The effects of cow genetic group on the density of raw whole milk

Abstract

The density of milk is dependent upon various factors including temperature, processing conditions, and animal breed. This study evaluated the effect of different cow genetic groups, Jersey, elite Holstein Friesians (EHF), and national average Holstein Friesians (NAHF) on the compositional and physicochemical properties of milk. Approximately 1,040 representative (morning and evening) milk samples (~115 per month during 9 mo) were collected once every 2 wk. Milk composition was determined with a Bentley Dairyspec instrument. Data were analysed with a mixed linear model that included the fixed effects of sampling month, genetic group, interaction between month and genetic group and the random effects of cow to account for repeated measures on the same animal. Milk density was determined using three different analytical approaches – a portable and a standard desktop density meter and 100 cm3 calibrated glass pycnometers. Milk density was analysed with the same mixed model as for milk composition but including the analytical method as a fixed effect. Jersey cows had the greatest mean for fat content (5.69 ± 0.13%), followed by EHF (4.81 ± 0.16%) and NAHF (4.30 ± 0.15%). Milk density was significantly higher (1.0313 g/cm3 ± 0.00026, P < 0.05) for the milk of Jersey breed when compared to the EHF (1.0304 ± 0.00026 g/cm3) and NAHF (1.0303 ± 0.00024 g/cm3) genetic groups. The results from this study can be used by farmers and dairy processors alike to enhance accuracy when calculating the quantity and value of milk solids depending upon the genetic merit of the animal/herd, and may also improve milk payment systems through relating milk solids content and density.

Partitioning of casein and fat in Cheddar cheese manufacturing as affected by cheese milk standardisation: A review

“…On average, bovine milk contains $4.7% fat and 3.9% protein, including 2.9% caseins (consisting of 41% α s1 -, 8% α s2 -, 37% βand 14% κ-casein) and 0.97% whey proteins (83% being β-LG and 17% α-LA), 4.7% lactose and 0.7% minerals, of which citrate, potassium, calcium, phosphorus, sodium, sulphur and magnesium account for 20, 20, 14, 11, 4, 8 and 1%, respectively (Lin et al 2017b;Dunshea et al 2019;Li et al 2019;Parmar et al 2020). These values vary naturally due to a number of factors.…”