Effect of milk sampling techniques on milk composition, bacterial contamination, viability and functions of resident cells in milk

Abstract

-Three different milk sampling techniques were evaluated during milk sampling: a direct aseptic collection from the udder through a sterile cannula was used as the reference technique, compared with either a manual or a mechanical sampling method. In this study 30 high-yielding HolsteinFriesian dairy cows at different stages of lactation and free of udder infection were used. For each milk sample, the influence of milk sampling techniques was determined for the following parameters: somatic cell count, milk composition, bacterial contamination, viability, in vitro phagocytosis and overall killing of Staphylococcus aureus Newbould 305, and cellular chemiluminescence. Because milk sampling occurred throughout lactation, the differences between early, mid-and late lactation were estimated. It was concluded that bacterial contamination was not significantly different in manual milking samples and the reference technique; bacterial contamination was, however, significantly (P < 0.001) higher in machine milking samples than in the reference technique. Among the different sampling techniques, no significant effects on SCC, milk composition, viability and functions of the cells isolated from milk were observed. It was found that viability, intracellular killing and cellular chemiluminescence of milk PMN were significantly lower (P < 0.05) in early lactation compared to mid-lactation. Phagocytosis was significantly (P < 0.05) higher in early lactation compared to mid-and late lactation, and no significant differences were observed between mid-and late lactation. From this study, it can be concluded that despite a higher bacterial contamination obtained with the mechanical sampling method, the 3 milk sampling techniques described in this study can be used for the evaluation of milk cell functions. dairy cow / milk sampling technique / stage of lactation / milk composition / milk neutrophil functions Vet. Res. 32 (2001) 565-579 565

Innate immunity of the bovine mammary gland

“…On the one hand, their concentration is too low for an efficient phagocytosis in suspension [95]. Moreover, part of them are nonviable or in the process of apoptosis, in particular in cisternal milk, and are not in an activated state [22,196,197]. On the other hand, the presence of neutrophils in the milk of healthy glands seems to correlate inversely with a risk of intramammary infections [22].…”

Moderate Inflammatory Reaction During Experimental Escherichia coli Mastitis in Primiparous Cows

“…During this period a decrease in cell function of the PMN, resident in the healthy mammary gland Mehrzad et al, 2001;Vangroen-weghe et al, 2001) has been observed. The decrease in cell function was mainly related to the decrease in viability, oxidative burst, and intracellular killing by PMN Mehrzad et al, 2001; Vangroenweghe et al, 2001). …”

“…Several factors have been shown to play a role in the clinical outcome of Escherichia coli mastitis, namely farm management (Smith et al, 1985;Schukken et al, 1989aSchukken et al, , 1989bOliver et al, 1990;Lam et al, 1995;Barkema et al, 1999), bacterial factors (Frost et al, 1980;Hill, 1981;Linton and Robinson, 1984;Sanchez-Carlo et al, 1984a;Sanchez-Carlo et al, 1984b;Todhunter et al, 1991;Hogan et al, 1992;Cross et al, 1993;Nemeth et al, 1994;Hogan et al, 1995Hogan et al, , 1999Nagy and Fekete, 1999), and physiological factors (Heyneman et al, 1990;Gilbert et al, 1993;Kremer et al, 1993aKremer et al, , 1993bVandeputte-Van Messom et al, 1993;Dosogne et al, 1997Dosogne et al, , 2001van Werven et al, 1997;Mehrzad et al, 2001Mehrzad et al, , 2002Vangroenweghe et al, 2001;Burton and Erskine, 2003).…”

Mathematical Model of the Acute Inflammatory Response to Escherichia coli in Intramammary Challenge

“…There have been attempts to adapt those assays to milk PMN (Hoeben et al, 1997;Dosogne et al, 2001;Vangroenweghe et al, 2001Vangroenweghe et al, , 2002 but they are still expensive and time-consuming. Consequently, they cannot be applied in large-scale field studies, as required in programs of selection for mastitis resistance.…”