A comparison of monthly and bi-monthly production records of Queensland dairy cows

Abstract

Monthly records of butterfat production for 27 herds over three years, comprising 4505 complete lactations, were used to compare three estimates of the total yield : namely, those based on monthly records, records for the odd alternate months and records for the even alternate months. Although there were frequently large differences between monthly and bi-monthly estimates of individual productions, cows were ranked similarly within herd and year by both methods of testing. However, comparison of herd averages indicated that bi-monthly records are not suitable for between-herd comparisons. Sire ratings calculated from the three sets of records were similar and the rankings of bulls within herds were almost identical.