The level of udder emptying and milk flow stability in Tsigai, Improved Valachian, and Lacaune ewes during machine milking

The objective of this investigation was to evaluate the stability of milk flow curves and the volume of residual milk in relation to milk flow curves in breeds Tsigai, Improved Valachian, and Lacaune (n&nbsp;= 16 heads per breed) milked twice daily. Milk flow type stability was evaluated at morning milking (stabile milkings) during three successive days in the middle of two months (June, July). After the following fourth morning milking (OT milkings) in both months, oxytocin was injected intravenously at a dose of 2&nbsp;UI. Afterwards the ewes were milked again in order to remove residual milk. The milk flow curves were classified into four types: 1 peak (1P), 2 peaks (2P), plateau I (maximal milk flow over 0.4 l/min) (PLI), plateau II (maximal milk flow less than 0.4 l/min) (PLII). If all milk flow curves of one animal were of the same type within one month and within both months, respectively, the animal was characterized as the ewe with the stabile type of milk flow. Frequency of occurrence of single milk flow types (1P : 2P : PLI : PLII) during stabile milkings was 42 : 49 : 9 : 0% in June and 51 : 37.5 : 11.5 : 0% in July. 33 ewes (i.e. 69%) had the stabile type of milk flow within both months. But, more than 51% of them had 1P type of milk flow. Milk production varied according to milk flow curve during OT milkings (0.427 &plusmn; 0.015, 0.498 &plusmn; 0.024, and 0.655 &plusmn; 0.035 l for 1P, 2P, and PLI, respectively). The highest percentage of residual milk from total milk yield (RM/TMY) was observed in ewes with 1P (20.29 &plusmn; 0.85%), followed by ewes with PLI (12.31 &plusmn; 1.99%) and 2P (9.72 &plusmn; 1.36%) (P < 0.0001). Lacaune ewes had the lowest amount of residual milk (0.054 &plusmn; 0.006 l) and RM/TMY (9.86 &plusmn; 1.16%) compared to breeds Tsigai (0.088 &plusmn; 0.008 l; 16.47 &plusmn; 1.44%) and Improved Valachian (0.069 &plusmn; 0.010 l; 15.99 &plusmn; 1.78%) indicating their better udder emptying. &nbsp;