SIMPLIFICATION OF A4 TO AC4 METHOD OF TEST DAY YIELD OF EAST FRIESIAN SHEEP IN MACEDONIA

Abstract

Individual test day records for East Friesian dairy sheep in Macedonia for 3 year period, taken according A4 method of ICAR, were used for comparison of the two officially approved procedures, e.g. A4 and AC4 with the aim to test the effect of simplification in the milk recording in sheep on the measurement of their individual test day productivity. Data comprised of 1760 records from the Trubarevo breeding flock for ewes of age from the first to seventh lactation. The milking was twice a day and individual yield was recorded in the morning and in the evening of the day of test. Prediction coefficients were developed based on the average morning and evening month/year milk yield in the test day. Predicted daily milk yield based on the morning or on the evening yield was compared to the actual one. Actual, predicted productivity and the differences between the both, were analyzed for the effects of number of lambs born, period of test – suckling ewes and lambs were kept together or milking period ewes and lambs were kept separately, level of production and month of the year. Four way ANOVA was used to analyze the data. Results showed that, in general, AC4 method lead to underestimation of the actual yield (YA) with 0.3% using morning milking and to 0.3% overestimation when evening yields were used. Ewes having twins and triplet were underestimated with 1–2% with the morning milk recording, while in these with singles predicted yield was close to the actual milk yield. The morning recording of the milk yield during the suckling period led to underestimation of the TD yield with about 3%. The morning prediction of the TD yield in the milking period only is much more accurate. Ewes with high milk production are overestimated with 1% when the records of morning milk yield were used, while average and ewes with low milk production are underestimated with 1% and 3%. The prediction of the YA based on the morning milk yield led to about 1 % overestimation in the first part of the lactation, but resulted in about 4 % underestimation during the second part of lactation. The prediction of the YA was equal to the actual yield in the middle of lactation.