Effect of pasture versus indoor feeding systems on raw milk composition and quality over an entire lactation

Abstract

The aim of this study was to investigate the effects of different feeding systems on milk quality and composition. Fifty-four multiparous and primiparous Friesian lactating cows were divided into 3 groups (n=18) to study the effects of 3 feeding systems over a full lactation. Group 1 was housed indoors and offered a total mixed ration diet (TMR), group 2 was maintained outdoors on a perennial ryegrass pasture (referred to as grass), and group 3 was also grazed outdoors on a perennial ryegrass/white clover pasture (referred to as clover). Bulk milk samples were collected from each group at morning and afternoon milkings once weekly from March 11 to October 28 in 2015. Milk from pasture-fed cows (grass and clover) had significantly higher concentrations of fat, protein, true protein, and casein. The pasture feeding systems induced significantly higher concentrations of saturated fatty acids C11:0, C13:0, C15:0, C17:0, C23:0, and unsaturated fatty acids C18:2n-6 trans, C18:3n-3, C20:1, and C20:4n-6 and a greater than 2-fold increase in the conjugated linoleic acid C18:2 cis-9,trans-11 content of milk compared with that of the TMR feeding system. The TMR feeding system resulted in milks with increased concentrations of C16:0, C18:2n-6 cis, C18:3n-6 cis, C22:0 C22:1n-9, and C18:2 cis-10,trans-12. Principal component analysis of average fatty acid profiles showed clear separation of milks from the grazed pasture-based diets to that of a TMR system throughout lactation, offering further insight into the ability to verify pasture-derived milk by fatty acid profiling.

Scientific appraisal of the Irish grass-based milk production system as a sustainable source of premium quality milk and dairy products

“…The pasture-based system can ensure the absence of late lactation milk from any individual cow or group of cows in a herd by imposing a specific cow dryingoff (cessation of milk) strategy (Guinee and O'Brien, 2010), whereas the separation of late lactation milk is more difficult with the year-round calving pattern normally associated with confined milk production systems. O'Callaghan et al (2016) reported that a principal component analysis of the average fatty acid profiles showed a quite distinct and clear separation of milks throughout lactation in relation to the two feeding regimes. The study makes an important contribution to identifying how pasture-derived milk can be verified by fatty acid profiling.…”

“…The study makes an important contribution to identifying how pasture-derived milk can be verified by fatty acid profiling. An extended version of the study of O'Callaghan et al (2016) is currently ongoing and is focussed on identifying and comparing differences in milk (in relation to composition, sensory value, volatiles and processability) and milk products (butter, cheese, whole milk powder and infant formula) produced from grass and TMR diets. The findings can then be used to benchmark the profile of milk produced from the Irish grass-based system against that of TMR-based systems in use in the USA and other EU countries.…”

“…Irish cows are predominantly fed pasture for the majority of the lactation, which influences milk composition, processability and the sensory characteristics of the milk, which in turn determine the quality of Irish dairy products (O'Brien and Guinee, 2016). Studies on cows offered significant quantities of grazed grass (Kelly et al, 1998;Coakley et al, 2007;Wyss et al, 2010;Butler et al, 2011;O'Callaghan et al, 2016) revealed that their milk contained increased levels of the unsaturated fatty acids, conjugated linoleic acids (CLAs), vaccenic acid, and omega-3 fatty acids, which are considered beneficial to human health, compared to the milk produced by cows on other diets, such as grass silage and concentrate-based diets. This was considered a positive and important finding as unsaturated fatty acids are believed to be better for human health (Haug et al, 2007).…”

“…There is limited information available comparing the composition and quality of raw milk produced by cows on different feeding regimes over an entire lactation season. However, such a study has recently been carried out by O'Callaghan et al (2016). The study of O'Callaghan et al (2016) involved two cow herds; one was housed indoors and offered a TMR diet, with the second maintained outdoors on a perennial ryegrass pasture (a typical Irish grass-based diet).…”

“…However, such a study has recently been carried out by O'Callaghan et al (2016). The study of O'Callaghan et al (2016) involved two cow herds; one was housed indoors and offered a TMR diet, with the second maintained outdoors on a perennial ryegrass pasture (a typical Irish grass-based diet). The study was conducted from 11 March 2015 to 28 October 2015.…”