Effect of mid-line or low-line milking systems on lipolysis and milk composition in dairy goats

Abstract

Two experiments were carried out to investigate how milking in mid-line (ML) affects the lipolysis level and milk composition in goat livestock, in comparison with low-line (LL) milking. The first experiment took place, in triplicate, on an experimental farm. For each replicate, a crossover design (62 goats, two treatments, ML and LL, in two periods each lasting 4 days) was used. Milk samples were taken daily at 0 and 24 h after milking. In the first experimental replicate, some enzymatic coagulation cheeses were made, which were assessed by a panel of tasters at 50 and 100 days of maturation. In the second experiment, the lipolysis level and composition of tank milk from 55 commercial dairy goat farms (25 ML and 30 LL) were analysed, in milk samples taken in three different weeks. The results of the first experiment showed that ML milking increased free fatty acid (FFA) concentration in raw goat's milk significantly (0.71 v. 0.40 mmol/l, respectively). However, in the milk samples taken from commercial farms the FFA concentration remained unaffected by the milking pipeline height (0.59 v. 0.58 mmol/l for ML and LL, respectively). No significant differences were found in the milk composition, nor in the sensory characteristics in the cured cheeses, which suggests that factors other than the milkline height are able to influence the level of lipolysis under commercial conditions. Therefore, ML milking should not be discouraged, provided that the correct functioning and management of the milking operation and milk storage on the farm is guaranteed.

Optimal Parameters to Milk Murciano-Granadina Goats in Mid and Low-Line Milking Parlours

“…The use of low-line milking parlours allows for having one milking unit per animal in each platform, which will shorten the time employed to milk the entire flock. Moreover, low-line milking machines ensure higher vacuum stability in the short milk tubes [ 7 ] and potentially lower milk lipolysis [ 8 ]. However, mid- and high-line milking parlours offer better performance of the parlour expressed in animals milked per milking unit, as these systems let the operator turn the milking unit to both sides of the parlour, reducing the time in which the milking unit is not being used.…”

“…Moreover, mid- and high-line milking parlours make the installation of milk meters or automatic cluster removers easier [ 4 ]. In addition, several studies carried out in small ruminants have discarded the traditional idea in which mid-line milking parlours were related to poorer udder health [ 8 , 9 ]. The choice between low-line or mid-line milking systems is not easy for farmers and often depends on the farmer’s personality or the specific needs of each farm.…”