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The effects of cow genetic group on the density of raw whole milk
Parmar, P. Lopez-Villalobos, Nicolas Tobin, John T. Murphy, Eoin Buckley, Frank McDonagh, A. O’Mahony, J.A. Crowley, S.V. Kelly, A.L. Shalloo, Laurence
Parmar, P.
Lopez-Villalobos, Nicolas
Tobin, John T.
Murphy, Eoin
Buckley, Frank
McDonagh, A.
O’Mahony, J.A.
Crowley, S.V.
Kelly, A.L.
Shalloo, Laurence
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Date
2021-01-30
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Parmar P, Lopez-Villalobos N, Tobin JT, Murphy E, Buckley F, McDonagh A, O’Mahony JA, Crowley SV, Kelly AL, Shalloo L. The effects of cow genetic group on the density of raw whole milk. Irish Journal of Agricultural and Food Research 2020;59(1):215-223; doi http://dx.doi.org/10.15212/ijafr-2020-0115.
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.