INFLUENCE OF EWE ENTRY ORDER INTO MILKING PARLOUR ON MORNING MILK YIELD WITH RESPECT TO EWE AGE AND YEAR OF MEASUREMENT

The objective was to analyse effects of ewe entry order into milking parlour with respect to ewe age and year of measurement on morning milk yield. The measurements (5528) of milk yield mostly in the middle of lactation were taken from 550 ewes of Slovak dairy breed over five years (on average two measurements per ewe and year). Mixed model included fixed factors: milking phase (MP1, MP2 and MP3), ewe age (2, 3 to 10), year (2013, 2014 to 2017) and interaction milking phase x ewe age, and random effect of ewe. Ewes were assigned to milking phases according to their entry order into milking parlour (taking into account batch number and stall number within batch). All fixed factors showed the significant effect on milk yield, except for milking phase: 482 ± 11 ml (MP1), 464 ± 8 ml (MP2) and 444 ± 15 ml (MP3), although ewes with earlier entry order had higher milk yields. Three- to six-year old ewes had higher milk yields than two- and seven- to ten-year old ewes. Significant differences were found predominantly between morning milk yields of three- and four-year old ewes (509 ± 12 ml and 538 ± 10 ml), five- to seven-year old ewes (decreasing from 525 ± 11ml to 471 ± 14 ml) on one side, and milk yields of eight-, nine- and ten-year old ewes (decreasing from 421 ± 17 ml to 311 ± 35 ml) on the other side. According to year of measurement, milk yield increased from 406 ± 12 ml (2013) to 530 ± 10 ml (2015), afterwards decreased and increased again (406 ± 9 ml and 510 ± 26 ml). The significant differences were found only between some years. An interaction milking phase x ewe age showed that milk yields tended to follow patterns found when these factors were analysed individually. Higher milk yields were found in four- and five-year old ewes of MP1 group, lower milk yields were found mostly in nine- and ten-old ewes of MP2 and MP3 groups. Only few levels of this interaction showed significant differences between each other.