Abstract
Consumer perception of organic cow milk is associated with the assumption that organic milk differs from conventionally produced milk. The value associated with this difference justifies the premium retail price for organic milk. It includes the perceptions that organic dairy farming is kinder to the environment, animals, and people; that organic milk products are produced without the use of antibiotics, added hormones, synthetic chemicals, and genetic modification; and that they may have potential benefits for human health. Controlled studies investigating whether differences exist between organic and conventionally produced milk have so far been largely equivocal due principally to the complexity of the research question and the number of factors that can influence milk composition. A main complication is that farming practices and their effects differ depending on country, region, year, and season between and within organic and conventional systems. Factors influencing milk composition (e.g., diet, breed, and stage of lactation) have been studied individually, whereas interactions between multiple factors have been largely ignored. Studies that fail to consider that factors other than the farming system (organic vs. conventional) could have caused or contributed to the reported differences in milk composition make it impossible to determine whether a system-related difference exists between organic and conventional milk. Milk fatty acid composition has been a central research area when comparing organic and conventional milk largely because the milk fatty acid profile responds rapidly and is very sensitive to changes in diet. Consequently, the effect of farming practices (high input vs. low input) rather than farming system (organic vs. conventional) determines milk fatty acid profile, and similar results are seen between low-input organic and low-input conventional milks. This confounds our ability to develop an analytical method to distinguish organic from conventionally produced milk and provide product verification. Lack of research on interactions between several influential factors and differences in trial complexity and consistency between studies (e.g., sampling period, sample size, reporting of experimental conditions) complicate data interpretation and prevent us from making unequivocal conclusions. The first part of this review provides a detailed summary of individual factors known to influence milk composition. The second part presents an overview of studies that have compared organic and conventional milk and discusses their findings within the framework of the various factors presented in part one.
Key words
Introduction
Composition of bovine milk is influenced by many factors related either to the individual animal or to the animal’s environment. Elements such as diet (
Ferlay et al., 2008
; Larsen et al., 2010
, breed (Soyeurt et al., 2006
; Palladino et al., 2010
, individual animal genetics (Soyeurt et al., 2008
, stage of lactation (Craninx et al., 2008
; Stoop et al., 2009
, management (Coppa et al., 2013
, and season (- Coppa M.
- Ferlay A.
- Chassaing C.
- Agabriel C.
- Glasser F.
- Chilliard Y.
- Borreani G.
- Barcarolo R.
- Baars T.
- Kusche D.
- Harstad O.M.
- Verbič J.
- Golecký J.
- Martin B.
Prediction of bulk milk fatty acid composition based on farming practices collected through on-farm surveys.
J. Dairy Sci. 2013; 96 (http://dx.doi.org/10.3168/jds.2012-6379): 4197-4211
Heck et al., 2009
, as well as the interactions between them (Macdonald et al., 2008
; - Macdonald K.A.
- Verkerk G.A.
- Thorrold B.S.
- Pryce J.E.
- Penno J.W.
- McNaughton L.R.
- Burton L.J.
- Lancaster J.A.S.
- Williamson J.H.
- Holmes C.W.
A comparison of three strains of Holstein-Friesian grazed on pasture and managed under different feed allowances.
J. Dairy Sci. 2008; 91 (http://dx.doi.org/10.3168/jds.2007-0441): 1693-1707
Piccand et al., 2013
; Stergiadis et al., 2013
, affect milk composition, with many of the mechanisms behind these effects not fully understood. Therefore, when attempting to study the effect of one specific factor (e.g., diet) on cow milk composition, it is necessary to eliminate other influences. Those factors that cannot be eliminated must be accounted for and their effects considered and minimized.Currently, there is no evidence that consumption of organic food leads to meaningful nutritional benefits for human health (
Forman et al., 2012
; - Forman J.
- Silverstein J.
- Bhatia J.J.S.
- Abrams S.A.
- Corkins M.R.
- De Ferranti S.D.
- Golden N.H.
- Paulson J.A.
- Brock-Utne A.C.
- Brumberg H.L.
- Campbell C.C.
- Lanphear B.P.
- Osterhoudt K.C.
- Sandel M.T.
- Trasande L.
- Wright R.O.
Organic foods: Health and environmental advantages and disadvantages.
