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Schönborg, Therese, 2020. Variation in protein profile of bulk milk from Northern Sweden. Second cycle, A2E. Uppsala: SLU, Department of Molecular Sciences

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Abstract

The protein composition of milk samples from Norrland, Sweden was investigated by capil-lary electrophoresis, in order to evaluate the variation in protein profile from different breeds at different collection periods during the year. The protein profile is of importance for pro-cessability of the milk, and is known to be influenced partly by genetics. Bulk milk samples from 13 farms with Swedish Mountain Breed (SMB), Swedish Jersey (SJB), Swedish Red and White (SRB) and Swedish Holstein (SH) were analysed for content of αs1-, αs2-, β-, and κ-casein, as well as α-lactalalbumin and β-lactoglobulin. The samples were also analysed in regard to total protein content, fat content and casein micelle size (CMS). Sampling took place during three periods; November, February and September, and the breeds were com-pared between the “indoor period” (November and February) and “outdoor period” (Sep-tember) as well as during the whole period of investigation. For analysis during the indoor versus outdoor period, SMB and SJB was set as one cluster. The analysis showed significant differences between the breeds during the period of investigation as well as between the indoor and outdoor period. During the period of investigation SJB had the highest inclusion of κ-casein, which was 3.29 percentage points higher compared to SRB and 1.67 percentage points higher than SH. SJB was found to have a significantly lower inclusion of β-casein compared to SH, SRB and SMB with a difference of 7.20, 5.92 and 5.64 percentage points respectively. SJB was found to have a significantly higher inclusion of β-lactoglobulin com-pared to SH by 1.24 percentage points. Significant differences was found between the clus-ters when the indoor and outdoor period was compared. The SMB/SJB cluster (indoor) and SMB/SJB (outdoor) was found to have a significantly higher inclusion of κ-casein by 2.31 and 2.99 percentage points respectively compared to SH (indoor). SH (indoor) was found to have a significantly higher inclusion of total β-casein compared to SMB/SJB (indoor) and SMB/SJB (outdoor) by 3.47 and 4.67 percentage points respectively. No significant differ-ences regarding protein composition within any breed was found between the indoor and outdoor period. The fat content in SJB milk was found significantly higher compared to SMB, SRB and SH during the period of investigation by 2.44, 2.21 and 2.53 percentage points respectively. The CMS differed significantly between the breeds between the indoor and outdoor period. SH (outdoor) was found to have a significantly larger CMS compared to SH (indoor), SMB (indoor), SRB (indoor) and SJB (indoor) (p=0.018, p=0.023, p=0.012 and p=0.034 respectively). It was concluded that the protein profile varies between breeds, and that season of collection only had a limited effect on the milk- and protein composition. The small variance regarding season could partly depend on the low sample size. More ex-tensive studies are needed in order to support the results.

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Proteinsammansättningen i mjölkprover från Norrland, Sverige undersöktes med kapillär elektrofores för att utvärdera variationen i proteinprofilen från olika mjölkkoraser under olika perioder under året. Proteinsammansättningen är av betydelse för bearbetning och yst-ning av mjölken och påverkas delvis av genetik. Mjölktanksprover togs från 13 gårdar med Fjällkor (SMB), Svensk Jersey (SJB), Svensk röd och vit boskap (SRB) och Svensk Holstein (SH) och analyserades med avseende på innehåll av αs1-, αs2-, β- och κ- kasein, såväl som α -laktalalbumin och β -laktoglobulin. Proverna analyserades även med avseende på totalt pro-teininnehåll, fettinnehåll och kaseinmicellstorlek (CMS). Provtagning skedde under tre pe-rioder; november, februari och september, och mjölkproverna jämfördes mellan "stallperi-oden" (november och februari) och "uteperioden" (september) samt under hela undersök-ningsperioden. För analys gällande stallperiod jämfört med uteperiod grupperades SMB ochSJB till ett kluster. Analysen visade vissa signifikanta skillnader mellan raserna under under-sökningsperioden samt mellan stallperioden och uteperioden. Under undersökningsperiodenhade SJB det högsta innehållet av κ-kasein, vilket var 3,29 procentenheter högre än SRB och1,67 procentenheter högre än SH. SJB visade sig ha ett signifikant lägre innehåll av β-kaseinjämfört med SH, SRB och SMB med 7,20, 5,92 respektive 5,64 procentenheters skillnad.SJB hade ett signifikant högre innehåll av β-laktoglobulin jämfört med SH med 1.24 pro-centenheter. Signifikanta skillnader hittades mellan raserna när stallperioden och uteperi-oden jämfördes. SMB/SJB (stallperiod) och SMB/SJB (uteperiod) hade 2,31 respektive 2,99procentenheter högre innehåll av κ-kasein jämfört med SH (stallperiod). SH (stallperiod)hade ett signifikant högre innehåll av totalt β-kasein jämfört med SMB/SJB (stallperiod) ochSMB/SJB (uteperiod) med 3,47 respektive 4,67 procentenheter. Inga signifikanta skillnadergällande proteinsammansättning hittades inom någon ras när stallperioden och uteperiodenjämfördes. Fettinnehållet i mjölk från SJB var signifikant högre jämfört med SMB, SRB ochSH genom undersökningsperioden, med 2,44, 2,21 respektive 2,53 procentenheter. Signifi-kanta skillnader hittades gällande CMS vid jämförelse mellan raserna under stallperiodenoch uteperioden. SH (uteperiod) hade signifikant större CMS jämfört med SH (stallperiod),SMB (stallperiod), SRB (stallperiod) och SJB (stallperiod) (p=0,018, p=0,023, p=0,012 re-spektive p=0,034). Sammanfattningsvis varierar proteinprofilen mellan raser och säsongverkar endast ha en begränsad effekt på mjölk- och proteinsammansättningen. Den låga va-riansen beträffande säsong kan delvis bero på det låga antalet prover som analyserats. Meromfattande studier behövs för att stödja resultaten.

Main title:Variation in protein profile of bulk milk from Northern Sweden
Authors:Schönborg, Therese
Supervisor:Johansson, Monika and Priyashantha, Hasitha and Bernes, Gun
Examiner:Johansson, Anna Maria
Series:UNSPECIFIED
Volume/Sequential designation:UNSPECIFIED
Year of Publication:2020
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:VY001 Agricultural Science Programme - Animal Science 270 HEC
Supervising department:(NL, NJ) > Department of Molecular Sciences
Keywords:Mountain Breed, Swedish Jersey, Swedish Red and white, Swedish Holstein, Capillary Electrophoresis, protein composition
URN:NBN:urn:nbn:se:slu:epsilon-s-15823
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-15823
Subjects:Animal husbandry
Language:English
Deposited On:22 Oct 2020 07:42
Metadata Last Modified:22 Oct 2020 08:10

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