Sources of Variation in Milk Flow Characteristics at Udder and Quarter Levels

Abstract

The aim of this study was to describe and analyze effects of parity, stage of lactation, milkability (3 groups of cows with differing peak flow rates), time of milking, and quarter position on milk production and milk flow measures at udder and quarter levels. Particular emphasis was put on changes to the decline phase and in duration of overmilking. More than 75,800 quarter milk flow curves and more than 19,300 udder milk flow curves obtained from 38 cows throughout lactation were analyzed. Stage of lactation significantly influenced all studied variables at both udder and quarter levels. At the quarter level, the duration of decline phase and the decline ratio (decline phase as a percentage of milking time) decreased from mo 1 to 2 and then gradually increased as lactation advanced. In contrast, at the udder level, duration of decline phase decreased throughout lactation but beginning at mo 2, the decline ratio increased as lactation advanced. The duration of the overmilking phase of quarters increased from mo 1 to 3 and then decreased in the course of lactation. Parity did not influence peak and average flow rates, the duration of increase phase, or the decline ratio at either udder or quarter levels. All milk flow measures were higher during morning milking except the duration of increase and decline phases at the quarter level and the duration of increase phase at the udder level. Milk yield and the duration of increase phase were not affected by milkability at either level. Quarters from udders with high milkability had longest duration of decline phase and the shortest overmilking phase. Milkability did not influence duration of the decline phase at the udder level. Quarter position influenced all measured variables of milk yield and milk flow. Rear quarters had significantly higher milk yield, longer time of milking, higher peak, and higher average flow rates than front quarters. Front quarters had shorter duration of increase and decline phases than rear quarters. The duration of the overmilking phase was almost double for front quarters. There were also differences in measured flow rates between left or right quarters on respective front or rear positions. Measured characteristics reported in this study may be important in setting default parameters in automated milking systems.

Effect of pre-stimulation on milk flow pattern and distribution of milk constituents at a quarter level

“…Therefore, this study could be considered as direct evidence that milking without pre-stimulation negatively influences the milk flow not only at the beginning of milking but also at the end of milk flow. The longer duration of the decline phase at a quarter level is connected with significantly higher SCC (Tančin et al, 2002(Tančin et al, , 2006. The majority of the machine-induced infections occur near the end of milking and a possible explanation could be taken over from Philpot and Nickerson (1991).…”

“…The time of milk flow was adapted from the milk flow graphs made by Lactocorder and represented the time between the start of milk flow and the point when the milk flow approached the x-axis. The duration of single milk flow phases is described by Tančin et al (2006) and in Figure 1.…”

“…However, the most effective study to see the effects of milk ejection reflex on milk flow should be done at a quarter level (Tančin et al, 2003(Tančin et al, , 2006. Recently we have found a positive relationship between the duration of the decline phase of milk flow and somatic cell counts (Tančin et al, 2002).…”

Comparison of the effects of quarter-individual and conventional milking systems on milkability traits

“…Among other things, the shape of milk flow curves is affected by milking conditions (Rittershaus et al 2002, Sandrucci et al 2007. Tančin et al (2006) reported that morning or evening milking significantly influenced all measured milk flow traits because of different milking intervals. All milk flow measures were higher during morning milking except the duration of incline phase (tAN).…”

“…Milk yield, udder health and milkability are important factors which have an impact on the dairy industry in developed countries (Petrovski et al 2006, Tančin et al 2006. Machine milking requires gentle, complete and fast removal of milk from the udder under optimal technical and hygienic conditions to maintain animal health (Bruckmaier & Hilger 2001, Lee & Choudhary 2006.…”