Stability of milk flow kinetics in sheep during machine milking

Abstract

The goal of this investigation was to describe the milk flow kinetics in response to machine milking in ewes of Tsigai (TS, n = 13), Improved Valachian (IV, n = 12), Lacaune (LC, n = 12), TS x LC (50%, n = 12) and IV x LC (50%, n = 12) breeds and to determine a possible relationship with milk production. Individual stability of milk flow kinetics over the lactation was also evaluated. Milk flow data were recorded during three consecutive evening milkings in the middle of May (ewes on their 74±12 d in milk) and during one evening milking in the middle of next three months (June, July, and August). Three types of milk flow kinetics were described for evaluation (one emission 1P, two emissions 2P, and one milk emission with steady-state milk flow PL). On the basis of milk flow profiles during three consecutive evening machine milkings in May three groups of ewes were created for further study; the first group (2Pc): ewes with 2P pattern (n = 22), the second group (PLc): ewes with PL pattern (n = 32) and the third group (1Pc): ewes with 1Pc pattern (n = 7). The ewe was considered as having stabile milk flow profile when all milk flow types were the same in May and at least three of four were the same throughout lactation. The profile of milk flow kinetics of individual ewes was very stabile among three consecutive evening milkings in the middle of May but a pattern of milk flow changed throughout lactation. The ewes with stabile milk flow patterns over lactation represented 69 %. The highest stability was seen in the group 1Pc (100 %) and the lowest in the group PLc (55 %). 2Pc group showed milk flow pattern stability at 70 %. In total, the frequency of occurrence of 2P, 1P and PL for whole period was 39 %, 28 % and 33 %; respectively. These results provide an important evidence of difference in milking ability between two main sheep breeds used in Slovakia (Tsigai and Improved Valachian) and Lacaune breed.