Seasonal variation in the Dutch bovine raw milk composition

Abstract

In this study, we determined the detailed composition of and seasonal variation in Dutch dairy milk. Raw milk samples representative of the complete Dutch milk supply were collected weekly from February 2005 until February 2006. Large seasonal variation exists in the concentrations of the main components and milk fatty acid composition. Milk lactose concentration was rather constant throughout the season. Milk true protein content was somewhat more responsive to season, with the lowest content in June (3.21 g/100 g) and the highest content in December (3.38 g/100 g). Milk fat concentration increased from a minimum of 4.10 g/100 g in June to a maximum of 4.57 g/100 g in January. The largest (up to 2-fold) seasonal changes in the fatty acid composition were found for trans fatty acids, including conjugated linoleic acid. Milk protein composition was rather constant throughout the season. Milk unsaturation indices, which were used as an indication of desaturase activity, were lowest in spring and highest in autumn. Compared with a previous investigation of Dutch dairy milk in 1992, the fatty acid composition of Dutch raw milk has changed considerably, in particular with a higher content of saturated fatty acids in 2005 milk.

Chemical characterisation and application of acid whey in fermented milk

“…It must also be considered that milk skimming by centrifugation may vary, resulting in changes in the final content of lipids in the product. As Heck et al (2009) have observed, of the main components of milk, lactose has the lowest level of variation, whilst lipids are the component with the highest level of variation; protein has an intermediary level of variation. In the present study, lactose had a low variation, whereas protein presented a higher coefficient of variation.…”

“…During winter, the animals receive nutritional supplementation to overcome shortage of fodder. Heck et al (2009) analysed milk samples from the Netherlands for a period of 1 year and detected that both protein and lipids levels were maximum in the winter when animal feeding includes around 30 % more concentrate, which is rich in starch, in relation to fodder, which is rich in fibre. This starchrich feed increases the production of propionic acid in the rumen and it is the main glucose precursor, resulting in hormonal signs in cows and increasing milk protein concentration (Heck et al 2009), which is in accordance with the results found in the present study.…”

Mapping and fine-mapping of genetic factors affecting bovine milk composition

“…Summer milk contained larger proportions of C18:0 and unsaturated C18, and smaller proportions of short and medium chain FA compared to winter milk, which is in agreement with literature (Palmquist et al, 1993;Soyeurt et al, 2008;Heck et al, 2009). Differences between winter and summer milk fat in our study could be partly due to differences in lactation stage, as cows in summer were on average 80 days later in lactation than in winter (247 versus 167 days).…”

“…Most concentrate feed supplied to Dutch dairy cows have high concentration of C12:0, due to the presence of ingredients such as palm kernel expeller (47%) and extracted coconut (48%) both rich in C12:0 (Grummer, 1991;Heck et al, 2009). The high herd correlation for C12:0 might be because on a herd the same type of concentrate is fed to cows in both winter and summer.…”

“…Substantial seasonal variation in milk fat composition has been found in European countries (Precht and Molketin, 2000;Thorsdottir et al, 2004;Heck et al, 2009). The main cause for this seasonal variation seems to be the differences in diets: in winter cows in Northern Europe are usually kept inside and fed silage whereas in summer cows are mainly on pasture and fed with fresh grass.…”