Pediatrics. 2012; 130 (http://dx.doi.org/10.1542/peds.2012-2579): e1406-e1415
Załecka et al., 2014
. Studies purportedly comparing organic and conventionally produced milk are rife with complications. To be able to determine whether organic milk differs from conventionally produced milk, all factors that influence milk composition must be identical except for the factors that specifically define the farming system (organic or conventional). If more than the system factor varies between compared milk samples, it is difficult to determine whether results derive from the differences between the farming systems or are the consequence of other factors. Recent reviews (Magkos et al., 2003
; Dangour et al., 2010
; Guéguen and Pascal, 2010
; Smith-Spangler et al., 2012
remarked on the lack of “true” comparison in studies evaluating organic and conventionally produced foods (including milk and dairy products). Many studies comparing organic and conventionally produced milk are inadequate in their discussion of the factors actually causing the results they present. Commonly, factors that could have contributed to the reported differences (between organic and conventional milk) have not been considered (e.g., differences in diet, breed, and animal health). Most studies proclaiming a comparison of organic and conventional milk used diets that varied in their amount of fresh forage and concentrate for organic and conventional cows, respectively. Consequently, the presented results are most likely related to the effect of the differences in diet, rather than to the fact that cows consumed organic or conventionally produced feed. On the contrary, studies that identify specific production differences for organic and conventional milk (e.g., higher amount of pasture in the diet of organic cows) fail to consider the influence of the farming system (organic or conventional) on their results (Palupi et al., 2012
. Additionally, comparisons among studies are problematic because it is difficult to account for any number of variables, including sampling conditions (e.g., frequency of sampling, time of sampling, samples taken from individual cows vs. bulk milk vs. multiple farms), inherent differences in farming systems between regions, levels of input, and even regulatory differences in conventional and organic production between nations.Regulations regarding organic dairy farming, although similar in principle, vary in detail (Table 1) between countries (e.g., pasture access and use of antibiotics). Therefore, heterogeneity of organic regulations may contribute to the variation in organic milk composition between countries.
Table 1Country-specific regulations for organic dairy farming in regard to pasture access, forage feeding, and use of antibiotics
Country | Pasture access | Forage feed | Antibiotics use | Regulation |
---|---|---|---|---|
United States | Grazed for 120 d per year | During grazing season, 30% of total forage intake must come from pasture. | Producer must not sell, label, or represent as organic any edible product derived from any animal treated with antibiotics. | Organic foods production act provisions 2014 ( US Government Printing Office, 2014 |
Canada | Pasture access during grazing season | During grazing season, 30% of total forage intake must come from pasture. 60% of DM in daily rations consists of hay, fresh/dried fodder, or silage. | Milk withdrawal time. Animals that require more than 2 treatments shall undergo a 12-mo transition period. | Organic Production Systems General Principles and Management Standards 2011 ( Canadian General Standards Board, 2011 |
European Union | Pasture access for grazing whenever conditions allow | 60% of DM in daily rations consists of hay, fresh/dried fodder, or silage. A reduction to 50% for a maximum period of 3 mo in early lactation is allowed. | Milk withdrawal time. When animals that require more than 3 treatments, or more than 1 course of treatment if productive lifecycle is <1 yr, the produce derived from the animal may not be sold as organic. | Guidance document on European Union organic Standards 2010 ( Department for Environment Food and Rural Affairs, 2010 |
Japan | Pasture access, no less than twice a week | Feeds other than fresh or dried fodder or silage are less than 50% of the average feed intake, in dry weight. | Prescribed drugs or antibiotics are used only when therapy with veterinary drugs other than these is not effective. | Japanese Agricultural Standard for Organic Livestock Products, 2005 (Ministry of Agriculture Forestry and Fisheries) |
New Zealand | Ruminants must be grazed throughout the grazing season 150 d | For herbivores, a minimum of 50% of feed must come from pasture. | Use of synthetic allopathic veterinary drugs or antibiotics will cause the animal to lose its organic status. | AsureQuality Organic Standard For Primary Producers, 2013 ( AsureQuality, 2013 |
Australia | Grazing of animals in natural/rangeland areas is considered part of an organic production system | After treatment with allopathic veterinary drugs or antibiotics, the products can be marketed as organic or bio-dynamic after a minimum management period of 180 d. | National Standard for Organic and Bio-Dynamic Produce, 2013 ( Organic Industry Standards and Certification Committee, 2013 |
1 Organic livestock standards for producers are compulsory.
2 Milk withdrawal time = at least 30 d or twice the specific medication’s withdrawal period, whichever is longer.
3 Treatments = combined parasiticides and antibiotics per year.
4 Organic livestock standards for producers are voluntary.
5 Several organic livestock standards, which are voluntary and chosen by farmer according to their organic production style.
The problems outlined above account for the inability of previous studies to reach a consensus on whether compositional differences exist between organic and conventionally produced dairy foods. Consequently, comparison of research studies should be undertaken with the awareness that study-specific factors can have a significant effect on animal production and milk composition and might have contributed to reported differences.
