Fedtsyreprofilen i mælk fra malkekøer - potentiale og perspektiver

Projektet SOBcows har i samarbejde med RYK gennem 16 måneder i 2015/16 analyseret for indholdet af fedtsyrer i kontrolmælken fra alle ydelseskontrollerede køer i Danmark. Rapporten præsenterer opgørelser på målingerne og evaluerer potentialet i at bruge viden om mælkens fedtsyreprofil i avl og produktion samt i forhold til fedtsyrernes betydning for human sundhed. En litteraturgennemgang viser, at fedtsyresammensætningen i komælk varierer betydeligt og er påvirket af en række faktorer relateret til fodring, race og management. Fodring med græs- eller urtebaserede rationer øger mælkens indhold af umættede C18-fedtsyrer, og tilsvarende øger fodring med mættet fedt indholdet af palmitin– og stearinsyre (C16:0 og C18:0) i mælkefedtet. Litteraturen viser desuden en stor forskel i mæl-kens fedtsyreprofil både mellem køer indenfor racer og mellem racer. Til brug i produktionsovervågning kan ændringer i mælkens fedtsyreprofil afspejle store vægttab i starten af laktationen, mens et forhøjet indhold af fedtsyrer med ulige antal C-atomer kan tyde på køer med SARA (sur vom). Effekten af forskellige fedtsyrer og fedtsyregrupper på den humane sundhed er under diskussion, og forsk-ningen er ikke entydig. Dog viser den aktuelle viden, at der sandsynligvis kan opnås en sundhedsfremmende profil i mælkefedtet ved at øge indholdet af umættede fedtsyrer og reducere andelen af palmitinsyre. Tek-nologisk vil det samtidig bidrage til smør med en blødere og mere smørbar tekstur. Flere umættede fedtsyrer og mindre palmitinsyre i mælkefedtet kan muligvis også påvirke smagen af osteprodukterne. Resultaterne fra godt 3,5 mio. mælkeanalyser viser, at faktorerne race, laktationsstadie, laktationsnummer, produktionsform og måned alle har effekt på mælkens fedstyresammensætning. Udbinding og store mængder frisk græs i rationen ændrer fedtsyreprofilen i retning af flere umættede fedtsyrer og mindre pal-mitinsyre. Data viser også, at Jersey adskiller sig fra de øvrige racer ved en højere andel mættede fedtsyrer og en tilsvarende lavere andel umættede fedtsyrer. Resultaterne viser desuden, at fedtmobilisering i starten af laktationen påvirker fedtsyreprofilen i mælken, og andelen af monoumættede fedtsyrer er størst i perio-den, hvor køerne mobiliserer. Endelig viser data avlsmæssig variation for de enkelte fedtsyregrupper, og det er derfor muligt at påvirke sammensætning af mælkefedtet gennem avl. Data fra mælkeanalyserne er anvendt til en foreløbig beregning af arvbarheden hen over laktationen, og de beregninger viser, at alle fedtsyrekategorier har en genetisk variation og enkeltfedtsyrerne har arvbarheder på højde med den samlede fedtydelse. Det betyder arvbarheder i intervallet 0,25-0,44 afhængig af race og paritet. De genetiske sammenhænge varierer betydeligt gennem laktationen og er påvirket af den øgede kropsmobilisering i de første måneder efter kælvning. En anvendelse af fedtstyrebestemmelserne i avlen vil derfor kræve en opdeling af laktationen i mindst to perioder. En eventuel fremtidig selektion for fedtsyre-grupper bør desuden ske ved at konstruere et indeks, som samtidig kan sikre fremgang for de ønskede fedt-syregrupper (mono- og polyumættede samt kortkædede fedtsyrer) og tilbagegang for den mættede pal-mitinsyre, samt sikre at uønskede sideeffekter for andre egenskaber ikke indtræffer. Perspektiverne i at avle efter ændret fedtsyreprofil i mælken afhænger af, om mejerierne og markedet i fremtiden vil afregne mælken for de enkelte fedtsyrefraktioner frem for betaling for den samlede fedtfraktion som i dag. Samlet kan det konkluderes, at der er et betydeligt avlsmæssigt potentiale, og hvis der kommer et dansk marked for mælkeprodukter med særlige egenskaber, vil det være oplagt at ændre det avlsmæssige niveau i gunstig retning og samtidigt udnytte de fodringsmæssige muligheder for at producere mælk med en sundhedsfremmende fedtsyreprofil. Datamaterialet her og fedtsyremåling af samtlige mælkeprøver i ydelseskontrollen giver en unik position i forhold til det

