| Effects of week of lactation and genetic selection for milk yield on milk fatty acid composition in Holstein cows. | |
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MedLine Citation:
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PMID: 16230694 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Control (CL) and select line (SL) dairy cows (n = 22) managed identically but differing in milk yield (>4100 kg/305 d) were used to determine differences in milk fatty acid profile as lactation progressed. Milk yield was recorded daily and milk samples were collected during wk 1, 4, 8, 12, and 16 postpartum for milk composition analysis. Milk samples from wk 1, 8, and 16 were also analyzed for fatty acid composition. Select-line cows produced more milk (44.4 vs. 31.2 kg/d) and milk components than CL cows during the 16-wk period. There was no difference in rate of milk yield increase, but peak milk yield for SL cows was greater and occurred later in lactation. There were no differences in milk SCC or milk fat, protein, or lactose content. Selection for milk yield did not affect the content of most individual milk fatty acids; however, compared with CL, SL cows had a reduced Delta(9)-desaturase system and tended to produce milk with lower monounsaturated fatty acid content. Selection for milk yield did not affect milk fatty acid origin but the percentage of de novo fatty acids increased and preformed fatty acids decreased as lactation progressed. Milk fat trans-11 18:1 and cis-9,trans-11 conjugated linoleic acid increased with progressing lactation (10.7 vs. 14.1 and 3.1 vs. 5.4 mg/g, or 31 and 76%, respectively) and were correlated strongly among wk 1, 8, and 16 of lactation. Temporal changes in the Delta(9)-desaturase system occurred during lactation but these changes were not correlated with milk fat cis-9,trans-11 conjugated linoleic acid content. Results indicate prolonged genetic selection for milk yield had little effect on milk fatty acid composition, but milk fatty acid profiles varied markedly by week of lactation. |
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Authors:
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J K Kay; W J Weber; C E Moore; D E Bauman; L B Hansen; H Chester-Jones; B A Crooker; L H Baumgard |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of dairy science Volume: 88 ISSN: 1525-3198 ISO Abbreviation: J. Dairy Sci. Publication Date: 2005 Nov |
Date Detail:
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Created Date: 2005-10-18 Completed Date: 2006-03-02 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 2985126R Medline TA: J Dairy Sci Country: United States |
Other Details:
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Languages: eng Pagination: 3886-93 Citation Subset: IM |
Affiliation:
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Department of Animal Sciences, The University of Arizona, Tucson 85721, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cattle / genetics*, physiology Cell Count Diet Fats / analysis Fatty Acids / analysis* Female Lactation / genetics*, physiology* Lactose / analysis Linoleic Acids, Conjugated / analysis Milk / chemistry*, cytology Milk Proteins / analysis Postpartum Period Selection, Genetic* Stearoyl-CoA Desaturase / metabolism Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Fats; 0/Fatty Acids; 0/Linoleic Acids, Conjugated; 0/Milk Proteins; 63-42-3/Lactose; EC 1.14.19.1/Stearoyl-CoA Desaturase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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