This review focuses on the chemical composition of bovine milk and summarizes the variety of different milk components that have been analyzed in regard to their quantitative and qualitative presence in organic and conventionally produced milk. It also aims to show how different milk components are influenced by a variety of individual factors and their interactions, and how the resulting variations can be perceived as differences between organic and conventional milks. It reinforces that these factors need to be considered when evaluating existing studies or designing comparative experiments. Variations within organic and conventional production methods have also created differences that have so far prevented development of a method to test the authenticity of organic milk products. A brief discussion of proposed tests to identify organically produced products is also included.
Factors that influence milk composition
Numerous and varied factors influence milk yield and composition that, ideally, should be controlled when conducting a trial examining factors that may change milk composition. These factors can seem relatively minor, but they could account for a significant amount of variation. A study conducted by
Roche et al. (2009)
between 1995 and 2001 showed that the combined influence of weather, herbage quality, and herbage mineral concentration explained up to 22% of the variation in dairy cattle production. In a different trial, Roesch et al. (2005)
compared cow performance from organic and integrated farming systems and found that milk yield positively correlated with breed (especially Holstein), concentrate feeding, routine teat dipping, and greater outdoor access during winter independent of the system. They concluded that lower milk yields (in organic and integrated cows) are a result of the individual animal and on-farm level factors such as breed, nutrition, management, and udder health. A study by Waiblinger et al. (2002)
, investigating 30 small, family-run dairy farms, suggested that milk production was lower on farms where management had negative attitudes toward interacting with cows during milking. Various factors that influence milk yield, as well as fat, protein, and lactose concentrations, at the farm and individual animal levels are compiled in Table 2.Table 2Summary of factors influencing milk yield, fat, protein, and lactose concentrations
Factor | Milk yield | Reference | Fat % | Reference | Protein % | Reference | Lactose % | Reference |
---|---|---|---|---|---|---|---|---|
Altitude | Higher in highland vs. lowland | Bartl et al. (2008 | ||||||
Breed | Higher in Holstein vs. Simmental | Roesch et al. (2005) | Higher in Jersey vs. DF, MRY, and GWH | Maurice-Van Eijndhoven et al. (2011 | Highest in Jersey, lowest in DF | Maurice-Van Eijndhoven et al. (2011 | Higher in Brown Swiss vs. Jersey | Carroll et al. (2006 |
Higher in HF vs. Jersey | Palladino et al., 2010 | Higher in Minhota vs. HF | Ramalho et al. (2012 | Higher in Jersey vs. HF | Palladino et al., 2010 | |||
Higher in HF vs. Jersey and Brown Swiss | Carroll et al. (2006 | Higher in Jersey vs. HF | Palladino et al., 2010 | Higher in Jersey vs. Holstein | Croissant et al. (2007 | |||
Higher in Jersey vs. Holstein | Croissant et al. (2007 | Higher in Brown Swiss vs. Holstein | Carroll et al. (2006 | |||||
Fertilizer | Lower with higher N application | Hermansen et al. (1994 ; Mackle et al. (1996 | ||||||
Grazing allocation (frequency) | Higher if allocation every day vs. every fourth day | Abrahamse et al. (2008 | Higher for allocation every fourth day vs. every day | Abrahamse et al. (2008 | Higher if allocation every fourth day vs. every day | Abrahamse et al. (2008 | NS | Abrahamse et al. (2008 |
Grazing high sugar grasses | Positively correlated | Miller et al. (2001
Increased concentration of water-soluble carbohydrate in perennial ryegrass (Lolium perenne L.): Milk production from late-lactation dairy cows. Grass Forage Sci. 2001; 56 (http://dx.doi.org/10.1046/j.1365-2494.2001.00288.x): 383-394 | Positively correlated | Roche et al. (2009) | ||||
Grazing pasture | Lower vs. concentrate | Coleman et al. (2010 | NS | Coleman et al. (2010 | NS | Croissant et al. (2007 ; Coleman et al. (2010 | Unknown | Coleman et al. (2010 |
Lower vs. TMR | Croissant et al. (2007 | |||||||