Viden om mælkens fedtsyreindhold giver nye muligheder

Dataanalyser af godt 3,5 millioner mælkeprøver fra ydelseskontrollen viser, at det er muligt at påvirke sammensætning af mælkefedtet gennem avl. Det giver nye muligheder for at skabe merværdi på mejeriprodukter

The fatty acid profile of the milk is measured on all cows in Denmark

The fatty acid profile of the milk is measured on all cows in Denmark The GUDP financed project SOBcows has in collaboration with RYK (Registration and Milk recording) collected a detailed fatty acid profile on all the cows, which are in the Danish milk recording system. In the past 16 months during 2015 and 2016, we have collected approximately 3.5 million milk samples. The samples were analyzed with the Foss application note 64, which registers 11 fatty acids or fatty acid groups. It is the first time that the milk fat from so many cows is registered in such detail. The data can be used to exploit the possibilities for genetic selection and feeding strategies to change the fatty acid profile in the milk into a desired direction. The initial genetic analysis showed that the heritability across the lactation was between 0.25 and 0.44 depending on the breed and parity of the cow. During the lactation, the cow mobilizes fat especially in the first part of the lactation to fulfill the energy requirement to produce milk. This was reflected in the change of the genetic variation over the lactation. This implies that if you would like to change the fatty acid profile of the cows by genetic selection you need to divide lactation in at least two periods. Additionally, the collected data showed that the feeding regime of cows had significant influence. Milk from organic farms shows a much larger variation in saturated fatty acids over the year compared to conventional farms. Especially when cows are going outside on fresh grass, the favorable unsaturated fatty acids increase, while the unfavorable fatty acid, like C16:0 decreases. At the moment there is still an ongoing discussion on the effects of the different fatty acids on human health. With today’s knowledge, one would like to have fat with a reduced saturated fatty acid content and increased unsaturated fatty acid content. However, it is more complicated because the chain length of the (unsaturated) fatty acids also has an influence on human health, where the short chain fatty acids lean towards a positive to neutral effect, the middle chain fatty acids, especially C16:0 lean towards the negative side. With regard to human nutrition it is most likely that changes in the fat composition would benefit those products with high fat content, like butter and cheese. As an example, on the English market a special milk with lower saturated fat content than the regular milk is sold. In conclusion we showed that when there is a Danish market for milk products with special fatty acid profiles we will be able to change the milk fatty acid profile, both by genetics and feeding into the desired direction

Keeping up with a healthy milk fatty acid profile requires selection

The effect of various fatty acids and fatty acid groups on human health is under discussion, and results are not unambiguously. However, current knowledge shows that a health-promoting milk fat profile is likely to be obtained by increasing the content of unsaturated fatty acids and reducing the proportion of palmitic acid. From a milk product point of view this would contribute to butter with a softer texture which is easier to spread. The objective of this study was to investigate the genetic impact on the milk fatty acid profile measured as g/100 g total fat for 7 FA fractions and 4 individual FA. Milk samples from all cows in the Danish herd testing scheme were collected from May 2015 to December 2017 and analyzed at a certified laboratory using MilkScanTM FT+/FT600 equipped with special software for predicting 7 FA fractions: saturated FA (SFA), Mono-unsaturated FA (MUFA), Poly-unsaturated FA (PUFA), short chain FA (SCFA), medium chain FA (MCFA), long chain FA (LCFA), and transFA; and 4 individual FA: C14:0, C16:0, C18:0, and C18:1. Heritabilities for test day measurement of the different fractions and individual FA were at the same level (0.08 to 0.16) as heritability for overall fat yield for both Danish Holstein and Danish Jersey. Genetic correlations between the fraction of unsaturated FA and total fat yield were however unfavorable indicating an unfavorable trend for the healthy FA contents unless selected for. Correlations between breeding values for FA (groups and individuals) and the different traits in the Nordic Total merit index were in general below 0.15 for both Holstein and Jersey. This suggest that selection for FA (groups and individual FA) can be carried out without harming other traits in the breeding goal. It is therefore proposed to substitute the present Fat index in the total merit index with and index composed of the FA’s weighed together based on their health promoting values and their values in relation to product quality

