Effect of milking pipeline height on machine milking efficiency and milk quality in sheep

This experiment studied the effect of milking pipeline height (mid- vs. low-level milking system) on milking efficiency and milk composition. The experiment was of 8 wk duration: 2 wk preexperimental period and 6 wk experimental, in crossover design (2 x 2). Ewes were milked in a 2 x 12 milking parlor with 2 milking pipelines set at a milking vacuum of 36 kPa with a pulsation rate of 180 cycle/min and ratio of 50%. Height of the milkline had no effect on yield of milk at the time of milking, yield after stripping, milk composition, SCC, and number of teatcup fall-offs. Nor did milkline height have any effect on milk lipolysis or on the distribution of fatty acids. The level of free fatty acids was higher in evening than in morning milk (60.5 vs. 25.6 mg/L). Likewise, the increase in the degree of lipolysis between the receiver (40.4 mg/L) and the refrigeration tank (45.8 mg/L) underlines the importance of the milk delivery line design. The parameters (time and flow rate) that define the first peak in the milk emission kinetics were statistically different between lines, so care must be taken when comparing milk emission curves from both types of pipeline.