Genotype | Higher in High NA vs. High NZ and Low NA | Coleman et al. (2010 | Higher in High NZ vs. High NA and Low NA | Coleman et al. (2010 | Higher in High NZ vs. High NA and Low NA | Coleman et al. (2010 | Higher in High NZ vs. High NA and Low NA | Coleman et al. (2010 |
Higher in NA90 than NZ90 | Macdonald et al., 2008
A comparison of three strains of Holstein-Friesian grazed on pasture and managed under different feed allowances. J. Dairy Sci. 2008; 91 (http://dx.doi.org/10.3168/jds.2007-0441): 1693-1707 | Higher in NZ90 than NA90 | Macdonald et al., 2008
A comparison of three strains of Holstein-Friesian grazed on pasture and managed under different feed allowances. J. Dairy Sci. 2008; 91 (http://dx.doi.org/10.3168/jds.2007-0441): 1693-1707 | Higher in NZ90 than NA90 | Macdonald et al., 2008
A comparison of three strains of Holstein-Friesian grazed on pasture and managed under different feed allowances. J. Dairy Sci. 2008; 91 (http://dx.doi.org/10.3168/jds.2007-0441): 1693-1707 | Higher in NZ90 than NA90 | Macdonald et al., 2008
A comparison of three strains of Holstein-Friesian grazed on pasture and managed under different feed allowances. J. Dairy Sci. 2008; 91 (http://dx.doi.org/10.3168/jds.2007-0441): 1693-1707 | |
Heritability | Correlated | Soyeurt et al. (2007 | Correlated | Soyeurt et al. (2007 | Correlated | Soyeurt et al. (2007 | ||
Management attitude | Positively correlated | Waiblinger et al. (2002) | ||||||
Parity | Higher | Roesch et al. (2005) ; Craninx et al., 2008 | Higher | Craninx et al., 2008 | ||||
Season | Minimum in summer | Heck et al., 2009 ; Larsen et al. (2012) ; Stergiadis et al., 2013 | Minimum in summer | Heck et al., 2009 | Minimum in autumn | Heck et al., 2009 | ||
NS | Larsen et al. (2012) ; Stergiadis et al., 2013 | |||||||
SCC | Negatively correlated | Maréchal et al. (2011 | Negatively correlated | Ballou et al. (1995 | Negatively correlated | Auldist et al., 1998 | ||
Stage of lactation | Correlated | Craninx et al., 2008 ; Palladino et al., 2010 | Correlated | Craninx et al., 2008 ; Palladino et al., 2010 | Correlated | Palladino et al., 2010 | ||
Sunlight hours | Positively correlated | Roche et al. (2009) | ||||||
Teat dipping | Positively correlated | Roesch et al. (2005) |
1 DF = Dutch Friesian; MRY = Meuse-Rhine-Yssel; GWH = Groningen White Headed; HF = Holstein-Friesian.
2 Low NA = national average-genetic-merit North American Holstein-Friesian; high NA = high-genetic-merit North American Holstein-Friesian; high NZ = high-genetic merit New Zealand Holstein-Friesian.
3 NZ90 = a 1990s high Breeding Worth Holstein-Friesian of New Zealand origin; NA90 = a 1990s high Breeding Worth Holstein-Friesian of North American origin.
The factors considered most influential, however, vary depending on study conditions and aims. Stage of lactation, for example, can be neglected when bulk milk samples are collected from a farm with an all-year-round calving system, but it becomes significant when milk samples of individual animals are taken or when block calving is practiced (
Nantapo et al., 2014
. As major influences are accounted for and controlled (e.g., cows in one trial are all of one breed, with similar genetics, at the same stage of lactation, fed similar diets), previously minor factors (e.g., pasture composition) become more important.Analysis and (potential) alteration of milk FA composition are key areas of dairy research because of the rapid response of FA profile to changes in diet. Other factors influential for milk FA composition are breed, energy status, stage of lactation, udder health, and season. The latter predominantly reflects alterations in diet, especially when these are rich in forage. Chemical and botanical composition of fresh forages varies throughout the seasons, and conservation for hay or silage affects the nutritional value of forages. The seasonal transition of dairy cows from outdoor grazing to indoor housing and the accompanying change in diet can be observed in milk composition (Larsen et al., 2010;
Kuczyńska et al., 2012
. The effects of breed and season on milk fat composition are summarized in Table 3, and the effects of different forages on milk FA are listed in Table 4.- Kuczyńska B.
- Puppel K.
- Gołȩbiewski M.
- Metera E.
- Sakowski T.
- Słoniewski K.
Differences in whey protein content between cow's milk collected in late pasture and early indoor feeding season from conventional and organic farms in Poland.