Detailed milk fatty acid profiling of the Danish dairy cattle population

Abstract Milk fatty acid (FA) composition can be manipulated through feeding, and especially effects of grazing have been shown to promote a healthier milk FA profile due to increasing contents of beneficial FAs, like conjugated linoleic acid (CLA) and α-linolenic acid (C18:3, the main n3 FA in milk). In addition to diet-based manipulations, selective breeding for specific FA could also be a strategy for altering the FA profile as milk FA display low to moderate heritabilites (0.07-0.34 in Danish Holstein). Since 2015, milk samples from all Danish dairy cows under yield control have been analyzed using mid infrared spectroscopy. The FOSS Application Note 64 has subsequently been used to predict content of seven FA groups (short-chain FA (SCFA), medium-chain FA (MCFA), long-chain FA (LCFA), saturated FA (SFA), mono-unsaturated FA (MUFA), poly-unsaturated FA (PUFA), and trans FA (TFA)) together with four individual FA (myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1)). This access to millions of FA profiles in milk enables large-scale in depth analyses of factors affecting FA profile of milk and accurate genetic parameter estimation. Initially, more than 3.5 million milk samples from three Danish dairy breeds (Holstein, Jersey, Red) and crossbred cows have been analyzed from May 2015 to October 2016. The results showed significant (P ≤ 0.05) effects of cow breed. As reported earlier, Jersey cows have a higher de novo synthesis, resulting in higher proportions of SFA, MCFA, SCFA and C16:0 compared to the other breeds. For parity (only checked in Holstein), the proportion of SFA and SCFA increased with increasing lactation number, whereas the proportion of MUFA and C16:0 decreased. PUFA had the lowest proportion in 2nd parity and the highest in 1st parity. Also, significant effects of production system (organic vs. conventional) was found, as organic dairy cows due to legislation have to be on pasture during summer. In months, where cows were fed fresh grass, the proportion of unsaturated FA increased, whereas the proportion of saturated FA decreased. This was seen in both organic, and to a lesser extent, in conventional milk. A healthier FA profile can be obtained by increasing MUFA and PUFA in milk. However, health aspects in relation to SFA are more complex, but there seems to be a general agreement that most SFA have neutral or even slightly positive effects, whereas palmitic acid exerts a negative effect on human health due to its role in increased LDL cholesterol. Thus from a consumers perspective, our results suggest that organic summer milk from 1st parity Holstein or Red cows are preferred during the grass season, whereas conventional milk may have a healthier FA profile during winter. To explore specific seasonal effect in relation to pasture-based diets in more details, milk samples from 160 cows from eight herds are collected to investigate whether bulls with extreme SFA% breeding values are reflected in the FA milk profile from their daughters. The collected milk samples will be analyzed by AN64 MIR, as well as by gas chromatography, to provide additional information e.g. in relation to CLA and C18:3 and the n3/n6 ratio. So far, milk samples have been collected prior to summer grazing and will be collected again in June 2017, where most cows in the experiment will be on pasture. In conclusion, this study has shown that the choice of breed, parity, lactation stage, season, production system and genetics affect the FA composition of milk. Different strategies may therefore be applied to alter the FA profile, but generally, which could be exploited for product differentiation for e.g. new healthier innovative dairy products

