Udder quarter milk composition at different levels of somatic cell count in cow composite milk

Abstract

Automatic milking systems have made possible the separation of high-and low-quality milk at the udder quarter level during the milking process. The aim of this study was to investigate the composition and yield of milk from individual udder quarters to determine whether deteriorated milk composition occurs in udders that are assumed to be healthy and whether quarters with high-quality milk are found in udders with high milk somatic cell count (SCC). Milk samples were collected on one occasion from 90 cows at udder quarter level and cow composite level. The milk was analyzed for content of total protein, whey protein, casein, fat, lactose, citric acid and SCC; milk yield was registered. The cows were divided into three groups depending on the SCC of their composite milk. Cows in group 1, cow composite SCC , 100 000 cells/ml, were assumed to have healthy udders. However, instances of increased SCC and decreased milk quality were discovered in one or more udder quarters of approximately 30% of the group. Cows in group 2, cow composite SCC of 100 000 to 300 000 cells/ml, and group 3, cow composite SCC . 300 000 cells/ml, were assumed to have affected udders. However, the majority of these cows had one or more udder quarters in which increased SCC and deteriorated milk quality were not detected. Calculations of bulk-tank milk values, when separation of milk from affected udder quarters was performed, indicate that SCC changes to a much greater degree compared to the other milk components. These results show that milk from affected udder quarters suffers compositional changes, but calculations of simulated separation indicate that the compositional changes in bulk-tank milk are small. The effect of separation of milk from individual udder quarters on bulk-tank milk needs to be further studied.

Evaluation of quality changes in udder quarter milk from cows with low-to-moderate somatic cell counts

“…As discussed previously, the bacteriological sampling may give false-negative results, as there is a cycling of bacteria and SCC during mastitis (Forsbä ck et al, 2009). In our study, we found bacteria in four out of five cows in Group 2 and in three out of six cows in Group 3.…”

“…Findings by Forsbä ck et al (2009) further justify studying the ways in which raw milk composition differs in separate udder quarters with increased SCC at a low-to-moderate increase in cow composite SCC. In addition to analyses of gross milk composition, that is, total protein, whey protein, fat, lactose, citric acid, SCC and bacterial content, it is relevant to study the following components to gain a better understanding of how mastitis influences milk composition.…”

“…In an earlier study by Forsbä ck et al (2009), it was found that 30% of cows with cow composite SCC , 100 000 cells/ml had one or more udder quarters with SCC . 100 000 cells/ml, indicating that these quarters were affected.…”

Lipopolysaccharide challenge of the mammary gland in cows induces nitrosative stress that impairs milk oxidative stability

“…However, mixing of milk from infected udders with milk from non-infected ones could not be detected by measures such as determination of SCC, proteose peptone content and % of casein, which worked well at the individual cow level as predictors of udder inflammation . Thus, the results of this and former studies Leitner et al, 2008;Forsback et al, 2009 and indicate that it is important for the dairy industry to develop analytical tools that will allow to prevent combining low-quality milk, such as milk rich in somatic cells and nitrite, with high-quality milk in order to ensure optimal yield and quality of curd from milk designated for cheese production.…”

Real-time visual/near-infrared analysis of milk-clotting parameters for industrial applications

“…Several studies in goat, sheep and cow milk have shown that the infection status of the animal's udder (Gonzalo et al, 1994;Auldist et al, 1996;Baudry et al, 1997;Fantuz et al, 2001;Leitner et al, 2004a and2004b;Merin et al, 2008;Forsbä ck et al, 2009) and stage of lactation (Coulon, 1994;Leitner et al, 2011a) are directly related to milk quality, its composition and suitability for cheese making. Thus, some, but not all, bacteria causing mammary infection significantly reduce curd yield and quality, as well as in animals at late lactation.…”