J. Sci. Food Agric. 2012; 92 (http://dx.doi.org/10.1002/jsfa.5663): 2899-2904
Table 3Effect of breed and season on individual milk fatty acids
Fatty acid2 | Breed | Season | ||
---|---|---|---|---|
Effect | Reference | Effect | Reference | |
Even-chain SFA | ||||
C4:0 (butyric acid) | Higher for DF than MRY, GWH, and Jersey | Maurice-Van Eijndhoven et al. (2011 | NS | Palladino et al., 2010 |
Higher for Brown Swiss than Jersey | Carroll et al. (2006 | NS, for herbage | Larsen et al. (2010) | |
Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |||
NS, spring or winter | Rego et al. (2008 | |||
Lower in winter with maize silage and by-products, NS with pasture | Larsen et al. (2010) | |||
C6:0 (caproic acid) | Higher for DF and MRY than for GWH and Jersey | Maurice-Van Eijndhoven et al. (2011 | NS | Palladino et al., 2010 |
Higher for Jersey than Brown Swiss | Carroll et al. (2006 | NS, spring or winter | Rego et al. (2008 | |
Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |||
C8:0 (caprylic acid) | Holstein lower than Jersey | Croissant et al. (2007 | Lower in summer | Palladino et al., 2010 |
NS, for herbage | Larsen et al. (2010) | |||
NS between Minhota and HF | Ramalho et al. (2012 | NS, spring or winter | Rego et al. (2008 | |
Higher for DF and MRY than GWH and Jersey | Maurice-Van Eijndhoven et al. (2011 | Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
C10:0 (capric acid) | Holstein lower than Jersey | Croissant et al. (2007 | Lower in summer | Palladino et al., 2010 |
Minhota lower than HF | Ramalho et al. (2012 | Higher in spring than winter | Rego et al. (2008 | |
Lowest for GWH; highest for DF | Maurice-Van Eijndhoven et al. (2011 | Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | |||
C12:0 (lauric acid) | Holstein lower than Jersey | Croissant et al. (2007 | Lower in summer | Palladino et al., 2010 |
Minhota lower than HF | Ramalho et al. (2012 | Higher in spring than winter | Rego et al. (2008 | |
Higher for DF and MRY than GWH and Jersey | Maurice-Van Eijndhoven et al. (2011 | Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | |||
C14:0 (myristic acid) | Higher for DF and MRY than GWH and Jersey | Maurice-Van Eijndhoven et al. (2011 | Lower in summer | Palladino et al., 2010 |
Minhota lower than HF | Ramalho et al. (2012 | Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Highest in winter, lowest May to July | Kliem et al. (2013 | |
C16:0 (palmitic acid) | HF lower than Jersey | Palladino et al., 2010 | NS | Palladino et al., 2010 |
NS between Minhota and HF | Ramalho et al. (2012 | NS | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
Lowest for GWH; highest for Jersey | Maurice-Van Eijndhoven et al. (2011 | May higher than August when lower content of lucerne | Larsen et al. (2010) | |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Higher in winter than spring | Rego et al. (2008 | |
Highest in winter, lowest May to July | Kliem et al. (2013 | |||
C18:0 (stearic acid) | NS between Minhota and HF | Ramalho et al. (2012 | Higher in summer | Palladino et al., 2010 ;Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 |
No difference for DF, MRY, GWH, and Jersey | Maurice-Van Eijndhoven et al. (2011 | May and August lower than June when lower content of chicory and lucerne | Larsen et al. (2012) | |
NS between HF and Jersey | Palladino et al., 2010 | NS, spring or winter | Rego et al. (2008 | |
Highest in June, lowest in October | Kliem et al. (2013 | |||
Odd-chain SFA | ||||
C13:0 | NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Lower in summer | Palladino et al., 2010 |
C15:0 | Minhota higher than HF | Ramalho et al. (2012 | Lower in summer | Palladino et al., 2010 |
HF higher than Jersey | Palladino et al., 2010 | Higher in spring than winter | Rego et al. (2008 | |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Higher in summer | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
C17:0 | NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | NS | Palladino et al., 2010 |
Higher in spring than winter | Rego et al. (2008 | |||