Fedtsyreprofilen i mælk fra malkekøer – Potentiale og perspektiver

Projektet SOBcows har i samarbejde med RYK gennem 16 måneder i 2015/16 analyseret for indholdet af 11 fedtsyrer/fedtsyregrupper i kontrolmælken fra alle ydelseskontrollerede køer i Danmark. Dataanalyser af godt 3,5 mio. mælkeprøver viser, at det er muligt at påvirke sammensætning af mælkefedtet gennem avl. En foreløbig beregning af arvbarheden hen over laktationen viser, at alle fedtsyrekategorier har en genetisk variation og enkeltfedtsyrerne har arvbarheder på højde med den samlede fedtydelse. Det betyder arvbarheder i intervallet 0,25-0,44 afhængig af race og paritet. De genetiske sammenhænge varierer betydeligt gennem laktationen og er påvirket af den øgede kropsmobilisering i de første måneder efter kælvning. En anvendelse af fedtstyrebestemmelserne i avlen vil derfor kræve en opdeling af laktationen i mindst to perioder. Samlet kan det konkluderes, at der er et betydeligt avlsmæssigt potentiale, og hvis der kommer et dansk marked for mælkeprodukter med særlige egenskaber, vil det være oplagt at ændre genetikken i gunstig retning og samtidigt udnytte de fodringsmæssige muligheder for at producere mælk med en sundhedsfremmende fedtsyreprofil. Datamaterialet her og fedtsyremåling af samtlige mælkeprøver i ydelseskontrollen giver en unik position i forhold til det

SOBcows - Specialized organic breeding goals and breeding schemes within dairy production

This presentation provides an overview of the results from the projects "The optimal cow" and "SOBcows". The aim of "The optimal cow" is to derive economic values for breeding goal traits in four different production systems, among them an organic production system. The aim of "SOBcows" is to enhance the size and the profitability of the organic dairy production by adapting the breeding material to organic production circumstances and by indicating sustainable methods for sustainable niche production based on animals with specific genetic characteristic

Potentiale og perspektiver - Fedtsyremålinger på enkeltkøer

Præsentationens to budskaber er: 1) Det er muligt at ændre mælkens fedtsyreprofil ved hjælp af avl fordi mælkens fedtsyrer er arvbare og fordi de er lavt korrelerede til egenskaberne i avlsmålet og 2) Danmark har nu en unik position når mælkens fedtsyresammensætning bliver interessant for landmænd og mejerier

Realization of breeding values for milk fatty acids in relation to seasonal variation in organic milk

Prediction of detailed milk fatty acid (FA) composition by mid-infrared spectroscopy (MIRS) offers possibilities for high-throughput indirect measurements of detailed milk compositional parameters through the milk testing system, which can be used to differentiate the FA profile by genetics or specific management or on dairies for milk quality evaluation. Since 2015, milk samples from all Danish dairy cows under milk testing have been recorded using MIRS. The MIRS software from the FOSS Application Note 64 was used to predict contents of 7 FA groups and 4 individual FA. Data generated from the application note have been used to estimate breeding values for sires for percentage of saturated fat (SFA%) in milk. To investigate whether extreme SFA% breeding values of sires were reflected in the detailed milk FA profile from their daughters, milk samples from 194 cows in 7 organic herds were collected and the detailed FA composition measured by gas chromatography. From each cow, milk samples were collected twice to explore specific seasonal effects of pasture-based diets in relation to sires' estimated breeding value (EBV) for MIRS-predicted SFA% (MIRS-SFA%). The results showed a significant difference in SFA% measured from GC (GC-SFA%) in milk from daughters of sires having high SFA% EBV compared with daughters of sires having low SFA% EBV. The EBV group (low or high) also significantly affected most FA except C13:0, C15:0, C17:0, and C18:1 trans-11. Contents of SFA with even chain-lengths were all higher in the high EBV group, whereas C14:1, C16:1, and the other unsaturated C18 FA had a higher content in the low EBV group. All FA were significantly affected by season. The SFA% decreased from indoor spring feeding to summer pasture, as did FA with chain length ≤16 carbons, whereas long-chain FA (>C17) all increased during summer pasture. The results show that use of MIRS-predicted EBV for SFA% will most likely display a correlated response on the detailed FA composition in milk. In the current study, the combined action of feeding and genetics resulted in a 10 percentage-point difference on average when comparing milk SFA% from daughters of high SFA% EBV sires during indoor spring feeding from one farm to milk SFA% from daughters of low SFA% EBV sires during summer from another farm