Influence of vacuum level, pulsation rate and pulsator ratio on machine milking efficiency in local Greek goats

Abstract

Effects of vacuum level, pulsation rate and pulsator ratio on machine milking efficiency in local Greek goats were studied in three separate experiments lasting 12, 10 and 11 weeks in three different years. After weaning (49 days) all goats were milked for 14 days at a vacuum level 44 kPa, a 90-pulsations/min and a 50:50 pulsator ratio (this 2-week interval was considered the familiarization period). In the first experiment, three groups (treatments) of goats were subjected to 70, 90 and 120 pulsations/min at milking. For the second experiment another three groups were milked with a vacuum level of 36, 44 and 52 kPa. For the third and final experiment, three pulsator ratios; 65:35, 50:50, 35:65 were compared in three groups. Results suggest that a faster rate (120 pulsations/min) and a higher vacuum level (52 kPa) decreased the percentages of machine milk (MM; from 60.6 to 55.1% for the rate and from 77.3 to 67.9% for the vacuum) and total machine milk (TMM) while increasing the percentage of machine stripped milk (MSM) and hand stripped milk (HSM; from 17.1 to 20.3% for the rate and from 5.7 to 10.0% for the vacuum). Milking time decreased as vacuum levels increased from 36 to 52 kPa and as pulsator ratios increased from 35:65 to 50:50 and 65:35. The pulsator ratio did not modify the percentage of the above milk fractions (MM, MSM, HSM and TMM) but did increase the average milking rate. Optimum conditions for machine milking of local Greek goats appears to be a vacuum level of 36–44 kPa, a pulsation rate of 70–90 and a pulsator ratio of 65:35.