Branched-chain FA | ||||
C13:0 iso | Lower in summer | Palladino et al., 2010 | ||
C14:0 iso | Higher in spring than winter | Rego et al. (2008 | ||
C15:0 iso | Minhota higher than HF | Ramalho et al. (2012 | Higher in spring than winter | Rego et al. (2008 |
C15:0 anteiso | NS between Minhota and HF | Ramalho et al. (2012 | NS, spring or winter | Rego et al. (2008 |
C16:0 iso | Minhota higher than HF | Ramalho et al. (2012 | ||
C17:0 iso | NS, spring or winter | Rego et al. (2008 | ||
C17:0 anteiso | Higher in spring than winter | Rego et al. (2008 | ||
Unsaturated FA | ||||
C14:1 cis-9 (myristoleic acid) | NS between Holstein and Jersey | Croissant et al. (2007 | Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 |
NS between Minhota and HF | Ramalho et al. (2012 | |||
HF higher than Jersey | Palladino et al., 2010 | |||
C16:1 cis-9 (palmitoleic acid) | Holstein higher than Jersey | Croissant et al. (2007 | Higher in winter than spring | Rego et al. (2008 |
Minhota higher than HF | Ramalho et al. (2012 | Higher in winter | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
C18:1 trans-9 (elaidic acid) | NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Higher in winter than spring | Rego et al. (2008 |
C18:1 trans-10 | NS spring or winter | Rego et al. (2008 | ||
C18:1 trans-11 (vaccenic acid) | NS between Holstein and Jersey | Palladino et al., 2010 | NS | Palladino et al., 2010 |
Higher in Holstein than Brown Swiss | Carroll et al. (2006 | Total trans 18:1 highest Aug/Sep/Oct | Dunshea et al. (2008
Seasonal variation in the concentrations of conjugated linoleic and trans fatty acids in milk fat from commercial dairy farms is associated with pasture and grazing management and supplementary feeding practices. Aust. J. Exp. Agric. 2008; 48 (http://dx.doi.org/10.1071/ea0728610.1071/EA99132): 1062-1075 | |
Higher in spring than winter | Rego et al. (2008 | |||
Higher in summer | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |||
C18:1 cis-9 (oleic acid) | Holstein higher than Jersey | Croissant et al. (2007 | NS | Palladino et al., 2010 |
HF higher than Jersey | Palladino et al., 2010 | Higher in winter than spring | Rego et al. (2008 | |
Higher in Brown Swiss than Jersey and Holstein | Carroll et al. (2006 | Lowest in May/lowest content of chicory and lucerne | Larsen et al. (2012) | |
Higher in summer | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |||
C18:2 cis-9,12 (linoleic acid) | Holstein higher than Jersey | Croissant et al. (2007 | Higher in summer | Palladino et al., 2010 |
NS between Holstein and Jersey | Palladino et al., 2010 | Highest in May/highest concentration of red clover | Larsen et al. (2012) | |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Higher in summer | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |
C18:2 cis-9,trans-11 (CLA) | HF higher than Jersey | Palladino et al., 2010 | NS | Palladino et al., 2010 |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Total cis/trans 18:2 highest Aug/Sep/Oct | Dunshea et al. (2008
Seasonal variation in the concentrations of conjugated linoleic and trans fatty acids in milk fat from commercial dairy farms is associated with pasture and grazing management and supplementary feeding practices. Aust. J. Exp. Agric. 2008; 48 (http://dx.doi.org/10.1071/ea0728610.1071/EA99132): 1062-1075 | |
Higher in spring than winter | Rego et al. (2008 | |||
Higher in summer | Revello Chion et al. (2010
Variation of fatty acid and terpene profiles in mountain milk and “Toma piemontese” cheese as affected by diet composition in different seasons. Food Chem. 2010; 121 (http://dx.doi.org/10.1016/j.foodchem.2009.12.048): 393-399 | |||
C18:3 cis-9,12,15 (α-linolenic acid) | NS between Holstein and Jersey | Palladino et al., 2010 | NS | Palladino et al., 2010 |
NS between Holstein, Jersey, and Brown Swiss | Carroll et al. (2006 | Higher in spring than winter | Rego et al. (2008 | |
Highest in May/highest concentration of red clover, lowest in white clover | Larsen et al. (2012) |
