Dry period length in Montbéliarde cows and its association with selected production and functional characteristics

Abstract. The study evaluated the effects of selected factors (dry period number, milk yield in standard lactation and length of full lactation) on the length of dry periods. The effect of dry period length on milk yield and composition, the frequency of milk samples with different somatic cell counts (SCC) and the course of lactation were also analysed. The study included 491 cycles (dry period and lactation) and 4 998 results of test-day milking conducted in a herd of 230 Montbéliarde cows. The cows were kept in a free-stall barn and fed total mixed rations (TMR). The average length of the dry period was found to be 85 days. The first dry period was 34-45 days longer than subsequent ones, which may have been due to the cows becoming acclimated after having been brought to the farm as in calf heifers. Increasing milk yield in standard lactation was accompanied by significantly shorter dry periods. The most beneficial dry periods in terms of milk yield were those lasting 22-41 days. The lowest yield was noted in lactations preceded by a dry period reduced to 0-21 days. However, this milk contained the most fat, protein and dry matter and the SCC did not exceed 400 000 cells/ml in 73.3 % of cases. The decrease in daily milk yield from its peak in the 2nd month to the 10th month after calving was smallest in cows with dry periods of 57-84 days, which may suggest that lactations in these cows were the most persistent.