Document Detail

Effect of milking frequency on lactation persistency and mammary gland remodeling in mid-lactation cows.
MedLine Citation:
PMID:  20105527     Owner:  NLM     Status:  MEDLINE    
The objective of this study was to evaluate the effect of milking frequency on milk production and composition, mammary cell proliferation, apoptosis, and gene expression. For this investigation, 10 Holstein cows that were being milked twice a day in mid lactation were selected. To study the effect of differential milking, 2 quarters were milked once daily and the other 2 were milked thrice daily for 8wk. After that period, twice-daily milking was resumed for all quarters, and data were collected for an additional 6wk. Mammary gland biopsies were taken 1wk before differential milking (wk -1) and after 4 and 8wk of differential milking. Milk samples were collected weekly throughout the experiment. Once-daily milking resulted in an immediate reduction in milk yield, whereas thrice-daily milking resulted in an increase in milk yield. During differential milking, the daily milk yield of the quarters milked once daily declined by 0.54kg/wk, on average, but remained constant in the quarters milked thrice daily. Part of the difference in milk yield between the glands pairs persisted after twice-daily milking was reinitiated. In the quarters milked once daily, milk BSA concentration increased, indicating an increase in tight junction leakiness, and zymographic analysis of milk enzymes showed increased activity of several proteases. Reducing the milking frequency also increased mammary cell apoptosis and, surprisingly, mammary cell proliferation. Interestingly, milk concentrations of stanniocalcin-1 and insulin-like growth factor-I and mammary gland expression of several genes were also modulated by milking frequency. For example, expression of insulin-like growth factor I receptor was downregulated during once-daily milking. Last, expression of the short and long isoforms of the prolactin receptor and of CSN2 (beta-casein) were upregulated during thrice-daily milking. Taken together, these data suggest that milking frequency not only affects mammary gland remodeling and the expression of paracrine factors but also modulates hormone sensitivity.
P Bernier-Dodier; L Delbecchi; G F Wagner; B G Talbot; P Lacasse
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of dairy science     Volume:  93     ISSN:  1525-3198     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-28     Completed Date:  2010-04-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  555-64     Citation Subset:  IM    
Copyright Information:
Copyright 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
D?partement de Biologie, Facult? des Sciences, Universit? de Sherbrooke, Sherbrooke, Quebec, Canada J1K 2R1.
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MeSH Terms
Apoptosis* / physiology
Cattle / physiology*
Cell Proliferation
Dairying / methods*
Gelatinases / metabolism
Gene Expression Regulation*
Glycoproteins / analysis
Insulin-Like Growth Factor I / analysis
Lactation / physiology*
Mammary Glands, Animal* / cytology,  metabolism
Milk / chemistry,  cytology,  secretion
Serum Albumin, Bovine / analysis
Time Factors
Reg. No./Substance:
0/Glycoproteins; 0/Serum Albumin, Bovine; 67763-96-6/Insulin-Like Growth Factor I; 76687-96-2/teleocalcin; EC 3.4.24.-/Gelatinases

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