1 DF = Dutch Friesian; MRY = Meuse-Rhine-Yssel; GWH = Groningen White Headed; HF = Holstein-Friesian.
Table 4Effect of different forages on individual milk fatty acids
Fatty acid | Increased in | Reference |
---|---|---|
Even-chain SFA | ||
C4:0 (butyric acid) | Alpine pasture vs. pasture | Coulon et al., 1999 |
Pasture hay vs. grass silage | Baars et al. (2012 | |
C6:0 (caproic acid) | Pasture hay vs. grass silage | Baars et al. (2012 |
C16:0 (palmitic acid) | NS: WC or RC silage | Steinshamn and Thuen (2008 |
Hay or grass silage vs. pasture | Villeneuve et al. (2013 | |
Maize silage vs. pasture | Croissant et al. (2007 | |
C18:0 (stearic acid) | Pasture vs. grass silage | Elgersma et al. (2004 |
NS: WC silage or RC silage | Steinshamn and Thuen (2008 | |
RC silage vs. WC silage | Wiking et al. (2010 | |
Odd-chain SFA | ||
C13:0 | Pasture hay vs. grass silage | Baars et al. (2012 ; Villeneuve et al. (2013 |
C17:0 | Maize silage vs. grass silage | Vlaeminck et al. (2006 |
Branched-chain FA | ||
C14:0 iso | Pasture or hay vs. grass silage | Villeneuve et al. (2013 |
C15:0 iso | Grass silage vs. maize silage | Vlaeminck et al. (2006 |
C15:0 anteiso | Grass silage vs. maize silage | Vlaeminck et al. (2006 |
Pasture hay vs. grass silage | Baars et al. (2012 | |
C16:0 iso | Grass silage vs. maize silage | Vlaeminck et al. (2006 |
Pasture or hay vs. grass silage | Baars et al. (2012 ; Villeneuve et al. (2013 | |
C16:0 anteiso | Pasture hay vs. grass silage | Baars et al. (2012 |
C17:0 iso | Maize silage vs. grass silage | Vlaeminck et al. (2006 |
Pasture vs. hay | Villeneuve et al. (2013 | |
C17:0 anteiso | Maize silage vs. grass silage | Vlaeminck et al. (2006 |
Pasture or hay vs. grass silage | Villeneuve et al. (2013 | |
C18:0 iso | Grass silage vs. maize silage | Kliem et al. (2008 |
Unsaturated FA | ||
C18:1 trans-9 (elaidic acid) | Pasture vs. WC silage | Wijesundera et al. (2003 ; Elgersma et al. (2004 |
Grass silage vs. WC and RC silage | Wiking et al. (2010 | |
Pasture vs. grass silage or hay | Villeneuve et al. (2013 | |
Maize silage | Wijesundera et al. (2003 ; Kliem et al. (2008 | |
C18:1 trans-10 | Maize silage vs. pasture | Kliem et al. (2008 |
Pasture vs. grass silage or hay | Villeneuve et al. (2013 | |
C18:1 trans-11 (vaccenic acid) | Pasture vs. maize silage | Elgersma et al. (2004 ; Slots et al. (2009 |
Pasture vs. grass silage vs. hay | Villeneuve et al. (2013 | |
WC and RC pasture vs. maize silage | Wiking et al. (2010 | |
NS: grass or maize silage | Kliem et al. (2008 | |
C18:1 cis-9 (oleic acid) | Pasture | Ellis et al. (2006 ; Croissant et al. (2007 ; Heck et al., 2009 |
Pasture vs. grass silage | Elgersma et al. (2004 | |
Pasture vs. hay | Villeneuve et al. (2013 | |
NS: grass silage vs. maize silage | Kliem et al. (2008 | |
C18:1 cis-11 | WC pasture | Ellis et al. (2006 |
C18:2 cis-9,12 (linoleic acid) | Maize silage vs. fresh pasture | Kliem et al. (2008 ; Slots et al. (2009 |
Pasture vs. grass silage or hay | Villeneuve et al. (2013 | |
C18:2 cis-9,trans-11 (CLA) | Pasture | Elgersma et al. (2004 ; Croissant et al. (2007 ; Slots et al. (2009 ; Heck et al., 2009 ; Prandini et al. (2009 |
Pasture vs. grass silage | Ellis et al. (2006 ; Villeneuve et al. (2013 | |
Pasture or grass silage vs. hay | Villeneuve et al. (2013 | |
RC and WC pasture vs. maize silage | Wiking et al. (2010 | |
Hay | Prandini et al. (2009 | |
C18:3 cis-9,12,15 (α-linolenic acid) | Pasture | Lourenço et al. (2008 ; Prandini et al. (2009 ; Slots et al. (2009 ; Schröder et al. (2011 |
