Composition of major proteins in cow milk differing in mean protein concentration during the first 155 days of lactation and the influence of season as well as short-term restricted feeding in early and mid-lactation

Abstract

A variety of proteins contributes greatly to the unique nutritional and functional quality of dairy cow milk. Particularly, milk casein content and composition have substantial influence on the processing capabilities. In the present study, milk of 23 multiparous Holstein-Friesian cows, grouped as high-(3.49 ± 0.05%; n = 11) and low-protein (3.03 ± 0.05%; n = 12) cows, was sampled approximately weekly during the first 155 days of lactation to determine the course of relative milk protein composition (α-lactalbumin; β-lactoglobulin; α-, β-, and κ-casein). Furthermore, feed restrictions by 30% of dry matter intake in early and mid-lactation as well as experimental tissue biopsies were conducted to observe their effect on milk protein composition. Milk protein composition was relatively stable and displayed similar concentration patterns throughout the experimental period between both groups. Mean relative concentrations of α-, β-, κ-casein, α-lactalbumin, and β-lactoglobulin were 34.2, 31.4, 16.0, 2.1, and 9.7% of total protein, respectively. Feed restrictions did not alter milk protein composition, whereas the season influenced α-and β-casein as well as α-lactalbumin. Further, effects were observed in both groups at times of unfamiliar stressful situations caused by taking liver or muscle biopsies. As a result, the relative concentration of β-casein increased. Therefore, acute stress factors may lead to a deviation in milk protein composition and should be avoided.

Effect of summer season on milk protein fractions in Holstein cows

“…These results confirm those obtained by Bernabucci et al (2002) in a research carried out on dairy cows monitored in spring and summer in a commercial dairy herd in Central Italy, in this case the concentration of protein fractions was measured by electrophoresis on cellulose acetate. Gellrich et al (2014) recently observed seasonal effect on α-CN and β-CN, with higher β-CN as a percentage of protein in summer season. In this last paper, major milk protein analyses were conducted using a microfluidic electrophoresis and no data were presented on climatic condi-tions; thus it is not possible to adequately compare the present with the Gellrich et al study.…”

“…Bernabucci et al (2002) did not observe any difference for α-LA and β-LG between seasons. Gellrich et al (2014), in a research carried out in Germany studying the effect of season, observed greater α-LA concentration in summer compared with the fall season. Similarly, Brodziak et al (2012) found a significantly higher concentration of α-LA and a higher ratio of α-CN:β-CN in milk of cows from the spring-summer season, in comparison with the fall-winter period.…”

Effect of cow energy status on the hypercholesterolaemic fatty acid proportion in raw milk

“…Milk production increases in early lactation (Szencziová et al 2013) and despite simultaneously increased feed intake, the cow's metabolism goes through the negative energy balance (NEB) phase of lactation (Kadlecová et al 2014b). This standard course of the postpartum period of all dairy cows evokes body fat reserve degradation as an additional source of energy, concurrently followed by a decline in live weight (Řehák et al 2012), body condition score (BCS) (Stádník et al 2002;Ducháček et al 2012a) causing a simultaneous decrease of reproduction (Louda & Stádník 2000;Ducháček et al 2012b) and impairment of health (Vacek et al 2007), and/or changes in milk composition (Gellrich et al 2014). Lipomobilisation increases free fatty acid plasma content and triacylglycerol accumulation in the liver tissue affecting its structure and function (Shibano & Kawamura 2006;Jóźwik et al 2012).…”

Insights into the Interaction of Milk and Dairy Proteins with Aflatoxin M1

“…Casein, a major phosphoprotein found in milk is composed of several casein fractions that are distinguished by electrophoresis and are designated as α-, β-, and k-caseins (in order of decreasing mobility at pH 7.0). In bovine milk, casein composition, in mg mL −1 , consists approximately as follows: αs 1 (12)(13)(14)(15); αs 2 (3)(4); β (9-11); and k (2)(3)(4) [1,2]. These fractions vary in molecular weight, isoelectric point, and level of phosphorylation.…”

“…In cow milk, for example, the protein composition during seasons vary between 33.8-34.8, 31.2-32.6, 15.5-16.2, 2.0-2.1, 9.6-9.9, and 5.6-6.5 g protein/100 g total protein for α-, β-, and kcasein, α-lactalbumin, β-lactoglobuin, and other proteins (e.g. bovine serum albumin and lactoferrin) [4].…”