Changes in milk yield and composition after lamb weaning and start of machine milking in dairy ewes

Abstract

Stress from weaning may cause problems with milk ejection resulting in remaining milk in alveolar part of the udder and thus changing the milk composition. It is important to know current health status of the udder immediately after lamb removal. The aim of this study was to determine changes in milk composition during first three milkings after lamb weaning and especially the frequency of distribution of ewes differed by somatic cell count (SCC). The study was performed on 36 lactating dairy ewes of two breeds - Tsigai and Improved Valachian within first three milkings after their lambs were weaned. Totally, 108 milk samples were collected for analysis. On the basis of SCC the animals were divided into three categories: low – SCC < 0.5×106 cells.ml-1, middle – 0.5×105 < SCC < 106 cells.ml-1, high – SCC > 106 cells.ml-1. There were 64 percentages of ewes classified to low SCC category, 8 % - to middle and 28 % - to high SCC category at first milking after weaning. The average SCC was 5.39 ± 0.70 log10.ml-1 at first milking, 5.66 ± 0.73 log10.ml-1 at second, 5.68 ± 0.65 log10.ml-1 at third and 5.26 ± 0.61 log10.ml-1 at fourth milking. Significant negative correlation of SCC with lactose content (r = -0.467) and total milk yield (r = - 0.196) and order of milking and lactose (r = - 0.319) was found out. In conclusion, higher percentage of ewes with high SCC during first milking indicates health problems of the udder at the end of suckling period, and increasing SCC during next two milking could by caused by stress from weaning and starting of machine milking.