RC pasture | Lourenço et al. (2008 ; Butler et al. (2011 | |
RC pasture vs. WC silage | Steinshamn and Thuen (2008 ; Slots et al. (2009 | |
WC pasture or WC silage | Ellis et al. (2006 ; Slots et al. (2009 | |
RC silage | Elgersma et al. (2006) ; Ellis et al. (2006 ; Slots et al. (2009 | |
Pasture vs. hay vs. grass silage | Villeneuve et al. (2013 | |
Hay | Slots et al. (2009 |
1 WC = white clover; RC = red clover.
Conventional versus organic milk: main components
Milk Yield
Despite the existence of highly specialized, grassland-based, organic farms with cows producing more than 9,000 kg of fluid milk per year (
Muller-Lindenlauf et al., 2010
, milk production from organically reared cows is lower, on average, than that from conventional cows (Sundberg et al., 2009
. These differences are significant, with organic herds achieving 85% (range: 72 to 91%) of the yields recorded for conventional herds (Bilik and Lopuszanska-Rusek, 2010
; Müller and Sauerwein, 2010
; Stiglbauer et al., 2013
. Decreased production under organic management can be traced to lower energy intake, through either less concentrate feeding (Garmo et al., 2010
; Stiglbauer et al., 2013
or lower energy content in forages from organic systems. This is exemplified by Gruber et al. (2001)
, who conducted a 6-yr study with nearly identical diets for organic and conventional cows. They demonstrated that milk yields per cow and year were identical for both herds, but milk production per area grazed was reduced in the organic herd because of lower DM yields from organic pasture and, therefore, lower stocking rates per hectare. Consequently, diets similar in composition and ME content had the same effect on milk production, independent of whether the farming system was organic or conventional.Milk Fat Content
Results of research studies examining the fat content in organic and conventional milks are ambivalent.
Zagorska and Ciprovica (2008)
and Anacker (2007)
found increased fat content in organic milk, whereas trials undertaken by Sundberg et al., 2009
, Hanus et al. (2008b)
, and Kuczyńska et al., 2012
observed higher fat percentage in conventional milk. Samples of retail milk collected during October and November 2006 in the United States showed no significant difference for fat percentage between the 2 milk varieties (- Kuczyńska B.
- Puppel K.
- Gołȩbiewski M.
- Metera E.
- Sakowski T.
- Słoniewski K.
Differences in whey protein content between cow's milk collected in late pasture and early indoor feeding season from conventional and organic farms in Poland.
J. Sci. Food Agric. 2012; 92 (http://dx.doi.org/10.1002/jsfa.5663): 2899-2904
Vicini et al., 2008
. This result might be due to the federal standards for butterfat content for fluid milk products. Müller and Sauerwein, 2010
analyzed bulk milk samples of 35 organic and 33 conventional farms during 2002 and 2004 and reported similar amounts of milk fat between the 2 farming systems. Reasons for the reported differences can be diverse, with only a few publications mentioning potential causes. Higher fat concentration in milk from organic compared with conventional farms could have been caused by a preference for non-Holstein breeds in organic herds (Nauta et al., 2009
, resulting in a higher number of Jersey and other breeds (Palladino et al., 2010
. An increase in starch-based concentrates has been associated with a decline in milk fat concentration. Greater amounts of starch-based concentrates are commonly associated with diets of conventionally farmed dairy cows compared with organic cows (Rosati and Aumaitre, 2004
, because organic farming regulations restrict the usage of concentrates. Alternatively, an increase in milk fat percentage in milk from conventional farms may indicate a diet enriched with fat supplements (Vyas et al., 2012
; Lock et al., 2013
. A negative energy balance, predominantly found during the early stages of lactation and the winter period in low-input organic cows (Trachsel et al., 2000
, might also affect fat percentage in milk (Gross et al., 2011
. Additionally, a higher parity average (Craninx et al., 2008
, variations in heritability (Soyeurt et al. (2007
, and genotype (Coleman et al. (2010
can all be reflected in milk fat percentage. One result of inadequate descriptions of experimental trials is that conclusions from these studies need to be interpreted cautiously. Table 5 compiles several studies in which organic and conventionally produced milks have been compared concerning their fat, protein, and lactose contents and lists the reported causes, as proposed by the authors, for any differences.Table 5Differences in milk composition between organic and conventional produced milk
Milk compound | Reference | Reported causes for differences in composition between organic and conventional milk |
---|---|---|
Fat % | ||
Increased in organic | Zagorska and Ciprovica (2008) | No comment on breed or diet specifics |
Anacker (2007) | No comment on breed or diet specifics; higher amount of green fodder in the diet and use of clover silage in winter for organic herd | |
Butler et al. (2011 | Differences in diet but no specifics | |
Increased in conventional | Hanus et al. (2008a | Diet differences, all-year-round TMR for conventional cows, pasture grazing for organic cows during summer |
Sundberg et al., 2009 | Preference for non-Holstein and mixed breeds in organic herds, lower replacement rates in organic herds | |
Kuczyńska et al., 2012
Differences in whey protein content between cow's milk collected in late pasture and early indoor feeding season from conventional and organic farms in Poland. J. Sci. Food Agric. 2012; 92 (http://dx.doi.org/10.1002/jsfa.5663): 2899-2904 | Higher fiber intake | |
NS | Vicini et al., 2008
Survey of retail milk composition as affected by label claims regarding farm-management practices. J. Am. Diet. Assoc. 2008; 108: 1198-1203 |